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What's the recommended replacements for STOCK front and rear replacement springs. Have a buddy with 200K+ on a 96 SS that is sagging quite a bit. What to replace with???
 

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Can't answer, but occurred perhaps many out there would love your sacked out coils. Sell, don't discard.
 

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There's been no Exact replacement of recent. Some suppliers offer replacement SS springs but exact specs are unknown. There are a couple of close replacements from moog. Slight height differences, plus or minus and same for stiffness. Any preferences?
For rears:
5387 - a touch stiffer at 157lbs/in vs stock 154. negligible. and a touch higher, should sit about 0.3" (1/4 inch basically) higher.

5415 - 10% stiffer at 170lbs and 0.1" shorter

6381 - 30% stiffer at 199lbs and same height as 5387 with stock weight.
If you have more junk in the back, it would drop less than with a stock spring. I run these in the 91. You may want to pick different shocks depending on what kind of roads you have. They were too much for our rough new york roads with the soft bilsteins and would be loose when jacking up the rear. I found the station wagon(shorter) kyb to work great with them.

Fronts are a little tougher getting something close 'out of the box'. Are you adverse to cutting them?

584 - touch stiffer at 457lbs/in vs 440 stock and should sit 0.5" higher once settled. So if you cut the spring 1/4" shorter, you would be right at stock height and about 5% stiffer than stock

586 - little softer at 433lbs/in and around 1/8-3/16 inch shorter.

other choices require cutting for sure
 

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I'll have to do a little digging, as the name of the company escapes me at the moment, but I bought stock Impala specification springs from an aftermarket manufacturer last year.

I didn't like that both Eibach & Hotchkis rear springs dropped my car so much that my old exhaust system tail pipes (Clear Image) used to scrape when entering and exiting my dad's driveway.

I couldn't load the trunk with anything without it significantly dropping the rear of the car too much for my liking.

I also was not impressed/happy with the air bag route either, so that's what made me choose the stock spring height.

My pic in the SIG is with those springs installed.

....Okay, I was able to find the contact information for the company on my work PC. Here ya go:

Coil Spring Specialities: 785-437-2025

BTW, I also found a full-size photo I took right after install so you can see the ride height too.

 

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I can't remember the brand but I replaced my rear shocks with air shocks. Easy mod and they work very well. Adjustable and yields a solid ride.
 

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I had a thread a long time ago where I was decoding springs, but can't seem to find it. I'm fairly certain the stock SS rate was closer to 120 #/in. If you still have your SPID, post up your spring codes. Note if it's an Impala or Caprice too. RPO's for rear springs start with 8 and 9, like 8RS & 9RS, fronts will be 6 and 7. I can cross reference the RPO with the spring broadcast code.

I'm actually looking for a stock rate or SOFTER rear spring that also lowers the car about 1.5". I currently have the Moog 750 #/in front springs, and the car is still tail happy trailbraking into the corners, so trying to reduce rear roll moment, and roll stiffness.
 

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I'm actually looking for a stock rate or SOFTER rear spring that also lowers the car about 1.5". I currently have the Moog 750 #/in front springs, and the car is still tail happy trailbraking into the corners, so trying to reduce rear roll moment, and roll stiffness.
What Moog 750#in lowers the car 1.5"?
I am fairly sure the Moog 80098 and 7268 springs are similar and provide near stock height.

From the forum's information I increased the rear springs to match.
Moog 7268 Front Ford 150 97-03 Dodge Van 79-80 750Lbs
Moog 5419 Rear Caprice 79-96 173Lbs

How will a softer and lower spring help you?

I can cross reference the RPO with the spring broadcast code.
If you have this resource please post it for all.
 

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What Moog 750#in lowers the car 1.5"?
I am fairly sure the Moog 80098 and 7268 springs are similar and provide near stock height.

From the forum's information I increased the rear springs to match.
Moog 7268 Front Ford 150 97-03 Dodge Van 79-80 750Lbs
Moog 5419 Rear Caprice 79-96 173Lbs

How will a softer and lower spring help you?

If you have this resource please post it for all.
I was told the 80098 lowered the car about 3/4" from Impala height. I don't have fender trim, and am running a much shorter tire (255/40-17) so it's hard to eyeball where I'm at right now.

The spring info I have is in two different tables. I can match RPO to broadcast code, then look up the broadcast code to get rate and free height info. It's not all 1 database, and I can get to it because I work at GM.
The spring chart I have shows 5 different rates, but I don't think all these springs are just for B cars, they might be for other coil spring rear (Gbody??) Applications too. I see 19,21,24,27&37 N/mm for the rear. I'm fairly certain that the rear on an Impala or 9c1 are 21N/mm aka about 120#/inch, not 175. Oddly, 21N/mm is not on your chart.

Why is a lower rate what I want to try? When you go into a corner, the body will roll, since the front is heavier than the rear the body rolls more where the front wants to go. If you have a lot of roll stiffness in the rear, you will end up unloading the inside tire, lose grip and tend to oversteer. An extreme example of this is the 80's and 90's VW's, where they lift the inside rear. Nose heavy, high roll stiffness in rear, body rolls, rear suspension does not.


I can try a softer rate which MIGHT help that. Not sure. I can reduce roll stiffness by removing the rear bar too and let the rear become more compliant. I can also add more front bar to reduce roll up front.

I can lower the rear, which should shift the roll moment.

I don't think I need stiffer rear springs, especially since the car is lighter than stock, and I have no plans for passengers or cargo, it's strictly a race car now and has been for 10 years. I'm trying to make it a faster race car.


