ZR-71

I don't think I've ever seen this discussed here. Someone in the C4 section was asking about options on his car and I pull out the Black Book and look. But I came across something that's not clear.
I know our Z's have FX3 suspension, but in 1990 there was a Z51 suspension and from 1991 to 1995 there was a Z07 suspension. Both the Z51 and the Z07 are described as heavy duty suspension and heavy duty brakes. Now the Z07 also says it includes FX3 suspension. But nowhere in the ZR-1 description does it say heavy duty suspension or heavy duty brakes. Now I'm sure the ZR-1 has heavy duty suspension and heavy duty brakes even though it's not described as such. But if someone has a non ZR-1 with FX3, would they also have heavy duty suspension and brakes? And if not, why would the ZR-1 have the heavy duty stuff without having Z51 or Z07?
Just seems very confusing.

glass slipper

Here's everything you ever wanted to know about C4 suspensions:
http://corvetteactioncenter.com/tech/c4/susp_chart.html
The ZR1 included the heavy duty brakes/big brakes but did not include the "heavy duty" suspension. Z51 and Z07 got you the heavy duty (harder durometer) lower control arm bushings on the front and stiffer springs/stabilizer bars front and rear. FX3 does not get you the heavy duty suspension. The ZR1 has the big brakes, FX3, and no heavy duty suspension...in fact, the ZR1 has its' own spring rates that are actually softer than Z51/Z07 and starting in '92, the spring rates are even softer than the base car. Enjoy.

Barbara_S

Hey Glass Slipper,thanks - I just bought a full set of NOS control arms for my 88 Z51 car and didn't realize there was a different stock bushing. I won't be putting them on.

ZR-71 , since I have a Z51 and a ZR1 I keep wondering what GM was thinking putting a soft suspension in the fast car too. I may be wrong, but it seemed like they didn't sell all that many Z51 cars. Maybe the customers of the 88 and 89 cars caused the suspension decision.

Aurora40

I believe Hib had a write-up about this in the Heart of the Beast a few issues back. The ZR-1 does include the Z51 suspension. But apparently if the car had Z51 and FX3, it didn't get the Z51 spring rates and such. But you can see our cars have the power steering cooler that the Z51 includes. I believe this was true of any car ordering FX3 and Z51, not just ZR-1's.

I think it had to do with testing/certifying the adjustable shocks with only the base suspension. Once they'd done the testing with the stiffer springs, they packaged it as "Z07".

But your ZR-1 RPO label should include Z51 on it. Mine does. I don't know why it didn't include the Z51's faster steering rack?

WVZR-1

I believe you'll only find Z51 on '90 cars. '91 and later cars showed FE1 for suspension no Z51, I don't believe there are exceptions. It was not at all uncommon in the early mid '90s that an RPO was treated as a sales option and INCLUDED options not included on the SPO label.

FASTAZU

After reading this I checked the 90 I had ...FX3 & FE7 H.D. F&R SUSP. Also says Z51 PERF HDLG PKG ??

My 91 only lists FX3 & FE1

glass slipper

I just checked my '93. It has FE1, FX3, and J55 (big brake package). No Z07.

Aurora40

Ah, interesting!

WVZR-1

I've never spent any time researching it by "my guess"is that it would have to do with the Challenge cars and a required availability to satisfy the build requirements! That would explain the 88/89 cars maybe. It likely was included on most "mules" etc and just went to the '90 production as a standard RPO. Maybe to use the builds already completed. I've never tried my car "lock to lock" for total turns but I assumed it really was there. Just a "WAG"!

Aurora40

My previous 'vette was an '87 with Z51. I think the Z has the standard steering rack. The Z51 one was absurdly quick.

WVZR-1

Bob,

To correct my "WAG"!

There's only one rack for '90 cars regardless of options, base cars & ZR1's. I think the "real deal" on your '87 was Z52(SPORT HNDLG PKG) or just FE7(HD SUSP). That shows a different part # rack vs standard suspension base cars.

terryszr1

i have 2 90s 1564 seems to have softer springs and seems to turn around alot slower than 2924 it turns on a dime and the springs are alot stiffer . i bought the 2924 car off the original owner, who had every piece paper for all work on the car. which show no work or changes to the suspension. how can one find out whats what / ? can one get numbers off the rack aor springs directly/ thanx for any help

Aurora40

My '87 was definitely a Z51 car. Maybe they dropped the steering rack at some point from that package?

WVZR-1

I think it was only the FE7(HD SUSP) or a Z52(SPORT HANDLG PKG) that gave you the rack! There's no mention of a service rack for any Z51options that I see.