Spring Rate

[ger man]

Hi Guys!
Do somebody know the Spring Rate of the original
fitted Eibach springs of the Griffith & Chimaera?

Regard Dennis

[magpies]

progressive I believe

I have a set that will be going onto classifieds

[MisterT]

I spoke to the man at Eibach a couple of years ago when I was trying to sort my Griff spring rates.

I quoted him my original TVR spring part numbers and this is what he came back with;

Front C0098 48.6 N/mm x 5.709 = 277.5 lbs/in

Rear D0103 38 - 60 N/mm (progressive rate spring) x 5.709 = 217 to 342.5 lbs/in

The conversion factor he told me to use was 5.709 x the rate in N/mm

Edited by MisterT on Saturday 26th October 22:58

[ger man]

thanks Mr.T
that's helpfull

[dumbfunk]

This is really interesting - I thought the standard practice for upgraded suspension was to have similar or higher rates but reversed. That is to say, softer on the rear.

My Nitron are f325/r250 I believe. The upgraded set I had from Joospeed were the same.

[TA14]

dumbfunk said:

This is really interesting - I thought the standard practice for upgraded suspension was to have similar or higher rates but reversed. That is to say, softer on the rear.

The D0103's will be softer at the rear most of the time.

[QBee]

Fascinating. My recently fitted springs are 400 lb front, 375 lb rear. They feel fine, but so did the previous ones. Guess it is the spring/damper combination that matters.

[ger man]

QBee said:

Fascinating. My recently fitted springs are 400 lb front, 375 lb rear. They feel fine, but so did the previous ones. Guess it is the spring/damper combination that matters.

what damper do you use? the original bilstein ? and the springs are upgraded eibach?

[phazed]

Sooooo, why aren't we fitting progressive rate springs when we upgrade or are they more for general/comfort use?

[K4TRV]

phazed said:

Sooooo, why aren't we fitting progressive rate springs when we upgrade or are they more for general/comfort use?

I think you will find that all "after-market" shocks up to the very top-end have their valving optimised for linear springs.

Not until you are heading north of Nitrons, will you find any manufacturer prepared to optimise valving against rising rate springs?

AIMVHO and from conversations some years ago with Joolz.

T

[A900ss]

The above info on standard spring rates is really interesting.

I've recently replaced all my coilovers on my car and am occasionally bottoming out at the rear a little and am looking for advice. When really pressing on, I think the rear is a touch soft.

I have replaced the standard coilovers for a set of aftermarket coilovers that are adjustable for rebound and have 400lbs springs on the Front and 325lbs springs on the Rear. Constant, not progressive rate.

However with the rears bottoming out occasionally and feeling a tad soft when really pressing on, I'm looking for advice.

I guess that upping the rebound will have no difference whatsoever as it is the compression damping that needs to be stiffened. I am currently on 9 clicks out of a max of 13 at the rear (and 7 out of 13 at the front).

I could put more ride height in to the springs as they are running slightly lower than original. This is done by rotating the collar underneath the spring but I don't think this is adding any preload as it will already have taken up the slack (is my thinking correct?).

Another option is to change the springs at the rear from 325‘s to 375 or 400‘s. This will only cost about £50 so could be well worth experimenting.

I think the rear spring rate is a bit too soft for my driving style (Sunday toy, quite quick, bumpy/twisty B roads) as when I pull out to overtake and floor it at the same time, it feels like the car has a bit or 'torque steer' from the rear and I'd like to dial that out if possible.

Thoughts from people who know more than I do are most welcome.

PS - I'm carrying too much timber at 17.5 stones so at won't help

Edited by A900ss on Tuesday 29th October 20:38

[RobertoBlanco]

+1 Very interesting!
I seem to have the same problem with T350, GAZ Gold Pro and corresponding springs.
Was thinking about getting more ride height as a first go.
What can be done apart from that? New springs and which ones?

Cheers

[QBee]

RobertoBlanco said:

+1 Very interesting!
I seem to have the same problem with T350, GAZ Gold Pro and corresponding springs.
Was thinking about getting more ride height as a first go.
What can be done apart from that? New springs and which ones?

Cheers

What are your spring rates? I understood they were 400 front and 375 rear on a T350.
I would try upping your rear ride height first. Easy job, especially on a ramp. Solved my bottoming issues.
I think the cars generally settle a bit with use. My GGPs with T350 springs were fitted to my Chimera 2000 miles ago and have already needed adjusting up by about 10mm.

[MisterT]

A900ss said:

...with the rears bottoming out occasionally...

I could put more ride height in to the springs as they are running slightly lower than original.

