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Kidasters
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Houston, Tx
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Hey guys -

Bad day today. One of the tabs that holds the pin on the clutch arm broke today. In order to fix it, I'm going to replace the transmission cover. it looks like to do that, I'm going to have to remove the swing arm and drive shaft. Any hints or tips for this job? Not looking forward to this one.

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 6865
Have you diagnosed why it

Have you diagnosed why it failed? I suspect that the small c-clip holding the pin in place came loose, allowing the pin to work out of the boss which ended up breaking it out. There are fixes for that...replacing the bolt with one that is threaded on the end and using a nylock nut.

You should be able to undo the 4 bolts at the back of the transmission output shaft and move the whole rear end backwards to give enough clearance to get the transmission out. A few other things will need to be removed such as the brake rod wing nut, probably the muffler mounts. You'll also need to remove the battery and battery box. The swingarm pins need to be pulled as well. In the end, they'll need to be tightened in a special sequence. Plus you'll need a special tool to get to the thin nuts on the inside of the swingarm holding the pins in place. It's a modified 27mm nut with the outside edge ground down as well as the inside chamfer removed. Snowbum has some info on this here:

http://bmwmotorcycletech.info/inputsplinesthrowout.htm

You'll need to reshim the transmission since the rear cover is going to be different in dimensions that the original. Here's a page on general gearbox overhaul and it talks about the shimming as well:

https://www.schweizerschrauber.ch/mot/gearbox.html

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

Kidasters
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Houston, Tx
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I'm not completely sure

My guess as to why it failed is (per Snowbum's write-up) is that it started to work it's way out, and that's what caused it to fail.

Damn - I was hoping that I could replace the cover without pulling the entire transmission, but that does not seem to be the case.

It's probably for the best, so that I can get everything apart and cleaned properly.

So disappointed.

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
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Yeah, the cover will need to

Yeah, the cover will need to be heated at various spots in order to get it off. I've seen Matt Parkhouse do it at one of the MOA Nationals.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

Kidasters
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Houston, Tx
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There's more than that

I'll also have to pull the drive flange off to get the cover off.

The BMW factory tool (23 1 700) is impossible to find.

Any thoughts on this too? Just use a gear puller?

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
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This is a pretty critical

This is a pretty critical joint...I think you need the proper tool or something that will do the same job...a simple puller probably won't cut it. The flange is on with some serious torque, like 150-170 ft-lbs.

Cycleworks has the puller...plus there's a DVD on transmission work:

https://www.cycleworks.net/

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

Kidasters
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Houston, Tx
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Brilliant!

Kurt - you rule. This is the one:

https://www.cycleworks.net/index.php?main_page=product_info&cPath=29_52&...

I'm purchasing it. Thanks!!

Kidasters
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Houston, Tx
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Still making small progress

Hey Guys -

A couple more questions.

To remove the transmission, it says shift into 4th or 5th, as it is imperative that the transmission doesn't move. Since the clutch is basically broken, I shifted up to what I thought was 5th last time I messed with the bike. I had to move it today, so I wanted to go back down to Neutral.

And, one click down, I was in Neutral. So - turns out I had it in 2nd. So - my question to the group, is there a better way to find 5th? Or, is there another way to immobilize the transmission for this work?

Also - I was worried about my 75 R90/6 having the same problem. I was looking at it, and the linkage is slightly different on the 75 than the 78. On the 78, the cable hooks directly to the fork at the end of the lever that pushed the throwout bearing. On the 75, it is much more complicated. The clutch cable hooks to a small chain that wraps around a gear on the end of the throwout bearing lever. The pin looks different too.

It made me nervous, so on my 75 I put a cotter pin on the slot at the bottom of the pin. But, it still doesn't look like there is anything holding the pin in on my 75. I'm thinking about not riding the 75 until I can replace the pin on it as well - as I don't want to replace 2 transmissions.

Replacing the pin seems like it should be pretty straightforward, but I'm sure there will be scope creep.

Looking for advice.

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
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You say "remove the

You say "remove the transmission"...what does that mean? Are you trying to get it out of the bike? If so, it doesn't matter what gear it's in.

As for the different mechanism on the '75, sounds like that's what called an Easy-Clutch...maybe something like this:

http://www.benchmarkworks.com/articles/howto/clutch.html

The '75 and '78 would have had similar stock clutch engagement setups...some differences, but not that much.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

Kidasters
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Houston, Tx
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You have all the answers

Yes - it is an Easy-Clutch! Perfect.

For removing the transmission, I'm just trying to do what it said in this guide:

http://bmwmotorcycletech.info/inputsplinesthrowout.htm

Plus - he seems to say that there should be service on the input shaft every so often, and I figured while I was there I would do that.

I've decided before I ride it more, I'm going to remove the pin and replace it with a bolt. That's the safe thing to do.

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
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I've used Snowbum's notes to

I've used Snowbum's notes to lube the splines on my transmission. For the life of me, I don't see the need to put the transmission in top gear. He's usually very detailed on things so maybe there's a reason...I must be missing something.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

Kidasters
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Houston, Tx
Joined: 02/17/2013
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Replaced the pin with a shoulder bolt

OK -

Replaced the pin on the R90/6. Only had to remove the seat, battery, and battery tray to do it. Shoulder bolt in place made of 316 stainless steel, should be good for awhile.

At least I won't repeat this problem on that bike.

Kidasters
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Houston, Tx
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So - when you do the job

Do you put the transmission in 2nd? Or leave it in Neutral? What do you do?

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
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So, you're just removing the

So, you're just removing the transmission from the bike? Or sliding it back to get a sneak peak of the input splines? I still don't see why it has to be in any gear. When I lubed my splines in a similar manner as Snowbum describes, once I had everything pulled back far enough, I had to rotate the splines a little bit around in order to get at all sides. I suppose it has to be in a gear so that the gear wheel can be turned in order to turn the splines. But generally, one could probably work around it.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

Kidasters
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Houston, Tx
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I'm going to remove the whole

I'm going to remove the whole thing. I think it will be easier and less messy to replace the cover on my bench. Plus - I need to service the splines as well.

When you've done it, do you do it with the bike in gear? Or what?

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
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Not in gear...doesn't make

Not in gear...doesn't make sense to me. Once you've removed the carb air horns, air filter and housing, battery and battery tray, there should be enough room to simply slide the trans back and out. Well, of course, the driveshaft bolts at the back of the transmission have to come off. And I suspect that the swingarm pins need to be removed so the whole rear part of the bike can slide back to allow the transmission to slide back and out. I'm probably missing a few things, but that's the big stuff.

Can't figure out why being in gear matters. Thinking

One thing...before removing the swingarm pins, etc., break the output flange transmission bolts free. Do this by stepping on the rear brake and getting your wrench onto the heads of the bolts. Install new bolts when going back together...the short bolts without the lock washers. Don't use the older longer bolts which were locked in place with the lock washers. Short bolts with a dab of blue Loctite and a good grunt with the toolkit wrench.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

Kidasters
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Houston, Tx
Joined: 02/17/2013
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maybe that's why

Maybe he's saying put it in 5th in order to break the output flange bolts free.

OK - I feel more confident about doing this now. I appreciate all the comments.

schrader7032
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VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 6865
I don't think putting it in

I don't think putting it in 5th gear helps break the bolts...maybe but I'm not sure. Say it's in 5th gear and you begin to turn the flange bolts...it's possible I suppose that turning the bolts will cause the transmission gears to rotate which in turn causes the engine to rotate. Seems to me much easier to just step on the rear brake to resist the torque of the bolts.

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Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

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