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1985 BMW K100 with Dnepr Sidecar

Mike Jones - March 2003

This is my current project, which has been in the planning stages since May 1988, with no action taken until late 2002.

In May 1988, an '85 BMW K100 came up for sale in the local newspaper. Having an eye for a good deal, and desiring to elevate my image from rice burner rider to Beemer operator overnight, I quickly did some research (old magazine articles), called the guy up, and sped to the location of the K100 at beyond the upper edge of the maximum legal speed limit, riding the 84 Aspencade which I had purchased to elevate myself from rat bike rider to something more respectable in the first place. Part of the reason I was in such a hurry was the old warning "well, someone else has called on it too, and they say they are coming over".

I got there first.

The owner told me he had purchased the bike in 1985, from Joe Harrison Honda in San Antonio, and that he was selling it because he was too tall for it, and he had negotiated with his wife a deal by which he could get a satellite TV system if he sold the K100. With the bike came a windshield, BMW System helmet, soft luggage bags, a BMW System tank bag, and an odometer with 7985 miles on it, all the for grand total of 3100 dollars.

When I saw the bike I knew I would buy it. With earnest cash money placed on the table in evidence of my sincerity, I asked could I take it for a brief test ride. Sure. I still remember that ride. It was a gorgeous early evening, north of San Antonio, in the area of Scenic Loop Road, and I was gone for awhile. Upon my return, there was a black Trans Am parked in the driveway, and the guy and his girl talking with the owner. Flipping up my face shield, I announced "This motorcycle is sold", which crushed the Trans Am driver. He should have driven faster.

Almost immediately, my goal was to put a sidecar on it, having become a sidecar enthusiast with my original 1982 XJ650RJ (Seca 650) with Velorex 562 sidecar. I requested and received a thick package in late May 1988 from BMW In St Louis, who were doing EML sidecar conversions. When I saw the prices, I realized it might be a long time before I could stick a boat on the Beemer.

The K100, back in 1988, off on a ride somewhere.
Some transplated Texas fowl.

You can criticize these bikes around me and get away with it. Early K bikes have gobs of power, a timeless styling, bulletproof motors, but do have a few problems. They buzz through the handlebars, have soft front suspensions, a wicked drive shaft jacking effect, and a completely stupid fuel filter mount inside the tank that I snapped off the first time I replaced the filter. It took a few hours, but I was able to clean up the sharp edges on the broken tube and install the filter anyhow.

Early K bikes were also subject to speedometers which would fail or operate in an erratic manner unless one gave them a sharp rap. The fork seals failed fairly quickly, because of razor sharp insect bodies impacted on the exposed fork tubes. After fixing them, I installed fork boots. The stock mirrors don't hold up to high speed work. HOWEVER, the very early K bikes retained the traditional throttle stop screw method of cruise control, altho the screw itself was not supplied. My throttle stop screw came from a 1972 R75 project bike.

The sidecar project on hold, I rode the bike for a few years, unwilling to put too many miles on it, mostly fearful of having an accident which would ruin the chance of ever having a sidecar on the bike. I rode it less and less, until 1994 or so, when I covered it with a sheet in my garage, uncovering it at rare intervals for maintenance. I had basically quit riding, but I wasn't going to sell the K bike, because I still wanted to put a sidecar on it. The mileage was less than 29000.

During the summer of 2002, when I began rebuilding the Seca, I subscribed to a couple sidecar mailing lists and began buying stuff on ebay for the Seca/Velorex reincarnation. It was during this time, I came across an unused Dnepr sidecar no one had bid on, so I wrote to the vendor. After confiding that the body had a couple cosmetic dents, he told me he would sell it to me for 500 dollars and shipping (750 total). Aside from Russian made rubber, inferior wheel bearings, and industrial looking weld work, this Canadian sourced sidecar was structurally the same as the Ural sidecars being sold for 2500 dollars in the US. Checking up on the vendor, I noticed positive feedback from another individual buying an identical sidecar. I contacted that buyer, and ended up having an email conversation with Lowell Neff.

As I was continuing to work on the Seca project, the realization slowly crept up on me that the K100 sidecar project really was going to happen, and maybe for not a whole lot of money. On-line auctions, mailing lists, internet web sites, and a number of independent sidecar parts fabricators were going to make this possible. Between November 2002 and March 2003 I found and purchased the following:

  • A subframe and mounting kit for the K100 from Jay Giese, at Dauntless Motors, complete with weld-in clamps with which to modify the Dnepr sidecar frame.
  • A front wheel from a K bike to use as the sidecar wheel, thus ditching the Russian made items. Found in the Internet BMW Riders classifieds section.
  • A used set of Unit leading links that came off a 1985 K100RT, found thru a little used sidecar mailing list.
  • A modified upper shock absorber mount that incorporated an eyebolt and a right sidecover already trimmed to clear the attachment, I got these items from the same guy who sold me the Unit leading link, he had used the eyebolt to attach a Hannigan to his 85 K100RT.

