SlotForum banner rear wheel grub screws too tight

2759 Views 34 Replies 21 Participants Last post by  Martyn_
I've just bought a new Audi R8C (CA12C) which has had its rear wheel grub screws over-tightened in the factory. I've ruined three new allen keys trying to loosen the screws, only have two undamaged allen keys left and don't want to ruin those. I need to loosen the grub screws to reposition the rear wheels, which have been fixed too far inboard at manufacture.

I've tried alternately gently heating and cooling the axle and wheel assembly, which succeeded in loosening one screw, but the other is still jammed tight. Any ideas how to undo it?
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Two ideas that might be worth a try
You could try penetrating oil.
Have you tried a hardened tip Allen wrench for those screws?
Reducing vibration does make a difference to the faster cars. I cannot say I've noticed much difference with hard bodied cars, but it's possible a top driver would be able to detect a difference.
Unless the motor is dynamically balanced, its likely there will be far more vibration from the motor than the wheels.

If you really want a wheel/tyre that is in balance, the only way is to balance it with the tyre glued and trued.
Wheels can be balanced before fitting the tyre, but the balance usually changes somewhat with the tyre fitted. Just occasionally there's one that's pretty much in balance without doing anything, but mostly I find I need to add some balancing weight to the wheel each time a new tyre is fitted.
Putting a flat on the axle would change the balance, normally this would just make it a different amount out of balance, although just occasionally one might end up in static balance. Many but not all the wheels I've balanced are heavy on the grub screw side, so putting a flat on the axles would make the balance better on some wheels and worse on others. That sure isn't dynamic balance.
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