Hi.

Let me first say that this is not for a evo, but for a old 4wd celica ( st165)

I am having HUGE problems with wheel hoop\stepping as soon as the tires loose traction when running my hoosier drag radials.

This car have been on the drag strip for a few times a year, and the car have behaved good up until recently. could do burnouts\and leave the line spinning.
But at some point the car have been starting to get EXTREME wheel hoop ( really violent stepping) as soon as the tires loose traction. resulting in broken drivetrain parts. ( so violent that even the windshield cracked.)
( 3 rear axels, 2 front axels, and a leaky gearbox all in the last 3 runs where the car lost traction of the line..
The car have never had a problem with hoop before now.
The car have been taken completely apart between these runs, and all bushings are perfect ( poly in everything, including rear cradle,engine mounts,\rear diff bushing)
running Hoosier drag radials, and BC coilovers with 10/8kg springs ( most after-market coilovers are stock with 6 front and 4 rear).
Tested with different tire pressure to lower traction (18,22,32psi) full soft and full hard settings on coilovers=no difference....
It`s really starting to become expensive to try to figure this out.. ( car was doing perfect flat burnouts every time up to a point, and now i can`t even leave the line with wheel spin.

Since the car behaved good up until a point, i would assume something have changed. but can`t see anything wrong ( alignment is perfect\same)
On road tires there is no problems. only on a prepped track with drag radials.

I also do some road racing with this car, and i can`t feel anything wrong with it then either, but is it possible that the dampers is starting to let go? ( can`t feel anything wrong with them at 150mph on a road race track ) but will a bad damper with a hard spring be able to cause this problem?

I hope someone have some hints on what i should look at.

(PS: asking on the evo forum since the celica drag racing community is non existing )

 

Drag radials inherently wheel hop on a well prepped track because the compound is soft enough to get the grip, but the sidewall is too stiff to absorb the shock. If you don't care about your 60ft use street tires that will spin instead of hop or get a bias ply tire that has a soft enough sidewall to not hop. No other options.

 

So are the evo guys also having this problem?

The higher tier cars seem to be able to run the ok? (gtr,lambo)

 

they probably have higher tier suspension setups helping is my assumption. in your case, a softer suspension would probably help, since the tire can absorb the shock, the suspension would

 

Get a set of MH slicks