looking for help figuring out what went wrong with front coil spring replacement (Page 2/2)
Signupacct MAR 19, 11:24 PM


help me to understand your calculations and conclusion that the 6730 is too stiff

I am not asking for any other reason than to learn something regarding this

the SMS6730 or I may have referenced in previous posts as RC6730 but the same spring the prefix letters I think are unique to the vendor

thank you in advance
Rick Vanderpool MAR 20, 12:09 PM
Your indicated you bought RC6730 from Husky, so I looked up that item. Here is the page listing the specs for that spring.
https://www.huskyspring.com/Home/ProductDetail
The spring rate for that spring is 1501 pounds per inch, which means it takes 1501 pounds to compress the spring 1 inch. your calculations put each front corner at 705 lbs., which would result in a compression of less than 1/2 in. There are other factors which affect spring rate calculations but they would all reduce the required rate.
Having said all that, the evidence that this is the issue is the fact that the car sits way to high and doesn't move down when you sit on it.
Rick

The link doesn't go directly to the spring in question. Put RC6730 in the search box and select the item that is listed. them click on the specifications tab.

[This message has been edited by Rick Vanderpool (edited 03-20-2023).]

Signupacct MAR 21, 02:16 PM
well

the selection of the RC6730 was not a casual process and was led to believe that was going to meet the specifications for the car

as I double check the process I can see that somehow the process broke down

the 6730 spring according to Husky is the lightest for a chevy chevette with no a/c as the 6556 and 6558 are rated even heavier


the 1987 Pontiac Fiero GT with a V6 and a/c was pretty common

so how would you recommend determining the proper spring specs and also specs for what was oem (such as spring coil wire diameter, inside diameter, number of coil winds, uninstalled height, spring rate per inch)

I did find the following number 10034101FJF but I am unable to convert that to any specifications or to currently available spring part number.

obviously I thought I did but maybe not








[This message has been edited by Signupacct (edited 03-21-2023).]

PhatMax MAR 21, 03:52 PM
Read this….

https://www.fiero.nl/forum/Forum2/HTML/139002.html
Signupacct MAR 21, 10:38 PM
great read

unfortunately it references a car way lighter than mine and no specific mention of oem spring part numbers for a 1987 pontiac fiero gt v6 with a/c

appreciate the mention

still hoping someone has an idea what the oem part number is for the front coil springs and the specs for those springs such as

diameter of the coil wire, the inside diameter, the uninstalled height, the rate per inch, how many winds


the best I have for oem part number is the 10034101FJF but have no more information than that

oem specifications would help identify other aftermarket springs that might work

[This message has been edited by Signupacct (edited 03-21-2023).]

PhatMax MAR 22, 05:24 AM
Perhaps this company has the spring rates on file. I know they can make whatever you need.

Kevin Crane
Coil Springs Specialties
PBX "G"
632 W. Bertrand Avenue
Saint Mary's, KS 66536
785-437-2025
fieroguru MAR 22, 05:46 AM

quote
Originally posted by Signupacct:
still hoping someone has an idea what the oem part number is for the front coil springs and the specs for those springs such as

diameter of the coil wire, the inside diameter, the uninstalled height, the rate per inch, how many winds



Looks like you have the original springs out, so all you need to do is measure them to get the needed information to calculate the spring rate. It will be about 200 lb/in +/- 10%.
https://www.thespringstore....rate-calculator.html

You can do the same with your new springs to verify the rate.
Signupacct MAR 22, 12:04 PM
great suggestions both

unfortunately as for measuring the springs that came out the previous owner that I purchased it from lowered it

and cut some off

also it appears that the husky catalogue and the numbers appear suspiciously wrong

someone in previous post suggested that by the specs in the husky catalogue and the phone rep that the springs inch rate was twice what it needed to be but i asked husky to double check their numbers becuase they dont agree with the 6730 springs they shipped

I will reach out to the suggested spring sources and see what they have


stay tuned

[This message has been edited by Signupacct (edited 03-22-2023).]

