thinking out loud about coilovers

[Aurora40]

Could you use coilovers with the existing leaf springs? Like in the 50 in-lbs range?

The only gain would be if possibly they were narrow enough (due to being low-rate springs) that you wouldn't have to do all the usual relocation stuff like move the rear top mount or move the front anti-roll bar. And you wouldn't lose the anti-roll bar behavior of the leaf spring.

But you could stiffen the ride, have some control over individual corner ride height, corner weighting, etc.

Just thinking out loud...

[rkreigh]

the callaway guys do this on their c6 suspension. not a bad way to go, but I'd go all the way and do the full coil overs, it eliminates the "cross talk" of the buggy spring and really isn't too difficult to modify the car.

you can now adjust the car ride height, spring rates and preloads and get the full benefit of the coil overs.

[GOLDCYLON]

Bob are you thinking about autocrossing or?

[Aurora40]

what I was thinking was, could I install the coilover set I have without having to modify the car as much. I am not sure I want to cut up the rear mount or relocate the front sway bar (I'd probably do the heim jointed links instead), etc. Really all I want is the car slightly stiffer.

I've also been thinking that perhaps I should just get some aftermarket "sport" composite leaf springs.

I'm kind of thinking though it's probably the actual spring retainers that interfere with stuff, not necessarily the spring itself, so it's probably a dumb idea.

[rkreigh]

the earliest cars had the stiffest suspension. if you want to go stiffer, I would go coil overs, or talk to vette brakes and products and see if they have a stiffer stock spring for our application

the mods to install the coil overs are the "clearances" needed for the coil fitting over the shock to give it a bit more room via the angle

the mods really aren't too bad to do. I'm of course a lazy corvette owner so I had haibeck do it.

but there are quite a few shops around that would do the work just fine!

the "helper" springs I don't think would work without needing the same type mods as the coil overs and I haven't seen this application on the c4, only the c6

[XfireZ51]

Ron,

You know of anyone who has used the 84 Z51 springs on the ZRs?
How about the 84 Z51 steering rack?

[cward]

I used Z51 springs on #364 before going to coilovers. The Z51 springs helped some but still the height was too high for the type of racing I was doing. The coilovers did wonders for my car. There was no comparison between the cornering ability before and after. Corners I had rated at 140 I was doing at 160 with the coilovers with no drift. The previous year with the Z51 springs it was 140 with drift. Big difference if you are racing the car.

Curtis

[UKZR1]

Jeal used to do coilvers that didn't require any of the mods that the DRM set does. The springs were narrower so everything fitted in without clearence problems. Very hard ride though - great for the track. Cliff (LoTu5) still has these on his. However I think he is thinking of the DRM coilovers now.

[mbabbitt]

I used Z51 springs on #364 before going to coilovers. The Z51 springs helped some but still the height was too high for the type of racing I was doing. The coilovers did wonders for my car. There was no comparison between the cornering ability before and after. Corners I had rated at 140 I was doing at 160 with the coilovers with no drift. The previous year with the Z51 springs it was 140 with drift. Big difference if you are racing the car.

Curtis

Curtis,

What pound size springs were you using front and rear? I'm doing something similiar, but not quite what you were doing.

THANKS

Mark

[HADI-ZR1]

Bob,
Go for it!
i use 500 lb spring in front and 400 lb rear.

[cward]

Curtis,

What pound size springs were you using front and rear? I'm doing something similiar, but not quite what you were doing.

THANKS

Mark

I used 8" tall springs to prevent binding since I put the car down on the ground. I am trying to remember the lb ratings. I think it was 450 - 375 but I am not sure. It could have been 475 - 350. I just can't remember for sure. With the shocks set to full hard, the car was VERY stiff. Normal people would not drive that setup on the street. It would jar you at every little bump. I would change the shock settings to soft to drive on the street. Even then, it was not a soft ride, but I did not mind. Heck, I was running full open exhaust too. So obviously comfort was not part of my agenda.

As well as I remember, I asked Randy at DRM to suggest spring rates after describing the type of racing I was doing. I used his suggestions as he has forgotten more about suspensions than I will ever know. The shocks were revalved to Moracco(sp) specs. Heim joints too. My setup worked on a relatively smooth ORR. I would have had to go softer at a rougher course. When the car was that stiff, it had a tendency to come off the ground at times when hitting larger bumps. I knew the Big Bend course and was able to handle the course at speed. I do remember getting airborne at least once during the last race at about 160 or so. That stiff setup was to allow the car to be right down on the ground without allowing very much travel in the suspension so the tires (front) would not touch the wheel wells or only touch lightly on the inside on very hard bumps. Also allowed setting caster and toe to exactly what I wanted for high speed without getting on the edges too much in the corners. What you had to worry about was bumps in the corners as the car would move sideways quickly. That is where knowing the course helped.

That setup would be good for a smooth autocross or road course. Caster, camber and toe would be different. In ORR you want different things out of the car than in autocross or road course racing. Brakes for instance. You don't use the brakes very much in ORR so my stock brakes with good pads and SS lines worked just fine. No cooling tubes to the brakes either. Your goal in ORR is as little air under the car as possible. Car was setup tight so instead of brakes, you controled the car in the corners with the go pedal. You might use the brakes going into corners but not in the corners unless you made a bad mistake on getting into the corner. You try not to do that. Bad mistakes have a tendency to catch up to you after awhile. Even little mistakes can get your heart to pumping a little faster if you are trying to go fast. But that is what makes ORR so much fun, trying to go fast around corners. One of the things I tried to do was balance the car corner to corner with the correct weight in the seats equaling my weight and the navigators weight. And getting the car level side to side. Then if you did it right, you could adjust the tightness with tire pressures during the practice runs. The setup for the 2002 race was as close to perfect as I ever got the car. It is never perfect like a Cup car because of the different surfaces encountered in a 59 mile highway. You just try to setup the car to handle it all and then it is up to the driver. In the 2002 race, I was driving the corners too slow. The car was so much better than the year before I was trying to adjust my corner speed up on the fly and I was not adjusting enough as I was still learning how good the car was. In some ways I wish the weather had permitted the full race rather than the shortened 20 miles each way on the north end of the course. I would have had a very fast run coming back north if we had run the full course. But probably would not have run 200. I would have stuck to the rules and tried to win my class. So my top speed would have been only 180. But it was shortened and I did what I did.

Curtis

[cward]

After rereading my last post, I want everyone to know I have CRS and that race was over 6 years ago. Corey might remember what my spring rates were. Also, the spring height was 2" less than normal height for ZR-1. That might be 8" or 10", I can't remember for sure. It is a bitch getting old. :-)

Curtis