Advantages and disadvantages of stretching the C4 wheelbase?

[55 Rescue Dog]

I'm still trying to visualize what can happen to the C4 chassis dynamics, when the wheelbase gets stretched from 96.2 inches out to 115 inches? I can see several things it affects so far, a couple good things, and a couple bad, like turning radius for one. It is like 40 feet on a stock tri-five, and C4. Would it only be a 19 inch larger radius from stock, or how much more added to the turning radius?

[Rick_L]

The C4 front suspension has less total steering travel than a 55-57. There are other mods that are typically done to a 55-57 that reduce the steering travel. This is going to bother some and not others. So it's a tossup IMO.

I don't know whether the C4 front suspension has full "Ackerman effect" or not when used with the stock C4 wheel base. The "Ackerman effect" will be reduced when using the 55-57 wheelbase. However, many cars don't have full "Ackerman effect".

The "Ackerman effect" is when the inside front wheel turns at a greater angle than the outside front wheel. "Full Ackerman" is when a line drawn from the lower ball joint to the joint at the end of the steering arm extends to the center of the rear axle. What this does is eliminate any scrubbing of the front tires when turning. If a C4 had full Ackerman, then you'd have 83% Ackerman with the trifive wheelbase (the line would intersect with the center of the car ahead of the axle). That's not too bad as many cars intentionally are built with 75-80% Ackerman, with good results. And, it's hard to build a front steer setup with low Ackerman, because the tie rod ends move outboard when doing so, and this moves them closer to the wheels, potentially creating interference.

[chevynut]

Maybe you should just build a shortie and quit worrying about it. :D

[55 Rescue Dog]

I not worried too much, because it a not an easy design problem to fix, but was more interested in feedback from someone that has actually driven a C4 conversion. Can it turn a tight fast corner well, or is like trying to make a u-turn with a bus, with the front tires dragging in the turn? Although it wouldn't change the Ackermann, but would changes in wheel offsets and altering the scrub radius have any effect on steering angles at the tire centerline for tight turns, and turning radius?

[markm]

The only thing I know is Junkstang II stuff is too slow for a 55. I have seen one that takes a country mile to turn around.

[chevynut]

I not worried too much, because it a not an easy design problem to fix, but was more interested in feedback from someone that has actually driven a C4 conversion. Can it turn a tight fast corner well, or is like trying to make a u-turn with a bus, with the front tires dragging in the turn?

Why don't you ask the guy you bought the frame from? You said he's built and driven hundreds of these cars with C4 suspensions so he should be able to tell you. :p


would changes in wheel offsets and altering the scrub radius have any effect on steering angles at the tire centerline for tight turns, and turning radius?

I don't see how changing wheel offset could change steering angles. If you want to change steering angles and turn radius, either change out the rack with one that has more travel and the correct pivot points, or remove the steering arms and replace them with shorter ones. You could change the Ackerman at the same time if you wanted to. That's what AME does with their C5/6 suspensions to lower the rack.

[NickP]

I not worried too much, because it a not an easy design problem to fix, but was more interested in feedback from someone that has actually driven a C4 conversion. Can it turn a tight fast corner well, or is like trying to make a u-turn with a bus, with the front tires dragging in the turn? Although it wouldn't change the Ackermann, but would changes in wheel offsets and altering the scrub radius have any effect on steering angles at the tire centerline for tight turns, and turning radius?

When you purchased your new C4 chassis, I assume you asked these questions of the builder and the multitudes of customers he has that you mentioned, yes or no? FWIW, I doubt to many of the clientele within the C4 Trifive market purchased or built their ride to "turn a tight fast corner". I suspect the preponderance are sleeping in their snug trailers or garages (finished ones) and the remainder remain incomplete with no desire to take a corner fast. I suspect, a good many of the builders went this route simply for the cool factor and a few for the improved ride.

What escapes me with regards to your continual hypothesizes, is are you now questioning your path/purchase?

