There have been a few glimpses in past posts that there is just a bare hub where the front wheel should be. Things finally came together to get that taken care of.
I put in an order and this box arrived.
Inside was a shiny new 21" tubeless rim.
Older rims were marked Akrnot, Spain, but this is marked Behr, Germany. The markings are sand blasted on.
I wanted to make up something distinctive and decided to try some powder coat. A little research told me that polyurethane powder would be well suited for wheels, and I found this 'Black Cat' polyurethane powder from Caswell Plating
. I also got a roll of high-temp powder coat masking tape from them.
My first real attempt at powder coating. I was really happy with the result. I masked off the bearing bores to keep the coating out and applied two heavy coats.
I made up this bearing driver to install the wheel bearings in the hub.
To prepare the rim for coating I needed to sand blast the polished finish off the new rim. It was a hard thing to bring myself to do considering the time I have spent polishing GS rims, but once I got the rim in the sandblaster and pulled the trigger I went at it with determination. The blasted rim.
I sent out inquiries for R100GS spokes to both Buchanan's Spoke & Rim
and The Devon Rim Company
. I received a very queer reply from Buchanan's recommending spokes threaded on both ends and 80 nipples per wheel.
Doug Richardson of Devon Rim seemed to understand what I needed and even with shipping from the UK and a currency exchange fee gave me a better quote than Buchanan's. The only difficulty I had with Devon Rim was their inability to do credit card sales. I need to send them a personal check, which I found a bit out of date. All went well though, and these polished stainless spokes arrived in a small heavy package.
The powder coat oven I have access to is not big enough to fit a 21" front rim, so I needed to make up some way to heat the rim to 390 degrees Fahrenheit and hold that temperature for 15 minutes. My solution was to heat the rim with two propane torches while I spun it on a wheel stand. Here's my setup.
I found a discarded bead frame rail in a dumpster that I used for the stand. I just did a very quick fab job cutting the sections and welded them together. I laced four spokes into the wheel, just enough to support the rim as I turned it gently. The torches are propped in position by large c-clamps.
I needed to keep both torches at full to get the rim to come up to temperature. I think three torches would work better.
I used this infrared thermometer
from Harbor Freight
to monitor the rim temperature.
Anyway, after two coats and lots of spinning I was really surprised at what came out.
After getting the rim coated I had everything needed to start the wheel build. I used copper based anti-seize on the spoke threads and the hub nipple bores.
Lacing the wheel was pretty straight forward. Since the brake caliper is mounted on the left I laced the hub with the hub markings on the right so the markings would be visible as on the original wheel.
To get a close to equal initial spoke length I used this M3 screw with nuts as a depth gauge through the top of the nipple. Also shown here are some grub screws. I ended up not using these. I'll see how things work out without them.
To keep track of where I was I put these marks on the wheel. The tape on the rim with the red circle marks the axial high point. The blue was to mark the rim weld.
Here are the tools I used to build the wheel. A dial indicator, a torque wrench, masking tape and markers.
Here's how I setup the dial indicator. It was a little tiring to bend over to read it though. I put a little grease on the rim to lubricate where the dial indicator plunger slid on the rim. I didn't want to put the indicator on the outside of the rim for fear of scratching that finish.
After I got the radial and axial run-out in control I set the dish with this straight edge.
In the end I had a radial run-out of 0.7 mm and an axial run-out of 0.4 mm. The BMW service manual gives a factory tolerance of 1.0 mm and a service limit of 1.3 mm for both.
Here's the finished wheel with a TKC-80 mounted.
I can now finally after many months roll the bike around.