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OLKY55
08-23-2014, 06:04 PM
This is more a philosophical question than anything, but why haven't any of the spindle manufacturers come up with a spindle using a flipped lower ball-joint? It seems like the car could be lower with a level a-frame and still use the stock-style a-frames. I realize you don't get Corvette geometry, but at least you wouldn't have to modify the frame. It's just something I've been curious about for a while.

chevynut
08-24-2014, 09:49 AM
Olky55, I guess I really don't see the advantage. The lower a-arm should theoretically be level from the pivot at the frame through the balljoint center, so if the balljoint was higher the a-arm end would have to be lower, thus raising the car with a given spindle position. I'm not sure why some new cars use this "flipped" balljoint configuration. To lower the car all they really have to do is raise the spindle location, as they have done with dropped spindles. I don't see how a "flipped" balljoint helps them do that. One thing they could do to improve performance is to make a taller spindle, like those available for early Camaros and other cars. I don't think those are on the market for Tri5s.

OLKY55
08-24-2014, 12:16 PM
Chevynut,
The way I was looking at it, if the lower a-frame is level, the wheel could be raised by the thickness of the spindle and nut - thus lowering the car by that amount. I'm sure there are other considerations like clearance for steering and such. Us engineers just wonder about these things.:)

Rick_L
08-24-2014, 04:15 PM
I pretty much agree with Cnut here. The ball of the ball joint is what creates the geometry. Whether the ball joint pin points up or down is kind of irrelevant, and the rest is just metal connecting what needs to be connected.

A couple of minor points. Having the ball joint pin point down puts the joint in compression as long as there's weight on the tire. A little bit of belt and suspenders. The other thing is that the dropped spindles were originally meant as a stand alone modification and for the most part still are. Flipping the ball joint would require some other changes.

rockytopper R.I.P 5-13-2017
08-25-2014, 11:13 AM
This is more a philosophical question than anything, but why haven't any of the spindle manufacturers come up with a spindle using a flipped lower ball-joint? It seems like the car could be lower with a level a-frame and still use the stock-style a-frames. I realize you don't get Corvette geometry, but at least you wouldn't have to modify the frame. It's just something I've been curious about for a while.

SC&C offers upper adjustable A-arms with a taller howe ball joint and drop springs. They will achieve front corvette suspension geometry on a stock trifive frame. Just an FYI.
Rocky

chevynut
08-25-2014, 12:00 PM
SC&C offers upper adjustable A-arms with a taller howe ball joint and drop springs. They will achieve front corvette suspension geometry on a stock trifive frame.
Rocky

I don't think so, if you're referring to a C4 Corvette. The steering axis inclination, anti-dive, and other geometric factors cannot be changed by changing a-arms and balljoints. It looks like the Howe balljoints might be 1/2" or so taller than stock which isn't very significant.

Drop springs will change the angle of the lower a-arms, by raising the end of them so they point downwards toward the center of the frame. That is not the way they're supposed to sit at ride height. The correct way to lower a car 2" or more is dropped spindles. This stuff all has to work as a system.

You can probably get more caster, slightly more camber gain, a change in roll center (by raising the upper balljoint), and that's about it from those parts.

The parts you mention may improve the geometry of the Tri5 suspension, but in no way do they "achieve front corvette suspension geometry". If you think they do, please provide information to prove it. Do you know anyone who has done a thorough analysis of both geometries to compare them?


http://scandc.com/new/system/files/imagecache/product_full/balljoints1_2.jpg

chevynut
08-25-2014, 12:11 PM
SC&C offers upper adjustable A-arms with a taller howe ball joint and drop springs. They will achieve front corvette suspension geometry on a stock trifive frame.
Rocky

I don't think so, if you're referring to a C4 Corvette. The steering axis inclination, anti-dive, and other geometric factors cannot be changed by changing a-arms and balljoints. It looks like the Howe balljoints might be 1/2" or so taller than stock which isn't very significant.

Drop springs will change the angle of the lower a-arms, by raising the end of them so they point downwards toward the center of the frame. That is not the way they're supposed to sit at ride height. The correct way to lower a car 2" or more is dropped spindles. This stuff all has to work as a system.

You can probably get more caster, slightly more camber gain, a change in roll center (by raising the upper balljoint), and that's about it from those parts.

The parts you mention may improve the geometry of the Tri5 suspension, but in no way do they "achieve front corvette suspension geometry". If you think they do, please provide information to prove it. Do you know anyone who has done a thorough analysis of both geometries to compare them?


http://scandc.com/new/system/files/imagecache/product_full/balljoints1_2.jpg

rockytopper R.I.P 5-13-2017
08-25-2014, 12:29 PM
I am no expert on this subject by any means. You will need to talk to Marcus at SC&C. He wrote the book on this subject 610-381-6100. But I run this setup on my 65 cutlass and the only difference is they use a taller ball joint on the lower A-arm also on the A-bodys. Which is basically giving you a taller spindle without spending as much $$$. My front in alignment specs are -1* camber,+5* caster and 0 toe. For serious road racing or autocross they go as much as -2.7 degrees of camber on this setup. Just a quick look see link the C6 alignment is the same more or less. I'm sure C4 & C5 are similar. According to Marcus a longer lower ball joint is not necessary because the trifive stock geometry is better than a 60's a-body which has bad bump steer issues. I have purchased this for my nomad and Marcus has stated the front alignment will be about the same as my cutlass has which matches a modern vet or very close.
Rocky
http://forums.corvetteforum.com/c6-tech-performance/3107257-base-c6-wheel-alignment-specs-etc.html (http://forums.corvetteforum.com/c6-tech-performance/3107257-base-c6-wheel-alignment-specs-etc.html)

chevynut
08-25-2014, 12:34 PM
A tri5 spindle looks to be abut 11 1/4" from balljoint to balljoint, based on my crude measurements. A late C4 Corvette spindle is about 13 1/2" tall. I realize that's only part of of the geometry, and the location of the inboard a-arm mounts also affect it. The C4 Corvette has 6 degrees of caster, 8.7 degrees SAI, and about 11-12 degrees of anti-dive built into the upper a-arms angles. I know a lot of anti-dive is not always desirable, but I would think it would be on a car that's driven hard.

