Spring pre-load?

[votan]

Just got a new set of GAZ Gold Pro shocks with spring rates 500 front 450 rear.
I want to keep the car as low as possible but without sagging in to much when entering the car or hitting speed bumps.
What would be the best pre-load in inch for the front and rear?

Intentionally I would just do 1 inch pre-load front and rear, but would like to hear some more qualified rates.

[spitfire4v8]

The preload in this instance is irrelevant .. it's whatever you end up with after you've got the ride heights and corner weighting that you require .. the only way after that you will alter preload is by altering the extended length of the damper and I'm guessing you won't be doing that ..

[scotty_d]

Those spring rates seem very heavy. Are you doing a lot of track work?

[nawarne]

As Joolz says, it's pretty irrelevant.

Wind up the lower platform when mounting springs/dampers on car....just to allow you to get jack out when 'that corner' is finished.

Set final ride height by adjusting lower platform when all 4 corners done. Most folks go for 140mm rear and 130 mm front measured from o'rigger gusset plate to ground...Then get a good geometry set up.

Nick

[Walford]

spitfire4v8 said:

The preload in this instance is irrelevant .. it's whatever you end up with after you've got the ride heights and corner weighting that you require .. the only way after that you will alter preload is by altering the extended length of the damper and I'm guessing you won't be doing that ..

Do you mean length of spring ?

[spitfire4v8]

No i mean damper. for any given spring rate the spring platform will be set to take the load of that corner and bring it up to the desired ride height. If you then jack the car up so the wheel is in full droop that gives you a pre-loaded spring only if the extended damper has less distance between the spring seats than the open length of the spring. The actual spring length is irrelevant because whatever the length of spring you still have to move the spring seat to give you the ride height you require. Whether the spring is 8inches or 12 inches doesn't change that, it only changes the position the adjustable spring platform starts at. You would have no preload if the extended damper ended up with spring platforms far enough apart that they were further apart than the open length of the spring. For all other times you will have to preload the spring to get sufficient load carrying from a given spring rate, but it's not important to know the preloaded ammount because all you'll be concerned with is that you have a spring rate that gives you the ride and load carrying ability that you want, and that the fully extended damper spring seats aren't so far apart as to unload the spring completely, as that is an MOT fail.

[votan]

Thanks for all your tips. Will test some setups.

@scotty_d... I mostly do fast road use.... but the original Bilstein dampers with the slightly softer springs didn't feel right. So I'm going for a stiffer setup. Trying to find a good compromise between the soft standard and track setup. And 500/450 should be ok for that... i'll check it out later this week when I finally have put everything together.

[Walford]

spitfire4v8 said:

The actual spring length is irrelevant because whatever the length of spring you still have to move the spring seat to give you the ride height you require

The 400lb Nitron springs are 50mm shorter than the stock TVR ones