Guys,
I would like to upgrade the suspension on my 1988 IROC 5.7L/T56. My goal is to create the most optimized street set-up possible. No auto X or racing use. The car already has Hotchkis LCA's, SFC's, and Panhard bar, the rest of the suspension is completely stock.
This is what I am thinking please add or comment as you see fit, my budget is pretty much wide open at this point:

• Koni yellow shocks and struts.
• Alum control arm bushings
• Front and rear weight jacks ---- please help with spring rates and heights.
• LCA relocation brackets
• J&M Strut Mounts

This is where I am stuck..... what else should I be looking at upgrading?
I was going to do a UMI Road Race K member, but a lot of the posts I read said that this was bad weight to loose and could actually hurt handling performance.
I was also thinking of lowering about 1.5 - 2" but form what I was reading that would also effect handling in a bad way and to limit the lowering to about 1".
What is the best torque arm to go with? Is this one any good?
http://www.globalwest.net/tsc-20.html

Again I am looking for any other parts that are actually worth upgrading.

Thanks,
Clint

 

Polyurethane sway bar bushings and end links, if you don't already have them, a 3 point strut tower brace, and a bump steer kit if it will fit with your wheel setup. Other than that, at this point the best thing you can do is put the car on a diet. Lighter hood, light wheels without spacers or adapters, light brakes, aluminum driveshaft, mini starter, bucket seats, aluminum heads, aluminum engine driven accessories, and remove the spare if you don't drive great distances. Aftermarket a-arms are said to reduce a little unsprung weight as well and will save you the task of pressing the aluminum bushing housings in but they are pricey and not quite as beefy as the stock units if you're extremely hard on the car and like hitting things in the road with it.

For weight jacks, you want 750- 900 lb/in in the front and you want about a 5:1 ratio front to rear, so just divide the front rate by 5 and pick the closest rear rate(750:150, 850:175, 1000:200, etc). Height wise, 8" up front seems to be the ticket and 9 or 10" in the back. I can go from above factory to slammed down on the bump stops with this setup. For reference on ride, I have 850's and with the ride height about an inch under stock with the struts turned down to full soft the ride is firm but not bad... at 26" with the struts up a full turn it's a little rough. You can fine tune the handling if you are able to get the car on a set of scales, or picking up a plethora of sway bars from the junkyard or craigslist partouts for cheap and experimenting with rake, bushings and bar sizes until the car feels and looks right.

There is a lot more to be gained through different length ball joints, lowering the panhard bar, and other means of playing with suspension geometry, but none of that's really worth it unless you're auto-xing or road racing, chasing down those last few seconds and are able to calculate and test to get everything right and avoid throwing the car way off balance. The parts listed, a little tuning with heights, shock and strut settings and sway bars and a good alignment will make a really good handling street car that should hang with about anything else in the canyons or mountain roads, and should you decide to go beyond that you'd have a great base to start with.

 

Delum front control arm bushings,

If your rear are LCA hare solid with poly bushings replace them with some with hiem joints. A Rear Panhard with hiems as well as a rear panhard drop bracket.

Also what midnightfirews6 said.

 

When you say street do you mean comfort cruiser? Cause if that's you goal, you are headed in the wrong direction.

 

Good point

 

Not necessarily. Relatively soft springs, big sway bars, leaving the Koni's on full soft and reducing unsprung weight as much as possible would make for as comfortable a ride as you're going to get out of a third gen and it would handle fairly well. Rubber bushings do deflect a bit and absorb some bad ride quality with the stock or parts store shocks/sturts, but with a good set of high quality shocks and struts it's best to do away with as much deflection as possible and let the them do their job.

Moderately stiff springs and slightly less stiff bars will ride firm but not bad as long as you stay off the bump stops. As long as the car has a decent amount of travel, the spring rates are kept below 900lb/in, and Konis are used the ride will be bearable. The softer you go obviously the better the ride will be, though there is obviously a tradeoff between comfort and handling.

 

Thanks for all the input so far guys!

I guess I should have been more clear, I do not want it to be a comfort cruiser, I am looking for a good street suspension built for performance but not race car rough. Like midnightfirews6 said I " a really good handling street car that should hang with about anything else in the canyons or mountain roads"

So what torque arm setup? Is the De-coupling arm like the global west one worth it?
Also, can you recommend a tire and wheel size? I am thinking about 17" just don't know which brand and size is best to go with, I don't want to have to hack the car up at all.

 

You have a nice list of parts and some excellent advice here. I am very into my autoX so my set up is probably a little more than your looking for but i have all the parts you listed in your first post. My is that a lot of your parts list is only going to increase your wow factor if your building a street car. You don't need a tubular K-member or A-arms for a street car. I don't have any reason to give you not to run del-a-lums on the street but fresh rubber bushings or even poly bushings would probably suit your street car and your wallet very well. I'd recommend 750-800 front springs and 150-175 rear unless you have a hefty stereo then probably 200. Call Ground Control when you order, the techs at ground control can give you better advice than me. Knowing the weight of your stereo will help them if you know it.

If you already enjoy the handling and ride of your car, you would benefit most from only doing springs with slightly higher rates, shocks and struts, new bushings and ball joints, and maybe a good alignment (slightly performance, a lil extra +caster, maybe 1* of neg camber, 0 toe for the street). I mean weight jacks and Koni's alone is over $1000. How much you want to spend on what is already a great street machine from the factory?

Oh and torque arm. anything that gets the mount off of the tranny is good for a street car. IMHO the "best" is a custom one like unbalanced engineering makes for he fourth gen. it has a long arm and a short arm that work together to give you the best of both worlds. A short arm will react faster and work well with lower spring rates. A long arm is as good as stock (which is pretty good). Both the short and long arms have their advantages, I can't remember what they are but one is not "hand down" better than the other. I'm partial to the UMI units with the driveshaft safety loop.

 

I've read many places that a 9.5" wide wheel with 275's is an excellent set up. they say the 275's fit better on the 9.5" wheels than the 9" wheels.