Front and rear spring rates question
Thread Starter
Melting Slicks
Joined: Jan 2002
Posts: 2,238
Likes: 4
From: Milan
Front and rear spring rates question
My rear leaf spring is damaged. In the center there is a crack so I bought an used one.
The used one comes from a 96 LT4.
The original suspension pkg in my car is FE1 (the soft base package for a '90 ).
I thought: “ ….good! This spring from a LT4 will be with a rate stiffer compared to my FE1 soft base package…” WRONG!! Even the Z51 on a ‘96 LT4 is lower in rate compared to a FE1 on a 90!! See this link: http://www.zr1.net/ZR1_suspension.html
The only think I know about the spring I purchased is that it comes from a 96 LT4. I don’t know the suspension package. If it comes from a FE1 the rate will be 26.0 N/mm (the 90 FE1 was 39.9 N/mm!), if it comes from a F45 the rate will be 26.0 N/mm and if it comes from a Z51 it will be 33.0 N/mm.
Stamped on this spring there are some codes. Could I have additional information (rates) from these stamped codes?
If I install this slow rate rear spring I need to use a front lower rate spring too?
The LT4 engine is only on 96 Grand Sport corvette?
The GS corvette is only a 96 production? It exists a GS convertible?
-Thanks-
-Beppe-
The used one comes from a 96 LT4.
The original suspension pkg in my car is FE1 (the soft base package for a '90 ).
I thought: “ ….good! This spring from a LT4 will be with a rate stiffer compared to my FE1 soft base package…” WRONG!! Even the Z51 on a ‘96 LT4 is lower in rate compared to a FE1 on a 90!! See this link: http://www.zr1.net/ZR1_suspension.html
The only think I know about the spring I purchased is that it comes from a 96 LT4. I don’t know the suspension package. If it comes from a FE1 the rate will be 26.0 N/mm (the 90 FE1 was 39.9 N/mm!), if it comes from a F45 the rate will be 26.0 N/mm and if it comes from a Z51 it will be 33.0 N/mm.
Stamped on this spring there are some codes. Could I have additional information (rates) from these stamped codes?
If I install this slow rate rear spring I need to use a front lower rate spring too?
The LT4 engine is only on 96 Grand Sport corvette?
The GS corvette is only a 96 production? It exists a GS convertible?
-Thanks-
-Beppe-
Melting Slicks
Joined: Apr 2000
Posts: 3,198
Likes: 2
From: Northern CA
Re: Front and rear spring rates question (conv90)
If the spring code is RHZ, it is probably from a '96 FE1.
The LT4 is available on all '96 regular, CE, and GS models, coupe and ragtop. GS is '96 only. There is a GS ragtop.
The LT4 is available on all '96 regular, CE, and GS models, coupe and ragtop. GS is '96 only. There is a GS ragtop.
Melting Slicks
Joined: Jun 2002
Posts: 2,168
Likes: 16
From: Phoenix AZ
Re: Front and rear spring rates question (conv90)
To answer your question about having to change the front spring, I don't think it will be necessary as long as it doesn't cause problems with the car's handling (oversteer/understeer) and even then changing sway bars can help bring it back to neutral. I have found in my track testing that softening up the rear spring can be beneficial because it allows more weight transfer to the rear under acceleration. It also makes for a smoother riding car on the street. I am using a base spring on the rear of my street car and a Z51 spring on the front and the ride and handling are both much improved over the Z51 front and rear setup.
Burning Brakes
Joined: May 2001
Posts: 1,163
Likes: 13
From: Coto de Caza CA
Re: Front and rear spring rates question (vetracer)
The front Z51 with base rear works great. I thought it sounded nuts, but then I got to try a car with that setup, it put power down great and turned even better. :cool:
Thread Starter
Melting Slicks
Joined: Jan 2002
Posts: 2,238
Likes: 4
From: Milan
Re: Front and rear spring rates question (RX7 KLR)
The front Z51 with base rear works great. I thought it sounded nuts, but then I got to try a car with that setup, it put power down great and turned even better. :cool:
Base rear on a'84 = 72.0 N/m
Base rear on a '86 = 39.0
Base rear on a '90 = 39.0
Base rear on a '96 = 26.0 !!!!!!
Z51 on a '96 = 33.0
My new rear spring comes from a 96 but I don't know the suspension package.
I can say only it is more larger (over 4") at the ends ant is seems a little thinner than my cracked old base rear spring.
Is there a way to raise the rate of a spring? (spacers..... or others tricks..)
Thanks
-Beppe-