Mystified

[chevynut]

A late C4 Corvette has a turning circle diameter of 40.0 feet curb to curb according to my specs book, or a turning radius of 20 feet. A stock tri5 has a curb to curb turning circle diameter of 39.0 feet according to GM:

http://chevy.oldcarmanualproject.com/chevyresto/56057.htm

Turning radius is a linear function of wheelbase, so a C4 suspension in a tri5 should have a turning radius of about 20*115/96.2 or 23.9 feet.

As Rick mentioned, a lot of tri5s have had modifications that can reduce the steering angle.

[BamaNomad]

As long as you have posi-traction, a little 'right foot' action during the turn can reduce the turning radius... :)

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

As long as you have posi-traction, a little 'right foot' action during the turn can reduce the turning radius... :)

Bama that's the old school way before cars could grip and steer into a corner lol. With the C4 setup you got now best to jerk steer hard right to unweight it then throw it back to the left or vise verse and get all 4 tires drifting if you lack the steering radius you need then line her out and pour the coal to it lol.

[55 Rescue Dog]

So from what I have seen so far is, the C4 tri-5 has a turning circle of 47.8 feet, which is the same as a 1/2 ton crew cab pick-up. That doesn't sound good at all.

[NickP]

So from what I have seen so far is, the C4 tri-5 has a turning circle of 47.8 feet, which is the same as a 1/2 ton crew cab pick-up. That doesn't sound good at all.

Maybe your frame guy will give you a refund and you can build a VW.

[chevynut]

So from what I have seen so far is, the C4 tri-5 has a turning circle of 47.8 feet, which is the same as a 1/2 ton crew cab pick-up.

How often are you going to be at full lock while driving anyhow?



That doesn't sound good at all.

So sell it or fix it so it's the way you want it. I already told you how you can fix it if you want more steering angle. Out of the hundreds or perhaps thousands of these cars built with C4 conversions, I've not heard anyone complain about steering radius.



When you purchased your new C4 chassis, I assume you asked these questions of the builder and the multitudes of customers he has that you mentioned, yes or no?

What escapes me with regards to your continual hypothesizes, is are you now questioning your path/purchase?

Exactly. :p

[chevynut]

Maybe your frame guy will give you a refund and you can build a VW.

:D:p

[55 Rescue Dog]

When the ass end of the car starts to come around, you need all the opposite lock you can get to try and save It !!! I first got sold as to how awesome the C4 conversion chassis is, right here on this site. I'm still hoping to figure out how the make it work, now that I see it has some inherent problems, that I have also learned from this site, and many others. No free lunch...
My original 96 B-body chassis plan I should have tried to make work, instead of the C4 that I will have to try and make work. duh. A couple more ways I've learned the hard way again. There is no fn way to make a try-5 handle like a Corvette, but if it drove like a 96 Impala SS that would be great.

[markm]

As long as you have posi-traction, a little 'right foot' action during the turn can reduce the turning radius... :)

You got that right as long as you have a Posi-Track, Sure-Grip or Powerlock, one of Henrys dysfunctional 9 inch Traction-Loks good luck.

[chevynut]

Here's your solution. Cut down your frame to 96.2" wheelbase and make the body fit :D:




https://farm8.staticflickr.com/7247/7112378385_44c858acd4_o.jpg

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

Cnut is that the French made 55 CIAT lol.

[BamaNomad]

Bama that's the old school way before cars could grip and steer into a corner lol. With the C4 setup you got now best to jerk steer hard right to unweight it then throw it back to the left or vise verse and get all 4 tires drifting if you lack the steering radius you need then line her out and pour the coal to it lol.

I'm as 'old school' as one can get... When I owned my '70 Roadrunner -F60-15 Polyglas tires - with NO power Steering, but I had posi.. I even used this technique when parallel parking.. :)

[chevynut]

I first got sold as to how awesome the C4 conversion chassis is, right here on this site.

You asked for and got feedback on the other site too, and I offered to have you to talk to some of my customers but you refused to do so. I assume you talked to Rick who your bought your frame from and some of his "hundreds" of customers you claimed he had about all those "issues" you had with the conversion before you bought it. There's a ton of information out there and lots of guys driving them. If you think you got sold a bill of goods, it's nobody's fault but your own.

