Help With Suspension Codes Please!
Team Owner
Joined: Dec 2007
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If it was the small stuff, wait until you get stiffer parts in, it feels better.
Thread Starter
Le Mans Master
Joined: Oct 2007
Posts: 9,675
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From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
2024 C5 of the Year Winner - Modified
2023 C5 of the Year Finalist - Modified
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St. Jude Donor '09-'10-'11
See how you like the Big bar, heim jointed, Bilstein, soft spring setup first; it will be virtually identical to mine. Here is how mine handled Infinion:http://s161.photobucket.com/albums/t...inion15433.flv
Here is a picture at a high speed autocross from a few years ago with the stock suspension just after I lowered it.
I think the bigger bars would take most of the lean you see out.
Thread Starter
Le Mans Master
Joined: Oct 2007
Posts: 9,675
Likes: 3,410
From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
2024 C5 of the Year Winner - Modified
2023 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
St. Jude Donor '09-'10-'11
Just an update, like everyone thought I am stuck with the base FHA and NYR spring rates. I still want to know where the FE7 code came from, though? 
If anyone could explain the codes to me Im just curious. Seems there are some conflicting theories. Thanks for all the help figuring this out. 
If anyone could explain the codes to me Im just curious. Seems there are some conflicting theories. Thanks for all the help figuring this out.
Drifting
Joined: Oct 2008
Posts: 1,934
Likes: 92
From: Rochester Hills Michigan
Just an update, like everyone thought I am stuck with the base FHA and NYR spring rates. I still want to know where the FE7 code came from, though? If anyone could explain the codes to me Im just curious. Seems there are some conflicting theories. Thanks for all the help figuring this out.
If anyone could explain the codes to me Im just curious. Seems there are some conflicting theories. Thanks for all the help figuring this out. All I can think of is that the spring codes on the build sheet are controlled by FX3 even if FE7 (from Z51) is called out. Dunno. A GM engineer told me that the FX3 shocks were tuned for the base springs, not for the stiffer springs.
If you decide to go for an FHB spring, be careful. My '92 has an FHB spring, but it is not the same rate used for '88-'91. '88-'91 is 90 N/mm, but '92-'95 is 73.2 N/mm.
Thread Starter
Le Mans Master
Joined: Oct 2007
Posts: 9,675
Likes: 3,410
From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
2024 C5 of the Year Winner - Modified
2023 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
St. Jude Donor '09-'10-'11
Sorry to hear that.
All I can think of is that the spring codes on the build sheet are controlled by FX3 even if FE7 (from Z51) is called out. Dunno. A GM engineer told me that the FX3 shocks were tuned for the base springs, not for the stiffer springs.
If you decide to go for an FHB spring, be careful. My '92 has an FHB spring, but it is not the same rate used for '88-'91. '88-'91 is 90 N/mm, but '92-'95 is 73.2 N/mm.
All I can think of is that the spring codes on the build sheet are controlled by FX3 even if FE7 (from Z51) is called out. Dunno. A GM engineer told me that the FX3 shocks were tuned for the base springs, not for the stiffer springs.
If you decide to go for an FHB spring, be careful. My '92 has an FHB spring, but it is not the same rate used for '88-'91. '88-'91 is 90 N/mm, but '92-'95 is 73.2 N/mm.
Drifting
Joined: Oct 2008
Posts: 1,934
Likes: 92
From: Rochester Hills Michigan
Yeah if I change springs Ill want the '88-'91 Z51, which I believe is 115 N/mm. The FE1 spring I have now is 90 N/mm. I was thinking of just saving up for a new spring with 0 miles on it from van steel or VBP. Do these leaf springs lose stiffness over time or with more use?
The springs can delaminate. That is visible when you look at it. I haven't heard of one sagging, but my '92 only has 18,000 miles
Here's my build sheet. My car has the stiff springs and 30/24 mm bars...
Melting Slicks
Joined: Sep 2003
Posts: 2,269
Likes: 118
From: N. Babylon NY
Kubs
as you may recall from my other thread, I am trying to find a good compromise for 92 fx3 6spd.
I have the VBP front 1070 front spring and a 488 rear spring. What I am finding is that most of the ride quality is felt from the rear spring (as also pointed out to by MK ZR1). When I first installed the rear spring it felt way to stiff. I have since lowered played with the ride height (lowered the rear) and it seems to ride a little better. I drove it to Atco NJ last week from NY. After speaking with Gary several times from VBP I may only reduce the rate by 15%. IMHO it drives better with the stiff springs. I can't wait to go to LimeRock next season.
Not that it pertains to this thread-but my car went a 13.28 @ 106mph at Atco. Stock with tri-y LT headers and 1.6 rockers and over 100,000 miles. Got to love these cars!
Steven
as you may recall from my other thread, I am trying to find a good compromise for 92 fx3 6spd.
I have the VBP front 1070 front spring and a 488 rear spring. What I am finding is that most of the ride quality is felt from the rear spring (as also pointed out to by MK ZR1). When I first installed the rear spring it felt way to stiff. I have since lowered played with the ride height (lowered the rear) and it seems to ride a little better. I drove it to Atco NJ last week from NY. After speaking with Gary several times from VBP I may only reduce the rate by 15%. IMHO it drives better with the stiff springs. I can't wait to go to LimeRock next season.
Not that it pertains to this thread-but my car went a 13.28 @ 106mph at Atco. Stock with tri-y LT headers and 1.6 rockers and over 100,000 miles. Got to love these cars!
Steven
Last edited by STEVEN13; Dec 5, 2009 at 05:51 PM. Reason: Added comment
Drifting
Joined: Oct 2008
Posts: 1,934
Likes: 92
From: Rochester Hills Michigan
There were big complaints about the ride of the '84 Z51. They softened the front and rear spring rate for '85 and used bigger bars. They went to a higher than '84 front rate in '88, but never went back to the '84 rear spring rate. It took me a while to realize that the high rear spring rate is what the ride complaint was with the '84 Z51.
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Melting Slicks
Joined: Feb 2006
Posts: 2,753
Likes: 14
From: backwoods upstate ny
in lab 'life cycle' flex testing, the fiberglass springs last so long that life expectancy is not an issue...fg life is many times what steel spring does.
heat is an issue... if you're sitting in gridlock, beauty sunshine, 12:01 pm on 21jun, a/c running, no external breeze, on fresh blacktop -- your rear spring is in trouble...exhaust pipe 'heat shields' help bunches but not total reprieve.
btw, conversion factor: N/mm x 5.71 = lb/in
heat is an issue... if you're sitting in gridlock, beauty sunshine, 12:01 pm on 21jun, a/c running, no external breeze, on fresh blacktop -- your rear spring is in trouble...exhaust pipe 'heat shields' help bunches but not total reprieve.
btw, conversion factor: N/mm x 5.71 = lb/in
Last edited by redrose; Dec 5, 2009 at 07:34 PM.
Thread Starter
Le Mans Master
Joined: Oct 2007
Posts: 9,675
Likes: 3,410
From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
2024 C5 of the Year Winner - Modified
2023 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
St. Jude Donor '09-'10-'11
Thanks for the info guys. I was actually about to trade what I thought was my Z51 (NYU) rear spring for an '84 base (BMF) spring, until I found out I dont have the Z51 rates. I think if I were to change rates I would go with the FHB and BMF spring for an in between soft and stiff setup. All I have to do now is save money for it. Ill run the soft springs more for now.