Total cost, including shipping, less than 2500 dollars. Add that to the original cost of the bike and the total rig was coming in at a nice 5600 dollar range, not bad for a not-quite full conversion, and less than buying a conversion kit from EML or EZS.

The Dnepr sidecar and my Seca 650
The Dauntless subframe parts.

None of this stuff was purchased without a lot of thought beforehand. For months, I had been torturing Jay Giese via email without ever buying anything. Lowell Neff commented that the Dauntless subframe was different, simpler than the Neff product, but did not criticize it in any way. Bob Darden, of Texas Sidecars, added that he bought his subframes from Dauntless and that problems with them were rare. Doug Bingham called me a couple times to give me help, and I enjoyed talking to him.

The leading links were a source of concern, with new units costing between 1400 and 1600 dollars. Folks would advertize looking for these items, and there was no indication of how much a used set would cost anyway. Both Unit and Lowell Neff make leading links in the same price range. On February 27, 2002, while at work, a sidecar mailing list digest arrived with one single post contained within..."Unit Leading Link for sale". Within an hour, I had contacted the owner, and we agreed on a fair price. These had been used for 4 years, and were in very good condition, requiring no modifications, as they had come off the same model of motorcycle.

As of right now, this very minute on March 11, 2003, I have every single piece required to modify and bolt together the K100 to the Dnepr sidecar. It is somewhat strange to consider that I have been working on the Seca/Velorex for 10 months and only now am nearing completion, and this new big rig might only take a couple weeks to assemble. But then, the Seca/Velorex involved the complete assembly of a motorcycle in parts and complete refurbishment of the sidecar.

The Unit front suspension, on the workbench. I had never seen Units in real life until these arrived.
I often just go hang out in the garage, cause there's a lot of cool stuff there to mess around with.

March 16, 2003 - Leading Link Installation

Ok, I installed the Unit Leading Links in a simple process taking about an hour. I replaced the triple tree pinch bolts, as the allen key sockets had gotten a bit dinged up. I found Grade 8 replacements at Home Depot.
The calipers bolted on pretty easy, and the wheel rotated freely, but the brake lines themselves are not yet hooked up. The holes thru the caliper mounting lugs (on the Unit) are larger than what one would expect for a 10 mm bolt, and it looks to me there should be a sleeve to allow the caliper to shift laterally to prevent binding on the rotors.
Things I needed to watch out for...mainly making sure the upper Koni shock mount clamps were at the same height, and not twisted slightly out of position. If the clamps are twisted towards the wheel, the shock could actually contact the mudguard.
I bought an inexpensive scissors jack for 20 bucks so I could just pop it under the oil filter cover and raise the front wheel. Previously, I have been using blocks of wood in different thickness to prop things up. Don't know why I waited so long to purchase this inexpensive shop tool.

On Wednesday, March 19, I called Unit, in England, to ask about the spacers, and was told there were no spacers (bushings) installed for the K100 calipers, that the holes may be a bit sloppy, but everything would be fine once the calipers were bolted down. Ok. Also, to set the initial geometry so that the swingarm was 90 degrees to the downtubes with no weight on the front wheel, and to adjust the suspension, move the upper shock mounts upwards to decrease trail, or move them down to increase it.
From the Yahoo group SCT, I learned that bleeding the brakes was gonna be tough, cause the bleed port isn't vertical, its horizontal (we will see), plus, there is a small possibility that the brake pads might be a tiny bit "not flat" to the rotors, and maybe take a few hundred miles to seat back in.

March 22, 2003 - Sidecar Frame Modification

Jay Giese had included a couple of weld-in clamps to replace the ball/collet arrangement on the sidecar frame, along with a simple sketch of the basic trim to the sidecar frame. Like many simple directions, they are a basic outline, a mere hint at what may actually be required. By the time I was done, I had about 6 hours of hand labor invested.

The work was done with a 12 inch bi-metal hacksaw with 18 teeth per inch, with a few drops of Marvel Mystery Oil for lubrication. Final "trim for fit" was accomplished with files. Working metal by hand is very enjoyable, and with proper tools, the result looks good.

The only real problem was that after cutting off the forward curved arm, the clamp would not fit properly, because the cross section of the frame was egg-shaped. In order to solve this, I trimmed further along the tube. The welded lug for the forward strut had to be cut away as well. It will be relocated.

The Units bolted on, the brakes installed and bled.
Typical trim required for the Dauntless clamp modification.