I sure would like to see someone compare the C4 suspension to the one Rocky mentioned using some suspension modeling software.

chevynut
08-25-2014, 12:38 PM
I am no expert on this subject by any means. You will need to talk to Marcus at SC&C. He wrote the book on this subject 610-381-6100. But I run this setup on my 65 cutlass and the only difference is they use a taller ball joint on the lower A-arm also on the A-bodys. Which is basically giving you a taller spindle without spending as much $$$. My front in alignment specs are -1* camber,+5* caster and 0 toe. For serious road racing or autocross they go as much as -2.7 degrees of camber on this setup. Just a quick look see link the C6 alignment is the same more or less. I'm sure C4 & C5 are similar. According to Marcus a longer lower ball joint is not necessary because the trifive stock geometry is better than a 60's a-body which has bad bump steer issues. I have purchased this for my nomad and Marcus has stated the front alignment will be about the same as my cutlass has which matches a modern vet or very close.
Rocky
http://forums.corvetteforum.com/c6-tech-performance/3107257-base-c6-wheel-alignment-specs-etc.html (http://forums.corvetteforum.com/c6-tech-performance/3107257-base-c6-wheel-alignment-specs-etc.html)

Rocky, "alignment" is not the same as "geometry". You can get the same alignment with just about any suspension. Alignment refers to the angles of the tires at rest, and while turning at ride height, things like caster, camber, and toe. Geometry refers to the static and dynamic position of the suspension, which is determined by the angles, lengths, and positions of the suspension components. Geometry determines things like anti-dive, scrub radius, roll centers, ackerman, etc.

Rick_L
08-25-2014, 12:51 PM
A C3 Corvette spindle is approximately 1" taller than a 55-57 spindle. But it also has 7º of steering axis inclination compared to a 55-57's 3.5º. The extra height of the spindle gives you a favorably different camber gain curve. The extra steering axis inclination is better suited for wider wheels and tires, as it reduces the scrub radius.

You can put a C3 Corvette spindle on a 55-57 by making a spacer bushing for the lower ball joint pin, and shortening the upper control arm about 3/4". It also lets you run the C3 12" rotors. Down side is that there's no dropped spindles available.

A tall upper ball joint would get you the camber gain.

The reason for the camber gain is primarily from having the upper control arm having the ball joint higher than the control arm's shaft.

rockytopper R.I.P 5-13-2017
08-25-2014, 02:30 PM
Rocky, "alignment" is not the same as "geometry". You can get the same alignment with just about any suspension. Alignment refers to the angles of the tires at rest, and while turning at ride height, things like caster, camber, and toe. Geometry refers to the static and dynamic position of the suspension, which is determined by the angles, lengths, and positions of the suspension components. Geometry determines things like anti-dive, scrub radius, roll centers, ackerman, etc.

I agree, however if you tried to align a stock trifive with the specs I listed I can assure you the geometry would be way screwed up. The adjustable upper arms allow for the modern alignment settings as well as give you the corrected geometry at the same time. It may not be exactly "corvette geometry" but it will yield very similar handling results in the end. I believe the stage II package is designed around the C5 vet geometry according to Marcus. If you really wish to know I'm sure he would give you that information but be prepared to talk for hours when you call him.
Rocky

Rick_L
08-25-2014, 02:38 PM
rockytopper, you are reading way too much into the adjustable control arms.

You can't get 5º of caster with a 55-57 front end unless you modify something to move the upper ball joint to the rear about 1".

If you try to install the 1" taller ball joint, you need shorter control arms.

Those tinker toy control arms possibly allow you to do that. But it's not because of the arms, it's what you might be able to do with them.

And there's no way a street driven car can utilize 2.7º of negative camber. Your tires will wear out in 100 miles, maybe 25.

rockytopper R.I.P 5-13-2017
08-25-2014, 03:24 PM
rockytopper, you are reading way too much into the adjustable control arms.

You can't get 5º of caster with a 55-57 front end unless you modify something to move the upper ball joint to the rear about 1".

If you try to install the 1" taller ball joint, you need shorter control arms.

Those tinker toy control arms possibly allow you to do that. But it's not because of the arms, it's what you might be able to do with them.

And there's no way a street driven car can utilize 2.7º of negative camber. Your tires will wear out in 100 miles, maybe 25.

Rick, I never said to use 2.7 deg negative caster on a street driven car. The Tinker toy arms as you call them do in fact move the upper ball joint aft when adjusted. I'm not sure if it's one inch or how much but it changes the geometry for the better. I have the tinker toy arms laying on the roof of my nomad I will check to see what alignment specs are specified for the trifive vs the a-body version that I have on my cutlass and report back.
Rocky

Rick_L
08-25-2014, 05:22 PM
The arms don't change the geometry for the better. They possibly enable the tall ball joints by having enough adjustment. They possibly enable an alignment of +5 degrees caster.

