Friday, September 21, 2012


The end product of 3 months of work.

Hello and welcome to the final installment of my BMW Duo-Drive Sidecar Conversion.
You can read Pt I of the build here,
Pt II of the build here,
Pt III of the build here,
and Pt IV of the build here.

Looking through all the pictures I shot and revisiting all the modifications that we did to my sidecar build, I could probably write another 2 installments of this build. We made many modifications to this outfit, for quite a number of reasons. One of them was simply because we could. Ad Donkers of LBS Sidecars is the type of guy that likes a challenge, so for example when I threw out the locking hub idea for the sidecar wheel to him, he wanted to do it not only as a personal challenge but also because it was a very practical idea. The same can be said of many of the optons that we built on this outfit. We worked very well together, and the outfit turned out better than I imagined truth be told.

The Stern Rox sidecar, which is more of a performance sidecar than an overland or RTW sidecar, had to be altered to accept the Mobec Duo-Drive unit, as I didn't want the Duo-Drive unit hanging down underneath the floor of the chair too much, so we decided to push it up into the sidecar by 3" and increase the clearance under the sidecar. This involved cutting out about half of the original floor and re-glassing a new floor 3" higher up inside the tub. 
If I never smell epoxy and fiberglass resin again, it'll be too soon. I had a white dry nose for a week after all the cutting and sanding was finished.

The floor mold in place.

The driveshaft mold in place in the trunk.

Pour on and brush out a layer of resin......

....and lay down the fiberglass mat.

More resin to thoroughly soak the fiberglass mat.....

....then make sure to brush all the air out.
4 hours later it was ready.

Meanwhile, the Stern Rox sidecar comes with a turn signal and a running light frenched into the front nose cone of the chair. Since I was mounting the stock BMW turn signal I took off the right side of the bike to the sidecar and had the Warn running lights installed, these had no purpose whatsoever, so rather than leave them there I decided to make extra work for myself, so I removed them and filled them in to give a smoother look the the front.

Much better now.

This is what the underside looked like after I took off the molds.
The tunnel on the left is for the drive shaft from the Final Drive of the bike to one end of the Mobec Duo-Drive.

This is the inside of the trunk showing the inner drive shaft tunnel.

About 3 hours of sanding and spot filling and the tub was ready for painting.

While the sidecar was getting painted and the metalwork was getting powder coated, another modification I made was to replace the stock clutch with the Wunderlich Sintered Clutch Plate, an almost indestructible clutch that will handle the extra weight and drag that a sidecar will put on the motor.
As I mentioned in another post the 70k mile original clutch was in remarkably good condition, good for at least another 100k miles, seriously. I guess one of the reasons is that I only use the clutch to shift into first gear. To upshift from 1st gear you should never need to use the clutch.
There's a technique to learning it, not difficult at all, but once you find the sweet spot the gears will slip into each other like a hot knife through butter.

The carrier plate of the Wunderlich TRW Sintered Clutch is hardened stainless steel, and the 2 friction plates are made of a high quality material riveted to the carrier plate with heat resistant rivets.

The other mechanical modification I made was to the Final Drive, a weak link in the 1150 and 1200 boxer engine for some, but in my case I have been lucky and never had any issues.
Since I changed the final drive unit completely by going from a 31/11 ratio to a 37/11 ratio it gave me a chance to replace the final drive bearing and specifically make a modification to the little oil channel in the housing, which I will share in detail with you now.

The inside of the final drive housing on the 2004 model BMW R1150 GS Adventure. In the upper right is the bearing housing.

This is the oil channel inside the final drive bearing housing. It allows the oil in the final drive housing (cardan) to pass through and lubricate the final drive bearing.
The final drive bearing is an oil bearing, not a grease bearing, so the amount of oil going through this hole is directly proportional to the longevity of the bearing.

By enlarging the oil channel by 50% you allow more oil to pass through to the bearing. 
More oil, happier bearing.

However, there are two other oil channels you need to enlarge in order for to get the most from this modification.
The first is the final drive bearing shim ring. You need to enlarge it to the same size of the oil hole in the bearing housing.

The shim ring before cutting.

The shim ring after cutting.
As you can see the cut made is almost double the size which will allow a much greater flow of oil through the passage to the final drive bearing.

