Suspension geometry analysis

[55 Rescue Dog]

Sure, just like all engineers drive the car before they design the suspensions, right? LOL! Of course the rear roll center matters in the whole scheme of things, as does camber gain with an IRS which will outperform a solid axle. But this debate is about the effect of a taller balljoint and other mods to the FRONT of the car. If you want to analyze the rear suspensions, and look at all those "endless variables", start your own thread. Otherwise, please stay on topic.

Sorry again, but I do believe that AFTER the engineers design a front suspension they drive it at a place, I think, called GM proving grounds, before the design is approved, and released into production, and sold to the public.

[markm]

Sorry again, but I do believe that AFTER the engineers design a front suspension they drive it at a place, I think, called GM proving grounds, before the design is approved, and released into production, and sold to the public.

I believe that was part of the plan for the race track at Indy when built.

[rockytopper R.I.P 5-13-2017]

Here's a link to the Howe site. What is your upper balljoint part number?

http://howeracing.com/p-7929-howe-22304-fits-k6034.aspx

Change	0"	+.1"	+.2"	+.3"	+.4"	+.5"	+.9"
Part No.	22380	22381	22382	22383	22384	22385	22389A
Dim. X	1.186"	1.286"	1.386"	1.486"	1.586"	1.686"	2.086"
Dim. L	3.15"	3.25"	3.35"	3.45"	3.55"	3.65"	4.05"

22381 +.1"
22382 +.2"
22383 +.3"
22384 +.4"
22385 +.5"
22389 +.9"

Laz I have no part number but my measurements equal the .9 exactly. I thank i have been saying 1/2 inch all along which probably caused alot of disagreement about this using that does not correct the problem so I will eat ever word I ever said and agree with you and Rick. However using a .9 taller ball joint does correct the problem. Sense I had never ever done the numbers but knew it worked because you can still deny all you want but my daily driven cutlass is a good comparsion as to how much improvement is realized with this. For the record I have already done the analysis to back up the number. You may input the .9 ext ball joint in your model and publish the numbers I will agree with them. I'm resting my case because what I have really said all along or was trying to is this corrects the IC and Roll center location. I still believe having it on the wrong side is not good and I still dont think the roll centers you are using in that case are correct. I have found no information to support that other than you and Rick. If there is good info to support the case of having ic on wrong side please share it. I also agree the rear comes into play in the big picture as to tires alignments spring rates shocks etc etc but thats not what we are duscussing here. Im sure the C4 will have an edge in racing performance over the bolt on solution but want be night and day. So if your building a cruiser most folks will be happy with the bolt on fix. We've shown both bolt on and C4 are close in price or can be. C4 does have curb appeal so both are Good. If I get more info from Mark I will share.
Rocky

[Mike56]

I'm following this thread and i'm learning from it. Some of this is beyond me know but it's soaking in as you go. I'm looking forward to your conclusions( table/chart) on the affects of different suspension part changes. I hope to apply that to improve the handling of my car. I'm also enjoying the differing opinions as they tend to bring out more information, drawings, and resources. Keep up the good work.

[rockytopper R.I.P 5-13-2017]

I'll include this photo sense Rick brought in tire size. This is my current steering limit. Hope its enough lol. The wheel shown is a 17x8 zero offset tire is a nitto 555 with 25.95 dia and 10.4 section. The other side of the car has a stock steel rim and 205 tire. It is hitting the helwig sway bar in this photo. I do not have rotters on they will move wheels out .25 eash side. So I call this my limit and will build and set steering stops here.

[chevynut]

I have no part number but my measurements equal the .9 exactly. I thank i have been saying 1/2 inch all along which probably caused alot of disagreement about this using that does not correct the problem so I will eat ever word I ever said and agree with you and Rick.

Thanks for verifying that. A .9" taller balljoint will have more effect than a .5" taller one, obviously. That's why I kept asking you why you didn't go with the longer one. I'll add that to my model and work on it with a 10.65" tall spindle.

However using a .9 taller ball joint does correct the problem.

It does put the upper balljoint above the pivot thus moving the instant center to the opposite side of the car. It also improves the camber curve, but I'm not sure by how much at this point. I was waiting for you to verify the balljoint length before I went any further with the analysis. I think we should forget the 1/2" taller balljoint and analyze the .9" taller one. We still have a disagreement about the effect of dropped spindles versus 2" dropped springs and I hope the analysis clears that up too.

Sense I had never ever done the numbers but knew it worked because you can still deny all you want but my daily driven cutlass is a good comparsion as to how much improvement is realized with this.

You keep saying I deny it . I have never, EVER said that a taller spindle is a bad thing. I have only objected to your claim that angling the lower a-arm up using 2" cut springs is better than "junk" 2" dropped spindles. As I've said many times the 2" dropped spindles drop the CG without negatively affecting the suspension attitude.

I'm resting my case because what I have really said all along or was trying to is this corrects the IC and Roll center location.

