Off-throttle problem

[Pazz]

Bit of a concern here, I had this problem after fitting coilovers and dropping the car.

As I release the throttle from being on full load (at the point the stock bov releases) the car feels like it sways to the left.

I thought at first it was an alignment issue, however alignment was done just this monday with camber and toe arms pre-fitted. The problem doesnt seem to be as bad after alignment but its still there.

The setup which, I witnessed, was done with a light beam kit. The setup was 0.5degree neg rear camber 1deg neg front camber with toe-in at the rear of around 1deg total.

However the front definetly doesnt seem to be tracked correctly. So its going back. But could it be a mounting or bush possibly causing the problem?

 

[Nicely]

I've had a 'laser' alignment done before and landed up with tracking which was fook loads out. Took it to be sorted at a place where they used the old mechanical bolt on tracking!

Have you checked the damping is the same on all four corners?

 

[Matt_S]

If youre ride heights and preload havent been set equally that can do that.
But the last time I had something as severe, it turned out they had fcuked the alignment.
Try toe all over the place, 7 deg castor one side and 4 deg castor the other :wack:

Stooopid cooonts!

 

[Pazz]

I'm pretty sure the damping is the same all round, possibly a couple of notches harder on the front. But I will reset it and select a setup again.

I will also drive the car onto a flat surface and check the ride height. As for pre-load I will be pretty fooked off if its this, as wouldnt this mean taking the struts off? I just thought I'd finished taking it apart, not that I dont enjoy it. But its finding the time.

To add to the fun, I am pretty certain the front wheels are unbalanced. So they are going back to where I had them balanced tomorrow. Fookin dojy mechanics who cant even do the simplest of jobs. And just to confirm - none of the weights around the rim have fallen off.

Seems to be getting pretty impossible to find a decent alignment/wheel shop these days.

 

[Pazz]

It seems to be the most noticable at high speeds.

 

[Pazz]

Damping is set even all round at just slightly harder than middle setting.

Ride height has been checked today and is bang on level all-round. (front and back respectively)

Tracking is still yet to be looked at but pretty certain its not straight.

The car still pulls to the right under acceleration then jolts to the left upon lifting off.

Pre-load is still a suspect.

 

[Matt_S]

OK, have you got even depth treads on the rear?
Have you a mech diff on there?

 

[Pazz]

Tyres are pretty new and tread looks pretty healthy, nice and even from side-to-side.

Diff is the stock HLSD. I thought about changing the diff oil now, but its next service date is coming up soon (first in the UK) so I'm going to pop down to APT for receipt etc. If its not sorted by then I will ask them what they think.

 

[Matt_S]

OK. The reason I said that is cos one day after a drift day in the S14, I put some wheels/tyres on the car that 'looked' like even tread.
Drove off up thew road and on the motorway I was having to hold the steering wheel stright when under acceleration. The car would change lanes in about 2 car lengths with no hands on the wheel :wack:
It was Ok when on contstant throttle tho :wack:

Turns out, the tyres werent quite as level on the tread as Id thought. With the locking mech diff, under accleration the diff was locking up (as they do) but with the differing rolling radius' the car was in effect 'steering' towards the smaller (lower treaded) tyres side...
Got to the nest services and changed them to some proven wheels/tyres and the car was as it OK again

 

[Pazz]

Good idea. I will swap all the wheels over to the opposite side. Just for trial and error to see if it then starts to sway/pull to the other side.

 

[Nicely]

Just be warned that if the tyres are directional, they'll be the wrong way wrong if you swap wheels side to side.

 

[Pazz]

I had realised this Nicely.....only just when I was about to fitt them...DOH!

As a fail safe, I used the stock S15 wheels which I know are 100% ok.

What was interesting is that I noticed after taking the wheels off and a few measurements that there was a slight 2-3mm difference in the distance between top of strut and first locking collar. So spring seat collar was tightened a tad and ride height to match.

I know this may sound a little eager after only one test drive, but the problem appears to of gone. Can a 2-3mm preload difference be enough to cause the problem? So I am now thinking either bad tyre wear or bent wheel .

Recap of the problem: The car was literally pulling to the right under heavy acceleration, then when thorttle was released a jolt/sway to the left.

Many thanks for the help everyone, I've never experienced this problem on a motor before.

 

[Matt_S]

Its Ok to run them the wrong direction, but bear in mind they wouldnt clear water as well as theyre intended too.

May be an idea to pull the rear shocks off and double check all preloads etc.

 

[Pazz]

UPDATE:

Yesterday I swaped the rear wheels over. I had directional tyres so they were rotating opposite to what they were meant to, but it was a dry day so wouldnt make a difference.

The interesting news is that the car began to pull to the opposite side now that the wheels had been swaped. So the problem has to be to do with the wheels and/or tyres.

Both tyres appear to have plenty of tread which is even.

I have fitted the stock S15 wheels for the time being, which are stupidly narrow and very dangerous in my oppinion.

 

[Matt_S]

Just get them spun up on a balancer mate to make sure theyre not buckled etc. And maybe measure the circumfrence (sp) of each tyre.

 

[Pazz]

They have been spun on a balancer. But good idea to see if the circum is the same. I'm getting pretty stumpted as to what to do next after that...

Thanks for the help with this Matt!

 

[Matt_S]

No worries. Glad I can (hopefully) help you sort this out!

 

[Pazz]

I've done my best to measure the circumference of the two tyres but the degree of accuracy was pretty apauling. I measured the rims considerably better and all seems ok.

I think I am just going to have to take the plunge and buy a new set of tyres for the rear. Will just have to cross my fingers that the problem isnt with the rims themseleves.

 

[Matt_S]

Have you not got a tape measure? :wack:

Just wrap it round!?!?

 

[Pazz]

I have tried it, but you just cant get it very accurate, due to it kinking. I have a fabric measure but its not long enough.