hathi

Ok today was having a talk with a friend about adjusting your ride hight. He was trying to tell me that if you crank up your adjuster nut on the springs that the suspension gets softer. This can not be true, can it?

I say that the spring will still have the same stiffness!

What do you people have to say?
Could some of the racers please chime in here, and tell us which one is right?

FastEddy

My Feedback: (1)

More or less a SINGLE RATE spring should not be SIGNIFICANTLY effected by a Pre-load.
There was an article about this several years back in one of the Mags.
I dont recall what Mag it was.

MONAROMAN

Its called preload...

wind the adjuster down so as to tighten the spring and add more force = stiffer suspension

wind the adjuster up so as to loosen the spring and lessen the force = softer suspension

thats a pretty basic one

FastEddy

My Feedback: (1)

The amount a single rate spring is compressed should have LITTLE effect on the STIFFNESS of the spring. It is a SINGLE RATE spring and if its a good one will have the same rate throughout a majority of its compression.

Take out any other shock component as a factor and the ride height adjustment alone should not effect the "STIFFNESS of the spring.
Raising the ride height will not do anything more then just that, raise the ride height.

tom111

MONAROMAN is right, I think it is also depends on where you are driving your car & what are you aiming for, if you are going for off road you can make them softer & if you are going for on roan you can make them stiffer for better balance & grip.

ttoks

if you have yru suspention set up right, you will have sag in the suspension, more pre load will, at the same ride hight as before give you harder suspension, but of course it's going to sit higher, so it will have the same spring rates untill you get to the point that you've maxed out the shock travel when your vehicle is sitting on the ground, once you get to that point the pre load will effect the springs rates significantly, 9 times out of ten is will just give you high or lower ride hight though.

Apache-

It just sets the ride height of your car.
Does nothing to the spring.
The car its weight is carried by the springs.
So no matter high or low, this remains always the same.

People who talk about pre-load are thinking wrong unless they are restricting the travel of the wishbones.
The suspension / shocker then can not go and move out freely.
In this case when the travel limiters are used restricting the downgoing movement of the wishbone, then you can talk of adding pre-load by turning the adjustment ring.
The same spring is then put under higher tension, you then get more pre-load.
This will feel as if you were using a harder spring configuration.

Such a set-up is rarely made in off-road. The above descriped is more a thing/trick for on-road racing.
A car can be set very low using these travel limiters and limiting the outgoing movement / limiting the droop.
By limiting travel you can balance the car, it is often used to take away grip on either the rear or front axle.

In off-road you wish to have in most cases as much suspension travel as possible to absorp the bumps, jumps etc.
Limiting them makes only sense on high grip astroturf tracks which are ultra ultra flat without bumps. There is exept for the one-off track in Salou no such track I know off.
For offroad it is therefor much better to invest in a stiffer spring when you feel the one you are using is too soft; rather than limiting the suspension travel and loose what is precious (suspension travel) for good handeling.

Setting up shockers correct is one of the most difficult things and is one of the major keys to get a car going like lightning or make it handle horrible.
In off-road probably the most important together with the choice of rubber.
Racers adjust for each track their suspension. Or better, they change it even each heat if they think it can be improved.
In +90% of the cases it still can be improved, hence why pilots keep working on their cars and suspension foremost in off-roading.

The choice of the spring is just part of it. There are numerous types of springs and opinions on these vary.
For sure the rebound determined by the oil and the flow holes, shape of piston, one way restrictors and more of these things have a huge influence as well.
It is a very complex system of parameters and a study of its own.

All I can advise is go to a track or spot where you can drive under same circumstances and then start to experiment with springs, oil and ride heigth. After this you can take it further to shape of pistons, progressive springs, one-way blocked pistons etc. etc. You need to know then exactly what you are doing and foremost why. Watch cars of other racers that sem to drive very easy over a track and ask them what they use for oil and springs. Most of them will answer you what they are running. Note that different makes of oil cannot be compared. Stck with one brand and go from there so you know what you are using.
Hope it answered your 1st question.
It brings along possibly 1000 others.

vertigo performance

Preload is ride height, a single rate spring is single rate no matter where in its compression it sits. This is why the baja has 2 rear springs per side, allows smooth controllable ride and better landings off of jumps.

mnf1sand

Wow this thread gave me a headache. Hathi your buddies right providing the vehicle is not riding on any up or down stops, also known as droop screws. SO if the vehicle is floating free on the spring and you add a spacer you added ride height, if you remove a spacer you would lose ride height. The spring rate and function has not changed. Now throw in the droop screws and and spacers pushing the spring and suspension tight then your adding preload which has effect of the vehicles handling also.

Apache-

The Baja double spring is a single rate as well.
The upper and lower have the same pitch and thread diameter. So the rate {N/m} is completely the same as with a single spring.
The good thing about this double spring is that there is an option to place 2 different springs.
This could then work the same as a single progressive spring.
By exchanging upper and lower springs you can then set your own (progressive) spring easily.

To state the baja is a better controleable ride I highly doubt. It lacks loads of grip on the rear.
The Baja's run here on astro turf, dirt tracks, hard tracks all thinkeable types of surfaces. We've been to several races, also all the European GP's. If it would be so well controleable it would win, this is not the case (yet) after I have seen the car in numerous races now for one year. A well set-up marder outrans a baja easily. And there are lots of other makes that make a marder look pale on the track when it comes to handling...

The Baja handles bumps excellent, that I fully agree.
But that has more to do with the huge shock travel of the Baja rather than the springs.
Handling and controlling the car is rather lousy compared to for example a hormann.

As for preload & ride height mf1sand got it right.

hathi

This is the answer what Im looking for.

We were not have a discussion on ride hight.... sorry should have made that more clear, he thinks that the spring rate would change... my bad