Swing arm race and bearing install

Installation of the swing arm bearings.

Here is the order of the parts. The first part is a cup that only goes on the side of the swingarm opposite of the drive shaft. All it does is prevents grease from traveling into the crossmember of the swingarm. The other side does not require one.

First install that cup/plate into the swingarm and make sure it sits flush on the small lip.

I stuck the races in the freezer with hopes they would shrink enough to make the instal a bit easier.
The races can be driven in by hammering them in with a 30mm socket or if you have the Cycleworks race puller, the aluminum plate is also meant to be used as a driver.

Here is a 30mm socket (i know, the socket is upside down. I threw it in there for the photo):

Here is the Cycleworks plate being used as a drift:

Race installed:

Greased up bearing (be sure to pack it well with grease):

Then goes the collar with the flat side down, against the bearing:

Then goes the dust seal:

I prefer to install the collar through the rear of the dust seal, and then insert the dust seal into the swinarm:

One side done:

The process is exactly the same for the other side except for the grease protection cup.

New U Joint for the driveshaft

I finally got the swing arm back from the local mechanic.
I took the old driveshaft to him to install it in the swingarm and he noticed that there was a bit of slop in the U joints. So we had them replaced. These aren’t BMW parts but you can find people making them. I’ve since seen some on E-bay with grease fittings. My mechanic has been using these for quite some time now so I trusted his knowledge on this.

BMW /5 Wheel Offset information

I took my hubs and rims to get laced last weekend. I brought an extra set of assembled wheels for reference and the guy doing the lacing said BMW’s didn’t have an offset (meaning they were “0” or centered). So i took the extra set home thinking he was the expert. However, it is a shop that mostly specializes in Japanese bikes.
I remembered reading something about there being an offset many years ago and I looked into it. It turns out that the /5 motorcycles do have an offset (because of the drum brakes and hub).
Some say that wheels with disk brakes do not have an offset but not according to the spec sheet.
I called the the person doing the lacing and he was very nice to talk to.
His name is AL and the shop is Johnson and Wood in North Hollywood.

Here is a piece of advice written by the BMW motorcycle guru Duane Ausherman:

Before you cut the old spokes, install the wheel, with or without a tire. Measure to each side of the swing arm. This will tell you just how centered it is. If you need to move it over a bit, calculate it.

Then lay the wheel down on a flat surface. If it is a drum brake, it is very easy. Have the drum side down. Now find 3 nuts that will just fit under the rim. The thickness of the nuts gives you the current off-set. Now calculate in any correction needed for the wider tire.

Now find 3 nuts of the off-set you desire. Hold the rim off the flat surface to give you the off-set. Lace the spokes in by hand and a bit at a time bring the nipples up to snug. The rim is now laced to the correct off-set that you desire. Put it in your tuning jig and finish up. As long as you do equal tightening to each nipple, the off-set won’t change.

I have done many dozens this way and it is much faster than using the BMW off-set tool.

Attached is the BMW spec sheet from 40 years ago. Hopefully this will serve as a guide for others out there who are lacing rims.

Busy work while I wait

I’m waiting for my local mechanic to install new races and wheel bearings in the wheel hubs.
I’ve been waiting nearly a month… ugh.
I am also waiting for him to install a new U-Joint on the drive-shaft and then install the driveshaft in the swingarm.
Unfortunately, these are things i am relying on an expert to do because they require proper welding, proper tools or careful installation.

So… i might as well start re-assembling small stuff like the turn signals (which were coated to match the frame)…


Fork seal installation

A quick ‘How To’ install the fork seals.

You can pop the old seals out with a screwdriver or something else to pry them out. Just be cautious you don’t score or damage the inside of the fork leg/lower.

First make sure the fork lowers are clean.

Then sit the fork seals flat onto the top of the fork tube. It helps if you have a large socket, or something similar to help drive them in. I happen to have a 36mm socket that fits the diameter of the seal pretty good. It might be better if it was 34 or 35mm but it still did the trick.
I placed the socket over the seal, and tapped it in with a hammer. Here is a photo of the job with the seals about half way in:

Here are the two fork lowers with the seals fully inserted:

Rotor Removal

Once again, I had to return to the old donor engine block for some spare parts. The rotor on the engine to be rebuilt was a rusted mess. The rotor on the donor engine looks brand new. I will test it with an voltmeter to be safe, but being that it is so clean, i am not too worried.

To remove a Rotor, you need to have the rotor puller bolt.
BMW sells it, Huckey BMW sells one, Motoelekt.com sells one… it is between $5-$10. Or, you can search online on how to make your own. (click the photo to enlarge it)

Once you removed the alternator,
To remove the rotor, all you will need is a 6mm hex bit and a 13mm socket.

Loosen the rotor bolt with the 6mm hex bit and remove it completely. You may need to block the engine from rotating.

Then screw in the puller bolt.

Begin slowly tightening it with the socket until the rotor pops off the crank. That’s it. Done.