The slight steering angle reduction has been mentioned and discussed here on several threads before. You were too obsessed about my horrible single shear dogbone mounts and how a torque arm is so much better than a pinion bracket and how bad coilovers are, and other BS to pay attention to those "details", I guess.



I'm still hoping to figure out how the make it work, now that I see it has some inherent problems, that I have also learned from this site, and many others. No free lunch...

I don't understand what you keep agonizing about how to "make it work". It works just the way it is. The C4 suspensions work a helluva lot better than the tri5 suspensions, and probably a lot better than your "Camaro" that you hacked up...to "make it work". There are thousands of Tri5's out there with C4 suspensions and nobody complains but you, and you haven't even driven one yet. Guys who have them say they love them, and nobody I've ever heard about regrets doing it. I personally think you're just looking for an excuse to dump it and to justify it to yourself after spending so much on it because it's too big of a project for you to handle. That's probably what you should do so you can quit complaining and looking for "issues" and "problems". :p



My original 96 B-body chassis plan I should have tried to make work, instead of the C4 that I will have to try and make work.

LMAO! You were going to try to put a 55 Chevy body on a 96 Impala frame? Turning Diameter - Curb to Curb (ft): 43.6 :D And you think a 1996 Impala drives better than a 1996 Corvette? It has a perimeter frame with no body mounts matching up so an entire custom floor would have to be built. The engine probably isn't in the right location, bumpers don't bolt up, no radiator support, nothing matches a tri5 body. What are you smokin' RD? :eek:


There is no fn way to make a try-5 handle like a Corvette, but if it drove like a 96 Impala SS that would be great.

It's a Corvette with a lengthened wheelbase that doesn't change much but the steering radius and with a slightly higher CG....of course yours is WAY higher :eek:. The suspension geometry is the same whether under a Corvette body or a Tri5 body. It has an IRS and unspring weight is lower than the Impala. It's just a better performance platform made the same year. If you can't understand that, nobody can help you.

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

I'm as 'old school' as one can get... When I owned my '70 Roadrunner -F60-15 Polyglas tires - with NO power Steering, but I had posi.. I even used this technique when parallel parking.. :)

I was using the technique as late as 1987 with my DPS style 302 fox body sedan lol badest thing on the road at the time ran 13ish second qtr with 210 hp 5 speed lol. But very light in the seat lol and no way as thimble as my 1985 IROCZ. Both rated to 140 and 145 top speed but the stang was a hand full past 120 the IROC was 1 finger all the way to the top even if it took a little longer to get there lol...

[NickP]

There is no fn way to make a try-5 handle like a Corvette, but if it drove like a 96 Impala SS that would be great.

WooHoo! 2+ tons on a .9" longer wheel base than a trifive with a power to weight ratio of 106 watt/kg / 48.1 watt/lb. Having said that, it is a nice ride for getting groceries.

[chevynut]

WooHoo! 2+ tons on a .9" longer wheel base than a trifive with a power to weight ratio of 106 watt/kg / 48.1 watt/lb. Having said that, it is a nice ride for getting groceries.

Yeah, that'll work just fine. :D I just don't understand this constant whining about the "deficiencies" of the C4 setup. IMO it's far better than most anything out there for a tri5. Kyle Newman proved how well it works.

http://www.hotrod.com/articles/1208phr-goodguys-del-mar-street-machine-autocross/

Del Mar Goodguys 2012
Street Machine Autocross Results




Driver:
Car:
Best lap:


