Can anyone explain tracking/alignment to me? (tyre wear issue)

[Dobz]

Don't forget that the rear bushes on the front wishbones of the 130TD1 sport and FR TDi are crap.

They have voids in them and allow the wishbone to move around.

This causes TOE OUT to be added during thottle and TOE IN to be added during braking.

With the torque of the diesel - the car is allways going TOE OUT when you boot it and killing the tyres.

Get the bushes at the back of the front wishbones changes for the solid rubber ones from the CUPRA TDi.

Between the bushes and the 4 wheel tracking I now see much less wear on the tyres.

Where did you get the bushes done and how much did it cost?

 

[muddyboots]

This causes TOE OUT to be added during thottle and TOE IN to be added during braking.

With the torque of the diesel - the car is allways going TOE OUT when you boot it and killing the tyres.

Other way round

Under braking the front wheels will be pushed backwards, pivoting on the front bush, causing them to toe out.
Under acceleration, the front wheels will try and pull forwards, pivoting on the front bushes, causing them to toe in.

FWD cars are usually set to toe-out a bit anyway, so under braking the toe-out will become excessive, and this would lead to inner edge wear.

 

[DEAN0]

Under braking the front wheels will be pushed backwards, pivoting on the front bush, causing them to toe out.
Under acceleration, the front wheels will try and pull forwards, pivoting on the front bushes, causing them to toe in.

Thats what I thought at first but - NO - not correct.

under braking the WISHBONE OUTER PIVOT ( Not the wheels ) are the items being pushed back on the ibiza. This happens because of the void bushes at the back of the front wishbone.

When this happens the lower outer pivot on the WISHBONE moves back and in towards the steering rack. This effectively reduces the track width vs the steering rack and pushes the front wheels to TOE IN.

Under throttle the opposide happens - The wishbone outer lower pivot moved forward and out - effectively increasing the track compared to the steering rack and causing the front wheels to TOE OUT.

I had this checked and measured by a friend who sets up race cars and works very hard to remove suspension induced geometry changes.

Where did you get the bushes done and how much did it cost?

The bushes are genuine Seat Ibiza Cupra ones. They are ( or were ) about £10 per side. Fitting them is the hassle.

 

[muddyboots]

Of course.
I completely forgot about the effect of the tie-rods; makes perfect sense.