For comparison, this is how the shim ring sits and blocks the oil flow if you don't cut it.

The second modification you need to make is to the bearing seal.
Cut a little slot just like in the picture above. The combination of all three 
will significantly increase oil flow and reduce or eliminate any final drive bearing issues that these motorcycles are sometimes prone to.

The spare tire carrier.
It looks complicated, but it had to be made in such a way that it allowed the spare tire to be lifted up and away from the front to allow the tilt up windshield of the sidecar to come back and open fully.

The spare tire spacer is also a spare rear wheel spacer. We made it to the same specs as the rear wheel spacer since it's a custom item and not a BMW Parts Dept item, so it pulls double duty. In the event of something happening to the rear wheel spacer in the middle of Mongolia and having to wait for a replacement, I now have an instant fix rather than waiting 2 months for LBS to fabricate up another one and try to mail it to me on the side of a mountain with no actual address.

Another modification was building a 33 litre Stainless Steel auxiliary fuel tank underneath the sidecar. Made from heavy gauge Stainless Steel, it also does double duty as a skid plate (yes, the bottom plate is that thick).

An external pump hose will be permanently attached to the drain nipple in the top left of the tank and the output hose of the pump dumps the fuel into the main tank.

This was also a good time to go through all the wiring and check all the connections. Some were good, and some were badly corroded. I soldered most of the new connections and gave all connectors a good coating of electric grease.

The next day the metalwork came in from the powdercoaters, 
which meant 'Final Assembly'.

This was a moment I was ignoring all along so as not to get caught up in the moment and rush through anything, but now here it was at long last. 

The very first parts to go back on the bike were the two new fork tubes, but they first had to be drilled and tapped for a bearing grease nipple fitting.

The very first part put back on the bike for the last time. 
A sweet moment for me.

And then the leading link.....

...and the front shocks.

Once the subframe was mounted to the bike, the sidecar frame could be bolted in place.

The cradle where the Duo-Drive will sit.

The Mobec Duo-Drive installed with the outer axle. The outer axle is an unaltered half shaft from a Suzuki Vitara 4X4. We made a 2cm spacer to make it fit perfectly without having to cut it.

The exo-cage for the front nose of the sidecar. Behind the cage on the table are the rest of the powder coated parts awaiting assembly. 

I used the original BMW turn signal from the right side of the motorcycle rather than an aftermarket one, it looks good and keeps it simple. Ad was not in agreement with this, he didn't think it looked good.
 I do, and thats all that matters, right?.

The Bosch car battery in the bottom of the picture is being measured up for an external battery tray. It's a little smaller than a full-size car battery, but has the same power. 
Having the ability to be able to carry an extra battery gives me much more cold starting power since the next 6 months of my travels will take me through to Sweden, Norway, Finland and Russia starting in October of this year and going through February of 2013 where average temperatures will be about -25° and go as low as -50°. The small Odyssey motorcycle battery, strong as it may be, just doesn't keep up with severe winter temperatures, as I found out in -25° in Colorado in January of last year.

At this point we were ready to put on the boat otherwise know as the sidecar.
All shiny and freshly painted, way to clean for me, but by the time I reach Oslo in October, it should have a nice patina to it.

It was at this point when the sidecar was mounted in the frame, that I allowed myself to get a little excited, but not much, I knew there was still a lot of work ahead. I wasn't looking forward to the wiring, but it's something I knew I had to do myself, so when I have electrical issues down the road, I'll know exactly how it was wired and where to start looking.
The same can be said about the construction and assembly of the outfit. I've been involved with every aspect of the design and the build of this outfit right from the very start, so if problems arise down the road I'll know every aspect of the construction, how it was built and put together, so I'll have no problem with handling any type of repair on the outfit, even roadside.

The upskirt shot showing the Duo-Drive protection plate and the bottom bands of the stainless steel auxiliary gas tank. The three bands are not support bands, the tank has tabs that allow it to hang from the sidecar frame. The bands are extra protection skid bands.

We also made a tow bar, not to tow a trailer, but as added rear end protection and also drive shaft protection because we ran it under the driveshaft. The inclusion of the two 'wings' on either side of the bar extend the protection laterally.