1. Mary Pozzi
’72 Chevy Camaro
31.105


2. Aaron Ogawa (manufacturer)
’70 Dodge Challenger
31.113


3. Brian Hobaugh
’68 Chevy Camaro
31.569


4. Gerald Lum
’71 Chevy Camaro
31.913


5. Kyle Newman (manufacturer)

’55 Chevy Bel Air

32.321


6. Brett Campbell
’67 Chevy Camaro
32.530


7. Kyle Newman

’57 Chevy 210 wagon

32.656


8. Brandy Morrow (manufacturer)
’70 Chevy Camaro
32.810


9. Dick Eytchison
’65 Chevy Chevelle
33.362


10. Mike Wright
’69 Chevy Camaro
33.507


11. Chris Meyer
’70 Chevy Camaro
33.610


12. Chris McCrea
’69 Chevy Camaro
33.928


13. Roy Rozelle
’69 Chevy Camaro
34.024


14. Gregg Blumdell
’69 Chevy Camaro
34.257


15. Paul Alderman
’70 Chevy Camaro
34.309


16. Tom Kamman
’69 Plymouth Barracuda
34.334


17. Mike Young
’65 Ford Mustang
34.515


18. Allen Palmer
’59 Chevy Corvette
34.618


19. Robert Hall
’68 Chevy Camaro
34.662


20. Bryce Baumgart
’65 Ford Falcon
34.817


21. Richard Trujillo
’69 Ford Mustang
34.892


22. Aaron Raymond
’69 Chevy Camaro
35.118


23. Robb McIntosh
’69 Chevy Camaro
35.123


24. Nick Herrington
’67 Ford Mustang
35.150


25. DJ Arerill
’71 Ford Mustang
35.393


26. John Wityak
’65 Ford Mustang
35.724


27. Tim Callahan
’66 Chevy Nova
35.740


28. John Butler
’66 Chevy Chevelle
35.889


29. Tray Borgen
’69 Chevy Camaro
36.028


30. Tony Evans
’72 Chevy Camaro
36.190


31. Mike Fitzsimmons
’67 Pontiac Firebird
36.913


32. Dennis McNeil
’72 Chevy Chevelle
37.338


33. Tommy Wisdom
’68 Dodge Dart
37.831


34. Frank Temblador
’69 Chevy Chevelle
37.832


35. George Reiss
’72 Chevy Chevelle
39.328


36. Leonara Bridges
’72 Plymouth Barracuda
39.515


37. Alex Nine
’71 Datsun 240Z
40.512


38. Paul Leeds
’66 Ford Mustang
43.298

[chevynut]

And here's the results from the 2013 Del Mar Autocross:

http://www.hotrod.com/articles/2013-del-mar-goodguys/

SM Greg Thurmond 64 Chevy Corvette 54.086 PRO
SM Gregg Blunder 69 Chevy Camaro 54.385
SM Kyle Newman 55 Chevy Bel Air 54.486
SM Casey Cronin 68 Chevy Camaro 54.841
SM Robert Pierik 71 Chevy Camaro 55.345
SM Dan Weishaar 70 Dodge Challenger 55.37
SM Rodney Prouty 68 Chevy Camaro 55.414
SM Tom Kamman 69 Plymouth Barracuda 55.452
SM Matt Alcala 69 Chevy Camaro 55.61
SM Brianne Maier 66 Ford Mustang 55.65
SM Bob Gawlif 71 Chevy Camaro 56.134
SM Steve Rupp 68 Chevy Camaro 56.233
SM Jane Thurmond 64 Chevy Corvette 56.4
SM Tdd Vierra 56 Chevy Wagon 56.521
SM Chris Meyer 70 Chevy Camaro 57.574
SM Robbie Conklin 68 Chevy Chevelle 58
SM Gerald Lum 71 Chevy Camaro 58.091
SM Dick Eytchison 65 Chevy Chevelle 58.35
SM Chad Humphreys 69 Ford Mach 1 58.516
SM Kyle Newman 57 Chevy 58.715
SM Dennis McNeil 71 Chevy Chevelle 59.118
SM Richard Trujillo 69 Ford Mustang 59.249
SM Aaron Raymond 69 Chevy Camaro 59.426
SM Mike Fitzsimmons 67 Pontiac Firebird 59.667
SM Nick Herrington 67 Ford Mustang 59.932
SM Mike Young 65 Ford Mustang 60.028
SM Evan Osborn 67 Chevy Camaro 60.281
SM Robb McIntosh 69 Chevy Camaro 60.342
SM Ralph Hollis 70 Pontiac GTO 61.093
SM Christian Dilauro 69 Chevy Camaro 61.134
SM Chris Humphreys 71 Chevy Camaro 61.203
SM John Barkley 72 Chevy Camaro 61.242
SM Tim Davis 66 Ford Mustang 61.524
SM Chuck Rust 65 Chevy Covair 61.783
SM George Reiss 64 Pontiac Lemans 64.047
SM Mike Colon 69 Chevy Camaro 64.13
SM Jerry McNulty 65 Ford Mustang 67.04

