Wheel Bearing installation on 1980sc ?

[nicfranc]

I recently installed new front Rotors & Bearings, rebuilt my Brake Calipers and installed
new brake lines on my 1980sc.

I packed the new bearings with Red Line bearing grease and installed them according to the Bentley manual.
I then took it out for a test drive and went through the recommended brake imbedding procedures.

I noticed when I hit 60 mph a faint high pitched whine coming from the front right wheel area.
Are my bearings too tight ?

Wheel bearings and the adjustment of the Bearing Lock Nut allowing for the proper play is a bit of an inexact science to me.

What are the telltale signs of an improperly adjusted Lock Nut ?
What method do you use to get it right ?

[Kemo]

maybe a rub from the dust shield? did you recheck the play in the wheel after the shakedown run? I usually over tighten the wheel bearings to seat them, and then back off until you can barely move the washer underneath.

[jimrs2000]

Way back in the day when I was training in the Airforce my instructor said "You can't teach a feel", that is exactly what this is.

When I do it I tighten up the nut as tight as I can get it without over straining anything!! this makes sure the bearing outer races are seated properly, I then back the nut off until the rotor will turn freely but without any play in the bearing.

Hope this helps.

[KTL]

Did you install new bearings and races or just the bearings?

Wheel bearings are better too loose than too tight (similar to adjusting valve clearances on engine!) so better to err on the loose side.

I do the same approach- crank down finger tight and back it off. Be sure to wiggle the rotor a bit and finger tighten again. Then back it off and check the thrust washer "clearance" by putting a flatblade screwdriver along the edge of it and try to shift the washer without leveraging the screwdriver against anything. Just use your hands. You want the thrust washer to shift with some resistance.

It's definitely a feel sort of thing. But again, better to be a little loose than a little tight.

Nice jackstands! Those ESCO stands are really nice.

[nicfranc]

Originally Posted by KTL

Did you install new bearings and races or just the bearings?
Nice jackstands! Those ESCO stands are really nice.

I removed the inboard and outboard races and their bearings and installed new ones from our host. The job went very smoothly using the information found on this forum.
I heated the hubs and froze the bearings.

I used the lock nut adjusting method shown in this youtube video.
The video is actually the installation of the front wheel bearing of a Porsche 944 but it is very similar to the 911sc.
https://www.youtube.com/watch?v=O2lUqvga0n0


The Esco Jack Stands are great they allow me to raise the front nice and high.
I use standard 3 ton jack stands for the rear position under the torsion bar covers.

[tharbert]

I like this post from an old thread:

Originally Posted by 450knotOffice

I'm going to offer up slightly different advice here. The first time I adjusted my front wheel bearings exactly per the Bently manual (in the process of a full suspension refurb a few years back), I ended up with wheel bearings that were too loose. I followed the procedure to the letter and yet every time I checked the wheel play, it was simply too loose.

I happen to be good friends with a guy who is one of the best Porsche mechanics I've ever met. Over the years he's worked at some of the best high end shops in the area and has also spent time as a mechanic at the local Porsche dealership. The guy is an amazing storehouse of knowledge and experience - 30 years worth. Anyway, when I told him about the looseness issues I was having with my wheel bearings up front and asked him how he tightened the bearings, he shook his head and said that the procedure described in the book was designed to prevent backyard mechanics from overtightening the bearings, but that the procedure almost always resulted in too much play. So I asked him what he does.

He described a much simpler procedure that he said will put a slight preload on the bearings without over doing it, which is what you want. His method, after snugging down the nut to a firm finger tight condition while rotating the wheel rotor/hub, is to simply rotate the nut another 1/16 of a turn. That's it. Tighten down the allen screw and you're done. He also said that the idea of putting a bit of grease in the cap was simply a waste of grease. If it makes you (he meant me) feel better, have at it, but it does no good and simply creates more of a mess next time you need to get at the bearings.

I've used this procedure since then and have not had any bearing looseness or overheating issues since - and I've put a lot of hard miles on my car since. In fact, I just changed my front rotors a month ago and noticed my bearings still looked great.

Give it a try. It's a heck of a lot simpler than the idea of trying to tighten down the nut so the washer behind the nut can just barely be moved by a screwdriver. That's a procedure that leaves a lot of interpretation out on the table.

Link to thread

[KTL]

Reason I asked if the races were replaced is for two reasons:

1. Some people only replace the bearings. Since the bearing and race are technically a matched pair, sometimes replacing just the bearing can create misalignment.

2. Replacing the races takes patience. Need to ensure they seat squarely in the hub or else that can introduce misalignment. Good idea to check the race seating with a depth gauge to ensure they're not cocked in the bore.

Agreed the grease in the bearing cap is a waste of grease. I think a lot of people would be shocked how little grease is needed to feed the bearing. If you use a bearing packer, that's about all the bearing needs. Swab a little extra on the race before installation for good measure. That's all that is needed. Any more is just a waste of grease. No need to fill the cap or the hub with grease. Leaving them free of grease is actually better because the grease acts like an insulator to keep heat in. Leave grease off the hub interior and the cap to allow heat to sink into the hub and radiate outward.

But one could argue that insulating grease is a good thing. When the brakes get super hot, that heat from the rotor sinks into the hub. If you insulate the hub with grease, it can prevent heat from sinking into the bearing.

[nicfranc]

I checked the bearings and everything is in order.

I drove the car a few more times and put it through its paces and the whine seems to have dissipated.

Maybe the new rotors, pads and rebuilt calipers just had to work in.

Thanks for all the input.
This site and forum is the best tool I have.