Thing is, you can get the same thing with nonadjustable control arms that have the ball joint moved rearward. And the tall ball joints will require you to add shims to get alignment, which is easy enough to do.

And I'd be concerned that the adjustable arms would just overwhelm the average guy or the typical front end alignment tech.

rockytopper R.I.P 5-13-2017
08-25-2014, 07:31 PM
It's confirmed I can set the front alignment on the nomad same as my Abody setup.
Rocky

http://i282.photobucket.com/albums/kk243/rockytoppers1/image-35.jpg (http://s282.photobucket.com/user/rockytoppers1/media/image-35.jpg.html)
http://i282.photobucket.com/albums/kk243/rockytoppers1/image-36.jpg (http://s282.photobucket.com/user/rockytoppers1/media/image-36.jpg.html)

chevynut
08-26-2014, 08:46 AM
Again, "alignment" isn't the same thing as "geometry". You can get Corvette alignment with the stock Tri5 front end with the exception of caster, which you can get with simply a different set of upper control arms. That doesn't mean it has anywhere near the geometry of the corvette suspension.

I agree with Rick...I have never been a fan of adjustable control arms.

rockytopper R.I.P 5-13-2017
08-26-2014, 10:52 AM
Love or hate these arms are a very simple design. Two turn buckles. When you adjust them to spec the geometry is totally changed much like what Rick said the upper ball joint is pulled aft creating a totally new geometry in the suspension travel because you have changed the pickup points in the mechanism. Just an FYI it is far easier to align a car with these than using the old shim method. No shims are needed. I agree with Rick in that most alignment shops can't even align to a 3 dimensional alignment spec as I showed. I used NTB for my last build because they have the equipment that will. I dropped the car off gave them a spec sheet as shown above at the counter and picked my car up at lunch. I didn't even talk to an alignment person that I had the arms installed. It should be easy enough for anyone to figure out how to adjust 2 turnbuckles and watch a graph on the screen.

First link below is a picture of the C4 front suspension which you are very familiar with. Notice the top arm geometry is such that the spindle is slanted aft. If you compare this to the SC&C setup in the second link they look almost identical meaning they both have very similar geometry. Heck they even sale these arms to improve the c4 stock setup 3rd link. If you guys know of fixed arms on the market that do this I sure like to see them because most don’t have near as much geometry correction built in as these adjustable arms provide.

Rocky

C4 front
http://www.vettemod.com/forum/imagehosting/12695256a4f8b0e8f.jpg (http://www.vettemod.com/forum/imagehosting/12695256a4f8b0e8f.jpg)
SC&C front
http://www.carcraft.com/featuredvehicles/ccrp_1202_1967_chevy_malibu_real_street_eliminator _winner/photo_15.html
http://scandc.com/new/node/69 (http://scandc.com/new/node/69)

Rick_L
08-26-2014, 12:41 PM
Almost all of the tubular upper control arms for 55-57 Chevys have 5º of positive caster built in.

To install the long upper ball joints only means more shims at the control arm shaft. I don't know if any of the long ball joints on the market are available in the 55-57 Chevy bolt pattern.

I don't think you understand what Chevynut and I are describing to you.

chevynut
08-26-2014, 09:11 PM
When you adjust them to spec the geometry is totally changed much like what Rick said the upper ball joint is pulled aft creating a totally new geometry in the suspension travel because you have changed the pickup points in the mechanism.

It doesn't change the suspension geometry, just the caster. Nothing else changes. There is no new geometry.


First link below is a picture of the C4 front suspension which you are very familiar with.

No, the first link is not a C4 front suspension, it's a C5 rear suspension. What you are describing is caster and I don't believe a rear suspension typically has any caster. It's just the way they have the suspension sitting on the ground.


If you compare this to the SC&C setup in the second link they look almost identical meaning they both have very similar geometry. Heck they even sale these arms to improve the c4 stock setup 3rd link. If you guys know of fixed arms on the market that do this I sure like to see them because most don’t have near as much geometry correction built in as these adjustable arms provide.

It's pretty clear to me that you don't understand what the term "suspension geometry" means. You keep talking about alignment. Caster is alignment. How caster, camber, roll center, instant center, bump steer, etc. CHANGE during suspension travel is a function of suspension geometry, not of alignment. There is no way you're going to get C4 suspension geometry on a stock tri5 frame with aftermarket parts because the pickup points are all different. You can improve on it some, but that's about it.

rockytopper R.I.P 5-13-2017
08-27-2014, 08:09 AM
I give guys you are both right it's does not and will not give you"CORVETTE" suspension geometry. Ok you both “WIN”.


Now let’s be very clear I do fully understand the difference between suspension "geometry" & "alignment". Let us get past that.


The little racer’s trick using these adjustable arms and taller ball joints do in fact dramatically improve the suspension geometry period. You cannot just take a fixed upper trifive arm that has built in -5deg caster and stick a taller ball joint on it and not totally screw up the suspension geometry. I already made that statement above. The reason why is because the upper control arm length has to change in order to do that (Rick you already stated that yourself)and keep the suspension geometry were it should be. The adjustable arm does just that. If you apply shims to get the camber then you are changing the hinge points of the suspension probably not making an improvement for the better. I’ll say this one more time there are no fixed arms for a trifive that even come close to correcting the front original geometry to a modern performance suspension than these. The ones that do and here’s a good list from 2010 of options all carry a very high price tag and require you to buy a complete system to accomplish the same end result in terms of handling. Some on this list are a joke I’ll not mention those.

http://www.superchevy.com/how-to/chassis-suspension/sucs-1041-tri-five-chevys-2010-chevy-classics-suspension-buyers-guide/ (http://www.superchevy.com/how-to/chassis-suspension/sucs-1041-tri-five-chevys-2010-chevy-classics-suspension-buyers-guide/)


So if you wish to spend that kinda $$$ you might as well call chevynut himself and order his trifive C4 corvette rolling chassis. I’ll repeat this again as I have said on both forums. If you want c4 suspension he does have the best bang for the buck IMHO that I have seen my hats off to him.


