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Old 04-19-2013, 08:33 AM   #256
Pokie
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Yes, that's the best way to repair the kick start. I've been doing that for years.

I really like the four speed transmissions and don't have a lot of use for the fives. I have four "five speed" transmissions in boxes out in the shop, they all have the same problem. The shift rings that are pushed by the shifting forks are also part of the gears on the "cluster" shaft. These gears are thin and kind of weak and are also broken easily. That doesn't sound like a problem except they can't be bought separately, you have to buy the whole darned shaft! I think the last time I priced the shaft, it was in the $900 range and that was several years ago.

Back when I was wrenching, I used to collect as many trashed five speed transmissions as I could. If you take enough of them apart, you can press apart the cluster shafts and mix and match to get a few repaired. The problem here is it usually takes about five or six to get enough parts to complete one.
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Old 04-19-2013, 10:24 AM   #257
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Quote:
Originally Posted by Pokie View Post
The shift rings that are pushed by the shifting forks are also part of the gears on the "cluster" shaft. These gears are thin and kind of weak and are also broken easily.
That issue is almost exclusively limited to the early 5-speeds. That part was strengthened twice within the first few years of production. It would be extremely rare to encounter that after MY1977 or so.
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Old 04-19-2013, 10:36 AM   #258
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Originally Posted by Pokie View Post
Yes, that's the best way to repair the kick start. I've been doing that for years.

I really like the four speed transmissions and don't have a lot of use for the fives.
When I got my '73 /5 it was an orphaned waif-- the last one of last year's model, and a 600cc Toaster, when the new and improved /6's were on the showroom floor. Was able to bicker a good deal. At first I wished that I'd be able to get one with a 5-speed, but in retrospect, 5-speeds turned out to be so problematic (especially the early productions) that I'm glad I avoided them...

--Bill
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Old 04-19-2013, 03:39 PM   #259
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Whoa.... you guys on this forum scare me.

When friends ask me about my old airhead I keep working on, I tell them it's more like working on tractors (which they know about, and I don't know squat about), and it's not rocket science.

I say so because in the late 60's early 70's I worked in my dad's garage as a grease monkey along side some actual out of work rocket scientists on the Space Coast in Florida. They worked there just to put food on the table until things turned around in the space program. They actually BUILT the beer cans they shot off into the sky. As one of my surfing buddies once remarked, "These dudes know some far out stuff, man!"

I was in awe with the knowledge that kind of floated around the shop. I'm impressed with the knowledge floating around this forum.

I say "scare" in a nice way.
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Old 04-19-2013, 04:16 PM   #260
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I'm impressed with the knowledge floating around this forum.
Agreed.

Frankly, I've never seen anything like it. And it's more interesting when people share their stories - if we just limited ourselves to tech talk, things would get a bit dry around here. Some of this stuff has nothing to do with airheads or motorcycles for that matter. Don't care. Bring it on.
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Old 04-19-2013, 04:40 PM   #261
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Quote:
Originally Posted by skipn View Post
Whoa.... you guys on this forum scare me.

When friends ask me about my old airhead I keep working on, I tell them it's more like working on tractors (which they know about, and I don't know squat about), and it's not rocket science...
After living in the country for almost 25 years last month I finally broke down and bought a tractor. A 3-cylinder, diesel, ancient, gray market Japanese tractor. And, yes, it's a lot like working on an R-bike. Verified.



--Bill
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Old 04-19-2013, 06:08 PM   #262
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Originally Posted by skipn View Post
Whoa.... you guys on this forum scare me.

When friends ask me about my old airhead I keep working on, I tell them it's more like working on tractors (which they know about, and I don't know squat about), and it's not rocket science.

I say so because in the late 60's early 70's I worked in my dad's garage as a grease monkey along side some actual out of work rocket scientists on the Space Coast in Florida. They worked there just to put food on the table until things turned around in the space program. They actually BUILT the beer cans they shot off into the sky. As one of my surfing buddies once remarked, "These dudes know some far out stuff, man!"

I was in awe with the knowledge that kind of floated around the shop. I'm impressed with the knowledge floating around this forum.

I say "scare" in a nice way.
If you don't know squat about tractors how do you know working on an airhead is like working on a tractor????
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Old 04-19-2013, 06:10 PM   #263
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If you don't know squat about tractors how do you know working on an airhead is like working on a tractor????
Don't know anything about working on airheads, so I have a lot in common with tractors.
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Old 04-19-2013, 07:54 PM   #264
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Originally Posted by Tin Woodman View Post
And it's more interesting when people share their stories - if we just limited ourselves to tech talk, things would get a bit dry around here. Some of this stuff has nothing to do with airheads or motorcycles for that matter. Don't care. Bring it on.
You just said a mouth full.

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Old 04-19-2013, 08:52 PM   #265
Plaka
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Don't know anything about working on airheads, so I have a lot in common with tractors.
True dat. Tractors don't know about working on airheads either.
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Old 04-19-2013, 10:37 PM   #266
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See that pin/shaft pressed into the rear cover that the kickstart gear rides on? It is prone to loosening with use and can migrate into the case. Cure is to center drill and tap that shaft (5 or 6mm thread) and bolt a large flat/fender washer on the backside/outside. --Bill
Couldn't I simply red Loctite it into place then promise never to use my kickstart?
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Old 04-20-2013, 03:12 AM   #267
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You could, if it's loose. But drilling and tapping for the safety stop is like a belt and suspenders-- extra protection. And as long as you have the back cover off anyway, this is the best time.

Whatever.

--Bill
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Old 04-21-2013, 12:46 PM   #268
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Ah ha!

Minor discovery but at least I now know why the transmission was binding. First discovery was a red herring -



Bearing on intermediate shaft was misaligned. Couldn't figure out how it had been shimmed in that condition and fit in the case. Turns out it had slipped on the shaft when I heated the case and removed all three shafts. Next I tried to simulate how the dogs are aligned through all the gears. I would imagine the pro's are rolling their eyes - feel free to tell me I'm completely off track. This is first gear -



Neutral -



Second -



Third -



Fourth -



All the gears spin smoothly on the output shaft except for first - it's seized on its bushing. With great effort, I can spin it. It's obvious now that's been the problem all along. Sheesh!

Now that I'm focusing on the output shaft, I realize the other bushings are worn and the gears have a lot of play. Clearly, I need to replace all the bushings.
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Old 04-25-2013, 01:07 PM   #269
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My motivation is curiosity I suppose. The binding first gear was really bugging me so I went ahead and pulled it and the outer ball bearing off the shaft. There was no evidence of scoring or damage to the bushing at all. Much to my amazement, when I remounted the gear, it spun effortlessly on the bushing. No play whatsoever.

What little literature is available about 4 speed rebuilds tends to focus on ball bearings and end-play shimming - not bushings. Picked up a couple from my supplier and was shocked that they're more expensive than ball bearings -



I'm assuming they're bronze or Oilite (coincidentally, the Oilite trademark is owned by Beemer Precision, no connection to BMW that I can see). Still can't understand why there was so much friction (virtually seized) before vs. after. Could be the nature of bronze or Oilite.

Put the output shaft back in the transmission housing and realigned the forks - now silky smooth through all 4 gears and neutral.
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Old 04-25-2013, 08:31 PM   #270
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This is a great thread.

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