[NickP]

Hmmmmm, I didn't see any 1996 Impalas in the two lists. Whaaaaaaaaaat's up with that?

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

Hmmmmm, I didn't see any 1996 Impalas in the two lists. Whaaaaaaaaaat's up with that?

Probably because Good Guys don't let anything in newer than 1972 in the gate except on Sunday's for fun run AX.

The ole long boat impalas apparently hold there on this one is making short work of a C5 and some other exotics. Of course none of this proofs anything a skilled driver can make up for hardware shortfalls lol. Example I am the weak link in my cutlasses AX performance.....
https://www.youtube.com/watch?v=_lJHBujAEdQ


Newmans 55 is pretty sweet, he mentions running 17/275 tires in front and attempted to go 295/18 but said he had rubbing issues. It appears in most of his road course and AX vids he is running the 275. I Only see the bigger wheels in the photo shoots.

[chevynut]

The ole long boat impalas apparently hold there on this one is making short work of a C5 and some other exotics. Of course none of this proofs anything a skilled driver can make up for hardware shortfalls lol.

Yes, the driver certainly is a factor. But if the car lacks the performance, the driver can only do so well and it seems Kyle Newman did pretty good. And we don't know how good of an autocross driver Kyle is either. It would be cool to see Mary Pozzi drive Newman's car and some of the others so you could compare the cars.

But if RD is so concerned about autocrossing with all of this nitpicky shit he keeps bringing up, he'd be more concerned about the CG of his car.

[55 Rescue Dog]

I owned, and autocrossed 2 Impala SS's. They are actually a blast to autocross, and do quite well for a full size car stock, even with the extra weight, it is nimble, and fun to toss around. How many times have you autocrossed before Cnut, and NP?

[chevynut]

How many times have you autocrossed before Cnut, and NP?

That's irrelevant to the discussion about C4 suspensions, isn't it RD? How many times have you autocrossed a tri5 with a C4 suspension? :D

Maybe you should just build your car and if you don't like it, sell it. Or you should find someone or even TALK to someone who owns one (like Kyle Newman) and get the straight scoop from them. Then you don't have to agonize over all of these phony "issues" you keep hallucinating about.

[NickP]

I owned, and autocrossed 2 Impala SS's. They are actually a blast to autocross, and do quite well for a full size car stock, even with the extra weight, it is nimble, and fun to toss around. How many times have you autocrossed before Cnut, and NP?

In the late 60's, every weekend if possible. Was I any good, no. Did I enjoy it, yes. Why don't I do it now, no car to do it with. Would I cut up a trifive for the express purpose, no. Would I use a C4 under my next project, yes if I so desired to build again. Your inference relative to my personal experience in another attempt to belittle or instigate, goad or otherwise instill hostility is duly noted and ignored. Next question?

[55 Rescue Dog]

That's irrelevant to the discussion about C4 suspensions, isn't it RD? How many times have you autocrossed a tri5 with a C4 suspension? :D

Maybe you should just build your car and if you don't like it, sell it. Or you should find someone or even TALK to someone who owns one (like Kyle Newman) and get the straight scoop from them. Then you don't have to agonize over all of these phony "issues" you keep hallucinating about.
Your the one that brought up the subject of autocrossing, that you must have some experience at, since you mention it frequently on other threads. You must know all about the subject of autocrossing too, or maybe just read about it.