As for this simple bolt on I don’t have the suspension data or numbers to show how dramatically this improvement is on paper but I do have 4 years of seat time and track numbers to back it up.

How about you guys get in the seat with me and take a spin around the good guys AX course and see for yourself. Granted this is an A-body not a trifive. But I can only assume that one will get similar results in a trifive.
Time will tell us that answer sense I’m going this route and it will see some track time.

[URL="http://i282.photobucket.com/albums/kk243/rockytoppers1/th_IMG_2336.mp4%5b/IMG%5d%5b/URL"]http://i282.photobucket.com/albums/kk243/rockytoppers1/th_IMG_2336.mp4[/URL (http://i282.photobucket.com/albums/kk243/rockytoppers1/IMG_2336.mp4)]

The cutlass in the video has stock frame no added bracing, sc&c stage 2 kit (adjustable arms and tall ball joints), spc 550 inch /lb 2 inch drop springs, stock original f-85 front sway bar and belstien shocks, cpp 500 box, & cpp 11 inch 4 wheel disc. Nothing high end. The time posted here was faster than several C5 vets in the competition slower than others. I have been beaten by two wagons one a nomad and one a Pontiac safari both sporting art Morrison corvette chassis. It never got under my skin to be beat by camaros, corvettes etc but getting beat by a wagon got to me a little. That was until latter learning that both were packing 600 to 700+ hp and fitted with 6 speed manual trans and 13 inch wilwood brakes. After reading that in PHR I was darn proud I even stayed in the game with them on the go cart size track. I believe my automatic trans is handy capping me on these short venues.

Please carry on sorry to have high jacked this thread. The original posters intent is more or less achieved by this kit that’s all I was really trying to say. The taller ball joint is basically the same as adding a taller more modern spindle which was what I believe he was discussing.
Rocky

Maddog
08-27-2014, 06:38 PM
Real world, seat of the pants experience-now that's an interesting concept. Imagine building a product that you have never actually tested, except in theory:eek: I would be a little careful with those tall ball joints though. I remember when some were breaking, they (Pozzi et all) were quick to blame the aftermarket stock A body spindles, in fact it was the ball joints.

rockytopper R.I.P 5-13-2017
08-28-2014, 07:06 AM
Real world, seat of the pants experience-now that's an interesting concept. Imagine building a product that you have never actually tested, except in theory:eek: I would be a little careful with those tall ball joints though. I remember when some were breaking, they (Pozzi et all) were quick to blame the aftermarket stock A body spindles, in fact it was the ball joints.

Please pray for me Maddog LOL. I'm running CCP spindles Chinese made. I was told by my Mark himself that could be a mistake and that I should use the factory spindles because they would be much stronger material than todays. But it was to late for me sense I had already put on drop spindles with the disc brake kit (big mistake in handling) and no longer had my stock units when I purchased the stage II kit. Its to bad no one is making taller spindles for trifives.
Rocky

Rick_L
08-28-2014, 07:39 AM
Putting the C3 Corvette spindles on a trifive is not that big a deal if you think you need tall spindles.

rockytopper R.I.P 5-13-2017
08-28-2014, 08:18 AM
Putting the C3 Corvette spindles on a trifive is not that big a deal if you think you need tall spindles.

Would that force me into using a certain brake setup in front as opposed to using trifive spindles. As you know and we have discussed previously I'm wanting to run large 255 wide tires in the front. So I have been looking into using the zero off set brakes or now I'm seeing wildwood is offering one with a minimal .230 off set. I'm still wanting to stay with a 8 inch wide wheel with standard 4.5 off set if I can. This allows the use of a spare tire when all four are the same size. Now I know I may have fender issues and if I can't trim them to make it work then I will be forced into buying much more expensive wheels with custom offsets. The wheel tire calculator that I believe you and chevynut developed indicates I can run a 255 in front using a 5.25 back space. Might hit the frame no big deal on that. I would be very interested in learning more about that swap if I don't have to put large off set brakes on it because then the custom off set wheels want get me there and I will be forced to narrow tires and wheels in front.
Thanks
Rocky

chevynut
08-28-2014, 09:06 AM
Rocky, glad we're kinda on the same page now as far as the corvette geometry. This isn't about "winning" it's about getting the correct information out there. ;)

I don't see how you're going to be able to run a 255 front tire on a stock frame, but maybe it's possible. IMO there's no way you're going to do it with zero offset wheels and a stock wheel mounting width. The stock mounting width is about 59.25" and a 255 tire will make the tires 69.25" wide, which is almost certain to rub the fender on turning not to mention imo it will look funny. I recommend a 67.5" or narrower width on a lowered car. I'm not sure if rolling the lip or trimming the fender will prevent fender interference or not, but it's not the route I'd take. And the tires will most likely rub the frame too, which you can prevent with steering stops.

I'm not sure I see the desire to run the same tire on all 4 corners. A 255 tire won't fit in the stock spare tire well, I don't believe, and you can get a larger rear tire to fit.

