taguy16

I'm in the process of redoing the suspension on my '89 Camaro and am trying to make up my mind which springs to order. My immediate goal is to lower the car to get rid of most of the space the factory setup leaves between the tires and fender lips and keep the car street drivable, but eventually I want to turn the car into a track car so I can have some fun with it. I plan on installing adjustable front and rear spring spacers - to give the height a little adjustability - and use stock car springs (and adjustable shocks/struts). I'm wondering what a good rate for the street would be if I want a ride that won't shake my fillings loose - 750lbs (which looks to be about the same as the Moog 5662 recommended for the Z28)? How much length would you need to add to a 9 1/2" front 750# racing spring to keep the car high enough for street driving, yet not have large gaps between the tires and fenders, or would it be better to order 12" 750# springs and cut them as needed in case my spacers don't have enough adjustment to make a 9 1/2 spring long enough?

Based on what I've read here and elsewhere on the web 1000# for a spring rate seems to be the place to start with for a front track spring. Would this need to be 8 1/2" or 9 1/2" to keep the car off of the bump stops on most courses, with how much length needing to be added by the spacers?

I've read on here that 175# rear springs seem to work well on these cars: is this true for both the street and track? What would be a good length to go with for the rears with adjustable spacers?

I'm sorry to throw out such questions because I know they get asked frequently here. I've tried to find what I can on my own, but I have trouble making sens of some of the info. I appreciate any help with this so I don't end up wasting money of springs I can't use.

taguy16

I forgot to add my car no longer has any A/C equipment on it and it will be a stick shift car when I'm done with it, so it will be lighter than if it wasn't that way.

QwkTrip

iTrader: (22)

Do you have front and rear weight of the car? That's kind of necessary if you're going to try to dial in this stuff on your own because you'll need it for the spring length calculations.

I got my front and rear weight at a truck stop near me with a 3 pad scale. I put the front wheels on one pad and had the rear wheels on another pad. I stood on the third pad and it got my weight right so I figure the car weights were close enough too.

taguy16

No, I don't have the weight. I'm in the process of rebuilding the front end of it so that's all apart. I didn't think these cars varied that much in weight, other than whether or not they had A/C or not. I know the automatic transmissions and torque converters on these cars also weighed a lot, too, so a stickshift car is probably going to be maybe 100 lbs. or so lighter than a car with an auto in it.

QwkTrip

iTrader: (22)

If you examine all the front spring options at the Moog website it tells a story that Moog believes 11 inch compressed height is stock ride height. The motion ratio is 2:1 so 1 inch change at the spring is 2 inch change ride height. If you measure front axle weight and subtract all the unsprung weight, and measure compressed spring length as it sits in your car now, and you know your current spring rate, then you can calculate what spring you need to get to the ride height you want.

If you read that and you're saying, Whaaaaat??? , Then just buy a set of weight jacks from Ground Control, UMI, or Detroit Speed.

If you read that and you completely understand, Then just buy a set of weight jacks from Ground Control, UMI, or Detroit Speed.

Weight jacks have an added benefit of being able to corner weight the car. That's actually what it is for, but it's convenient for changing ride height too.
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Just FYI, the car will probably handle worse if you drop it low. Most of those people are posers, the cars don't actually work. The few that do it right change their suspension geometry but I'm not sure you can buy the needed parts anymore.

taguy16

Yes, I know lowering your ride height significantly from stock by using shorter springs messes up your front end geometry something awful. I believe lowering a car that way moves your roll center to somewhere below ground level. The better way to do it is with drop spindles. or I suppose you could change the location of the pivot points of the control arms on the crossmember, which I think would be hard to do on one like what's on our cars.

I also know weight jacks are meant for wedging a race car chassis, not for lowering a street car body - that's why I don't plan on using them. The Ground Control and UMI "weight jacks" to me look more like fancy adjustable spacers than true weight jacks like you see on race cars which use a complicated group of parts with some welded to such a car's tube chassis. Besides, I believe the GC whatchamacallits come with 1000# 8 1/2" springs, which I think would be terrible to use on any car driven on the street on a regular basis.

Like I said, I just want to get rid of some of the unsightly gap between the tires and fender lips (which on the front of my car was a lot) for now and be able to use race car springs. I've never had much luck with trying to get Moog springs to get a car to sit right reliably. Every time I've installed the springs Moog calls for they have made the car they were installed on car sit way too high, even higher than stock in some cases. On the other hand, I don't want to lay the car low like a tuner car.

QwkTrip

iTrader: (22)

The spring rates for weight jacks used to come in 25 lb/in increments. They don't tell you that unless you ask though. I don't think they have as many choices these days but the point is call and discuss your options. I have multiple springs in my garage that I've bought through the years.



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obeymybird

iTrader: (4)

Like Qwk said go with weight jacks from whoever 850-950 would be ideal for the guy that wants a great handling street car that can still cut up the autox track.175 in the rear will be fine as I run 200s and it is a touch stiff for my taste. And get koni yellows front and back anything less will be a waste and the car will suffer.

I can tell you right now all the fast thirdgen street cars/track cars are all running weight jacks in the front.