1990 ZR-1 Suspension - Restoration or Upgrade to 93+?

[Erik]

As the old girl is 30 years old, and though low mileage and well kept, I'm guessing there are lots of rubber parts in the suspension that ain't what they once were.Plus, time moves on, and even in the run of the ZR-1, there were improvements made. So, my question is, do I just restore it to what she was in 1990, or go mostly stock, and upgrade to the 1993+ FX3 setup. Hib Halverson has written a fair bit about the changes, and John Heinricy sure seemed to think they were a good thing. I understand the Bilstein controller needs to be updated too, but it isn't a big thing. Springs change also.

So my thoughts are first:
New stock FX3 Bilsteins or 1993 FX3?

And here's where it gets harder:
New bushings.

From what I understand, the stock bushings are no longer available. As I'm planning to keep my ZR-1 as a grand tourer, and the roads in this part of the world are not exactly smooth, I'd prefer not to add any impact harshness.

So what's the best option I have for bushings?

What are my goals? Great steering feel and response, a comfortable controlled ride with minimal impact harshness, and great stability.

Finally, I know there are some rear suspension kits available. Is there anything I want to look into there?

And yes, I'd prefer to keep it stockish, and not go to coilovers.

[secondchance]

To start, 90 to 91 from what I understand has stiffer springs (compared to 92 to 95) and softer shocks (again, relative to later Zs). Later FX3 shocks will bolt right in but may require later controllers. I believe actuators are the same. I think SRC controller may interconnect with BCM and have no clue if later controller will play nice with 90 to 91 BCM. If you go this route, may consider changing springs also. I would recomend trimming off pucks at the end of front spring to reduce higher ride height Of later cars. This probably was done to keep front air dam from scraping due to softer spring.

As for the bushings, you might consider Super Pro bushings which are softer compared to urethane bushings.

https://www.zr1.net/forum/showthread.php?t=31253

https://www.corvetteactioncenter.com...usp_chart.html

[Erik]

Originally Posted by secondchance

To start, 90 to 91 from what I understand has stiffer springs (compared to 92 to 95) and softer shocks (again, relative to later Zs). Later FX3 shocks will bolt right in but may require later controllers. I believe actuators are the same. I think SRC controller may interconnect with BCM and have no clue if later controller will play nice with 90 to 91 BCM. If you go this route, may consider changing springs also. I would recomend trimming off pucks at the end of front spring to reduce higher ride height Of later cars. This probably was done to keep front air dam from scraping due to softer spring.

As for the bushings, you might consider Super Pro bushings which are softer compared to urethane bushings.

https://www.zr1.net/forum/showthread.php?t=31253

https://www.corvetteactioncenter.com...usp_chart.html

My understanding is that the 93+ Struts got different, and better valving, so they could soften the springs and have the better struts look after it.

Thanks for the heads up on the Super Pro bushings. I'll take a look.

[Erik]

Maybe @hib halverson has some thoughts on this.

[Erik]

Oops. And after rereading a bit, the title should read "... or upgrade to 92+".

[Vette73]

Yeah urethane sucks....I mean yeah if you have roads where its as smooth as your hardwood floors in your house go for it..

I lowered my 91 in the back and totally love the look but replaced with urethane....Not happy with the ride on uneven roadways..

Going to put my stock bushings back in..Their in decent shape...

[CamP]

What do you mean by low mileage?

My '90 has 33k miles and all the rubber bushings are original and still in great shape. Still rides like a new car.

Surface cracks in the rubber doesn't necessarily mean the bushings are bad. In a low mileage car, those cracks are often superficial and the rubber underneath is still good.

[Erik]

Originally Posted by CamP

What do you mean by low mileage?

My '90 has 33k miles and all the rubber bushings are original and still in great shape. Still rides like a new car.

Surface cracks in the rubber doesn't necessarily mean the bushings are bad. In a low mileage car, those cracks are often superficial and the rubber underneath is still good.

But rubber does age. I remember reading ages ago that rubber bushings had a service life of about 15 years. Yes, this would be effected by sunlight, air, heat cycles, etc. So our pampered babies could be expected to exceed that to some degree. But any rubber part, once it's hit it's 30th birthday, is not gonna be what it was when new.

[Erik]

Originally Posted by Vette73

Yeah urethane sucks....I mean yeah if you have roads where its as smooth as your hardwood floors in your house go for it..

I lowered my 91 in the back and totally love the look but replaced with urethane....Not happy with the ride on uneven roadways..

Going to put my stock bushings back in..Their in decent shape...

Yeah, not a lot of suspension compliance in other areas to make up for that impact harshness.

[CamP]

Originally Posted by Erik

But rubber does age. I remember reading ages ago that rubber bushings had a service life of about 15 years. Yes, this would be effected by sunlight, air, heat cycles, etc. So our pampered babies could be expected to exceed that to some degree. But any rubber part, once it's hit it's 30th birthday, is not gonna be what it was when new.

I use to buy into that time thing until I replaced perfectly good rubber bushings. Lot of effort and money for nothing.

Now I focus only on mileage wear. If it's old but low mileage, I leave it alone.