Can you explain what you mean by this last statement? What is it about the mono-spring that is superior? Looking at your catalog, I see the setup that allows for adjustments to the actual wheel rate using the same spring. This is nice, but in my experience coil overs are pretty easy to swap springs on when you need to change the wheel rate. With either, you'd have to set the cross weights when you are done, and it looks to me like coil-overs would have the advantage here (for ease of adjustment).

I can think of many other reasons why coil-overs seem superior, but maybe I'm missing something. Just wondering if you could explain why this monospring setup is supposedly better, even in a race application...or point me to where it has been covered before?

 

What would you recommend for a daily street driver regarding the front spring? My main concern is to get the front raised up some and have it level side to side. I have lowered it, but it has gradualy become lower on only the left side (24.5" vs. 25.5 on the right). I think it is because of the spring, is this correct or could it be the shocks? If I am going to replace the spring I would like to get a handling improvement too. So should I get a new soft spring and get the shocks revalved or go with a firmer spring and get the shocks revalved? I will be putting on the 30/26mm bars and poly bushings at the same time. I use 273/315 tires if that helps.

So what spring should I get?

 

Always good to hear real life comparisons. :cheers: The '84 Z-51 optioned car with the factory Bilsteins will take a 1.0g on the skid pad. I haven't seen of, heard of, or witnessed through my racing experience a M-series BMW doing this, unless it was modified.
BMW M-series is a serious competitor :cheers: Love 'em

 

Brian Cunningham,
To answer Brians' question I run these size tires as we usually run A-X's on asphalt with only one driver. The smaller tire seems to heat up faster and stick better. I would love to run the larger tires, especilly at the Nationals or Wendover with the concrete and longer courses. Track events would be awsome too.
Why do you use them and have you had any clearence problems? Thanks.

 

No, I'm staying with the stiffer front spring. That seems to be the key to good handling. I think what is happening is that the stiffer front makes the car transition well and fights brake dive while the soft rear helps to dig out of the corners. The stiffer front doesn't seem to downgrade ride on the street, either, since we are sitting right in front of the rear axle-line.

 

Sounds to me like you need a new front spring. Shocks won't affect ride height. Get Vette Brake's regular spring for a street ride.

 

SCCA's stock classes don't allow removal (or addition) of rear swaybars. Front swaybars are allowed to be changed, deleted, etc.

>I run in autox in A-Stock with a C4 A LT1. Would removal of the rear swaybar be legal in that class? Do you think that it would provide better traction in the corners. I am running 255/45ZR 17 Kuhmos in the front and 275/40ZR/17 Kuhmos in the rear with factory selectride.

 

90pololt4
I like to run as much rubber as I can.
Sometime they take a bit to put some heat in them, I usually "sacrifice" a run, lighting them up at the start, making sure I use the brakes to heat the fronts.

Clearance is only a problem if I'm on the locks. Since I'm not parallel parking out on the track :D

 

Thanks stealthvette for the input. I don't want to move out of A stock. Appreciate your expertise.

 

VB&P,
The replacement sring arrived ans installed. Thanks for the good serive. I installed the extreme springs and now the car sits about a 1 1/2' higher front and back from where it sat before. There is only have four rounds of threads to lower the front and about 1" of threads on the rear 10" bolts. Do you know if this will lower the car that much or will I need to trim some of the rubber of the botton of the adjuster on the front spring.
I got the motor back in and all is running well. So now I have a few days to break it in and adjust suspension before Nationals. :cheers:

 

Hey Rodney, I thought you got both the tall and short adjusters, we make both. If you have the tall ones I'll send you the short ones no charge. :flag

 

If you notice the street spring rate's aren't as stiff as the Xtreme rate's. The lower the rate the bigger the bar, the higher you go in spring rate you'll have to start dropping the sway-bar size to get the weight transfer. Of course every driver is different and want's their car set-up a little different. Just like when I was younger and was riding skateboards, I liked my trucks tight and my brother liked his loose. Just two different set-ups and drivers to accomplish the same goal. :p:


[Modified by VBP, 8:28 PM 9/3/2002]

 

Transverse monosprings package better, last longer and save weight over coil-overs. Why is GM using the transverse composites on C-5 and C-6 corvette's and the new caddy's? GM is also developing a mono-spring for a new truck. We are currently making composites for many different types of vehicles and developing them for some oval racing. The main reasons are the consistancy and the increased life of the spring plus overall weight savings. Another advantage is where the center of gravity supports the vehicle, it is supported directly under the frame-rails which centers and lowers the center of gravity. The weight is saved by the spring itself and less metal to the shock-mounts thus saving weight again for less reinforcements. When Pratt Miller launched the C-5R campaign they were more familiar with coil-overs and didn't have enough time to test with composites. GM also can't get the higher rate's that we can due to our different spring design. In the past there hasn't been the adaptation of rate's and adjustability that we now offer from constant testing. :cheers:

 

What is the lowest spring rate you offer in the xtreme spring? I want something I can use on the street and I like the adjustability of the Xtreme, but not the price.

