Velo Rossa/V8 Suspension Questions - Please Help!

[Guest Skillet]

My name is Chris Larson, I posted some questions a while back in regards to building a Velo Rossa convertible on a V8 Z (1977). My car has been in the frame shop getting a little tweeking and now it is back and ready for restoration.

 

This is what I am planning on building:

Velo Rosa GTO convertible, Chevy 350 V8 (alum heads, intake, H20 pump, and intake), and T56 6 speed as per JTR manual. I am targeting 400hp. I am planning on major reinforcements like those described in the VR manual (rocker braces, additional floor rails that incorporate into the firewall, strut supports, and rocker to strut tower through firewall).

 

If you could make suggestions on some or all of the questions below I would be very grateful. I have searched the forum and could not relate previous suggestions to my application since everything is changing.

 

I need help with the following so I can purchase coil-over kits. Ross has asked me some questions that I am having a hard time answering. I plan on doing a little bit of Solo II racing and high speed touring (COMA) but mostly street driving. I have a racing history in go-karts and I have high handling expectations. I would like the car to be adjustable for soft street driving but stiff for occasional racing (hence externally adjustable struts). I have MSA anti-roll bars, urethane bushings throughout (everything), and plan on putting in Tokico Iluminas. I have also purchased bumpsteer spacers. I have also recently picked up an 88 Turbo LSD.

 

1) What should I expect the car to weigh and what weight distribution could I expect?

2) What spring rates would be the best for the front and the rear and what spring lengths?

3) How much should I section the struts and what factory replacement struts should I ask for?

4) I plan on running 225/50/15 (on 15X8 rims, tire diameter 23.25â€) on the front and 265/50/15 (on 15X10 rims, tire diameter 25â€) for the rear . Any problems in this? Offset suggestions with coilovers and getting the wheel to the edge of the body kit?

5) For this kit, how much does the car need to be lowered to look good? I would like for it to be low for handling performance and better looks.

6) With the bumpsteer spacers, do I ALSO need to move the control arm pivot bolt locations up as described in the JTR manual? They say that moving the bolt location does not affect bumpsteer, if this is the case, why do it? I am confused.

 

I also have a question regarding the LSD rearend. How do I know that it is good? Are there ways to tell if it is any good from a bench inspection?

 

Your help to any of these questions would be greatly appreciated.

Thanks,

Chris

[Guest Anonymous]

1........ 2500#'s 2......200#'s front and 225 #'s rear or get variable rate coilovers because the 200 + is stiff in your lightened car 3..... 2 inch section//// put the front Z car struts in the rear and 80's VW GTI front struts in the Z front tubes 4..... 3 1/2 inch wheel backspacing all the way around You need to drop at least 4 inches to get the car to look right which the 2 inch section will get you. 10 inch coilover springs. 5. Forget the bumpsteer spacers and your bumpsteer problems will be solved by moving the control arm bolt up per JTR instructions ......my opinion wait for others to respond

[Modern Motorsports Ltd]

Chris Larson:

Ross has asked me some questions that I am having a hard time answering

Ooops! I thought only I got the hard questions, especially at work lately!

 

Your 'racing history' and high handling expectations says a lot right off the bat. Sometimes I get guys who after a few q's I flush out that they've driven cushy stock cars all their life and want something that handles really well but no stiffer........their solutions are vastly different:) The tokico's allow you to run it softer on the street and stiffen it up for higher speed handling improvements (low speed you still don't need it much stiffer than the mid tokico setting as you need some weight transfer)

 

One q I have left is where do your Velo Rossa fenderlips finish up relative to stock fenderlips? If they end up further out at all then that's fine. 10" long springs can then be used as you'll have lots of room for your tires to sit beside your coilovers, 10's are preferred when possible as they allow more room before coilbind whereas 8's have less freelength until they bind so one should go a little stiffer on 8's..............I have to fit 7's up front on my ride and I run 375 lb/in but my rides a little different. I'd reccomend 175/225 f/r spring rates with tokico illuminas. If you truly want a more comfortable street ride you can go 150/200 and that will be a fair bit more comfortable for daily bumps. I'd hesitate to go below 225 for a rear spring rate with your torque plans combined with the lowered body and thus less desired strut movement. Depending on your height you need to drop your car (find out the framerail height of another velo rossa build) then sectioning will be required as tomahawk mentions.

[Guest Skillet]

Tomahawk,

Thank you very much for your feedback. I will use your recommendations. I have already purchased the bumpsteer spacers, which you said not to use. Should I send them back to MSA? I ordered them a couple months ago and they probably will not let me return them. Has anyone ever used both the spacers and moving the pivot?

 

Ross,

Yes, the fender lips are further out on the body kit. I am not sure exactly but I expect about 3 inches. I will be using 10" wheels and I want to get as much rubber back there as possible for hook up off the line. Of course, cornering is a big issue and I have been worried that the wider tires on the rear may present understeer issues. A slightly softer spring on the front or softer strut settings may help if this is a problem. If the 10" springs will not work, is it possible to go to the 8" springs using the same stut coil-over mods?

[Guest Anonymous]

Send the strut spacers back. The steering rack bushings are a big help and the 3 piece lower control arm bushing are great. There is a thread that I detailed my front suspension modifications including moving up the lower control arm. I have the GTO 250 kit and have wire Daytons 8x15. The reversed rim rears are heavily offset with less than 3 inches and the fronts are less offset. My Tomahawk has 10 inch X 15 with a 3 1/2 inch offset with the 10 inch springs with no problem. There was a recent thread on the Ferarri that I detailed the exact offset of the Daytons.If you cannot find it I will re-measure I would have rather had 10 inch Daytons in the rear of the GTO than the highly offset ones. You will probably be looking at a reasonable 3 1/2 to 4 inch offset for the rear.