The engine is in. Next up, building control cables, finishing the exhaust, and finishing all the various mounting bolts in the mini-lathe.
28 February, 2016
The engine is in
07 February, 2016
DKW Engine Progress
I have made some progress on the DKW engine build. It's been a fun process, but I have run into a few "issues" here and there. But nothing I couldn't overcome.
Step 1 was reassembly of the clutch. Top photo shows the assembly back together. Middle photo shows it being assembled. Getting all the "teeth" on the discs and basket lined up, while keeping the springs in place was sort of comical. And realize this entire assembly is about 3" in diameter, so lots of fiddly little parts. The third photo shows the entire assembly spread out. Like other moto clutches, this uses a series of discs and steel plates, that all clamp together. This way you can fit more clamping area inside a small diameter.
Then I got some of the internals installed into one half of the engine case. I had to buy a few NOS parts, including a new 1st gear, new layshaft, and of course all new bearings and seals. Doing the bearings was actually kind of fun. Stick the cases in the oven for a few minutes so they expand a little, and slip the bearings in with a little bit of pressing. Then as the cases cool, the bearings are nice and snug.
I took a lot of photos during disassembly, which was good. The factory engine manual is very helpful, but in a weird 1970s translated german to english sort of way. So a few sentences are confusing, and the terms they use for various shafts and shims made me scratch my head a few times. But everything went back together fairly easily.
The only real problem I ran into was there were apparently many different types of 1st gears, which was the only gear I need a replacement for. The original had a tooth knocked off. My 5-speed engine needed a 106-100 part#. The guy I bought the NOS parts from accidentally sent me a 106-200, which looks identical. But when I finally got around to fitting it, I realized it must have been a 1st gear from a 6-spd trans, as it was thinner. Luckily my source down in LA sent me a correct gear asap. But when I got it, it was labelled 106-000. It was the correct thickness, but the back side of the gear was lacking a small chamfer cut into. Without this chamfer, the backside of the gear lightly rubbed the aluminum case on the inside. Long story made even longer, my new little Mini-lathe came to the rescue. I chucked it up, and was able to cut a light chamfer into it, so it fit just fine.
At this point, I pulled out my NOS gasket kit. As the seller mentioned, the gasket we're laying very flat anymore. He didn't charge me much for a full kit, and it included the seals too, so I was expecting to have to recreate a few new gaskets. The big center case gasket was indeed shrunken a little bit, making it so that all the bolt holes were not lined up. So I scratched my head, and set about making a new gasket.
I used a spare wooden shelf board, and marked and drilled all the case bolt holes into it. This way I could stick the case bolts through it, based on their real position using the case as a guide. Then I carefully stretched the NOS gasket over the bolts, and marked around it. Then I trimmed the new gasket out with a razor, applied a tiny bit of permatex to one side of the case, set the new gasket on it, and let it sort of bond for 30 minutes. This helped it lay out flat, and kept all the holes in position. The last step was to turn that side of the case upside down, and fit onto the case half with all the gubbins in it. I was expecting this to be a pain in the arse, having to line up multiple shafts, multiple case holes etc., and fight a gasket lining up. Reality was it just slide down and fit easy. Sorry for the random order of the following four photos. Sometime blogger has a mind of its own.
Step 1 was reassembly of the clutch. Top photo shows the assembly back together. Middle photo shows it being assembled. Getting all the "teeth" on the discs and basket lined up, while keeping the springs in place was sort of comical. And realize this entire assembly is about 3" in diameter, so lots of fiddly little parts. The third photo shows the entire assembly spread out. Like other moto clutches, this uses a series of discs and steel plates, that all clamp together. This way you can fit more clamping area inside a small diameter.
Then I got some of the internals installed into one half of the engine case. I had to buy a few NOS parts, including a new 1st gear, new layshaft, and of course all new bearings and seals. Doing the bearings was actually kind of fun. Stick the cases in the oven for a few minutes so they expand a little, and slip the bearings in with a little bit of pressing. Then as the cases cool, the bearings are nice and snug.
I took a lot of photos during disassembly, which was good. The factory engine manual is very helpful, but in a weird 1970s translated german to english sort of way. So a few sentences are confusing, and the terms they use for various shafts and shims made me scratch my head a few times. But everything went back together fairly easily.
The only real problem I ran into was there were apparently many different types of 1st gears, which was the only gear I need a replacement for. The original had a tooth knocked off. My 5-speed engine needed a 106-100 part#. The guy I bought the NOS parts from accidentally sent me a 106-200, which looks identical. But when I finally got around to fitting it, I realized it must have been a 1st gear from a 6-spd trans, as it was thinner. Luckily my source down in LA sent me a correct gear asap. But when I got it, it was labelled 106-000. It was the correct thickness, but the back side of the gear was lacking a small chamfer cut into. Without this chamfer, the backside of the gear lightly rubbed the aluminum case on the inside. Long story made even longer, my new little Mini-lathe came to the rescue. I chucked it up, and was able to cut a light chamfer into it, so it fit just fine.
At this point, I pulled out my NOS gasket kit. As the seller mentioned, the gasket we're laying very flat anymore. He didn't charge me much for a full kit, and it included the seals too, so I was expecting to have to recreate a few new gaskets. The big center case gasket was indeed shrunken a little bit, making it so that all the bolt holes were not lined up. So I scratched my head, and set about making a new gasket.
I used a spare wooden shelf board, and marked and drilled all the case bolt holes into it. This way I could stick the case bolts through it, based on their real position using the case as a guide. Then I carefully stretched the NOS gasket over the bolts, and marked around it. Then I trimmed the new gasket out with a razor, applied a tiny bit of permatex to one side of the case, set the new gasket on it, and let it sort of bond for 30 minutes. This helped it lay out flat, and kept all the holes in position. The last step was to turn that side of the case upside down, and fit onto the case half with all the gubbins in it. I was expecting this to be a pain in the arse, having to line up multiple shafts, multiple case holes etc., and fight a gasket lining up. Reality was it just slide down and fit easy. Sorry for the random order of the following four photos. Sometime blogger has a mind of its own.
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