Spring Codes

[Ccmano]

This should be a sticky.... courtesy of Hib Halverson, found this researching for a friend. Thank you Hib!

It seems I have an FHA on my 90’.

H


C4 Spring Code Chart

compiled by Hib Halverson
©2007 Shark Communications

Preface Notes:

1) GM had two RPO subsystems during the C4 era. There were engineering RPOs and marketing RPOs. What consumers knew as Z51 or Z07 was actually a combination of the FE3 (96) or FE7 (84-95) HD suspensions with other performance-related options. Some GM parts data refers to FE3 or FE7. When those RPOs are listed, it refers to cars optioned with either Z51 (84-91, 96) or Z07 (92-95).

2) In MY89-91, Selective Ride Control (SRC), which many refer to by its RPO, FX3, could be ordered in combination with Z51, however, a little-recognized production change which always occured in those MYs when those two RPOs were ordered together was a downgrade to base level (FE1) springs, front lower control arms and stabilizer bars. In those MYs the only conditions under which FE7 was present were; 1) if the car was ordered with Z51 and without FX3 or 2) it was an 90 or 91 Corvette Challenge car.

3) For MY92-95, FX3 and FE7 was added. A new RPO, Z07, was released for this combination. For MY92-95, FX3 was, also, available as a stand-alone option.

Coupe, front*

HMZ 84 w. Z51
BMB 84 base, 85-87 with w. Z51
HKX, HMP 85-87 base
FHA 88-91 base, 89-91 w. FX3&Z51, ZR1*
FHB 88-91 w. Z51
AA 90-91 w. ZR1*
FSS 92-95 base, 92-93 w. FX3
FSK 92-95 w. Z07
FSM 92-95 w. ZR1*
HA 94-95 w. FX3
22173028 96 base
17999032 96 w. Z51
Per Mark Haibeck all ZR1’s he has seen came with FHA.

Convertible, front

HMN 86-87
FHC 88-91 base, 89-91 w. FX3
FSR 92-95 base
JA 94-95 w. FX3
22173029 95 w. FX3
17999031 96

Coupe, rear

BMF 84 base
BMH 84 w. Z51
NYR 85 base(?) 86-93 base, 89-90 w. FX3&Z51, 90-91 w. ZR1
NYU 85-91 w. Z51, 92-95 w. Z07
RHY 92-95 w. ZR1, 96 w. Z51
RHZ 94-96 base

Convertible, rear

RCA 86-96
22112254 94-95 w. FX3

[HAWAIIZR-1]

Thanks for posting Hans! I started trying to read this in bed waking up at 5:30 am Saturday. Hell with this and need to wake up and have coffee first.....too many codes for my brain LOL!!


Sent from my iPhone using ZR-1 Net Registry

[DRM500RUBYZR-1]

Great post and information, and all seems 100% accurate.


However, try finding a 100% correct new replacement spring.


They generally only offer 1 or 2 for the entire C-4 lineup, and the mounts / blocks are not already permanently fastened to the spring.


Because of this we often try to find undamaged used springs, with the correct code, rather than getting the new replacements which often result in poor ride height, a change in ride quality, and "movable" mounts.


Try explaining to the suppliers that you are searching for an FSM code new spring.


p.s.


If your ZR-1 is towed, DO NOT let them strap the car down by the frame rails, but rather have them only use tire/wheels straps!!!


When they tighten up the straps on the frame, pulling the car down it makes the spring flex in an unorthodox way, often causing it to begin splitting leading to failure.


Marty

[Marc Haibeck]

Hi Hans,

All ZR-1's have a FHA front spring. I have never seen AA or FSM springs.

[Ccmano]

Originally Posted by Marc Haibeck

Hi Hans,

All ZR-1's have a FHA front spring. I have never seen AA or FSM springs.

Thanks for the update Mark. Since posting this I’ve run into 3 Z’s with FHA front springs, including my own. To my knowledge Hib is usually pretty good with this type of information. I will add a note to the OP.
H

[Erik]

Originally Posted by Ccmano

Thanks for the update Mark. Since posting this I’ve run into 3 Z’s with FHA front springs, including my own. To my knowledge Hib is usually pretty good with this type of information. I will add a note to the OP.
H

Anyone have a clue what the spring rate difference is between the three?

[Joelbbvette]

Originally Posted by Marc Haibeck

Hi Hans,

All ZR-1's have a FHA front spring. I have never seen AA or FSM springs.

I have a photo of a 90 ZR-1 that was purchased with 600 miles and an AA Spring. Definitely original, system will not let me load a photo.


Joel

[Corvette95]

Originally Posted by Joelbbvette

I have a photo of a 90 ZR-1 that was purchased with 600 miles and an AA Spring. Definitely original, system will not let me load a photo.


Joel

Doing some research on ride heights brought me to this thread, I am attaching the build sheet to my 90 with an "AA" front spring. My car is early and also has steel half shafts. If anyone else has the AA spring (Joelbbvette) could you measure the front ride height?

[Corvette95]

Anyone know why the front AA springs have an asterisk beside it?

[Erik]

Originally Posted by Corvette95

Anyone know why the front AA springs have an asterisk beside it?

Did yours have an AA tag on the spring?