I'm running 245 tires on the front of my Nomad with the late C4 front end. They clear the fender and frame just fine, but I believe the C4 rack results in slightly less steering angle than the stock box, and the 8+ degree SAI causes the wheel to pivot differently than stock. I probably have 3/4" clearance to the frame in the back of the front tire at full lock. I might be able to run a 255 tire on it, but I'm not sure.

chevynut
08-28-2014, 09:20 AM
By the way, I have had maddog the troll on ignore for some time, but since you quoted his comment I'll say this. I have built 50 C4 conversion projects now, with not one complaint from any of my customers. The C4 Corvette suspension is a PROVEN design and I use the stock Corvette geometry, even to the extent of using the C4 cradle in front. The handful of customers that have cars running with my frames have provided nothing but excellent feedback. One guy is a race car driver in NJ and said he's amazed at how well the 57 he built using my front clip and rear kit handles and drives. His dad drives it daily. Other customers have tried every bolt-on upgrade and say nothing compared to the modern feel and handling of the C4 suspension. Super Chevy did an article on Newman's C4 conversion and it out-performed the 2010 Camaro they compared it to at the time. My conversion provides essentially the same upgrade that Newman's chassis does, since we both use the C4 suspension.

I have not driven my Nomad yet, but it was the first C4 conversion I ever did. I have been working on building the entire car from the ground up, and I will drive it in the fairly near future. I got into building these frame only due to demand from other guys, not because I wanted to build and sell them. Maybe if Maddog ever gets a tri5 he would have some credibility here, but to me he's nothing but a trouble-maker who thinks he knows more than he does.

rockytopper R.I.P 5-13-2017
08-28-2014, 09:48 AM
Well chevynut sense you want to get it right you and Rick need to fix the calculator lol. It says 68 inches is the magic number for a lowered trifive.

I have installed a 17x8 on my 55 4dr and a 255 tire 26 inches tall tire stock height and drove it around my pasture doing donuts with no rubbing issues inside or out. Now even though you and Rick may not buy into my geometry change using the adjustable arms and ball joints this setup on my 65 cutlass compared to the stock geometry does create a totally different SAI. The wheel being aligned at -.5 degrees camber and the - 5 degree caster now travels in a much tighter arc and is up and back compared to stock geometry. The big tire rubs the rear area of the inner fender at full lock because of this change. Before this change from the stock suspension with drop spindles you could not even put the same wheel and tire on the car and set it on the ground the fender would be sitting on top of it. According to the calculator it says you will end up right at 68 with a 5.25 back space with stock width and 255 tire.

You are right a wheel want fit the well anyway but I still plan to bring a spare when I come up to see you and spank you in a little rocky mountain road racing lol. I was in your neighbor hood last year but you weren't ready yet. Then you guys got washed away less than a month latter.

http://i282.photobucket.com/albums/kk243/rockytoppers1/IMG_5824.jpg (http://s282.photobucket.com/user/rockytoppers1/media/IMG_5824.jpg.html)

chevynut
08-28-2014, 10:17 AM
What calculator are you talking about Rocky? I did the original Excel version myself (not sure why Rick ever got any credit for it ;)) I have repeatedly said 67.5" is the correct number and that's what was in my spreadsheet. Others have copied the formulas into their own calculators and if they put some other limits on it, it's not my doing. I have empirically verified the 67.5" recommendation several times with car owners on the other site. Part of this depends on the year of the car, and the amount it's lowered. However, even a stock height car can have problems if the suspension is compressed enough while turning.

You CANNOT change the SAI by changing the upper a-arm length. It's a function of the placement of the balljoints relative to the spindle. Tell me how a different length a-arm can change SAI, and still keep the wheel aligned:
http://i224.photobucket.com/albums/dd84/Lotus-e-Clan/steering_axis_zps7786ba90.gif

I don't doubt that you can put a 255 tire on the front of a stock height car, especially a '55 with the tall fender opening. If you want to use that tire on the front of your dropped Nomad, be my guest. I'm just trying to help you. You might get away with a 68" width, depending on how much you lower the car and how tight your steering angle is. I know some guys have said their tires rub around that point with a stock suspension and steering.

Stop by next time you're in the neighborhood. Have you ever driven a Tri5 with a C4 suspension? Have you ever driven a C4 Corvette?

rockytopper R.I.P 5-13-2017
08-28-2014, 10:29 AM
Here is link. http://tri-5.chevyrides.com/front_tire.php

I thought this was gospel lol.

The geometry change is in the taller ball joint or joints in the case of the cutlass. Same as putting on a taller spindle. That is what changes the travel of suspension geometry. You have moved the pivot points of the spindle. Now with that said the trifive may be a entire bag of worms. I have just got my fingers crossed that it is going to do the same thing or close but I don't have the data points to put it in cad and built a kinematic model to see. Much easier to just put it on and see what happens easier than spending hours at the scope trying to figure it out. Besides I don't have much invested this is a cheap suspension. So if it does fail you might see me with my trailer picking up my new chassis with c4 goodies lol.

chevynut
08-28-2014, 10:56 AM
Well I don't remember who put that calculator on that website, but it wasn't me. I think he asked me if he could use the formulas. Like I said, the width limit is somewhat subjective, depending on the actual application. But 67.5" is what I've said it should be for years.


Now even though you and Rick may not buy into my geometry change using the adjustable arms and ball joints this setup on my 65 cutlass compared to the stock geometry does create a totally different SAI.

You CANNOT change the SAI by installing a taller balljoint. Look at the picture above. It does change the angle of the upper a-arm, by making the spindle taller, and that does change the camber curve and the location of the instant centers. So the geometry is changed somewhat, it's improved, but it's only by a small amount. I think the most significant thing you're feeling is the added caster.