Or, I can just learn to drive the car better, and not dump off the gas mid corner, transfer load off the rear of the car and make it loose.

I need to figure out something, I damn near spun the car in the dry, and the car was REALLY easy in the wet and caught two of my codrivers by surprise.

Below is a pic of the car trail braking, see how light the inside rear is?


Sent from my Moto Z (2) using Tapatalk
 

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I'm fairly certain that the rear on an Impala or 9c1 are 21N/mm aka about 120#/inch, not 175. Oddly, 21N/mm is not on your chart.
You can not compare a 9C1 with a impala. The 9C1 has the highest body height of all b bodys and the Impala the lowest.The 9C1has a built in extra rear height for the extra weight in the trunk.

18 103
21 120
27 154
37 211

That chart does not make total sense. FE1-FE4 then F40 for wagon and 7B3 for SEO. That is why a few pictures of a computer screen would make a great typed table.

Navy Lifer posted part#/Tag# to #/in but it would be nice to have a cross check.

I know little about racing suspension but I would think you would need to start with the front and back trim at factory level (not height) or the weight transfer during breaking or turning would be hard to predict.

Measure the rocker panel or the frame to get the road level correct.


Data is from 95Wagon
 

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You can not compare a 9C1 with a impala. The 9C1 has the highest body height of all b bodys and the Impala the lowest.The 9C1has a built in extra rear height for the extra weight in the trunk.

18 103
21 120
27 154
37 211

That chart does not make total sense. FE1-FE4 then F40 for wagon and 7B3 for SEO. That is why a few pictures of a computer screen would make a great typed table.

Navy Lifer posted part#/Tag# to #/in but it would be nice to have a cross check.

I know little about racing suspension but I would think you would need to start with the front and back trim at factory level (not height) or the weight transfer during breaking or turning would be hard to predict.

Measure the rocker panel or the frame to get the road level correct.


Data is from 95Wagon
You can, body height does not mean highest rate, just longest free height. 9c1 rates are the same as I'm all iirc, just higher ride height.

Got a link to Bills (navylifer) post?

Sent from my Moto Z (2) using Tapatalk
 

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This should give you a idea how #/in and road height are separate issues.

Your rear end may weigh different than any production car and it's front springs are stiffer so your solution will not be a production one. Moog replaces several springs with one replacement so I think you are going to have some trial and error mixed with calculating what your car's rear weight will do to what springs are available.

FRONT SPRINGS 1994-1996 (CHEVY) B-body

77 newton-meter rate, except SEO

SERVICE P/N TAG CODE LOAD RATE

22076515 TR HIGHEST
22076514 TP
22076512 TN, TS, TM
22076510 TL
22077450 TY LOWEST (OE for SS)

SEO only

SERVICE P/N TAG CODE LOAD RATE

22078017 SD HIGHEST
22078016 SC
22078015 SB
22078014 SA LOWEST

REAR SPRINGS--SEDAN ONLY 1994-1996 (CHEVY) B-body

27 newton-meter rate

SERVICE P/N TAG CODE LOAD RATE

22076523 RX, RK, RJ, HJ HIGHEST
22076962 HH
22132374 HK
22132375 HL LOWEST (OE for SS)


edited 10/18/2004

--------------------
Bill Harper ISSCA #127
 

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I had a thread a long time ago where I was decoding springs, but can't seem to find it. I'm fairly certain the stock SS rate was closer to 120 #/in. If you still have your SPID, post up your spring codes. Note if it's an Impala or Caprice too. RPO's for rear springs start with 8 and 9, like 8RS & 9RS, fronts will be 6 and 7. I can cross reference the RPO with the spring broadcast code.

I'm actually looking for a stock rate or SOFTER rear spring that also lowers the car about 1.5". I currently have the Moog 750 #/in front springs, and the car is still tail happy trailbraking into the corners, so trying to reduce rear roll moment, and roll stiffness.
https://www.gmheritagecenter.com/docs/gm-heritage-archive/vehicle-information-kits/Impala/1996-Chevrolet-Impala.pdf

PG 28 of 58
 

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I'm actually looking for a stock rate or SOFTER rear spring that also lowers the car about 1.5". I currently have the Moog 750 #/in front springs, and the car is still tail happy trailbraking into the corners, so trying to reduce rear roll moment, and roll stiffness.
Here are some choices compared to the stock SS springs: Look at the column that has 'height for 935' for comparison. Other height is from catalog listing and different application.
 

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This should give you a idea how #/in and road height are separate issues.

Your rear end may weigh different than any production car and it's front springs are stiffer so your solution will not be a production one. Moog replaces several springs with one replacement so I think you are going to have some trial and error mixed with calculating what your car's rear weight will do to what springs are available.
I knew I had posted something....lost to the great data crash in 2009, yet it's still out there in the ether!

One thing to remember is that tires impact the measurements--Impala SS had it's unique set of numbers--as did every other variant. Start mixing tire sizes and the numbers in the FSM are less useful. Put SS wheel/tire on a Roady sedan (in stock form), and the numbers might surprise you.

One other thing I've mentioned before, the TY front spring was not exclusive to Impala SS--I've seen it on the SPIL for wagons.

This is one example to use for comparison--probably straight out of the Moog catalog.
 

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I knew I had posted something....lost to the great data crash in 2009, yet it's still out there in the ether!
It is still there. The crash did it's most damage around 2009 and the very early posts.

I am very frustrated by the "Google Custom Search" even when I know who and when the search will show me current stuff not related to my search words but will not show me the old post.
 
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