or indeed axle tramp...

is this the same as anti squat?

been buying some axle brackets from rally design and they call the anti tramp brackets

[Edited on 22/4/07 by blakep82]

Tramping is normally caused by the windup of the rear axle under acceleration. The tramp bars stop the axle winding on the springs.
A typical set up on an escort would be 4 link bars that stop the tramp, and a panhard rod that locates the axle sideways.

Steve

do you mean like the prop shaft trying to twist the axle (lifting one of the wheels and pushing the other down)?

how do the link bars stop it?

No, normally a live axle is mounted on leaf springs only, so when you accelerate the wheels push the axle forward, but as they are only connected to the springs, they start to twist the springs. The wind up of the spring is what causes the tramp effect.
By locating the axle with bars you transfer the thrust straight to the body.

i see!

so, since we're all using 4 link systems we shouldn't be too concerned then should we?

With the 4 link set up, tramp disappears. With a 5 link set up, axle movement should be totally controlable, but you'll need a Watt's link or similar to do it properly. BUt you sound as if you know that anyways

i'll be working on my watts linkage very soon

I take it then that you now know the difference between anti tramp and anti squat? I'm guessing you knew the two set ups, but were unsure as to the names?

anti squat being a set up that prevents the back of the car pushing down on acceleration? (similar to anti dive on the front, to stop the front of the car dropping under braking?)

I'm not too good on suspension geometry, but really need to get the basics sorted in my head before building a car which will be horrible to drive

Yup, you got it right. Anti-tramp to stop the axle bouncing all over the place, and anti-squat to aid traction off the line.

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Originally posted by DIY Si
Yup, you got it right. Anti-tramp to stop the axle bouncing all over the place, and anti-squat to aid traction off the line.

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My understandinsg is simialr, but varies in one detail. The anti-squat tries to force the car up at the back, thus putting the weight plus the reaction force through the wheels, thus increasing grip. Lots of anti-squat will see the back of the car rise on launch. I may however have the wrong term for it, but I know it as anti-squat.
As you rightly say though, it will remove all/most of the front wheel grip, so flooring it mid corner wil see you understeer into a tree.

quote:

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Originally posted by DIY Si
The anti-squat tries to force the car up at the back, thus putting the weight plus the reaction force through the wheels, thus increasing grip.

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I'm sure about how it works, just unsure on the correct term. As you apply the power the axle will try to twist. This twist normally squats the car down by pushing the top trailing arm forward and pulling the bottom one backwards. However, if you angle the trailing arms up, this then decreases the effect of the twist and thus squat, eventually reaching 100% anti-squat as the car sits level at a full launch. 100%+ will see the car rise. That's probably badly explained and makes not much sense, but it should get some of what I mean across.

A 4 or 5 link rear can still allow axle tramp if it's not well designed, or the bushings allow too much movement - the Triumph TR7 was an example.

The old Chevette with it's torque-tube 3 link rear had so much anti-squat, it would visibly rise up at the rear (even with a modest 57hp!) Almost impossible to get wheel spin, but still very neutral handling.

Thanks for the clarification I am planning to re-design the suspension on my Cobra which currently has tons of squat off the line giving me quarter mile times of around 13.5 seconds which is much better than my motor deserves due to almost zero wheelspin off the line.

The car also handles a bit like a barge due mainly (I think) to rediculously heavy unsprung weight and very soft springs giving a wheel rate of around 75.

I will seriously concider building in a little anti-dive (another problem I have) and anti-squat.

All the above to go with twin turbos and homemade EFI to give around 650 hp (We can dream can't we)

Now if only I could find a cheap sequential box to go with it - will have to stick with TH400 for the meantime

[Edited on 24/4/07 by Ivan]

Hi some rather rash comments regarding the use of anti-squat above.

If interested in anti-squat then try some research on mallock clubman cars.

It is somthing that if you have a live axle is certinaly worth looking at if looking for better acceleration.

cheers matt