The finished item and how it looks in place. Just behind the drive shaft is where the as yet unfinished battery tray for the car battery will sit, attached to the frame of the sidecar right by the two allen head bolts in the top of the picture.

This shot was taken as it was being pushed out of the LBS Sidecars garage for the first test ride, which it peformed with ease, no problems whatsoever.

Just today the tonneau top was finished by Rob and Saskia Manders of Manders Auto Upholstery. Rob also did a little carpeting on the inside just to finish it off and give it a cleaner look. Thank you Rob and Saskia for a job well done.

Maarten Versteegen working on the graphics. Tomorrow morning they will be finished just in time for Wunderlichs event in Sinzig, Germany.

Today is Thursday Sept 20th, 2012. The outfit was finished last month but has taken nearly a month to iron out all, or most, of the 'little niggly things' like the final drive bearing making a funny noise so I had to take it out for the 4th time to check it and re-shim it. I'm so good at removing and replacing the final drive bearing I can do it in my sleep.
I'm sure that knowledge will come in handy in the field, literally.
I ought to do a complete and comprehensive list of all the improvements and upgrades that we did to this rig, as well as the upcoming 
"Russia in -40°" checklist. 

My next post will will probably be from Denmark, I hope. 
I intend to leave Holland by next Tuesday, Sept 25th with a stop in Monheim Germany to see my Friends Jurgen and Bub, and then up through Germany to Denmark. I had wanted to stop off in Berlin for a few days but have decided to leave this part of the trip for the way back in January in order to allow myself a good time buffer for Russia. Even though I don't run on a schedule, I have ben invited to a Motorcycle rally in Yaroslavl, Russia by the Black Bears MC whom I met at the 2012 EGT in Luxembourg. The rally is the first week of December so it's not a lot of time for me to travel 6,700kms in Winter in sub-zero temps, that's providing I make it all the way over to Moscow to begin with.

Have the day of your choice,



Anonymous said...

You're posts are completely inspirational to me. Thank you. Be safe!


Charlie6 said...

An outstanding writeup and set of pictures Murph! I am of course quite envious not only of your rig but of your upcoming riding. Be safe and yes, knowing your rig is incredibly important when something happens on the road.

You'll carry spares of stuff that can't be replaced easily of course, but that mobec its purpose to give you 2WD or reverse or both?


Charlie6 said...

never mind my question re the mobec-duo drive, I googled it. very interesting.

teekay989 said...

Wondering if your technique of using the clutch to only shift into 1st is good for any bike or just the BMW?


Rod Johnson said...

Absolutely Fascinating Murph!!! Wonderful photos, I wish
you the best on your travels, Thanks for sharing....

IRISH Murph said...

Matt, thanks.

IRISH Murph said...

Tony, any bike.
There's a sweet spot on all bikes, you just have to listen to your motor. The BMW 1150 GS has it around 2000 rpm, at 2200 with slight upward pressure on the gearshift lever simultaneously relaxing the throttle slightly, it'll effortlessly shift sans clutch.

IRISH Murph said...

Rod, thanks for the well wishes and appreciate the support.


IRISH Murph said...

Yea Dom, it's a full-time 2WD system with a viscous clutch, as the tug wheel starts to spin it locks up the sidecar wheel. Thats why we put in the locking hub, so as I can unlock 2WD when on highway, no need for it there.

Anonymous said...

Damn Murph! That's totally bad ass! I just returned from my 5th cross country USA trip.
Keep on rollin'!

Rick K said...

Your ride is one sweet machine! I look forward to seeing how it works for you over the next segment of your trip. It may interest you to know that the link to part 4 of the build up is broken.

IRISH Murph said...


5th cross country USA, nice one. Which route did you take tis time?.

Ride safe.


IRISH Murph said...


Thanks, it is indeed a sweet ride, turned out better than I thought.

Thanks for the heads up on the link, should be fixed now. Appreciate you paying attention.



David Fernandez said...

AMAZING JOB!!! Your transformation is just incredible... I'm shocked!!

Enjoy your trike!! xDD

David Pautz said...

Shiney side up rubber side down be safe and Thank you for sharing your journey with us very inspurational . Keep us posted when you can..

Thank you,
David Pautz
Menomonie WI