Z51 Suspension Determination

[SatansVette]

Greetings all;

I'm trying to figure out a way to determine whether or not my 1985 Corvette has the Z51 suspension. Neither a shop manual, my owners manual or the actual vin # seem to shed any light on this. Is there a way to determine such without such guess's such as the old standbye of measuring the number of times your steering rotates?

 

[vetteboy86]

That is one of the ways i was told. Isn't their an RPO code inside your center console that will give you that code. I also believe that your car should have Bilstein shocks if original which isn't a great possibility. I am not sure if the 85 had the aux cooling fan or not. I will check some more.


good luck
craig

 

[Jeffvette]

Welcome to the group.

Z51 had a quick ratio steering wheel. It should be 2-2.25 turns lock to lock. Base will be 2.75 turns. Also, there should be a RPO code in your center console that will say Z51. Also a larger front sway bar, 16x 9.5 wheels, oil cooler, booster fan in front of radiator and the Lower control will be stamped with Z51

What part of Portland are you in?

 

[SatansVette]

Well... years ago, when I rebuilt the suspension, I replaced the Steering rack and pinion with a NEW Z51 Steering rack (as I was unsure then of the suspension I had as I was simply ignorant to the issue), but now I don't want to base the determination of a Z51 suspension, on the steering rack.... see what I mean? I did the same with the shocks and wheels, but did replace with 9.5" wide wheels. This time, I am replacing all bushings... ALL bushings, Ball Joints, Tie Rod Ends, Rear Spring, Bilstein shocks and want to order the right ones, etc. Oh yes, and I restored the interior years ago and wouldn't you know it... can't locate the Service decal... ! I think it is Z51 suspension but just not sure... I'll see if I can find a stamping on the A Arm I do have the oil cooler and the Aux fan. I live in North Portland, off the Willamette river...Know the area?

 

[c4cruiser]

The Natioal Corvette Museum offers copies of the build sheet and the dealer window sticker. The build sheet (which is probably stipp glued to the forward top portion of the gas tank has all of the RPO codes that were installed on the car. The window sticker will have the options by name and the cost of the car and the name of the dealer it was sent to.

Go to https://www.corvettemuseum.com/library-archives/build_sheets/index.shtml where you can order the documents. The NCM also had dealer brouchures for all C4 years available in the Store for $5.00. You can surf around the site from the main page to see if they still have them.

While you're there, consider joining the Museum. The NCM is an absoutely tremendous place to visit and the membership dues help keep it going. The $50 annual dues are fully tax deductible and you get discounts when you buy from the store. Call the NMC toll-free number to ask any questions you may have. Great people and a great orgainazation!!

 

[SatansVette]

That sounds like a great idea... thanks for all the input.

 

[WhalePirot]

sticker under driver side rear stowage cover?

That's where my car lists the Z-51 option, on the RPO sticker. Given that you have the fan, which my car never had, and the oil cooler, I'd bet your car is a Z-51.

 

[c4cruiser]

RPO Z52 also included the secondary fan and the oil cooler. But you got a slightly slower rack (2 3/4 turns) and slightly smaller sway bars, softer springs and shocks compared to the Z51 package.

 

[Jeffvette]

Both Z51 and Z52 got the quick ratio steering

 

[Jeffvette]

I'll see if I can find a stamping on the A Arm I do have the oil cooler and the Aux fan. I live in North Portland, off the Willamette river...Know the area?

I would say you have the Z51.

I know the north end of Portland somewhat. I'm usually over in Beaverton hanging out with friends. Let me know if you need some help with your car.