R75/6 Wheel Bearings

Hello Airheads,

Does anyone know of a source for rear wheel bearings for a 1976 R75/6?

I have a bad one, my dealer says BMW no longer has them in their supply system. thanks, Bruce

bprigge said:

Does anyone know of a source for rear wheel bearings for a 1976 R75/6?

Click to expand...

If I recall correctly, they are simply 30203 tapered roller bearings, available at any bearing house anywhere on the planet for about US$5 (or less) each. Whatever they are, they are STANDARD bearings and there is no reason to pay an extra $20 for a box with a roundel on it as the container.

Thanks Flash412,

I got the bearings out last night, 30203 is the number on the bearings.
One was made in Italy an the other in China. Looks like a seal issue as
the bad one is full of rust and the race still fits the hub nicely. This isn't
as bad a situation as I originaly thought. Bruce

When I need a bearing, I usually check the local bearing supply first. Then if it's a special bearing made specifically for BMW, I get one from the dealer. There are stories about different bearing qualities from different bearing manufacturers, but since bearings are being made all over the world for installation in vehicles made all over the world, there is no point in worrying about relative quality.

When installing the new bearings, pay attention to the seals and "seal rings". IMHO, old style wheel bearing seals were always a little "sloppy", and with a little wear they don't seal very well. One advantage of the "old" /5 and earlier seals (in the screw-on caps) is that they are triple lip rather than single lip. I've also retrofit Japanese seals with multiple lips into various BMW wheels, but I can't remember any numbers. It takes a Honda or Suzuki parts man willing to let you rifle through his seal boxes to find the correct dimensions.

The problem with "sloppy" seals is that water can squirt under the seal and contaminate the bearing. A high pressure washer is sudden death for any bearings, but even a garden hose can squirt water under a sloppy seal.

On a recent bearing job, I installed thin washers on the axle just outboard of the seal rings, to make it slightly more difficult for a stream of water to squirt under the seal lip. It's just an experiment, and don't hold your breath waiting for a report.

Also, make sure the bearing preload is correct. If the bearings are loose, it's necessary to take up the slack on the axle spacers. Either get a thinner spacer, or carefully wet sand the spacer on a smooth surface to make it thinner. Gary Smith did an excellent series on wheel bearings in ON a few months ago that explains all the different styles and procedures.

I've also found that even when the local BMW dealer found a part to be "no longer available", I've gotten the part from www.maxbmwmotorcycles.com.

pmdave

Thanks PMDAVE,

I got the bearings through a local Bumper to Bumper car parts store.
On the left rear bearing I can see how a pressure washer can force water in
even with a new seal because the seal actually seals to the thrust collar that
slides over the axle. Seems like water intrusion is possible between the thrust collar and axle shaft. Maybe a little silicone seal on the inside of the thrust collar would completely seal off the bearing, but then when you push the axle through its going to take some of the silicone seal with it down into the bearing area. An O ring on the axle shaft where it passes through the
thrust collar would be perfect! I think its a design deficiency with the sealing
function that causes all the wheel bearing grief to begin with. (hope the BMW Gods don't strike me dead for saying that!) I've been riding motorcycles since
1963 and have never had a wheel bearing failure until this one and it looks like the second failure of this bearing as the left side has a 'made in China' imprint on the bad bearing.
I sure won't go near the bearing area with a pressure washer now that I see
how the seal arrangement is set up. The bad bearing was full of rust and a nasty mixture of grease and water, soap too I suppose.

The preload seems to be OK as I don't lose rear wheel 'wiggle' until I hit 20
foot pounds of torque on the axle nut. I torqued mine to 25 just to be on the
loose side although the book calls for 33 ft pounds.

All is well now, I'm heading out on a 5K road trip on May 7th. thanks, Bruce

Since you grease the axle before inserting, there will be a layer of grease between the seal ring and axle that should exclude water. (you DO grease your axle, don't you?)

And, normally a seal will maintain contact for thousands of miles and exclude dust, dirt, and rainwater. When it wears enough for the grease to start oozing out, it's time for a new seal.

The problem with pressure washers is that a high pressure jet pointed at the seal will lift the lip of the seal and allow the water (and grit) to squirt right into the bearing cavity.

What I'm trying now on one axle is a thin washer on the axle between the shoulder and the seal ring. That makes it slightly more difficult for a stream of water to hit the lip of the seal. It would also be possible to add a thin O ring outside of the seal, but hey, we'd be getting really anal attentive!

pmdave

Yeah, your right, we are getting anal attentive. At my car wash there is a
'tire soak' position on the spray wand function selector that gives you a very
low pressure stream of green soapy water. I'm just going to use that around the wheels. Or.... we could install a schrader valve anywhere on the hub and hook up 100 psi of air to it when we wash the bike. That
would blow water away fron the seals from the inside out. Oh never mind! Bruce

Avoid Chinese bearings!!!

Everytime we tried them in trailers we either had to keep tightening the preload or they failed. Very poor quality steel.

All other countries/brands worked fine. German, Timken (the USA ones) and Poland made have been the best for us.

That's the feeling around here too. I don't think anybodies bearing would have held up with all the contamination that was in this one though. Bruce

You can try All Balls Bearings as they list them.

This has to be one of the earliest threads ever on the forum! Not sure the others are around to see it again.

That said, there's another similar thread that was started within the past few days:

https://forums.bmwmoa.org/showthread.php?99189-30203-wheel-bearings-locally