Pulling to left under acceleration

Defcon5 · 13 Dec 2010 at 17:05

Under hard acceleration, if I let go of the wheel, the car pulls strongly to the left. With no throttle, it stays straight if you let go of the wheel. Also stays straight if you hold it straight, but the wheel is trying to turn. More acceleration = more severe pull. Speed makes no difference, only amount of throttle.

What could cause this? I initially assumed geo but why would it only happen under acceleration? Surely not torque steer? Plant the throttle in 6th at 70mph and it still does it.

Tracking is fine, will do a full geo check asap, but as I said, surely anything geo related would make it pull left regardless of throttle input

Car is a Lupo GTI, on height/damping adjustable Koni coilovers. Recently I have replaced the wishbones and ball joints, but this problem has come on more recently.

Thanks

Cuchulain · 13 Dec 2010 at 17:10

Check your tyres, rotate them and see if it starts pulling to the right

(sounds daft but happened to me many years ago).

Defcon5 · 13 Dec 2010 at 17:11

Thats my next port of call when I come of day shifts!

Why would that only affect it under acceleration though, thats the bit I cant get my head around

Smokey26 · 13 Dec 2010 at 17:13

Have you hit a pothole maybe and knocked a weight of the wheel. Might course it, i had a similar problem with my DC5, though the wheel started moving and becoming light the faster i went. Turned out id knocked a weight off.

Luke · 13 Dec 2010 at 17:16

Not torque steer from massive power output then?

Defcon5 · 13 Dec 2010 at 17:20

Luke said:
Not torque steer from massive power output then?

That would explain pretty much all the symptoms, but I very much doubt it!

BigglesPiP · 13 Dec 2010 at 17:48

Symptoms exactly match torque steer. Most powerful motor in that chassis? What do other Lupo GTi Users report?

Defcon5 · 13 Dec 2010 at 17:51

It has 125bhp, 112ft/lb ,weighs about a ton.

Left drive shaft is shorter than the right. It has an electronic differential to keep the wheels within a certain rpm of each other

I have had the car for 3 years, and never noticed it before. Its not reported amongst other owners as an issue

Smokey26 · 13 Dec 2010 at 17:54

112lbs torque.

next thing we know Honda's will be torque steering.

MagicBoy · 13 Dec 2010 at 18:03

Are the tyres identical?

I had similar problem when a front tyre was replaced after a puncture. Turns out that the existing Goodyear F1 GSD2 and the replacement GSD3 didn't mix too well on the same axle. All the geometry checked out fine, problem went away after I had a matching GSD3 fitted.

Then again I've got a few more torques. Well more than double.

BigglesPiP · 13 Dec 2010 at 18:09

Defcon5 said:
It has an electronic differential to keep the wheels within a certain rpm of each other

That'll be a regular diff with ASR then?

I have had the car for 3 years, and never noticed it before. Its not reported amongst other owners as an issue

Probably uneven tyre wear or tracking then.

Defcon5 · 13 Dec 2010 at 18:16

BigglesPiP said:
That'll be a regular diff with ASR then?

VW call it EDL (electronic differential lock) I dont know the specifics of it as id doesnt appear to do anything useful

I beleive it applies the brake to the spinning wheel to send power to the wheel with grip. It doesnt have traction control or anything like that

BigglesPiP said:
Probably uneven tyre wear or tracking then.

Why would that only affect it under acceleration though?

sigma · 13 Dec 2010 at 18:32

I'd get the tracking checked anyway, an ATS will do it for free, my local place is really good they showed me how badly it was out. It was out by 6 degrees IIRC and the car didn't pull at all!

Check the innner shoulders of your tyres for excessive wear.

BigglesPiP · 13 Dec 2010 at 18:32

Defcon5 said:
VW call it EDL (electronic differential lock) I dont know the specifics of it as id doesnt appear to do anything useful

I beleive it applies the brake to the spinning wheel to send power to the wheel with grip. It doesnt have traction control or anything like that

ASR is the same but is used for electronic diff functions and traction control.

Why would that only affect it under acceleration though?

Because there's a hundred different ways tracking and tire wear can go and all sorts of results.

Defcon5 · 13 Dec 2010 at 18:36

sigma said:
I'd get the tracking checked anyway, an ATS will do it for free, my local place is really good they showed me how badly it was out. It was out by 6 degrees IIRC and the car didn't pull at all!

I have been to two different places to check the tracking (jut tracking, not other geo settings checked) and both said it was fine

Ill swap the wheels around and see if anything changes

sigma · 13 Dec 2010 at 18:41

Wondering if a sticky caliper piston would do this? Certainly something to rule out, just hold your hand over each wheel and see if the left hand side is hotter than the other.

MagicBoy · 13 Dec 2010 at 18:41

What about the matched tyres?

Amoeba · 13 Dec 2010 at 18:42

Get a 4 wheel alignment check. Control arms move slighly under acceleration so can easily show these symptoms. You might find your passenger side front wheel has less toe-in than it should do (probably due to hitting a pot hole at some point!) which then moves to toe out when you boot it causing a bit of wander.

All speculation of course - you need to get it checked!

Defcon5 · 13 Dec 2010 at 18:45

MagicBoy said:
What about the matched tyres?

All the tyres are the same, however I have recently put the rears on the front and new tyres on the rear.

Sigma - I initially thought that, brakes are fine

sigma · 13 Dec 2010 at 18:52

Maybe a bent tie rod (guess you would have had to hit something for it to bed) or some bush under there is worn, don't really know enough about suspension personally but it might be worth jacking it up and having a nose around for anything obvious.