March 23, 2003 - Brake Line Installation - Bleeding

I installed the braided brake lines and filled/bled the front brake system. The final effort took about 30 minutes.

The braided brake lines have chromed fittings. They were assembled and took a great deal of effort to take apart. I resorted to placing them in a vise, in order to unscrew adjacent fittings. The fittings felt as if the threaded sections had galled themselves to each other. However, I saw no evidence of thread lock, teflon tape, etc, and I cleaned all the threads with brake fluid and a toothbrush, after which they assembled quite nicely. I screwed the lines into the calipers on the workbench. I had inserted a piece of 3/16 thk wood between the pads.

I had already drained all the old fluid out of the system. so removal of the existing lines from the "Y" connection under the steering head was not messy. There is an extra fitting on one end of the braided lines, which is tightened "last" in order to prevent twisting of the lines during installation. This extra fitting I located at the steering head end, not on the the caliper end.

Both lines were now connected to the bike and the calipers, the system completely empty, and the calipers sitting on the garage floor with the brake lines/bleed port fitting oriented straight up. I was going to fill the system from the bottom up, and had purchased a 6 dollar Sta-Lube "Fluid Oil Pump" (CRC Industries, Inc). It says "Not for use with brake fluid!" but this is because there is a soft rubber diaphram valve inside. I was only gonna use it once. I found it at Pep Boys.

Now, it just so happens this little pump slips right down inside the neck of the brake fluid container. I added a short length of vacuum line tubing bwtween this pump and the bleed port fitting, loosened the fitting and it took maybe 4 strokes of the pump for fluid to appear in the handlebar reservoir. The bleed port was cracked open a bit much so there was also a puddle of fluid on the floor. Oops. Drained off part of the reservoir fluid, and then filled the other caliper the same way. This process took maybe 5 minutes.

With the calipers on the floor, and the lines going straight up, the brake system has no downhill kinks anywhere. So I just turned the bars to the left a bit so the reservoir would be the high point, and all the bubbles came up thru the system, it took maybe 15 minutes. Now and then I would barely tap on the brake lever to let the bubbles burp thru the master cylinder. I tapped on the calipers and the brake lines a few times too.

The lever action was now very solid, so I pulled out the wood from between the pads, and bolted the calipers to the mounting lugs on the Unit. Since the rotor is thinner than the wood shims, it took a couple squeezes on the brake lever to fill the remaining brake system volume before I got a solid feel.

The calipers were installed and bolted down as part of the final tightening of the axle and pinch bolts, in order to avoid inadvertent binding of the brake discs to the rotors. I had a little bit of binding on the left hand side.

I fired the Beemer up and rode up and down the street about 25 times, feeling the steering, working the front brakes hard. The bike was perfectly ridable, but any handlbar inputs were magnified. Much less stable at slower/slow speeds. New sensation... to brake hard and NOT have the front end dive down.

When I finished riding, I put the bike up the the centerstand, jacked the bike so the front wheel would turn free, rotated it, and the binding had gone away. The wheel rotated freely with a quiet "hiss" of discs dragging. There were no leaks at any of the brake line connections, but the reservoir diaphragm looks like it needs replacing. It probably would be a good idea to replace the piston seals too.

The bike, the boat and the frame
The brake bleeding pump

Prissy likes to hang out in the garage, too.
Ready to attach the subframe.

April 14, 2003

This last weekend, I put the rig together. A week earlier, a neighbor had assisted with the welding of the modified Dauntless clamps onto the Dnepr sidecar frame. Now honestly, my original plan was to remove the rear end of the motorcycle to do spline lubing before assembling the sidecar, but I really wanted to put it together and ride it. I also did not have the spare K100 front wheel rim modified yet, nor does it have a tire mounted, so I decided to go ahead and use the Dnepr wheel for the initial installation.

The simple method by which I held the bike upright cost me less than four dollars for the hooks, since I already have plenty of extra wood lying around. The centerstand is attached with four bolts to the bottom of the transmission and the subframe uses those 4 bolts, so the centerstand has to be removed. Easy enough, but I saw I would have to invent an alternative method for attaching the brake pedal return spring.

The attachment of the subframe took an hour, using the upper engine mount, a bolt on the oil pan, and a crossover (cross-under?) tube to attach to the oil pan on the left side of the bike.

The primary subframe attachment. I think everybody uses these bolts for subframes on the K100. Visible just above the plate is the return spring for the brake pedal.
The subframe attaches to the right side of the bike, except for this additional piece crossing underneath.

