Wheel bearing mods.
by Michael Harris
Pituch told me a while ago about a possible fix to resolve the GTV6 wheel
bearing failure problem.
I have found that there is too much slack in the bearings, and this cannot be removed by tightening the nut one more 'notch' (at the next 'notch' the bearings are way too tight)
He suggested replacing the Alfa axle nut with one from a Mercedes 240D which is the same thread, and has a small hex pinch bolt to lock the axle nut in position (instead of the split pin method). Many P-cars also use this method.
The Mercedes nut system
seems to be better than the GTV6 system because the tightness of the axle
nut can be set very accurately, and then locked by tightening the pinch
bolt. (more resolution in the nut setting possibilities).
You will need to decide on just how tight to make the axle nut. One method I used was to remove the plastic Alfa crest from the center of the wheel, then mount the wheel on the hub & tighten the wheel nuts a bit (grease cap off). Now grasp the wheel at the top and bottom and rock it back and forth. Tighten the axle nut as needed. When adjusted properly, there should be only slight play in the bearings. Note that it should not be necessary to use a wrench to tighten the axle nut (of course, you will need a hex wrench (Allen key) to secure the pinch bolt.)
New Information - Apparently, late model (approx 1991) 75's were fitted with a similar pinch-nut (as a factory upgrade). You'll need two each of the following parts (instead of the Mercedes bits):
These would have been only available in Europe, but some Alfa Parts sources in the US are accustomed to ordering parts from Europe.
I hope you find this helpful - I would appreciate hearing your findings if you perform this upgrade.