Axel Tramp - Help needed

[maxhag]

Well, I've tried, but haven't been able to come to a solution. :peek:

My problem is Severe axel tramp in my AE86.

Where do I start.....
My suspension setup is:
GReddy coilover setup (front coilovers and rear adjustable spring perches and fully adjustable GReddy Shocks, stroke and damper), modified R31 rear end..

Now, For the last year, I have had some random positive offset wheels on the car, which were on the car when I installed my GReddy coilover kit. Never had ANY problem with axel tramp.

Recently, I have got some WORK EQUIP 01 rims, 15x8 -13 offset. When I put them on, I adjusted the rear spring perch heights and what I believe is the 'stroke' of the shocks, so the height looked 'JDM' (neg offset and low). Ever since then, I have had severe axel tramp problems.

The car drifts/slides without any problem, but if I try to spin the wheels from standing still, the axel tramp is totally fucked! Why do I need to spin the wheels from standing still you ask? Well I race in the Canberra hillclimb competition, and need to do a burnout to warm up my slicks for the 1 lap circuit.....

I have tried adjusting the spring heights and shock stroke (?) to fix the problem, but it is making no differance. Because of the variables, Iam not really asking for an off the shelf answer, but I am more asking about the causes of axel tramp with an AE86.

If someone here has the time to explain the causes of axel tramp, it might enable me to get my head around the physics of this problem, helping me with an adjustment solution. I am quite frustrated that it was once all ok with this suspension setup, but now cant return it to how it was. All advice is greatly appreciated....

Regards,
JoJo

[svenmate]

How new are the shocks? They are generally the main factor to tramping.

Secondly, I'd have a look at the bushes in your trailing arms. Old crappy bushes definitely make it worse.

Hope that helps :)

[maxhag]

The shock were brand new and I fitted them in December 2010. Up till now, they would have done about 1000km-1500km only.....
Bushes are standard items, but are in decent condition.....

[john84ie]

ive always found axel tramp from worn bushes in trailing arms,better of goin pollybushes and see how that works

[lolwat]

4agte powered ae86??? i have been told from people on here its caused from bushes and rear end is too stiff, was told by guys at work its rear end too soft and the tyres are "hopping" causing it

have you tried softening and hardening of your shocks at all?

[maxhag]

nah, not the problem. As I said, it was only after I adjusted the suspension for the new wheels that it started doin it.... Same bushes...

[john84ie]

wouldnt hurt to throw them in anyway,techno toy tuning go a good kit with all the bushings in 86 for cheap,good improvement

[lolwat]

if you have lowered it, you may need traction brackets, apparently (quick google) there was a few forums with yanks saying either put up with it, or try traction brackets(yes i know yanks are well YANKS :/)
personally with what your doing why wouldnt you run a nolthane bushes anyway???



if worse come to worse adjsut it back to the way you had it and change 1 thing at a time until it starts tramping again (yes alot of time)

[maxhag]

Yeah, I could proberly do with some better bushes in general, but the bushes are not the solution to this particular problem..... Iam really after more info on the physics of the cause....

[Skylar]

Now, For the last year, I have had some random positive offset wheels on the car, which were on the car when I installed my GReddy coilover kit. Never had ANY problem with axel tramp.

Recently, I have got some WORK EQUIP 01 rims, 15x8 -13 offset. When I put them on, I adjusted the rear spring perch heights and what I believe is the 'stroke' of the shocks, so the height looked 'JDM' (neg offset and low). Ever since then, I have had severe axel tramp problems.


So,
old wheels + greddy = fine
new wheels + lower car+ greddy = bad

From that, it seems the extra lowering has caused some of your axel tramp. Putting traction brackets in should help. All these do is raise the side view instant centre closer to where it used to be and cause the car to squat less when accelerating. Less squat = less suspension movement which brings me to the next point.

I read somewhere, (pretty sure it was carrol smith) said taking out a lot of bump damping damping said it helped reduce axle tramp a whole lot. It has to do with the damper being located at the back of the diff and not on top of it causing it to wind up in the (old and aged) trailing arm bushings.

Whadoyathink?

[lolwat]

Whadoyathink?
sounded good to me

[maxhag]

Thanks mate, good helpful points there.

Had another go at it and it it much better now. I had to lengthen the shock, as I had it too short, affecting the diff pinion angle Iam guessing. There is not much travel in the shocks now though, only about 2-3 inches, but the springs are 6kg spring rate, so there is not much movement in the suspension anyway. I now realise how I went wrong, wasn't focused on the diff angle....

Here is a pic to explain...

http://www.ae86drivingclub.com.au/dcimages/1/1/1/68611.jpg


Thanks to everyone for their help.....