Droop travel

[nicemd]

Hello, first post here...

I've noticed I have no droop travel at all on my rears on my Caterham.

I wonder if that could be a possible cause for having troubles getting the power down on corner exit?

The car is fitted with a Quaife ATB, and I've read that unlike other LSDs the Quiafe won't lock if one wheel is completely unloaded.

My theory is that on corner exit the lack of droop travel sometimes causes the diff not to lock and as a result I get inner wheel spin.

Does this sound like a reasonable theory?

How much droop travel is enough?

Any help is appreciated

/Niclas

[phoenix]

My first concern would be why you have no droop. Do you know? Is the axle being held up because the dampers are too short or by some other mechanical problem with the axle links? Or maybe you have an over-stiff rear anti roll bar (which would give the effect of no droop in roll only)?

You definitely want some droop, as without it even the smallest amount or roll will leave the tyre unloaded. Even if the LSD was working, the inside tyre would be doing know work at all, severely limiting your rear cornering grip as well as traction.

How much droop is harder to say, though I would think 25-30mm as a minimum. Do you know what kind of roll angles you achieve or are expecting to achieve?

[nicemd]

Thank you for your reply!

I haven't looked into why the droop is limited, but I assume it is because the dampers are fully extended.

The car has no rear ARB, but overall the car is pretty stiff with Caterham's race dampers, springs and front ARB.

Sounds like it worth doing some tests with lowering the car 1-2 cm and see if the symptoms disappear. (that would increase droop-travel, right?)

[phoenix]

Originally Posted by nicemd

Sounds like it worth doing some tests with lowering the car 1-2 cm and see if the symptoms disappear. (that would increase droop-travel, right?)

Yes it should, and will unless the springs are really stiff and not compressing at all under the weight of the car/driver.

[elitemotorsport]

You will defo want some droop, and 25 - 30mm on a 7 is probably not enough but if you have the option to lower the car and achieve that to start with it will at least begin to prove the point.

If you have enough ride hieght to lower it at all then you should, front and rear because it'll dramatically improve the cornering performance even forgetting the current problem you have.

D.

[nicemd]

I have checked now and the droop is limited by the damper, but the springs are really tight with the rear jacket up into the air. Is that called "spring preload", and should be set to almost none?

My rear tyres gets much more worn on the inner 5 cm, but I have only -0.5 degrees camber and almost zero toe. (cross-ply setup)

I wonder if that also could be an effect of the limited droop travel?

(I suspect the race dampers I have are too short for the road version of my car)

[tristancliffe]

Yeah, the springs are preloaded, so it sounds like the weight of the car isn't enough to overcome the preload. If you can reduce the preload you'll get more droop travel, but the rear ride height will drop. The spring rate (once the preload is overcome) doesn't change, so no advantage having preload if you don't actually want it.