Hi.

Let me first say that this is not for a dms, 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 )

How does the celica's 4wd system work? I could be possible that a limited slip mechanism or a coupling unit failed, and it is not shifting the power like it should anymore.

Worn shocks can also hinder traction, but usually not to that type of severity on an awd setup. Well, unless it's got a crapload of power?

You are really describing the plight of high horsepower fwd cars, so I'd be curious to see if its 4wd system is not working like it should anymore.

The car have a welded center and rear diff, so should not be a problem there.
And is just under 700awhp. ( should run close to 150mph trap )

2 things.

1. Drag radials are hard on awd cars. They grip hard but the side walls are not soft enough. Dsm guys have this exact same problem with radials, I would look into a high sidewall light bias ply tire, something like hoosier qtps or if you need something more streetable the m&h street/strip tires work great. You need something bias ply to flex and absorb the hop. If possible a full slick is another better option as the sidewalls flex a lot. Don't forget tires provide diff levels of traction as they wear. Your hoosier radials might be in the sweet spot and gripping before than before causing the hop that you might not have had when they were new and uncycled. I personally think a 15 inch wheel with a big tall tire is the best option, probably something 26 inches for your power level.

2. Check all suspension/motor/tranny mounts and bushings. You might have broke something and that could be causing the nasty hop. If u haven't already replace everything you can with performance bushings. Seems like you did already but doesn't hurt to check again. Also as stated above check your shocks. The coilovers you have on the car are not the best quality to begin with and might need a rebuild already.

Any vids of your car. I love all tracs and have always wanted a 185.

What clutch is in the car?

I dealt with the same issue towards the end of last season. I broke broke 5 t-cases back to back trying to rid this wheel hop issue. I am changing coilovers to a drag specific setup and dropping getting custom sprig rates to help with the weight transfer. Any reason why you went with such a stiff spring rate?

little-razcal said:

I dealt with the same issue towards the end of last season. I broke broke 5 t-cases back to back trying to rid this wheel hop issue. I am changing coilovers to a drag specific setup and dropping getting custom sprig rates to help with the weight transfer. Any reason why you went with such a stiff spring rate?

Click to expand...

It seems most off the shelf spring rates are very firm. I guess they expect everybody is an "circuit racer". Awd cars also need super firm rear rates to handle properly and not under steer while drag cars need softer rated especially to help with weight transfer and squat while coming out of the hole on the 2 step/ anti lag. From what I have seen most rated are way more circuit oriented.

I have some coils on my car the rates are too firm but at my power level I can deal with it. I personally think the op has an issue with his dampers and also with those drag radials. Radials break stuff, its a known fact. The Hoosiers are the softest sidewall radials and they work decent on evos but for some reason anything non bias ply causes issues on dsms and older awd cars, probably because most of them have bushings and mounts that are worn to shit. Qtps seem to work great for cheaters, any slick also works great and for light street duty I have heard amazing things about the m&h street strips. I'm gonna order a set of the street strips real soon. I have autocross tires currently on my Dsm and thankfully they are years old and don't hook otherwise I would expect wheel hop and broken parts due to th super stiff sidewall construction

turtleb00st said:

2 things.

1. Drag radials are hard on awd cars. They grip hard but the side walls are not soft enough. Dsm guys have this exact same problem with radials, I would look into a high sidewall light bias ply tire, something like hoosier qtps or if you need something more streetable the m&h street/strip tires work great. You need something bias ply to flex and absorb the hop. If possible a full slick is another better option as the sidewalls flex a lot. Don't forget tires provide diff levels of traction as they wear. Your hoosier radials might be in the sweet spot and gripping before than before causing the hop that you might not have had when they were new and uncycled. I personally think a 15 inch wheel with a big tall tire is the best option, probably something 26 inches for your power level.

2. Check all suspension/motor/tranny mounts and bushings. You might have broke something and that could be causing the nasty hop. If u haven't already replace everything you can with performance bushings. Seems like you did already but doesn't hurt to check again. Also as stated above check your shocks. The coilovers you have on the car are not the best quality to begin with and might need a rebuild already.

Any vids of your car. I love all tracs and have always wanted a 185.

Click to expand...

I wish i could use some bi-ply tires. but since i can`t use anything smaller than a 16" wheel, and my 24.5" high tires bearly fits as is, i don`t have a chance getting 26" in there.. so i`m stuck with these if i want to use the brakes i do now.

I have found 2 bushings that is still stock on the car ( forgot about them), and ofc it is the ones controlling toe on rear wheels... ( rear controll arms.)
Also seems that the locking nut that locks the hight of the coilover ( mcpearson) also is just a little loose, so that the coilover have about 1-2mm play making the wheel have about 2-3mm play when using a large bar to bend on the wheel itself. ( only one side )
This is only in the rear i can find anything wrong. But will start with changing these things.

little-razcal said:

I dealt with the same issue towards the end of last season. I broke broke 5 t-cases back to back trying to rid this wheel hop issue. I am changing coilovers to a drag specific setup and dropping getting custom sprig rates to help with the weight transfer. Any reason why you went with such a stiff spring rate?

Click to expand...

The reasson to the stiff spring rate was that when i first bought these coilovers. i was still running a stock center VC unit.
And since they are quite weak ( don`t ever brake, but are weak in terms of how much of the power they can send back to the rear wheels.) my theory was that if running a stiff spring setup, the weight would not shift so much towards the reas, and therefor the front tires would keep more grip stopping the front tires from spinning so much.
but since then i have moved on to a "welded" center, and this is not a problem any more.

turtleb00st said:

It seems most off the shelf spring rates are very firm. I guess they expect everybody is an "circuit racer". Awd cars also need super firm rear rates to handle properly and not under steer while drag cars need softer rated especially to help with weight transfer and squat while coming out of the hole on the 2 step/ anti lag. From what I have seen most rated are way more circuit oriented.

I have some coils on my car the rates are too firm but at my power level I can deal with it. I personally think the op has an issue with his dampers and also with those drag radials. Radials break stuff, its a known fact. The Hoosiers are the softest sidewall radials and they work decent on evos but for some reason anything non bias ply causes issues on dsms and older awd cars, probably because most of them have bushings and mounts that are worn to shit. Qtps seem to work great for cheaters, any slick also works great and for light street duty I have heard amazing things about the m&h street strips. I'm gonna order a set of the street strips real soon. I have autocross tires currently on my Dsm and thankfully they are years old and don't hook otherwise I would expect wheel hop and broken parts due to th super stiff sidewall construction

Click to expand...

Another theroy i have is that the spring rate for the coilovers are just to stiff for the dampers. ( they are 2x the "stock" rate for these coilovers) and because of that, the dampers are not able to control the spring from "bouncing" ?

aml15 said:

Another theroy i have is that the spring rate for the coilovers are just to stiff for the dampers. ( they are 2x the "stock" rate for these coilovers) and because of that, the dampers are not able to control the spring from "bouncing" ?

Click to expand...

This still doesnt make sense to me, as this is something that changed drastically recently. You stated the car would smoothly burn rubber and then suddenly its bouncing all over the place.

Something changed/wore out/bent/broke/gave/gives more now than before.

If nothing in the setup was changed by you, it only makes sense that something changed itself within the setup.