Chads996

No affiliation - just another parts supplier review.

Suspension. I had numerous options out there. A used set of Koni's popped up, Bilstein Firehawk, Leda's, etc. Being that I am on a budget, I decided to check out an old favorite vendor from my BMW track days. Ground Control.

Ground Control has made suspension components for years. The owner Jay Morris, a fellow car nut is VERY knowledgeable in his field. He works with KONI directly and custom fabricates his own coilover sets and bits. Previously I had single adjustable setup on my old E36 M3. It was fantastic. I loved it. Soooo...I noticed they had a setup for the 944's. I gave Jay a call.

Not only did they have the parts, Jay must have talked to me on the phone for over 45min about the good, the bad, and the myths out there about suspensions. Talk about service. I told him I wanted the double adjustable fronts and single rears...but I was not sure about the spring rates. He took another 20min to talk on that subject too.

I told him I had to say something on Rennlist as I am sure many of you would be interested. He beat pretty much EVERYONE on price. If you are looking into a suspension, big thumbs up for Ground Control:

Ground Control Website

Hope this helps.

C.


Here's the set I wanted:

MAGK944

+1000, I just got another set of rear coilovers from Jay last week and am very happy. The customer service was A1. I thought that I had worked out the spring rates for the rear using the various calculations from the posts here on Rennlist, but he advised differently, sent me pictures to explain why the calculations on the Rennlist posts were wrong.

The proof was in the pudding - I fitted and tried them out this past weekend, perfect - his advise was priceless!

EDIT: FYI 86na street, occational de, neutral to slight understeer - Springs 250#F/600#R (torsion bar delete); Sways M030(30mm)F, TurboS (18mm)R; Tires 225/50/15 F&R, Stock weight, stock 15in Fuchs 7/8 & stock tire pressures, solid bushes & mounts.

Mike

roman944

so if I do early car with 19mm rear sway and 15x7 Phonedials?

once the engine is sorted out and I try out the car on the track, either GC or LEDAs

MM951

Yes, GCs service is fantastic and prices are realistic compared to some of the other options out there.

the coilovers also look pimp

Funn944

+++ on Ground Control. Excellent product. great customer service. They'll give you great advice rather than just sell you something.

flosho

You have steel or allum rear control arms?

StoogeMoe

How do the camber plates compare to Racer's Edge offering?

Riff

Can you post those diagrams? I would love to see those calculations. I did my car last year and do not feel it has excessive understeer, though based on your car's set up, it should push very badly. This is not any sort of slam, just want to be as informed as possible.

TIA,

MAGK944

Alum, it's an 86

MAGK944

ok found the email on my home computer. I am sure Jay wouldn't mind me sharing this:

"On Rennlist everybody says that the distance from the shock to the wheel (aka torsion bar pickup) is about half, which is true. therefore the thinking is that the spring rate on the shock needs to be DOUBLE the wheel rate for equivalency.example: 400 / 2 = 200. By inference, then 400 pounds per inch on the shock equals 200 pounds per inch at the wheel (Torsion bar equivalent). THIS IS WRONG. If you look at the illustration, 400 pounds per inch at the spring equals 200 pounds per TWO INCHES. This is because, as you can see, there is not only leverage but distance invlolved in the rate. So: 400 pounds per inch on the shock equals 100 pounds per inch at the wheel (200 pounds per 2 inch). I felt this was too soft for your car, so I chose 600 which would be 150 pounds per inch torsion bar equivalent. this a good match for the 250 front, the critereia I use being ride frequency, which is not really a ratio."

VOoDOoGTX

i gota do coil overs and sways after then engine is done i know where im going

Van

Mike, that's called the "motion ratio" - but Jay is wrong on his math. I made the same mistake when I was doing calculations.

A 250# front to 600# rear bias is really a poor fit. That's way too much rear spring.

I'll dig up the thread that discussed it - I measured everything and made all sorts of diagrams and calculations. Karl from Racer's Edge suggested a simple test to MEASURE the actual motion ratio - and that was spot on. I had to admit my error and get on with life!

I'm not trying to be a know-it-all... it's just that I've been there and done that. It's quicker, and frequently cheaper, to learn from someone else's mistakes.

Here's the thread: https://rennlist.com/forums/944-turbo-and-turbo-s-forum/360494-poll-spring-rates-w-torsion-bar-delete-bonus-track-pics-enclosed.html

It's a good read, and the "ah ha" moment comes at post 65...

Van

Actually, re-reading that thread, I guess the rear motion ratio is about half the front's... Maybe the 250# to 600# isn't that bad.

MM951

What do you (+Gina &Mike) think of my spring rates? I feel like I'm way off now

MAGK944

It feels good to me, a little more understeer than I really like but as it's mainly a street car that's a good thing. I would if anything go to a 650# spring to make it a bit more neutral all other things being equal.

My set-up is in post #2 ^

There really are too many variables for me to say this would work with your car or any other car. It also depends on how you like the car to handle.