3rd. Times a charm?

Put a few miles on the bike after the 2nd. transmission removal with the hope that the rear seal might "seat" and quit leaking...no such chance.

Local bombing range in my back yard.



So I pulled the bike apart for the third time to replace the new rear seal with a replacement seal. The new seal material looked "healthier" than the one I installed previously. I also obtained a stock flywheel to replace the lightened flywheel which was on the bike. I removed the oil pump o-ring again to check it and it looked fine. I replaced it with a new one.

The newest seal:

The old oil pump o-ring and the first "new" seal.
Here is the lightened flywheel which I swapped out. Someone spent a lot of hours machining this fellow years back. I've never seen one taken this far.
The bike seems to idle steadier with the stock flywheel in place. I ran it a few miles yesterday after re-assembly and so far so good...no leaks.
I started the tear down at around 1:00 PM and had the bike back together and running at around 5:30. Flywheel removal is getting to be routine. Hopefully I won't have to do it for a while.....don't need any more practice at this point.

Sidecar Road Test

Sidehack rig back in one piece....for the time being anyway.....

Ran a short run up the freeway yesterday to road test the hack. The K-Block tires definately change the handling characteristics of the bike. There's now a lot more contact with the pavement. The ride is better with a passenger and / or load in the hack.

After a 25 mile run at freeway speed I stopped to look things over and see oil seepage from the transmission area. So either the rear main seal is still leaking or the oil pump seal is leaking. I'm leaning towards the rear main seal......I've read that new rear main seals can weep a bit initially when replaced so we'll see. I'll change the oil next week and add some seal conditioner and hopefully the seepage will stop. I don't cherish the thought of pulling the whole damn bike apart again....

I was going to start tearing down the R75/5 to part it out on EBay. Decided to list it as a running project bike to see what might happen. I'll be damned but my $1k. reserve was met and the bike will sell as is. I hated to tear apart a running bike anyway. Someone will have a good foundation to build a Cafe bike or ride it as a Rat bike. The bike is fun to ride as is.

I have a few other misc. used BMW parts listed too. Appears that the "after Christmas" BMW parts market is alive and well.

K-Block Sidecar Tires for BMW

On the road again.

Ran about 10 miles around the neighborhood today and all appears a-ok....no oil leaks and the new k-block tires are a instant handling improvement.

We've been busy, busy, busy since mid December. Including a couple weeks in Montana, then a 3 day camping trip with the Airheads BMW Club for New Years at Agua Caliente in the CA. desert.

I tore down the BMW and needed a couple of weeks to get all the parts together.
Finally acquired all the needed clutch parts. I had made plans to swap with another BMW guy to change the "lightened" flywheel for a stock flywheel but he didn't follow through with sending the flywheel. Not wanting to wait another week for a flywheel I decided to re-install the "lightened" unit.
I installed all new parts and found the old rear main seal loose in the housing and was able to remove it with no tools. The new rear main seal went in without a hitch. The crankshaft MUST be blocked from moving forward when the flywheel is removed. The oil pump cover o-ring was changed also. I couldn't really tell which seal the oil was leaking from.
Considering the fit of the old rear main seal, it likely was leaking from there.

The engine / clutch went together in one day and yesterday I spent swapping tires around.

I cleaned up the exhaust system / installed and refitted the sidecar mounting sub frame, airboxes, battery box, etc.

I had a pair of Michelin "K-Block" 18" sidecar tires and then acquired a 19" Avon sidecar tire for the front. I was able to modify my sidecar axle configuration to accept the 18" Sputnick wheel I had, but did not attempt to install the brake assembly. I purchased the Sputnick wheel / hub a few years ago and the near new K-Block tires were part of the deal. They appear to be nearly new and the rubber was still supple and not hard. I didn't want to run the K-Blocks until I had a set of three. Until recently I never saw that Avon offered a 19" K-block tire, they are frightfully expensive compared to the cheap tires I've been running.

The front k-block tire was a tight fit to the fender and I had to change out a couple of fender mounting bolts and remove the rear rubber cushion spacers for the fender mount to gain minimal clearance.


The tires went on easily with no problems and then I installed the battery to run the engine up. The motor fired up with the touch of the switch and ran great. No oil leaks evident after 15 - 20 minutes of run time. The bike is not ridable solo due to the tires and front end Earls fork....I guess a person could ride it but I didn't think it would be advisable.


The 18" Sputnick wheel is much heavier built with larger spokes and brand new bearings. It also has a Alloy hub cover to keep dust out of the bearing area.

Many sidecar riders use K-Block tires but many say that they aren't necessary. I wanted to see if I can gain more mileage from them in the wear department. I typically wear out a rear tire before 3000 miles and a front tire about 3000 miles. The K-Block tires cost about double the conventional tires so they need to gain a lot more wear miles to be ahead of the game.

The big square tires will definately put more rubber on the road and might effect my fuel mileage negatively, we'll see....

Today I'll mount the sidecar back up and should have the old girl ready for a test run.

So we'll have new "shoes", a complete new clutch assembly and a refreshed engine top end.

I also had found a pair of "Marzzochi" rear shocks for dirt cheap a while back. I was going to use them on my now "defunct" /5 project so decided to install them on the hack. They are an air assist shock, in Italian Red, lol.

I want to run a few hundred shake down miles to be sure the sidecar axle will perform properly and will need to re-torque the cylinder heads after a hundred miles or so.