Coilover springs and spring rate (Page 2/3)
sdgdf FEB 20, 09:15 PM

quote
Originally posted by Raydar:

I bought "guru's" kit. 12" springs. I told him what I had, and what I was doing, including the 3.4 DOHC swap. He suggested 250# springs.
It can be lowered from stock with that exact kit. Mine is as low as I'd pretty much ever want to go with it. (2-3 fingers between the tire and the wheel well opening.
Here are some pics of the assembly. Before and after.

This was what I removed from the car. These were 88 front springs adapted to the rear.
I decided to do "guru's" coilovers because I have plans for the car, and also needed the shorter springs for my GT. Purely cosmetic.


This is the strut with the perch and all the other stuff removed. Painted with rust converter/primer.


This is the assembled coilover and strut, ready to go back into the car. After I set the car on the ground, and drove it to allow everything to settle, I ended up dropping it about another 3/4". (There are calibrations on the sleeve. Made it very easy.) It's essentially the same height that it was before I started, which is what I wanted.


Ride height. It's maybe actually just a "tick" lower than this, now, but that's okay.






How long are your sleeves, like 6-7"? Mine from GC look like only 4"? I'm thinking pmbrunelle might be right and I need like 14" springs to have any adjustment range on the sleeve. And I'm thinking of stepping down to 300 lb/in.

Looking at these: https://www.summitracing.co...rts/eib-14002500300s they have them in stock at summit racing and can ship out tomorrow. Either that or 12" and they'd probably be at the limit of the threads on the sleeve.


Also what's the ID and length of the stock 88 front springs? I can get some eibachs at summit? 300 lb/in equal front and back or no?

[This message has been edited by sdgdf (edited 02-20-2023).]

pmbrunelle FEB 20, 09:38 PM

quote
Originally posted by sdgdf:
Looking at these: https://www.summitracing.co...rts/eib-14002500300s they have them in stock at summit racing and can ship out tomorrow. Either that or 12" and they'd probably be at the limit of the threads on the sleeve.



The spring rate describes how much the spring sags once the weight of the car is applied, relative to its free length. The spring rate also determines how stiff the ride is. I think that with 300 lb/in springs, you should go to 14" springs.


quote
Originally posted by sdgdf:
Also what's the ID and length of the stock 88 front springs? I can get some eibachs at summit? 300 lb/in equal front and back or no?



The stock front springs are not "standard coilover format" that can be easily replaced with aftermarket parts.

Probably you should take some time to research what you want to do with the front, rather than make a rushed decision while the car is stuck at the shop.

[This message has been edited by pmbrunelle (edited 02-20-2023).]

Raydar FEB 20, 09:44 PM

quote
Originally posted by sdgdf:

How long are your sleeves, like 6-7"? Mine from GC look like only 4"? I'm thinking pmbrunelle might be right and I need like 14" springs to have any adjustment range on the sleeve. And I'm thinking of stepping down to 300 lb/in.

Looking at these: https://www.summitracing.co...rts/eib-14002500300s they have them in stock at summit racing and can ship out tomorrow. Either that or 12" and they'd probably be at the limit of the threads on the sleeve.

Also what's the ID and length of the stock 88 front springs? I can get some eibachs at summit? 300 lb/in equal front and back or no?




My sleeves are ~6-7 inches. Just a guesstimate. I didn't measure. Paul will be able to answer that.
I was kind of curious why you were doing 400# springs, but a 3800 with an automatic is heavy, so...

Look at my assembled strut. Picture the adjuster cranked nearer the knuckle by ~3/4" (which is where I adjusted it after that pic was taken.) Not a lot of adjustment left before it bottoms out.
I think 14" springs might be too long for you. OTOH, the 4" sleeves might have all the adjustment you will need. Again, I'll bow to Paul's knowledge and experience.

My 88 springs were shortened by exactly one coil. The front ones, and the ones I installed on the rear. I couldn't tell you what the length is, either stock or modded, though.
I will mention that, at the "shortened" length (for the rear) I was able to install the "top hats" by pressing down manually and starting the nut on to the strut. I did not need a spring compressor. There was a little bit of pressure, but not much.

[This message has been edited by Raydar (edited 02-20-2023).]

sdgdf FEB 20, 09:48 PM

quote
Originally posted by fieroguru:

At a 400 lb/in spring rate, you will want a 10" spring.




Ok I found it but I lost it in the 2 dozen threads I have open, how did you achieve 575 lb/in spring rate on the front of your car? And I've read a lot of threads, some say equal rate front and rear, but stock is higher in the front, and your setup is higher in the front (575 and 400?). So go higher in the front.
sdgdf FEB 20, 09:54 PM

quote
Originally posted by pmbrunelle:


The stock front springs are not "standard coilover format" that can be easily replaced with aftermarket parts.

Probably you should take some time to research what you want to do with the front, rather than make a rushed decision while the car is stuck at the shop.





Yes this seems right, I found in a thread the ID of the stock front springs is 3.38" or something like that and the bumpstops limit anything smaller. I can't find anything on summit for springs with that ID with all the other specs I need. With that ID they're not a coilover type of size. So now I'm thinking of just getting the fronts from WCF or replicating fieroguru's 575 lb spring setup somehow (or I need to check if he sells them). I was getting excited about picking this all up from summit tomorrow and getting the suspension/wheels done on the car so I can move on to other projects with it. Compressing/decompressing springs isn't something I mess with so I've gotten impatient waiting on having the shop do it.