 

A little digression on the thread:
Testing, testing, testing is the only way to get it right.
With a car that has been on the track for 15 years all of these questions should have been answered.
It seems that every vendor has its own product to push and nobody does the "Consumer Report" independently.
or they are not talking. Everybody is great on sharing dyno numbers for each mod.
Lets see some skid pad numbers and lap times for each setup.

Note: The spring rate for the mono-spring is constant, while the inclined coilover is a decreasing rate.
Then you get the rising rate of the bump stop. I'm experimenting with foam bump stops to get a smoother transistion.

I like the extreme VBP springs with Koni's.
I feel that the additional internal spring rate with a monotube shock (Bilstein) doesn't work with low profile tires

Some of the missing information, for me, is:
What is actual measured wheel spring rate with various measured mono-springs?
There are various stiction problems with bushings and spring ends that make my measurements unsatisfactory.
r

 

Agree wholeheartedly with testing. Seemingly a hundred posts ago on this thread I mentioned a Road and Track test involving 7 different Vette tuners, each with their iteration of good Vette handling. I don't think VBP was represented, but most of the other big names were in a test including lap times on a road track with street tires.

BTW, it is quite possible to achieve level or even increasing spring rates with a coil spring using progressive rate techniques (varying coil wire diameter or coil wind spacing). The Germans have been doing it for years.

This thread discussion brings 3 maxims to mind:

1) Many roads lead to the same end.

2) Want to go faster? How much do you want to spend?

3) The two most indispensable techmologies to a racer are baling wire and duct tape.

 

When all is done and installed it is test and test and test. One driver likes it one way and just maybe another likes it too. It would be great if we could all share the testing we have all done.
So here I go. I started out with the base Z-51 set up. I added adjudtable Koni's. Better but not enough. Added all urathane bushing front and back better, but still not there. Took out the uratane front bushings and made offset upper and lower Delron bushings. Now where going faster and enjoying it more. Cut the rubber on the top of the front spring in half and the car is now starting to really turn. The rear is now starting to stick better. Decided I needed adjustable swaybars. Had some made and now I am getting it better with each drive. Of course I am still not driving the car like I stole it. Got lots of track time and tuning with the misses and I both driving. We as driver were slowly improving, probably way more than the car. Get my drift?
I always have felt if I can get a stable plateform that preforms the same all the time, then I can concentrate on improving me. I added adustable Ground Control shocks valved to match the weight of the car and the springs. Very good for a couple of months untill two of the shocks gradually lost pressure. All of a sudden the car is all over the place again. Found the problem, the shocks and decided it was time to go for the heavy springs and revalve the shcoks again, since they had to be repaired. Great company-Ground Control. Took care of it all at no chrage. So now with a rebuilt motor and new heavy srings and shocks, we start it all over again-test-test-test. All this for fun!!!! :cheers:

 

Some reading about the C4 design.

 

I'm suprized that noone has brought up the built in damping that composite springs have. We built an electric car in college that had no shocks at all. It was all taken care of by the spring.

Race teams like coilovers because they change spring at every track, and some even run different spring for qualifiing. Not to meantion a dozen or so shocks! :crazy:

 

The biggest weakness C4's have these days is aging, blown out shocks. The wheels spend more time in the air than on the ground. This is especially true of most '84 Vette garage queens pushing 20 years old.

Most amateur drivers would consider a '91 M5 to be one of the most "catchable" cars from that era. It makes everyone look like an expert. The car has the ability to "absorb" driver errors with amazing grace due to it's generous suspension travel, compliance and good geometry.

However, I can assure you any seasoned track racer looking for minimum lap times would look elsewhere. The first parts tossed in the rubbish on an M series track car are it's "forgiving rate" springs. Good high speed handling does not necessarily mean you can drink a case of beer, close your eyes at 100 MPH and rock the steering wheel. A Lincoln Town Car or Cadillac Coupe DeVille can pass that test too.