pban

Given a blank sheet of paper, a STI 3 RA and height only adjustable struts.

What spring rates would I use on the front and rear?

Cheers Paul

pban

ok so

what spring rates is everyone using with their coilover kits?

TaviaRS

Depends what they are using them for. Track? Fast road?

Looked in the Leda thread and the 2 weights mentioned are:

325f/225r
275f/225r

So 225lb at the rear seems consistent, front there is a 50lb difference. Not sure if that helps.

pban

TravisRS

Its a start mate. I used to have a STI 5 on leda B, it didn't feel as good as my mates MY98 on the same setup. I always felt that the extra weight his car had at the back with a heavy boot spoiler allowed him to run the rears stiffer. Mine seemed to skip bumps at the back if I set them any harder than 3 or 4. Getting back to the original point, my RA is probably even lighter than the STI 5 so wanted to try and avoid the same problem. Now my theory may be way off here but would slightly softer springs compensate for the reduced weight? A suspension guru would help here maybe

Paul

pban

bttt

Andy.F

Ideally, the springs are matched to the damper rate. It is unlikely that fitting softer springs will help much (unless they are way too hard to start with)
The 'bump' setting on the shocks is generally what determines the 'skittishness' of the rear end.
I have a similar issue with Leda's on my RA. With 2 passengers on board the car is fairly planted but it is bumpy as hell when I'm in it myself. They would probably be fine on a UK car

Have you tried uprated springs on your RA shocks ? I think the std shocks are quite stiff but the springs are too weak. The car runs down on to the long bumpstops most of the time and the shocks are valved to stop it leaping back up. I've found shortening the bumpstops and stiffening the springs works a treat
Leda's are now for sale !!!

Andy

pban

Andy

Thanks mate. I've bought some non bump/rebound adjustable dampers, they have height adjustment only. Just from my experiences with Leda B on my STI 5 has prompted me to think aboutb the spring rates. Something else I've noticed with the RA is that when I'm running low on fuel the ride height seems to be higher, when full up the car sits lower. I'll fit the dampers and see what happens me thinks. Is there anyway to measure the spring rates without the proper tool?



Paul

pban

Andy

I need a little giudence, what/where are the bump stops and how do you go about shortening them and by how much? What exactly did you do re stiffening your springs? Did you get them custom made?

What year RA is your car? Mine is 97 and has KYB struts

Cheers

Paul

pban

bttt

Claudius

Interesting question here.

The thing to keep in mind is that it is primarily the spring that determines the hardness of the suspension, and that the damper needs to be subsequently matched.

Therefore, in order to get the best grip for your car (weight distribution) and tyre combination, youll need to find the hardest spring that will still give grip and not, say, induce understeer.

On a road car like yours, that is probably around 70 N/mm for the front.

The problem you have is that your dampers are not bump and rebound adjustable, so I wonder how you could subsequently adjust the damper. Maybe play on the ride height? But then, what about the front / rear balance?

Claudius

I remember getting the valves inside the damper changed for a different size to make the damper stiffer. What about oil viscosity or gas pressure?

No matter how I look at it, I couldnt find a cheap or good answer. How about selling the suspension and buying adjustable ones? I got a good deal on a set of Proflex someone bought from a rally rental place that went bankrupt. Not that common I guess...

pban

Claudius

Have you seen this thread, still talking about my car.

http://www.scoobynet.co.uk/bbs/thread.asp?threadid=168633

What affects would result do you think if I were to fit slightly firmer rear springs say by 50lb less that I have now? This is what Andy F did I think. I appreciate springs are normally matched to the damper but how much of a window exists for spring rate changes? Would a change up/down by say 50-75lb be within the working/matched range of the damper? How would reducing the ride height affect the handling?

Paul

Claudius

Yes, I saw that a few days ago. When I read the first post, I clicked on "back" in my browser window, because it didnt make any sense.

Just looked again and saw that Simon explained that it is the other way around: car handles less well with more weight in the back.

A Scooby understeers a lot from the factory, so adding weight in the back will make it worse.

Ok, this doesnt make sense either, you are contracdicting yourself here. If the spring rate is lower, then the spring wont be firmer, but softer.

I dont know, depends on the damper. I dont know KYB. I mean I do know the brand, since this is OEM for Evos, but I dont know what type of "kit" you have there. Could you give me a URL to a technical datasheet or specifications for what you have?

Depends on the damper, but I suppose it would be ok (unless they are PEM style soft).

If you lower the car in the back, you will get more grip in the back, and thus could get too much understeer. Now if your car has the back not sticking, this could be worth a try. In fact, I think that this is what I would try before changing springs or anything.

[Edited by Claudius - 1/22/2003 11:02:48 AM]

Claudius

I meant OEM style soft (not PEM), but appearently editing out some of the crap spelling wasnt enough. Sorry

pban

Claudius

This was me changing my mind but not reading through my reply fully. Reference Simons comment about possibly changing the sprung/unsprung weight, I originally thought softer springs, then thought about what Andy F had said he'd done with the bump stops and firmer spring. I am

I have no details about the struts other than the fact they are standard. I think maybe confusion has come about from the origin of this thread, its no longer valid, I am talking purely about the standard car setup, which I don't like too much. I think the extra weight has given me more understeer which has cancelled out some of the oversteer that make my car nervous at the back.

Now all I need to do is find shorter but equally rated springs.

Paul


[Edited by pban - 1/22/2003 11:41:55 AM]

Claudius

You shouldnt change the springs on the standard dampers. That will make the car uncomfortable, inefficient and the shocks may blow.

Ideally, you should get fully adjustable dampers.

I bought some gravel spec Proflex (for road use) and the spring rate in the rear is half of that in the front (60N/mm front and 30 rear). Just food for thought

pban

Claudius

Thanks for all your advice, I think when funds allow an adjustable suspension will be purchased.

Paul