Subframe in place, the sidecar frame was placed next to the bike with wheel lead set at 11 inches and the wheel track at 50 inches. The Dauntless mounting arms are easy to install and adjust. I had to do some refiguring of the upper forward mounting arm, because the Dnepr strut was too long. I substituted a short Velorex strut. Now, I am not very pleased that I have long extensions of the threaded eyebolts sticking out of the struts, but I can get longer struts later.

The hardware on the mounting arms and the welded clamps is very stout stuff, all grade 8. It takes only a few turns of the hardware to achieve a tight clamp on any attachment. I really like that, and this helped speed the installation to a total time of about 4 hours.

With the frame bolted on, I felt I should fire the bike up and take it up and down the street slowly to see what it felt like, in case I needed to make adjustments. The steering was light, but the rig went straight, so I returned to bolt down the body.

The frame installed on the bike, the mounting arms are visible.
The tub bolted on, ready to take around the neighborhood.

The rig is really nice. The leading links provide very fast response to steering inputs. Compared to the heavy steering of the Seca 650/Velorex rig, the K100 is nimble. I had never operated a rig with leading links before, but I did not find them twitchy or uncomfortable. The K100 has enough extra power that it didn't seem to notice it is hauling a sidecar around with it, and the Dnepr is so well balanced with the bike that no ballast is required. The brakes do a good job of slowing the rig down, but with the quick steering, I found myself turning the handlebars and taking corners with hardly any braking at all.

The test ride did bring two problems to light. First, the metal body of the sidecar picks up a resonant vibration from the K bike engine, and at around 2800 rpm, the big body panels really start to sing. It goes away at about 3100 rpm, and damping the body panels will not be a problem. Meanwhile, it sounds like there is a Ducati next to me!

The second problem was the headshake. Beginning at about 20 mph, and increasing in frequency as I went faster, the headshake felt different than what I had experienced on my other few rigs, and I couldn't ride "through" it. It wasn't too intense, tho, and a light hand on the handlebars kept it minimal. Turns out the crappy Dnepr wheels aren't very round, ha ha, and the headshake was related to the spinning of the wheel. I substituted the other Dnepr wheel, and the headshake was less intense, but similar in frequency. Now I am glad I decided not to use the Dnepr wheels for the permanent installation. The extra K bike front rim is round, at least, and will require either new bearings to fit onto the smaller Dnepr axle, or a sleeve to fit on the axle.

There is still a ton of stuff to do on this rig, but I am very satisfied that I finally got a decent sidecar for this old K100. I have already heard a comment about the Dnepr not complimenting the K100 stying, but a good silver paint job will help the looks quite a lot. I will need to wire up the sidecar lights, put the new sidecar wheel on and re-rig the chair for the smaller diameter wheel....lots of stuff.

Now I have two sidecars that I can work on forever and never get finished!!

May 3, 2003

In order to solve my unround, untrue Russian wheel situation, I got a cast aluminum wheel from Dauntless Motors. It is the same type as the wheel on the Flying Tiger sidecar, and is made in China, however, the basic pattern is similar to the K bike wheel. It fits right on the sidecar axle, and I just had to make a couple spacers to position it correctly. It has a steel sleeve inside the brake housing for drum brakes, but won't work with the Dnepr brake. It is a 19 inch rim, so I used the "made in USSR" tire. The rim won't work with a tubeless tire.
The difference was tremendous, nice smooth ride, headshake nearly gone, so I tightened up the steering head bearings just a tad to eliminate that.

In order to attach the rear brake return spring, I made a simple "S shape" hook from 1/8 diameter rod and just hooked it over the front edge of the subframe plate. In the process, it solved a long standing intermittant problem. In the past, the rear brake would sometimes not activate the brake light. Turns out the return spring was too weak, and the new S hook stretches the spring out just a bit more, solving the problem. I always thought the problem was the switch itself.

The looks of this rig are growing on me, and the more I look at it, the more similarities I can see between certain lines and shapes on the chair and the bike. No hurry to paint it. Hmmm, a German bike with a Russian sidecar, front end made in England, American made subframe and a Chinese sidecar wheel.

Update October 7, 2003

In the last month, I dug out all the remaining cans of silver spray paint from the Seca 650/Velorex project and had my way with the green Dnepr. Actually, I spent a fair bit of time on the front fender of the bike and the sidecovers too, and managed to obtain a very nice, clear coated, 100 percent orange peel texture on all the plastic. It looks quite good to me.

In addition, I finally got tags for the K100 (been out of registration for 9 years!) and have been riding it on the public roads. There is still quite a lot to learn with a rig like this, considering the size of the rig and the quick steering, but the suspension is very well behaved. The rig does not wallow to the side when making turns and is very well balanced, no ballast required.

The sidecar painting finished, and with the cast aluminum rim that I will use for now.
Another project for my wife, out back in the yard.