But it's clear that angling the lower a-arm up at the balljoint by cutting the springs moves the roll center DOWN, and AWAY from the CG isn't it? I don't even have to do an analysis to see that. The IC moves downward and so the roll center drops. As the spindle length increases, the IC gets closer to the car and rises, improving the roll center. And don't forget, you ALSO said the 2" cut springs are better than the 2" dropped spindles. That is my main objection to your claims as I've said many times before.

I still believe having it on the wrong side is not good

Nobody has said it was a good thing. Why do you keep harping on that? Go back and read my comments on all the other threads about this issue.

I still dont think the roll centers you are using in that case are correct.

Not sure what you're getting at with that comment. I have completed the analysis of the stock suspension and the roll center is below ground up to 2" of compression. Once you get to where the balljoint is about 2" above the pivot the IC actually "flips" to the other side of the car but it's a long ways away and way below ground so the roll center is still below ground.

If there is good info to support the case of having ic on wrong side please share it.

There isn't any. It's a bad configuration and I don't think anyone has EVER said otherwise. Please don't say that again.

Im sure the C4 will have an edge in racing performance over the bolt on solution but want be night and day.

I think the difference will be dramatic. Also, when you consider all the other factors as you mentioned, like anti-dive, SAI, camber gain, scrub radius, the IRS roll center, and many other factors it's a completely different suspension system, FAR better than any stock or modified stock setup. That's why the guy on the other forum said the C4 car he drove was better than any Tri5 he's ever driven.

So if your building a cruiser most folks will be happy with the bolt on fix. We've shown both bolt on and C4 are close in price or can be.

That's not what you've been claiming though . I've read where you said here and elsewhere that your car drives like a C4 Vette, and you get the same suspension geometry at a lot less cost with a simple fix. When you first introduced the idea here you said you got the same "alignment" as the C4. As I've said, static alignment is a tiny part of the overall suspension picture. And yes, the C4 setup is cost competitive with all the bolt-on mods if you go all-out. Your extended balljoint addresses one aspect of the poor stock suspension design, but not all of them. If you get a chance, drive a tri5 with the C4 setup and tell us what you think. There's quite a few of them around.

[rockytopper R.I.P 5-13-2017]

I left the protouring community when I bought my nomad and joined this one. I learned from the PT community who live and breath making older cars handle better. Very few use drop spindles drop springs are preferred for the reasons I have stated. One main issue with drop spindle is it limits tire size amoung other things and the drop spring improves the camber because it uses the right part of the curve. I didn't make this up. Good reading here and from some of the best in the business.
Rocky

http://www.pro-touring.com/threads/2...from-old-site)

[Rick_L]

Yesterday while I was googling extended ball joints, I visited the SC&C website (rocky's guru). I also read a couple of posts by him on chevelles.com and another forum.

Turns out he sells dropped spindles, tall ones, and extended ball joints, all 3. He even sells a spindle that is dropped AND tall, I think for early Camaros.

What's up with that rocky?

[chevynut]

One main issue with drop spindle is it limits tire size amoung other things and the drop spring improves the camber because it uses the right part of the curve.

Rocky, how does a dropped spindle limit tire size? I guess I'm not familiar with that issue. And what are the "other things" you talk about that makes you call them "junk"?

Also, a lower a-arm that's pointing up at the outboard end at ride height is just plain wrong imo. As I said, it causes more tire scrub as well as negating part of the camber gain from the extended upper balljoint because the balljoint is moving inboard at a faster rate there. I hope my analysis convinces you of that, or changes my mind on the matter.

Are we discussing a car set up for pure racing, or one that's pro-touring?

[chevynut]

Good reading here and from some of the best in the business.
Rocky

http://www.pro-touring.com/threads/2...from-old-site)

And none of this from your link applies to a Tri5 as far as I know...it's all about 1st gen Camaros:

"The drop spindle kits use second gen parts, on a cast iron spindle similar to a second gen spindle with caliper mount cast in. The steering arm is two inches lower than a stock Camaro and the caliper mounts two inches higher in relation to the upper A frame, which can cause caliper to A frame clearance problems.

Several problems develop when you use drop spindles.

You can't fit wide tires, the tie rod end winds up two inches lower in relation to the wheel, so forget wide front rims.

Geometry stays stock which is not good on a Camaro.

You may have clearance problems with the upper ball joint to caliper.

You can't use any aftermarket disc upgrades, they won't fit.

Steering arms are cast in, so you can't bend them to fix bumpsteer. You would have to use a rod end and spacers on a stud.

Just installing shorter coils puts the stock spindles on a better part of the camber curve, which is an improvement all by itself. The lower A arm will not be level, which is not ideal but it isn't that bad.
David "

So what he's saying is you ideally DO WANT a level lower a-arm. In that case you need to lower the CG of the car some other way...like dropped spindles. You need to fix the upper a-arm orientation with a taller spindle. His comment about getting to the "right part of the curve" is getting the upper a-arm in a better position. That can be done with a taller balljoint. And he didn't even address the roll center dropping with the lower a-arm level, but implies that a higher roll center is good.

I'm not aware of any wheel clearance problems on a tri5 and the steering arm is removable.

THAT is why a dropped spindle is better than a dropped spring on a Tri5. He confirmed it for me.