[This message has been edited by sdgdf (edited 02-20-2023).]

sdgdf FEB 20, 10:11 PM

quote
Originally posted by Raydar:


My sleeves are ~6-7 inches. Just a guesstimate. I didn't measure. Paul will be able to answer that.
I was kind of curious why you were doing 400# springs, but a 3800 with an automatic is heavy, so...

Look at my assembled strut. Picture the adjuster cranked nearer the knuckle by ~3/4" (which is where I adjusted it after that pic was taken.) Not a lot of adjustment left before it bottoms out.
I think 14" springs might be too long for you. OTOH, the 4" sleeves might have all the adjustment you will need. Again, I'll bow to Paul's knowledge and experience.

My 88 springs were shortened by exactly one coil. The front ones, and the ones I installed on the rear. I couldn't tell you what the length is, either stock or modded, though.
I will mention that, at the "shortened" length (for the rear) I was able to install the "top hats" by pressing down manually and starting the nut on to the strut. I did not need a spring compressor. There was a little bit of pressure, but not much.





Since planning on the 400# I was looking through threads and fieroguru said at one point 100 lbs or so added with a swap doesn't add that much load on the springs so 400 might not be needed. I'm kinda curious though what his setup drives like, 575 up front and 400 rear.

Looking at your strut and sleeve mine is threaded all the way down to the knuckle. So I have maybe another inch down to the knuckle, but 2-3" less threading towards the top? Ha and with the shorter springs they shipped me that's where I'd need the adjuster, way higher up. This kit sucks for sure. I think with the range I can have the adjuster I might need 14"? It can go farther down than yours but not higher up. pmbrunelle mentioned wooden spacers to find out for sure to go 12 or 14". Or just use a spacer but I didn't want to use a spacer if I can just get the correct springs. Is there some benefit to having shorter springs instead of long?

[This message has been edited by sdgdf (edited 02-20-2023).]

sdgdf FEB 20, 10:39 PM
In an old thread https://www.fiero.nl/forum/Forum2/HTML/139057.html it was mentioned that 84-87 front springs are 1" longer than the 88s and can be cut down and fit on an 88 with a little bump in spring rate?

I also saw mentioned in another thread, that moog 6556 and 6558 are Chevette springs with close specs to the 84-87?

Then I sorted the moog catalog and saw 2 springs that could work:

moog-5576 Squared Tangential 13.69 9 3.5 0.62 385 1814 Constant Rate

About the same length as the 6556, with 385 lb/in springrate. Slightly larger ID by 0.10".

-or-

moog-2278 Squared Tangential 11 9 3.42 0.6 435 868 Constant Rate

Almost 3 inches shorter, it'd drop the front of the 88 by 2 inches? Basically the same ID. 435 lb/in springrate.

How well would these work???


for reference, moog catalog: https://www.moog-suspension...sal_coil_springs.asp

moog-6556 Tangential Tangential 13.75 9.63 3.45 0.5 197 808 Constant Rate

[This message has been edited by sdgdf (edited 02-20-2023).]

greenturnedblue FEB 21, 04:49 AM
I have the same ground control kit. They're meant to fit right on to the stock/'stock style' struts. That's why its called a 'coilover conversion kit', because they convert your existing stock struts into coilovers.

Anyways, to salvage the struts you've had the perches cut off of, you could get some exhaust tubing to sandwich between the threaded sleeve and the top of the lower mount bracket. You can see here I did something similar but only to raise the threaded sleeve up about an inch. Tough to see but beneath the sleeve there is some exhaust tube painted red.

Or you could get a threaded sleeve that is way longer. They are all pretty universal but find one the same diameter and same thread pitch and it will work. Lots of Honda civic guys use these things should be lots of them around on ebay etc. If I were to guess an 8-10" sleeve would be ideal

[This message has been edited by greenturnedblue (edited 02-21-2023).]

fieroguru FEB 21, 07:04 AM

quote
Originally posted by sdgdf:
With your kit?



With your kit or my kit it doesn't really matter. My sleeves are 4 3/4" tall, but when customers ask for springs stiffer than 350lb/in, then I cut the unthreaded portion of the sleeve off the bottom to increase the lower range.

Part of the service for anyone that buys my coilovers is we review the specific details of your application, what you are looking for from the kit, and I help guide you down a path to the spring rate that will work well for your specific setup and goals. This takes time and is more expensive, but avoids many of the issues you are having right now.

If you want to fix your car fast:
400 lb/in - buy a 10" spring
350 lb/in - buy a 12" spring
300 lb/in - buy a 12" spring
250 lb/in - buy a 12" spring

Adding a section of exhaust tubing to raise the sleeve also works.
Spadesluck FEB 21, 08:17 AM
You really need to do your homework on this. Throwing parts at the suspension without thought may not work out. Fieroguru pretty much spells it out for what you need, I would take his advice. Everything needs to be taken into consideration when doing this, ride height, type of driving, motor combo etc....

I have QA1 springs on all four corners of my car. I am running 450lb springs in the front and 350lb springs in the rear. I am using a 10" high travel spring in the rear and a 7" adjustment sleeve.

BTW, you are not far from a lot of Georgia Fiero club members.