Restoration Photos and Progress 1932 R4 Series 1
This is some progress photos of my newest project, a 1932 R4 series 1.
It is a 400cc single, with a three speed hand shift gearbox. I'm lucky in the fact that the original steering head ID plate was on the frame, and the number stamped in the ID plate, and frame, and engine all match. The bike has a lot of problems, needless to say. It was involved in a wreak sometime in it's 80 year old past, and the front forks were bent, and the frame is tweaked. I just now have the front end repaired. (which involved removing rivets, straightening the lower triple plate, and installing new rivets) I had to make all new pivot bushings and shafts for those tiny front swing arms. I have gone through, and finished, the gearbox and final drive, and drive shaft, so far. Now that I have a straight front end, I have to determine where the main frame is tweaked. But before I can have a good reference, I have to have two laced true wheels. And, of course, the wheels are not only WAY out of true, there are broken spokes, and naturally I will have to have spokes made, since they are not available. And the list goes on and on... Another year or so, and I may have it totally restored and back on the road.
R4 another progress photo
Here is the latest photo. More to follow as it goes together.
In this shot, you can see the gearbox is now installed. Notice the weird cross connection on the back of the output shaft. This is the hardy joint and instead of being a rubber disk, it is unlike any other BMW drive shaft joint. The end of the drive shaft, which as two cam like lobes, inserts into the cross, and two hardened pistons rest on the low sides of the lobes. Behind each hardened piston is two coil springs. There are two "pipe caps" for lack of a better description, that, when screwed into the cross, put pressure on the springs, which in turn puts pressure on the pistons. This mechanical arrangement acts to take up drive line shock, from acceleration and deceleration. There is also a polished, nickel plated sheet metal cover on the drive shaft, that covers this whole assembly, so it does not eat a hole in your ankle while riding. Very strange, but mechanically sound, way of getting the job done.
Also in the photo, you can see the horn mounted on a bracket off the side of the 3 speed gearbox. The cylindrical object just below and in front of the horn is the generator, which is driven by the cam chain. Notice also that because the center line of the engine is very offset to the bike's right side, and with it, the transmission, the kick start lever is not on the bikes left, but rather on the bike's right side. This means standing on the wrong side of the bike to start it!
What you cannot see in the photo is the throttle control on the right side of the handle bar. It has a mechanical lever that pulls a cable, that runs to the high low bean switch that is inside the headlight bucket. Also, there is a decompression lever. This cable operates a decompression cam in the valve cover, which lifts the exhaust valve and holds it open, so you can spin the engine up fast with the kick start lever. While the HEAVY flywheel keeps the engine spinning, one releases the compression lever, and then the bike will start. It is a blazing 13 hp and 400 cc, I have no idea how tough it will be to start, I have not gotten that far yet...
More will follow after this weekend's work on the bike.......
Sadly, it won't be ready for the national rally, but I will be there with several of my other bikes, so I'll see you at the Vintage Display. I will also be in the Vintage seminar, so come and listen if your interested.
Another R4 progress photo
I managed to get quite a bit done over last weekend. I spent two solid days working on it. From this view, you can see the final drive is installed, with the nickel plated sheet metal cover over the hardy joint on the drive shaft. I have completely wired the machine, with cloth wiring, covered by black braided sheathing, as used in the 1930's and 40's. I have added a brake light switch, (the original bikes had no tail light, and no brake light, only a reflector) and tail light wiring. I intend to use a Bosch JN-5 black cigar tail light on the top of the licence plate holder. I custom made all the cables, since none are available commercially. You can see, sort of hanging down, on the right hand control, the lever for the compression release. The odd brass cover on the final drive is a vented cover, that allows you access to the rear axle. This bike has NO wheel bearings in the rear wheel. The ring gear bearing acts as a axle bearing, and there is a frame mounted housing opposite the final drive, with a double row, self aligning ball bearing mounted in it. Yes, that means that this bike as a LIVE rear axle, that turns with the wheel! As I get further along, more photos will follow.
Another progress photo R4
This is the latest progress photo. The hand pin striping is finished on the frame, front end, and front fender. The front fender was hell to install. Very tight squeeze, and very tricky to get in place without scratching anything, but I managed.
RE: Where do you find these things?
[QUOTE=166926;797637]Wow! Where do you find these things? I have to say that I have endless amounts of respect and admiration for people that can do what you do with these bikes. Can't wait for more updates![/QUOTE]
Well, it's all quite random. I just luck out, when it comes to finding old BMW's. But, since I'm getting old (61) and have been a vintage enthusiast for the last 40 years and am in the restoration and vintage parts business, I do have a lot of contacts, so what can I say? I never buy anything sight unseen, and never overseas, since that is a good way to get burned. And, I always try and buy original condition, (no matter how bad) machines with matching numbers. Not "restored" bikes. No point in doing all that work and spending all that money unless it is a correct bike, as far as numbers go...
The R4 fuel strainer/gas gauge
Here is a straight down view of the duplicate brass fuel gauge/ fuel strainer that I made last weekend. I made both the top flange and bottom flange out of brass on the lathe. I made the supporting spiral piece of of flat brass stock, and formed it around an old R51/3 fork tube, using a dead blow hammer. I cut out and bent the fuel tabs out of flat stock and stamped the liter numbers in each one.
R4 - fitting the exhast system
Needless to say, as with most reproduction prewar parts, they never fit correctly.
I bought a header pipe out of Poland. This is the second one I ordered, since the first one that came out of Germany was completely wrong, and was for an R35, and wasn't even close to fitting. It was so far off it could not be modified.
This new pipe, as you can see, did not fit either. I had to modify it by cutting the pipe in two, half way down from the head, to the second curve. You can see the welding done to it, in the photo. Since the pipe was too short, I took a scrap piece of steel pipe, put it in the lathe, and turned down the outside diameter until it matched the diameter of the header. I then turned each end down until it would just barely slip into the inside of the header. I then put it all back on the bike, and adjusted every thing until the header cleared the front fender, and the frame, and would tuck in fairly close to the driver foot peg mount. I had to heat the header, and "dent" it in, just a bit, so it would clear the foot peg mounting nut. Then, I had to cut off about 2 inches of the end of the header, since it was impossible to shove the muffler onto the header far enough forward, so the center stand arm would come out in the "dent" on the bottom of the muffler, when the center stand was retracted. After I got everything fitted as described, I shielded the painted parts of the frame and fender, and tack welded both parts of the header pipe to the "extension" that I had made on the lathe.
After grinding and sanding the weld, I boxed up the modified header, and set it off to be bright nickel plated. Now I must sit back and wait for a month or so, until I get the header back. After I get the header back, I'll be able to start this engine for the first time, in at least 59 years..........