Welcome to the Corvette Forums at the Corvette Action Center!

73 RPO-Z07 Offroad Suspension & Brakes

Don Mason

Well-known member
Joined
May 10, 2005
Messages
59
Location
Georgia
Corvette
01 Convertible & 73 Coupe
This is my first posting on the site. I just found it earlier this week and it looks like there is a lot of expertise out there so I hope someone can help me out with my question. I have just purchased a 1973 L-82 coupe with what is supposed to be 18,000 original miles. The car sits visibly higher than other cars of this model. According to the 1973 GM Service Manual the car is about 2 inches higher in the front and an inch higher in the rear. These measurements were taken with the car sitting on 60 series tires and not the 70 series tires that were original equipment, so overall the car is probably even higher than it appears. My questions is if there is a way to determine by physical inspection if the car has the Z07 suspension and brake package and if the car would sit higher than normal with this package. The car came from the factory with no A/C, no P/S and no P/B. The seller says that he has the original invoice but he is still looking for it. I do not know if the build sheet is still anywhere on the car or not. The seller also gave me (what he claims) are the original tires which are Goodyear G-60 Polyglass tires. The spare has never been on the ground and the sticker is still on the tread. Once again, the Service manual says that the original tire was a GR70X15 and that there were no optional tire sizes. Any information would be appreciated. Thank you for your response.
 
Hey Don welcome tot CAC... I have a 73 Vette also if you need any info on the 73 vettes check out Toms web site on 73 Vettes there is a lot of usfull info at his web site for the 73 Vettes.. Hope that this helps you. If you have any questions you can e-mail me any time. Here is the link to his site.

http://1973-corvette.com/
 
No '73 Corvette was delivered with 60 series tires, they all had GR70s as you already know. I don't believe there was a ride height difference between the Z07 (or FE7) cars and regular suspension.

To find out for sure:
How many leaves on the rear spring?
Is there a rear sway bar?
What is the broadcast code on the shocks?
How many pins are holding in each brake pad?

Just as a guess, I would think that someone has changed out the stock springs for some aftermarket pieces. Are you sure the car has only 18K miles?
 
I agree with Vettehead Mikey. In fact if anything the Z07 suspension would ride lower than base. That's because they used 550 lbs. front springs which are stiffer, but about 1'' lower.
 
Thanks guys for your input so far. I will be under the car this afternoon after work so I can check out the items you have mentioned. I'm pretty sure the shocks have been changed, they are yellow and look fresher than the other components under the car. The car sends mixed messages about the mileage. The seller is a professional person and has been known to me for a couple of years. My wife has known him for about 8 years through her job. The car originally belonged to his brother and he has owned the car for the last 3 years. He is a quality individual and would not knowingly misrepresent the car and is only saying what he believes to be true. He did provide me with some work orders dated in the early 90s that reflect 15000 miles on the odometer at that time. On the other hand some things (like the suspension) appear to have been tampered with on the car and the incorrect air cleaner is on the engine. So the jury is still out on the mileage. I have already been told by one of the guys at Muskegon Brake that the heavy duty rear spring has 7 leaves and that the standard spring has 9 leaves. And yes, it makes sense to me that the off-road (or racing) package would have the car sitting lower than higher. I'll report back as the saga unfolds. Thanks again and I welcome input from anyone else out there.
 
Hello and welcome to the CAC.

I too have a '73, but with the L48, and like yours, my car rides about 2" higher than the manual says it should. Looking in to why has been on my 'to-do' list for a couple of years and I'm nearly there now so I'm very interested in any more detail on this.

John
 
A car with Z07 will have an 1.125-in front stab. bar. A rear bar and the bakes will have longitudinal caliper braces on the front two calipers. Also, the (J56) brakes will have two big cotter pins per caliper rather than on round pin. Lastly J56 has an adjustable proportioning valve.

As for trim height, I've not seen any car with HD springs and bars that sat excessively high.

I'm gonna bet the car has the wrong front springs and the wrong rear springs and/or wrong rear spring bolts.
 
Thanks guys for the added information. I was under the car last night and the rear spring does have nine leaves. I did not have a chance to check out the brakes, but I am 99% sure now that the suspension has been changed for what ever reason. Hib, thanks for the info on the brakes and sway bars, that is my next thing to look at.
 
Well guys thanks for all your input. All of my questions have been answered for now. I have verified that there are no HD brakes and no Z07 package. Oh well, It was nice to think about since only 400+ cars rolled out the door with these options. I'll just buy a pair of springs for the front from Mid America or Muskegon Brake and move on to other things on the car. Thanks again to everyone who responded and I am sure I'll be back with more questions as this project moves along.
 

Corvette Forums

Not a member of the Corvette Action Center?  Join now!  It's free!

Help support the Corvette Action Center!

Supporting Vendors

Dealers:

MacMulkin Chevrolet - The Second Largest Corvette Dealer in the Country!

Advertise with the Corvette Action Center!

Double Your Chances!

Our Partners

Back
Top Bottom