Looking at upgrading suspension for my 1988 IROC convertible, lots of bumps and shakes going over anything but smooth pavement.


What would you recommend as the best complete and affordable suspension package? I drive my IROC on the weekends and occasionally on weekdays. Don't race, just want to have a car with a suspension that rides well/comfortably and can corner confidentially. I don't want to have to mix and match parts- would prefer to buy a complete front/rear kit.


Thank you for any assistance!

 

Your suspension is 28 years old, those old dried up pieces are not performing like new, definitely time to freshen up! Moog factory replacement parts, poly sway bar bushings and end links, Koni struts and shocks. Eibach springs if you want to go lower. After that, a good alignment, and some good tires. Tires are significant in cornering confidence, it doesn't matter what your suspension set up is if you don't have the tires that can hold the G's.

Stay away from Hotchkis, their spring rates are LESS that your factory IROC's.

 

It get's difficult to get long winded on here with explanations.

Whether your looking for a complete or partial suspension upgrade I would recommend talking to a reputable manufacturer so that you have a complete understanding of what upgrading each component will do to your car. The last thing you want to do is spend money on a component that is not necessary for what you are trying to accomplish with your car.

It won't cost you a dime to call us so we can discuss in detail what you want to achieve with your car and your budget to accomplish it.We have a complete line of products for 3rd Gens. and are always building and testing new products.

http://umiperformance.com/catalog/in...=index&cPath=6

Craig

 

Thank you for the advice plum92_camaro. Craig I will give you guys a call, thanks.

 

I've bought pretty much all UMI suspension components for my '84 Trans Am build. It took a couple years to accumulate everything because I only bought parts when they had 4th of July & thanksgiving sales. Very happy with all my purchases. Their parts are very well made.

 

Thanks for the positive feedback battman!!

We strive to be the best in quality and customer service.

Craig

 

To be honest, from what you are describing I would use Stock OEM style replacement bushings. The more performance oriented Poly bushings, all the way up to a full spherical rod-end all transmit increasing amounts of NVH into the cabin of the car.

By refreshing the bushings with stock types you will be restoring the factory ride quality to the car. Which sounds like what you are really aiming for. Most, if not all of the suspension upgrades will come with an accompanying decrease in ride quality, and an increase in NVH.

A mild lowering of the car, with a an adjustable torque arm, LCA relocation brackets, a good summer tire, and a more performance oriented alignment should provide a massive increase in handling with a minimum of negative effects.

I would also look at your steering parts. Old parts = slop and that ruins the road feel in the steering wheel.

I went almost the full beans towards suspension/steering. I'm running the UMI Roto-Joint PH/LCAs and a Founders TQ Arm and LCA relocation brackets. For the front I've got the Founders strut mounts, GW Del-A-Lum front bushings, etc. To me, the increase in NVH is marginal, but my engine is pretty darn loud, and shakes the car on its own. So its hard to tell the true increase in noise. Big bumps are transmitted very loudly into the cabin.

 

I like to get feedback on the roto-joint -vs- factory ride quality.

I get calls daily on this question. The difficult part responding to this question is that everybody's threshold on road noise is at different levels.

Certain components transmit more noise than others but In a nut shell roto-joints seem to be very comparable to Poly bushings on a comfort level for the most part.

Craig

 

Its very difficult for me to quantify it as I never did an A-B test with them. I had a set of Spohn Poly LCAs, then I put the car away for a few years after I blew up the stock LT1, and when I brought the car out it also had a host of other changes along with the Roto-Joint rear parts. So its hard to measure the difference between them. I put my car away with a bolt-on LT1 and a shorty headers. When I brought it out again it had an 11:1 AFR headed cammed LT1 and was now running LTs.

Noise can also be subjective, certainly the Roto-joints transmit more vibration to the chassis than a poly joint, and even more than a factory bushing. Roto-joints are much harsher over highway expansion joints. When I'm driving to Road America, there are some sections of I-43 and I-57 which are bad enough that the first time I drove it I had to pull over because I thought I had a flat tire, and that was in my old Pontiac G6. But my GTA has fairly significant wind noise because of the C&C tops not sealing perfectly and being hard to adjust. So I have more cabin noise.

The only thing I could recommend is to get a SPL Meter, find a rough and smooth stretch of road, and make several passes with cruise control set to control speed, recording SPL measurements for an average. Then replace with the Roto-joints and repeat. Then you could compare the averages in both ambient road noise as well as impact noise and have an factual figure showing if there is an increase in SPL levels.

But from a subjective standpoint I don't feel the Roto-Joints are harsh at all compared to the degree of feedback they provide. The rear end in my GTA has never felt more communicative. I can feel the minute differences when the rear end tracks over highway seams between lanes. It feels like it rolls slightly to the left or right. The rear end doesn't wander, but you can feel the roll. I enjoy that the roto-joints are cheaply rebuildable and greasable.

 

I used a UMI strut mount, TDS wonderbar and Energy Suspension poly sway bar bushings. KYB gas shocks and struts.
This took care of 90% of the creaks and pops from the suspenion. Increased the handling and took the body roll out. The car rides really nice and have not noticed any added road noise. This made a HUGE difference in my vert and did not break the bank. I want to get some Alston SFC's next but just not in the budget yet.

 

This is why I left the poly on the chassis side, and Del-Sphere on the axle side! When I got the Jegster PHB lowering bracket, I maxed out the shank threads. I think I'm ok, but I wish someone made the Roto/Del-Sphere rod ends with a longer threaded shank on it.
Bill, maybe you should extend your rod...err, you're PHB.

And those collars in the bag are very important to be right sized.

 

The UMI roto-joints already have the collars as part of the sphere. You can see it on this pic.

 

I have almost all umi and red poly bushings in my stock 92z vert and after I completed it and put on Yokohama es100 on all 4 corners I took a hard corner about 45 or 50mph and cracked my windshield. Obviously my next purchase will be frame connectors. The car handles like a go-cart and adds a ton of fun to my mid-life crisis.

 

If anybody needs any info or pricing feel free to give me a call here at the shop.

I can put together a custom package depending on your application and budget.

Craig

 

What is best time to call?