In addition, I disagree with you as to your claim that a fixed geometry upper a-arm can't do what an adjustable one can do. All you have to do is build the fixed one just like the adjustable one once you have it adjusted where you want it. I believe most tubular arms on the market do just that....they give you added caster, and that's about it. You could use them with the taller balljoints and get exactly to where your adjustable arms get you. Alignment shims, if used, move the pivot a tiny amount when compared to the length of the a-arms so their use is insignificant.

Suspension geometry is all about the pickup points for the suspension pivots. If you don't move those, you really haven't changed much of anything. With a stock frame about all you can do is move the upper balljoint location around a little.

Try to find a tri5 with a C4 suspension in your area and see if the owner will let you drive it. ;)

Rick_L
08-28-2014, 11:17 AM
Lots of things to say here and I may miss some.

I don't take any credit for Cnut's spreadsheet which has been republished elsewhere. And never have. I have used it, and I've done the same calculations on my own, prior to its existence. I disagree with a couple of Cnut's numbers, but agree on most. I commented on those years ago when the discussion was new.

More on the C3 spindles. They have the same mounting width as the stock 55-57 spindles, except that they are wider by the difference in hub mount thickness between a brake drum and a hat type rotor, which is about 1/4" per side. I.e., the bare hub's mounting width is the same. With a 225 tire on a 7" rim with 4.5" backspacing, this means that it's 68.50" across the tires. And what that means is that the tires are going to rub if you have full stock steering travel. But almost every modified steering system has at least slightly less steering travel than a full stock steering system. With a CPP500 box you lose about 5º each direction (at the box). I'd have to calculate how much that would be at the wheel, it's roughly the same. A rack may have less travel yet, and will vary with the components used. At 68.50", yes it will rub but it will work at all but full lock, depending on ride height. Part of the clearance situation is suspension travel also - one of the times when tires rub is when you negotiate into a driveway where you're turning and may have a bit of suspension movement too.

A 255 tire is going to hit the frame at far from full steering travel with 0 offset wheels. So you just modify the problem, now you're hitting the frame instead of the fenders (which you may think is good, and that's understandable). But you may end up with a wide turning circle.

C3 spindles obviously wear C3 Corvette brakes. But also obviously, there are aftermarket brake packages for those cars just as there are for 55-57s.

On steering axis inclination: As Cnut showed in his diagram, the spindle itself determines SAI. You can't change it without changing the spindle. Aftermarket dropped spindles for 55-57s have the same SAI as a stock spindle.

And for both of you. "No complaints" isn't much of a testimonial as to the difference of some of these things. That may just mean that they don't know the difference or don't know why. (Not that they are wrong.)

chevynut
08-28-2014, 11:50 AM
I've done the same calculations on my own, prior to its existence.

The reason I put the thing together in the first place was because I was doing the calculations over and over again and got tired of it. Then I offered it to the Tri5 community as a tool since so many guys were asking what tire/wheel would fit their cars.


I disagree with a couple of Cnut's numbers

If I recall correctly, the one you disagreed with was the stock front mounting surface width. I took the numbers straight from the GM specification on track width and wheel offset to calculate it. You said you measured your car. I can see how it could differ slightly due to exact frame dimensions and alignment shims. The front track is specified at 58" and the stock wheel offset is 9/16" or .563". Adding them together you get a theoretical front mounting width of 59.125". I don't know what other numbers you may have disagreed with, but perhaps it was related to sheetmetal which can change from car to car.


Part of the clearance situation is suspension travel also - one of the times when tires rub is when you negotiate into a driveway where you're turning and may have a bit of suspension movement too.

Yes, and that's why it's not just about the amount of front end drop at ride height as I mentioned. If you compress the suspension enough it can rub if the front is too wide. 68" will probably rub under the right conditions. I don't think 67.5" will rub.

chevynut
08-28-2014, 11:59 AM
Here's a couple of pictures showing the SAI of the C4 Corvette suspension.

33983400

rockytopper R.I.P 5-13-2017
08-28-2014, 12:48 PM
I just did a quick model in cad of 4 bar link that has the stock trifive geometry I’m guessing. I found a picture of the suspension that someone wrote the dimensional relations between ball joint and bushing pivot locations on the frame. When you dial in -1 deg of negative camber the arm is being shortened. I now agree with you guys the geometry is changed but not by much as you have stated. However if you look at 27 inch tall tire at the top with one degree of camber the distance offset is .33 inches. And the suspension travel has moved inward at the same time although very little. But sense you start out with .33 in your favor you have much greater tire clearance than before at the fender and inner fender. That’s what I see on my cutlass. If you put a level on my tires there is about .45 inches inboard distance at the top of the tire.

As for a fixed arm doing the same thing as the adjustable one if designed that way I totally agree. However the problem is no one is doing it. If they did they could only use the taller ball joint. The adjustable arm will run either short or tall. The adjustable arm will also fix alignment problems that shims want fix. My cutlass could not be aligned to spec. We pulled all the shims out and would have had to grind the cross shaft or frame to get there.

Chevynut I have never driven a C4 vet that I recall. I have driven a c5 but I’m so big I don’t fit in them never have been able too don’t even fit in a C3. But my first new car was a 1985 irocz it turned .92gs on the skid pad. I think you’re only good for .88gs with C4 LOL. I actually posted on pro-touring when I began to look into making my cutlass handle better. And I said I just want it to handle as good as a 85 iroc z my only reference to cars that handled and when I posed the question to Marcus if the stage 2 kit would make my cutlass handle that good he said it’s going to handle a little better. It’s so close hard to tell.

