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.

Setback. Frame had to get repainted.

After i got the frame back from the powder coat shop, i kept looking at it in my garage thinking something wasn’t right. It was much too shiny. I got our original paint swatch back and low and behold, it wasn’t the correct color.
I have been dealing with the son of a father/son shop and he is on a long leave of absence…. and i’m not going to bother to ask why. The dad is amazing (Mike) and great to deal with. I brought everything back, he was super cool about it. It turns out, that he didn’t know that they were supposed to add an epoxy based clear coat which changes the color of the coating under it. So… after another few weeks of waiting. They finally finished re-masking everything and coating it with the clear coat.
Time to build!!!

Something is wrong. After getting the paint swatch, it was clear the color was incorrect.

Bingo. We have a match. License plate bracket is in the photo

Unwrapped a few more parts. Swatch is in the top left.

Frame and centerstand. To be assembled very soon...

Attaching Cafe seat pan to tail section

When i got the seat pan and the tail piece(see previous post), I immediately began to wonder how to mount the two together. BMW’s R100S seat and cowl is a great design and works well with the hinges. But this is a Short Wheel Base model and we are going with the fiberglass tail piece. The tail piece mounts to the subframe through the saddle mount bag loop at the rear of the subframe and a small ‘tang’ that goes into the main frame tube.
The suggestions I got for mounting the seat pan to the tail piece were:
Velcro
Industrial Velcro
Upholstery with snaps (no thanks)
And then finally… i found out about Well Nuts. BINGO!
Well nuts seem perfect because they act as a thin rubber buffer between the to parts. Also when you tighten them they pull the pan snug onto the tail piece.

To do the job, you are going to need about
– 7 Well Nuts
– 6/32 screws to match the Well Nuts – about .75 inches long
– Fender washers for the Screws
– and a 5/32 and 5/16 drill bit.

Well Nuts purchased at the local hardware store (who has lots of my money):

Screws (I went with Stainless Steel):
Fender Washers:

The first step was to mark 3 holes to mount the rear of the seat pan to the tail piece.

The holes are drilled with the 5/32 bit. Just big enough to get my screws through.
The Well Nuts in the photo will eventually live in the seat pan.

Then snug up the upholstered seat onto the tail piece as best you can, and mark through the holes.

I started by drilling holes into the seat pan with the 5/32 bit. BE CAREFUL. DRILL SLOW. If you ram the drill bit through the seat pan, it will go through the other side and ruin the upholstery.

After i drilled the holes in the seat pan, i mounted it to the seat and ran screws through the tail and into the pan to make sure they lined up.

i then widened the holes with the 5/16 bit. AGAIN. DRILL SLOW AND CAREFULLY.

Time to insert the Well Nuts into the rear of the seat pan:

Now that the seat pan is attached to the tail piece, I marked 4 additional holes for some extra reinforcement.
NOTE: Make sure these holes do not conflict with the subframe cross member that contains the fender mounting bracket.

With the seat pan attached, I drilled (5/32 bit) carefully and slowly though the tail piece straight through the seat pan. i did this for all 4 holes so they would match perfectly.

I then widened the holes on the seat pan ONLY with the 5/16 bit:

All done. 7 screws all lined up. Seat pan is securely attached to the tail section.

BMW Cafe tail and seat

A while back, we purchased some fiberglass parts from Craig at Boxer Cafe. Craig has been great to work with and talk to. He even made a custom front fender specially for us.

As with building any custom bike, the parts you buy may not be perfect. They usually require some modification. But they are a great starting point.

Here is a rolling mock up of the bike build before i completely tore everything apart for rebuild and powder coat:

Craig didn’t have seat pans ready when we purchased the bodywork so a month or so later, the seat pan arrived:

It was good to test fit and take notice of the specific clearances/gaps/and spaces we had to work with:

The lower front corners of the seat pan had a sharp corner to it. I thought it would end up tearing fabric over time so i rounded it out.

The seat went to Autos International in San Diego for upholstery.

Thankfully, somebody in the upholster shop has a keen eye and noticed that the seat pan is slightly uneven. The tail sections (seat Cowl) and seat pan are not symmetrical parts but should fit the bike without uneven gaps and without looking crooked.

So the seat came back to my garage with the foam attached and thankfully it did. I re-test fit everything and then shaved down some areas to even the gap between the tank and the seat.

Again, I’m glad the seat came back into my hands because I also realize that the foam was a bit too high. It made the seat just a bit too tall. I’m only 5’9″ and the bike’s owner is a bit shorter then I am. So some foam has to go so we can touch the ground with both feet.

More notes for the upholstery shop:

The seat was returned about a month later and it looks stunning. Smells good too! And great craftsmanship.


Seat and Tail together. I can’t wait to have this on a running bike.

I am probably going to do one final modification. There is a small piece of the tail piece that sticks out under the seat. I am going to shave it down before the tail piece goes to get painted.

Frame painted. Finally.

I don’t know what went on with my powder coat shop (Hy Tech) but finally, months after I dropped it off, they finished it.
We tried finding a few different powder coatings but nothing matched the Porsche silver we are trying to match to. We did find something else and it is really close to the color we are trying to match.
It is a High Temperature liquid coat that gets sprayed on similar to spraying on powder except it isn’t electronically charged like powder is. It can be applied to other surfaces then metal.
It is a catalyzed Polyurethane that is baked on in an oven. Though not as hot as powder baking… and not as low as baking car paint.
It is a custom silver color that is made for Stop Tech brake calipers. It is resistant to Brake fluid (which eats away any sort of paint). So if this is resistant to brake fluid, you know it is durable stuff.
It doesn’t go on as thick as powder.
And i believe there is a clear coat over top of it…

 
Like Santa came and left me some presents to unwrap:
Like Santa came and left me some presents to unwrap.
 
bright silver.
 
shiny.
 
View of the bottom of the swingarm:
View of the bottom of the swingarm.
 
Center stand, fork legs and rear of the frame:
Center stand, fork legs and rear of the frame.