[chevynut]

Your inference relative to my personal experience in another attempt to belittle or instigate, goad or otherwise instill hostility is duly noted and ignored.

It's his MO Nick. He asks leading questions that are actually criticizing something or someone, then when he gets his ass handed to him proving his ignorance, he changes the subject. It's happened ever since he showed up here asking for "feedback" on the C4 suspensions and ignoring all the advice he was given. Now he blames me and others here for his decision to buy a C4 conversion frame that has so many "issues" and "inherent problems". Notice how he never addresses or acknowledges the calculations, links, suggestions or any information given to address his concerns, or anything someone tells him? He just goes on to his next "issue" or changes the subject like he just did.

So far he's said that a single shear dogbone mount is going to break, with no proof of it whatsoever, and despite the fact that many others use the same thing including GM. He says a torque arm behaves differently than a pinion support bracket, which is BS and shows his total lack of understanding. He says coilovers don't work right on a C4 suspension, because GM didn't use them. He says the C4 aluminum parts will "fatigue" over time so they're no good but has zero proof of that ever happening to anyone, anywhere. He believes rubber doesn't "bind" but poly does despite the fact that GM says you have to put the car at ride height before tightening the suspension bolts with the stock rubber bushings. He says poly bushings on dogbones will cause the dogbones to twist and break, but nobody has ever had that happen and he can't prove that it can, and despite information showing that it's a negligible deflection. He says a narrowed C4 rear suspension is a bad thing despite it being done by many others, but can't explain why it's supposedly bad. He says it's better to lower the CG of a car by lowering the seats and other weight inside the car than to drop the suspension...lmao. Now he says that slightly reduced steering radius which has been mentioned before is such a big problem but it probably won't affect anything but parking and u-turns. I probably missed a half dozen or more other things. There's a diagnosis for people like that. You can't teach them anything because they don't want to admit they're wrong.

[55 Rescue Dog]

It's his MO Nick. He asks leading questions that are actually criticizing something or someone, then when he gets his ass handed to him proving his ignorance, he changes the subject. It's happened ever since he showed up here asking for "feedback" on the C4 suspensions and ignoring all the advice he was given. Now he blames me and others here for his decision to buy a C4 conversion frame that has so many "issues" and "inherent problems". Notice how he never addresses or acknowledges the calculations, links, suggestions or any information given to address his concerns, or anything someone tells him? He just goes on to his next "issue" or changes the subject like he just did.

So far he's said that a single shear dogbone mount is going to break, with no proof of it whatsoever, and despite the fact that many others use the same thing including GM. He says a torque arm behaves differently than a pinion support bracket, which is BS and shows his total lack of understanding. He says coilovers don't work right on a C4 suspension, because GM didn't use them. He says the C4 aluminum parts will "fatigue" over time so they're no good but has zero proof of that ever happening to anyone, anywhere. He believes rubber doesn't "bind" but poly does despite the fact that GM says you have to put the car at ride height before tightening the suspension bolts with the stock rubber bushings. He says poly bushings on dogbones will cause the dogbones to twist and break, but nobody has ever had that happen and he can't prove that it can, and despite information showing that it's a negligible deflection. He says a narrowed C4 rear suspension is a bad thing despite it being done by many others, but can't explain why it's supposedly bad. He says it's better to lower the CG of a car by lowering the seats and other weight inside the car than to drop the suspension...lmao. Now he says that slightly reduced steering radius which has been mentioned before is such a big problem but it probably won't affect anything but parking and u-turns. I probably missed a half dozen or more other things. There's a diagnosis for people like that. You can't teach them anything because they don't want to admit they're wrong.
So I guess you have never autocrossed, or raced at all. And, a car in the shop has no proof, until it is driven, no matter how it looks on paper, which ain't pavement. BTW you always tighten rubber bushings at ride height which puts the bushing in it's neutral position on any vehicle, if you knew how they work. U-turns suck when it takes more that one try in traffic.