Rick_L
08-28-2014, 01:39 PM
Cnut, yes the stock track width was a point we didn't agree on. I understand where you got your numbers. My numbers came from my own measurements. They are confirmed by my measurements after modification. I noticed that the spreadsheet you linked has my number in it.

And you're right, we discussed the sheetmetal dimensions in the rear along with many others at the time. There is a lot of variation between cars (especially ill repaired ones) so if one wants it to clear, you shouldn't take anyone's word for it.

chevynut
08-28-2014, 01:45 PM
When you dial in -1 deg of negative camber the arm is being shortened.

I agree if you're using the adjustable a-arm you're talking about, but the change is minimal if you consider the length of the a-arm. It makes very little difference as far as the IC location. The a-arm doesn't get shorter if it's a fixed one, it just moves inboard.


However if you look at 27 inch tall tire at the top with one degree of camber the distance offset is .33 inches. And the suspension travel has moved inward at the same time although very little. But sense you start out with .33 in your favor you have much greater tire clearance than before at the fender and inner fender. That’s what I see on my cutlass. If you put a level on my tires there is about .45 inches inboard distance at the top of the tire.

True, adding negative camber moves the top of the tire inboard giving you more clearance. A taller spindle magnifies that as the suspension is compressed. At 1 degree the top of the 27" tire would be .47" inboard of the bottom. Your .33" must be from the center of the lower BJ.


As for a fixed arm doing the same thing as the adjustable one if designed that way I totally agree. However the problem is no one is doing it. If they did they could only use the taller ball joint. The adjustable arm will run either short or tall. The adjustable arm will also fix alignment problems that shims want fix.

Why won't adding or removing shims fix it? I believe the stock tri-5 a-arm is actually pointing down slightly at the spindle at ride height. The taller BJ would raise it up, requiring you to add shims to maintain camber. The taller BJ only adds 1/2" or so as far as I can tell, so the impact to alignment (camber) is pretty small. Often these cars have TO MUCH negative camber and require offset shafts to correct it. I see no reason why a longer BJ couldn't be used with tubular a-arms, and shims used to correct the alignment. I'm sure it's been done.

I have read that a stock Z51 C4 Corvette can hit .94 Gs and they have even modified them to get 1.0 Gs. There were several suspension options on the C4s from 84-96.

chevynut
08-28-2014, 01:53 PM
I noticed that the spreadsheet you linked has my number in it.

Maybe that's why you got some credit for it. LOL! :) I don't doubt you measured yours differently than the specs. But the specs came from GM and some cars may actually measure at 59.125". I recommend using 59.25" as a conservative number but my original spreadsheet (a link on the website above) had 59" in it at the ime I put it together 11 years ago. Also, as Rocky pointed out you actually get a little more clearance with some negative camber. My calculations assume zero camber.


And you're right, we discussed the sheetmetal dimensions in the rear along with many others at the time. There is a lot of variation between cars (especially ill repaired ones) so if one wants it to clear, you shouldn't take anyone's word for it.

That's why I have always said to use the spreadsheet dimensions as a guide, and if you want actual numbers you have to measure your own car. The rest is simple math but the spreadsheet makes it convenient.

rockytopper R.I.P 5-13-2017
08-28-2014, 03:53 PM
Wow I didn't mean to resurrect old battles this rookie is just trying to learn lol.
So lets recap.
You two managed to prove that I didnt know what the heck I,m talking about so I lose.
but you 2 screwed up the calulator so 255 with 4.5 might fit??????
What do you know I win LOL... All in fun guys
Rocky

Maddog
08-28-2014, 03:57 PM
.................................................. .................................................. .......

You can put a C3 Corvette spindle on a 55-57 by making a spacer bushing for the lower ball joint pin, and shortening the upper control arm about 3/4". It also lets you run the C3 12" rotors. Down side is that there's no dropped spindles available.

A tall upper ball joint would get you the camber gain.

The reason for the camber gain is primarily from having the upper control arm having the ball joint higher than the control arm's shaft.


There are drop spindles available. The 59-64 Impala drop spindles are the same as C3 since the C3 spindle IS a 59 Impala spindle. The "modular" type made by CPP would be the most logical choice.

Maddog
08-28-2014, 04:00 PM
Rockytopper, what are you trying to accomplish with your car? Do you want to improve the auto cross type abilities such as used for Good Guys auto cross racing? It's interesting to note that many of the successful competitors are using Camaros and Chevelles with the type of simple improvements as you mentioned earlier, S&P adjustable arms, tall ball joints etc. I don't know how much a Tri5 will improve but it will definitely see much improved handling with these simple improvements.

Rick_L
08-28-2014, 04:32 PM
Rockytopper, you keep talking about changing the static alignment. The taller spindles give you a different camber gain as the suspension moves. Even if you start at 0 camber.

Hellwig has a video of a 56 going through an autocross course with before and after of their sway bars. This is a far bigger deal than the camber gain curve. I don't know if it's on their website, but it's been posted at trifive.com. Limiting the suspension travel with sway bars will have a far greater effect than the small gain you get from camber gain.

I have heard that the Howe extended ball joints can get bent pins in service. Does Howe have any kind of maintenance/quick check recommendations?

chevynut
08-29-2014, 07:43 AM
but you 2 screwed up the calulator so 255 with 4.5 might fit??????

No, the calculator is not "screwed up". The default front end width was the point of contention. I used GM specs, and Rick used his measurements. The GM spec is 59 1/8" and Rick measured 59 1/2" on his '55. The CORRECT way to use the calculator is to measure your own car, and use your measurements as inputs. Whatever they have on the website calculator you linked for defaults is his own doing, not mine.

