turbite

I need recommendations on springs in the back.

I've got 0900.225.0400 in the front (9 inch, 400 lb/ft) eibachs

The back is currently 0600.225.0300 (6 inch, 300 lb/ft) eibachs with tender springs.
This is in conjunction with the torsion bar, which I am removing.

I've got racing bilsteins all around.

Firstly, Is 6 inches long enough?
( huh huh ... huh huh )

I don't want to change the rates in the front currently.
What would be a good rate to use in the back for a balanced setup? 350?
What length? and do you use tender springs?

Mike Buck

IMHO, 6" is way too short, especially for that low of a rate

my springs are 8" all around, 600lb front and 500lb rear. My torsion bars are still in, but reindexed down. No tender springs anywhere and it all works pretty good if you ask me

What diameter springs are you using? Mine are all 2.5"

turbite

2.25" inner diameter (the middle number) all around I believe.

I don't wanna change the front from 400 yet, so you think 8 inch 350's will make sense in the back for this setup?

Do you use tenders with your eight inchers?

Oddjob

Im assuming this is a track car?

If you remove the torsion bars, you probably want to be in the 400-450 lb/in in the rears.

You wont need tender springs for the rears. But they are nice on the fronts with the short springs.

Im not sure what lengths are available in Eibach springs. I have used 8" Eibach and Hypercoils, and 7" hypercoils in the rear. With higher spring rates, over 400 lb/in, using 8" springs, I found that the lower perch and spring coil would rub on the trailing arm, so I went with 7". This was with Bilsteins, 2.25" Diam Springs. Other types of coilovers may not have the same spacing problems with rubbing on the trailing arm.

turbite

Oddjob:

It is a track car, but I do drive it on the street.
I'm not to picky about a harsh ride, but I don't want the car to upset it self if I hit a road size bump in the middle of a turn.

Maybe I should just ebay my current springs and go 500/400 or 500/450.

Oddjob

400 can be plenty stiff for track use. The cup cars used around a 405 lb/in progressive spring. It really depends on your home track surface. If its glass smooth, you can go stiffer, if its rough you probably dont want to go any stiffer.

If you go up to 500 in the front, you should be over 500 in the rear (w/o torsion bars), between 525 and 600. Obviously this will depend on wheel/tire sizes and sway bar sizes and driver preference.

TonyG

First off.. 400's are real stiff for the street.

And to balance the car, you'll need at least a 500lbs-550lbs rear spring w/o torsion bars (remember that the effective spring rate is not the same as the actual spring rate).

I hope the roads are smooth over there :-)

Anyway, for a 350lbs spring, a 9" is about the correct free length.

For a 450lbs spring it's about 8", and for a 550lbs spring it's about 7".

TonyG

PS> When are you gonna come on down?

turbite

Thanks Tony...

But I guess the big question is, in order to have 500lbs-550lbs rear spring *effective* what spring rate accomplish that?

And then, what springs do I need to get for the front for the setup to be balanced?

PS> Whenever theres a good first-timer friendly time trial.!
whats the PCA region called down yonder?

turbite

posted by Russ Murphy a while back:
http://members.rennlist.org/dan10101/944SpringRates.htm

Seems anywhere from 450-550 makes sense without the T-bar.

(even with my current 400 lb front springs)

Zu_langsam

a little off topic but what kind of coilovers are you playing around with in the rear turbite?

turbite

Zu_langsam, biltstein race (AK-37354) in the back, with eibach spring of, as of yet, unknown spring rate.

I do like to drive this thing to work sometimes, and taking it on random sunday drives...

I keep going back and forth on what I want to do.

Jeremy Himsel

If you go with a 500# or higher rear spring a 6" will be fine. Under 500 you'll need to step up to a 7" spring. I also use the 2.25" spring with 300 in front and 350 in the rear (no t-bars but it's a street car). If you plan on keeping the tender spring then the short length spring will work. Call Lindsey, they sell these set-ups all day long. How does the car handle now, does it push at the limit? With the t-bars in tact your rear spring rate is in the 550 to the 580ish range.

TonyG

I have 250lbs front and 350lbs rear, and the car will push at the limit.... which I experience often at the track.

A 300 in the front and a 350 in the rear would even be worse.

And Lindsey does sell the setups all day long.. you're right. But ask them who they went to figure out if a 350 rear spoing would work and what length to use :-)

The effective spring rate of a 350lbs spring in the rear is about 197lbs.... far softter than a 250 lbs spring in the front let alone a 300lbs spring. And as such.. it will push... which is what I set it up to do.

To really match properly a front spring rate of 400lbs, you would need a rear coil spring rate of at least 650lbs (effective rate of 366) or 700lbs (effective rate of 394). (and if you are going to have a car that rides like crap on the street... you might as well set it up properly for track use... because that's exactly where you're heading)

And that combination would be a a joke on the street. Yes you could drive it. But you wouldn't enjoy it for long. A women will drive in that car one or two times before he says no way. Give her a kidney belt and maybe she'll ride in it 3 or 4 times :-)

And here's the correct link to figure out spring rates vs effective wheel rates. Paragon Products has it on their web site, which was on a few other web sites years before.... But for now go to:

http://64.226.197.185/Paragon/Info/9...comparison.htm



TonyG

TonyG

>>>But I guess the big question is, in order to have 500lbs-550lbs rear spring *effective* what spring rate accomplish that?<<<


Between 900lbs and 975lbs.

Check out the link to the chart above.

TonyG

Zu_langsam

My daily driver 951 has 400# front springs in it and I wouldn't even call it harsh. Its not bad at all on the street.