Pulling
 

Morning all,

What might cause a car to pull to right under (only heavy) braking, and also, subtley pull the car to the left under acceleration??

Tyre pressures perhaps? "

2 seperate coincidental factors? My front calipers are in good shape, but the brake lines are original - could that cause an imbalance if one is getting tired?

I'm currently running knobbly old winter tyres with big blocks so perhaps thats a factor too..?

Tyres pressures are the most likely cause, followed by a seized or sticky caliper.

Tyre pressures first, if none of the callipers are getting hot (front or back) brake lines are either sound or bust so not so likely, Have you hit one of our famous British pot holes lately? that might have put the geo out.

I'm certainly not ruling out potholes - I seem to seek out more than my fair share. But I would have expected that to make the car pull one way or other all the time, rather than just under harsher inputs?

Usually rear tyre pressure or wear. I used to drive to work around a number of roundabouts on which I used to have some fun. My rear left tyre wore quicker than the right and I noticed a slight pull when they were over half worn, plus a little shimmy when going over catseyes etc. A worn rear toe arm bush might exacerbate it too.

Checked the pressures last night - sure enough the nearside rear was low. It has helped a little, but it still veers about under hard braking. In trying to diagnose, I've also found that the offside front is locking up fairly easily, so perhaps it is a caliper after all..

Not necessarily - the car has passive RWS and toes-in under braking loads for additional stability. Or in the case of cross-toe/thrust angle, additional instability.

If it's not defective tyres or a sticky brake, probably alignment. Even a knackered compliance bush will make the suspension do weird things.

I would also take a look at your rear trailing arm bars - check them for free play as well as the above.

Thanks all

It toes out under braking (when the rear is higher in its suspension travel). It toes in during compression, under load (ie when on throttle, to increase stability under acceleration). Hence lift off oversteer kills so many!