Turbo rear bearings

[Tom F2]

I have a crunchy rear wheel bearing in my 1977 930. It may have been caused by a sticking brake, and a trip to NYC. I changed brake hoses, but still the brake sticks. Master cylinder is new. The rear wheel bearings are original. I have two questions.

Has anyone seen a misadjusted rod from the pedal to the master cylinder cause a sticking brake, i.e., the master cylinder doesn't fully release?

Is it really a good idea to remove the trailing arms to do the wheel bearings?

Please take this as an open ended request for advice about this little project. At least the car runs great, though fuel mileage is only around 16 mpg, with 3,500 miles on new pistons and cylinders.

[MattAlpha]

When was that last time you opened up the wheel bearing, cleaned it and reassembled it?

Have you checked the linkage for the parking brake?

Are you feeling the brakes catch at the pedal (i.e. pedal is not traveling back up completely after you engage the brakes)? If you don't feel it at the pedal, then the MC most likely is working properly.

Just a few thoughts,
-Matt

[Tom F2]

Originally posted by MattAlpha
When was that last time you opened up the wheel bearing, cleaned it and reassembled it?

Have you checked the linkage for the parking brake?

Are you feeling the brakes catch at the pedal (i.e. pedal is not traveling back up completely after you engage the brakes)? If you don't feel it at the pedal, then the MC most likely is working properly.

Just a few thoughts,
-Matt

Parking brake is fine. The dragging brakes (both sides) are something hydraulic - when I open the brake fluid line, fluid squirts out, and the brakes release.

The brakes feel fine in use. I put in a new master cylinder, but I didn't change the length of the actuating rod from the pedal. I will check this, of course.

I have service records back to new. The rear calipers have never been removed from the car, which has just around 74,000 miles, now. So, it's safe to say that the rear wheel bearings are original.

A further question - should I plan on changing the spacer sleeve? In other words, do these usually deform? The manual indicates that they can be reused if clearance is at least 0.5 mm prior to crushing the sleeve with new bearings and at 145 ft. lbs. of torque on the axle nut.

[David]

The job is much easier with the arms off, not that it's easy. You'll need a press and probably some special drifts to get the bearings out and the new ones in.

I'd replace the spacer. Even if it doesn't look deformed, it's not worth taking the chance when you're doing this much work.

[Tom F2]

Also, can anyone explain these cryptic comments at the end of the factory manual instructions for adjusting the rear wheel bearings: "No axial play can be accepted, if a wheel bearing friction force of max. 1.5 kp (3.2 lbs.) is not exceeded with cotter pin inserted and tightening torque of at least 32 kpm (231 ft. lbs.) (adjustment of axial play and possibly further tightening to next cotter pin hole)?" What is wheel bearing friction force? It isn't given in units of torque.