The general theory of dampers is that they should be midway in their travel at ride height. If you are already sitting below normal ride height I would have thought its more likely you will bottom out because you'll have less compression travel in the damper, I dont think its necessarily a spring rate problem, just that you dont have enough compression before the damper is fully closed. I'd try a higher ride height before changing springs.

I only have 250lb springs on the back and it never bottoms out even on bumpy Linconshire roads but I have a close to standard ride height, and at this height there is more compression travel available in the damper than there is droop.

I started out on the suspension upgrade path with high rate springs and stiffly valved dampers and I hated the ride and the twitchy way it handled on the road (before anyone suggests the susp geo was wrong it was set up by Steve Guglielmi). On smooth roads it was great but there arent many of those around these days.

I've since softened first the springs (now F325lb/R250lb) then had the dampers revalved and it is now brilliant for my style of driving. I can push it down the lanes much more confidently now, traction is better and rear end breakaway under power is more predictable, in a nutshell I can drive it harder, faster and I enjoy it much more than I did with the harder setup.

IMO harder springs arent always best (unless you're on track). Bear in mind that on bumpy roads you want the suspension to 'travel' so as to keep the tyre in contact with the road, if the suspension is too stiff you will lose grip over bumps and the car will not handle as well as it might with a softer set up, that's my experience for what its worth.

I suspect your torque steer is more to do with thrust angle and the rear toe being slighty out compared to the centreline of the car than anything to do with spring rate

[jamieduff1981]

I understood the post to mean that he was grounding his chassis or exhaust on the road? If that's so, then ride height will likely still solve it. On 325lb/in linear rate springs then an extra inch of ride height will permit the equivalent G-load of an additional 650lbs on the rear axle to lower the car's chassis or exhaust to the road.

I must admit, if driving really hard I can ground my chassis too. I don't know what springs I have though.

[RobertoBlanco]

QBee said:

What are your spring rates? I understood they were 400 front and 375 rear on a T350.
I would try upping your rear ride height first. Easy job, especially on a ramp. Solved my bottoming issues.
I think the cars generally settle a bit with use. My GGPs with T350 springs were fitted to my Chimera 2000 miles ago and have already needed adjusting up by about 10mm.

Thanks for the advice.
As i see it the ride height on my car was set up with only driver sitting in the car and no passenger. So in general the passenger side sits lower when unladen. If i have my wife or a friend sitting beside me the tires rub on the inside arches on the passenger side on longer road bumps. so, no surprise here.
Trouble is, i just do not know the original ride height, as i bought the car with GAZ GP already fitted.

[RobertoBlanco]

MisterT said:

I've since softened first the springs (now F325lb/R250lb) then had the dampers revalved and it is now brilliant for my style of driving. I can push it down the lanes much more confidently now, traction is better and rear end breakaway under power is more predictable, in a nutshell I can drive it harder, faster and I enjoy it much more than I did with the harder setup.

That's an intersting thought. Will adjust the ride height first and then think of different springs then. As it seems even softer springs should do, so the fault on my car must definately be the rife height. Also adjusting the GAZ to harder settings didn't solve the problem (no surprise here....again).

[spitfire4v8]

jamieduff1981 said:

I understood the post to mean that he was grounding his chassis or exhaust on the road? If that's so, then ride height will likely still solve it. On 325lb/in linear rate springs then an extra inch of ride height will permit the equivalent G-load of an additional 650lbs on the rear axle to lower the car's chassis or exhaust to the road.

I must admit, if driving really hard I can ground my chassis too. I don't know what springs I have though.

the wheel rate is considerably less though, something like 200lb/inch? maybe even less than that. A normal set up would have some preload, then compress a couple/three inches on the floor. The rear end will weigh around 1000lbs so 500lbs on each wheel .. that's 2.5 inches at 200lb/in. so the wheel rate on most setups will be lower than 200lb/in?

[jamieduff1981]

spitfire4v8 said:

jamieduff1981 said:

I understood the post to mean that he was grounding his chassis or exhaust on the road? If that's so, then ride height will likely still solve it. On 325lb/in linear rate springs then an extra inch of ride height will permit the equivalent G-load of an additional 650lbs on the rear axle to lower the car's chassis or exhaust to the road.

I must admit, if driving really hard I can ground my chassis too. I don't know what springs I have though.

the wheel rate is considerably less though, something like 200lb/inch? maybe even less than that. A normal set up would have some preload, then compress a couple/three inches on the floor. The rear end will weigh around 1000lbs so 500lbs on each wheel .. that's 2.5 inches at 200lb/in. so the wheel rate on most setups will be lower than 200lb/in?

Yeah that's true - I forgot about the much larger moment the wheels have on the springs. Doh!

[QBee]

You will be surprised how much you can achieve by simply adjusting the ride height.