Matthew_Fiero JUN 13, 03:13 PM

quote
Originally posted by Signupacct:

I also replaced the upper and lower bushings and had The Fiero Store powder coat and install new ball joints along with the new bushings. The bump stops were reduced, by previous owner, by an inch according to overall bumpstop height information from this forum in a different post. So an inch was added back to the lower control arm, in the process of replacing the front coil springs, so the bump stop would hit at approximately the same point as before the car was lowered.

Joe k



Hello do you recall how you added an inch back to your lower control arm? I cut mine years ago and droped it 1 1/2" with 400lb springs and its a really rough ride that I don't necessarily want to have my whole life. I'm looking to raise it up another 1/2" and thinking of leaving the bumpstop the way it is. I don't believe I kept the cut pieces.

I wasn't expecting to not find any front springs on the market aside from kits on ebay. Currently searching for 1" drop front springs.

Anyway curious to see what you did to your control arm.

Thanks.
82-T/A [At Work] JUN 15, 03:03 PM
I don't know if this helps, but the WS6 suspension came with the stiffest springs. There were separate RPO codes for the springs for all four wheels. But if the car has the WS6 RPO, then all four springs will be the highest rated springs that were offered for the Fiero from the factory.

There were some other options, which I can't really remember them all... WS6 (of course), WS8, and Y99. Y99 was the Rally Suspension, which had softer springs.


Note that not all GTs got the WS6 suspension, but from what I understand, ALL 88 V6s got WS6 (GTs and Formulas).

Also very common were for the 84 and 85 SEs to come with the WS6 suspension, which meant they all got the higher spring rates too.


Just for completeness, WS6 option came with a bunch of RPO codes. It came with the highest spring rates, the stiffest shocks, and (usually) a steering rack with a different ratio as well. Double-check your car's RPO sheet and see if you have WS6 on there. If you do, you may want to consider just reconditioning your old springs. I didn't read the entire thread, but is there a reason why you're going to new ones? Was the car sagging? Sometimes just changing the shocks will restore the ride height.


Anyway, on my daughter's Fiero, she had WS6 suspension, but we swapped out the springs with another pair (same individual spring codes) from a very low mileage 87 GT that had blown a motor and was parted out (from Arizona).


Anyway, you can go to my copy of the Online Service Guide which I update now and then. The complete list of spring codes can be accessed here: https://www.pontiacperforma...les/OSG/springs.html



quote
Originally posted by Matthew_Fiero:
Hello do you recall how you added an inch back to your lower control arm? I cut mine years ago and droped it 1 1/2" with 400lb springs and its a really rough ride that I don't necessarily want to have my whole life. I'm looking to raise it up another 1/2" and thinking of leaving the bumpstop the way it is. I don't believe I kept the cut pieces.

Anyway curious to see what you did to your control arm.

Thanks.



Also... just thought I'd but in here and respond to this. One of the best / sportiest rides I've ever seen (that I liked) was on my wife's 2002 Volkswagen Jetta 1.8T. She sold it long ago... but we bought it new way back in the day, and she got the ultra-sport model... whatever it was. It was the one that had over 180hp on the 1.8T. But it was the suspension that I liked the most, and it made me realize how best to replicate that kind of feeling in every car I own.

Basically... her car had VERY stiff springs, but medium-stiffness shocks... and then of course, rubber bushings. I've done this on a couple of cars, and recently did this on my daughter's Fiero as well (since I may drive it on occasion). We went with rubber bushings on the control arms, WS6 springs, and Monroe progressive shocks and struts.

What this means is... when we're going over most bumps, potholes, and dips... the springs absorb most of the shock and road imperfections, NOT the shocks. This is nice because shocks can be jarring. The shocks themselves are progressive which means they get stiffer as they're compressed, but they're meant for a nicer ride. The stiffer springs are important because when we're making turns or evasive maneuvers, we want the car to be as flat as possible.

So going around turns, the car doesn't pitch, it remains totally flat, the car has a smooth and comfortable ride, and it doesn't bounce either, because the shocks completely prevent that. It's really hard to explain... but imagine having a car that can handle, corner, doesn't sway, is totally rigid, but it absorbs all the bull-**** road imperfections that you don't want to feel. This car is that... it's awesome.

We also went through the entire car, so there are ZERO rattles too... it's basically a new Fiero.

[This message has been edited by 82-T/A [At Work] (edited 06-15-2025).]