There is no way that a 255 tire with a zero offset wheel will "fit", meaning you can bolt it on but it will rub the fenders on a lowered car in turns.

rockytopper R.I.P 5-13-2017
08-29-2014, 01:03 PM
Well we shall see if they fit or not worst case Ill have to go to deeper bs. I did manage to strip on side of the car this morning.

Rick I am planning to run hellwigs front and back. If the taller Howe joints are bending I haven't had ant issues yet. And if they are I'd rather have it fail like that than snap a spindle arm off.

maddog I just want it to handle in the turns and be stable at high speeds. The cutlass does that. I only AX for fun and have actually become bored with the go cart size course. I enjoy cruising the winding back roads much more than chasing cones.
Rocky

Maddog
08-29-2014, 02:05 PM
Your 255 will fit with around 5.5" BS (8" wheel) but you need taller then 15" wheels to clear the upper ball joints, of course a 2" drop spindle will solve that issue. Still that's a wide tire for the front on a Tri5.

Rick_L
08-29-2014, 03:19 PM
Maddog, you left out the other mod required. You have to narrow the frame rails (hourglass cut).

I think even an AME frame only can wear a 245 tire.

Maddog
08-29-2014, 03:57 PM
I don't know that you have to do that to the frame, they may just rub. We'll hear more when he tries it. And I should have said "your 255 MAY fit with around 5.5" BS"

rockytopper R.I.P 5-13-2017
08-29-2014, 04:05 PM
They don't look that big to me lol. Compared to the cutlass the 55 has huge space within the inner fender. Ill be running these wheels & tires. This is 17 inch I have mounted here. I might go to 18's but no bigger. I still want lots of rubber I don't like rubberband look.
http://i282.photobucket.com/albums/kk243/rockytoppers1/IMG_7184.jpg (http://s282.photobucket.com/user/rockytoppers1/media/IMG_7184.jpg.html)

Maddog
08-29-2014, 04:15 PM
Stock height car, no problem. Try lowering it.

rockytopper R.I.P 5-13-2017
08-29-2014, 04:31 PM
Stock height car, no problem. Try lowering it.
I am lol. Here is the new spring compared to the old one I removed today.
http://i282.photobucket.com/albums/kk243/rockytoppers1/image-37.jpg (http://s282.photobucket.com/user/rockytoppers1/media/image-37.jpg.html)

Maddog
08-29-2014, 04:46 PM
What's the specs on those wheels?

Rick_L
08-29-2014, 05:08 PM
You still have stock brakes on it too.

rockytopper R.I.P 5-13-2017
08-29-2014, 06:30 PM
The wheels are 17x8 4.5 BS (zero off set) tires are nitto 555 255/45/17 26 inches tall 10.04 section width. The suspension is a factory ps setup I drove the car over several optisicals and dips etc and cut donuts in my pasture. No rubbing. I know the brakes are drums but as stated trying to find a disc that's close. You need to also factor in I'm running a stiff spring rate my suspension travel is no where near stock. My cutlass rubs so what. It only happens in very extreme conditions and I'm not damaging tire or fenders. If that's all that happens in the 55 I might not even spend the extra $$$ to get custom offsets. I,m building a driver not a perfect show and shine queen any way.

Maddog
08-29-2014, 06:56 PM
The wheels are 17x8 4.5 BS (zero off set) tires are nitto 555 255/45/17 26 inches tall 10.04 section width. The suspension is a factory ps setup I drove the car over several optisicals and dips etc and cut donuts in my pasture. No rubbing. I know the brakes are drums but as stated trying to find a disc that's close. You need to also factor in I'm running a stiff spring rate my suspension travel is no where near stock. My cutlass rubs so what. It only happens in very extreme conditions and I'm not damaging tire or fenders. If that's all that happens in the 55 I might not even spend the extra $$$ to get custom offsets. I,m building a driver not a perfect show and shine queen any way.


I'm with ya not against ya:) Did you already install the new springs? If so, it's been lowered some.

rockytopper R.I.P 5-13-2017
08-29-2014, 07:23 PM
Im with you I'm here to learn. This is my first attempt @ making a 1955 handle like a 1985 IROC Z has always been my dream after all I sold my 1955 2 dr ht 350 4 speed in 1985 for the down payment on a new iroc. if i had just waited a week
wouldn't need to sale the 55. the one that got away. I,ll listen to exerence over hipe any day. Honestly Guys no one is looking into making trifives that handle like sports cars other than the corvette setups. Nothing wrong with that. But I don't think it's the only option out there that can achieve similar results. And I may be way wrong. Just here to Learn.

Chevynut I was only joking about the calculator my attempt at humor was referring to not including the camber gain that's all nothing to do with your spread sheet vs the web.
Rocky

Maddog
08-29-2014, 08:41 PM
Yea, If I wanted a Corvette I'd buy one.

chevynut
08-30-2014, 08:13 AM
I drove the car over several optisicals and dips etc and cut donuts in my pasture. No rubbing.

I guarantee that if you get the top of the fender opening below the top of the tire by dropping it (as in your avatar) and/or compressing the suspension in a turn it will rub. The way you have it now it can't rub even with the tire sticking out past the fender. You're lucky it's a 55....a 57 rubs a lot easier.

It's good that you're trying different stuff than everyone else uses.

Rick_L
08-30-2014, 08:45 AM
If you want to use an 8" rim, you are going to need more backspacing. I have seen a 5-1/4" backspacing work with a Heidts spindle and 225 tire.