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Old 11-28-2013, 02:21 PM   #16
685
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Quote:
Originally Posted by disston View Post

BTW, the last gear on the output shaft is first gear but the gear next to it with dogs on both sides is 4th gear.
I think I knew that. I was referring to gear position as it comes off the output shaft.

I'm kinda thinking that as long as I don't try to "make things better" by mixing parts from different years and models, I should be in the ball park.

I don't have any sort of press yet. I've seen the pic of the press tool for pulling off the first (last one before the flange on the shaft) bearing. That bearing looks like it might be an impediment. On my replacement shaft assembly, it's already been pulled and wasn't included when I bought it. I'm thinking rather than trying to source the tool, I'll just spring for a replacement bearing (which is where all the info and worry about shims and end play come in.) My understanding is that it's not too tough getting the bearing back on--it's getting it off that's a problem. Plan B is that I have a friend at an automotive trannie shop that could probably safely press it off.

BTW, thanks to Rob & Disston, et. al. for the input. I'm not squeamish about trying this. And there is a very good BMW dealership in town, Ironhorse BMW, if I end up out of my comfort zone.
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Old 11-28-2013, 03:03 PM   #17
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The output shaft bearing is easy to pull using a bearing splitter. You can pretty much do all the bearings with a cheapo bearing kit off ebay. Whatever force your using to pull the bearings is a fraction of what they take when you're using the bike. Saying that I hate reusing bearings.

It was never meant as a definitive guide or to be techy but a few of us threw a thread together on UKGser after an airhead weekend to show the guys who went what was inside the gearboxes. It's just a whistle stop tour through a gearbox and a few of the issues http://www.ukgser.com/forums/showthr...head-Gearboxes

Rob Farmer screwed with this post 11-28-2013 at 03:22 PM
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Old 11-28-2013, 04:07 PM   #18
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Quote:
Originally Posted by Rob Farmer View Post
At the risk of saying Moorespeed again

Thanks Rob. I didn't know they had those. Also a great thread on UKGSER dot com.
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Old 11-28-2013, 04:25 PM   #19
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thanks for the pic of the bearing splitter. I don't know why the pic didn't show up in the thread. I can get one of those at Harbor Freight for about $30--that's what? Like 20 British Pounds?
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Old 11-28-2013, 05:07 PM   #20
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I own some HF tools. They are good enough but I haven't checked the pullers they have much. I do own a Chinese blind hole puller that I have used some. I mostly own Snap On or OTC pullers. The OTC Stinger line is also mostly made in China but is top quality. As good as most made in the uSA tools.



This is the OTC 4518 puller kit. It is only rated at 5 tons but I think is big enough for all the bearings in a 5 speed. It has a medium and a small bearing splitter.



This is the OTC 4517 puller kit. This puller is rated at 7 tons.

The 4518 sells for about $74 on Amazon dot com and the 4517 for about $95 on Amazon. Shipping is usually extra.

I post these so you can compare to what you see at Harbor Freight. In pullers as in most other tools the name brand does mean something.

A press, even a borrowed press, is the easier way.
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Old 11-29-2013, 08:54 AM   #21
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Quote:
Originally Posted by Rob Farmer View Post

It was never meant as a definitive guide or to be techy but a few of us threw a thread together on UKGser after an airhead weekend to show the guys who went what was inside the gearboxes. It's just a whistle stop tour through a gearbox and a few of the issues http://www.ukgser.com/forums/showthr...head-Gearboxes
I read, and saved, that thread. A spectacular writeup, and such a great effort. Thanks for posting it! The pictures are just awesome.
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Old 11-29-2013, 09:21 AM   #22
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Cheers from me as well, that thread helped me plenty.

One hint I don't think I've seen is that if you are going to remove the big spring, buy a few of the little retaining clips. I'm sure the design is better in later years, but for my '77, that little clip is a bear to get on intact. I got the second one on and felt lucky.
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Old 11-29-2013, 10:43 AM   #23
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I guess I don't quite grasp what your point is--I'm not trying to be a smart ass or snarky here. I'm not singling you out, but there does seem to be a trend towards making this all a bit more complicated than it needs to be.

I know that 74/75 were years of change in the gearboxes--and that parts from a 75 probably might be problematic in my 76 five speed.

If, as Disston says, 82/83 was a change year for the helical gears, I should be golden for helicals if both my replacement shaft and the offending shaft are from the same displacement and model year, no? At the very least as the offending gears are the 1 & 2 gears on the shaft (last ones before it outputs to the flange) I may be able to just pull those bad gears off and put the good ones in?
There are all kinds of changes all through that gearbox'es production. 74/75 is the tip of the iceberg. Gears from the same model year? After 35 years? Who knows what's in there?

Rob Farmer's photo shows a completely off topic change that happened in around '86? That change being a beefier cush drive since the earlier ones are prone to breaking. The later 17.5 PFA input shaft gears came to fit the earlier, smaller cush drives thusly looking identical to the 15 degree PFA gear. Comparing the two photos of completely different cush drive setups as an example of different PFA's could be very misleading.

There is nothing too complicated about rebuilding these transmissions but this topic affords no mistakes. It all depends on what parts you have to start with and what parts you got. What was in your box or what came out of another box? After 35 years? I would make sure what you have. If the PFA's are mixed up, your rebuild won't last very long and the damage is pricey.

More complicated than it needs to be? I am just trying to warn you of a common and very expensive mistake.

The gears involved are available from numerous sources if you look.
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Old 12-04-2013, 12:29 PM   #24
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Go for it!

They are simple gearbox's that take very little to build. A word of caution though, make sure your torque wrench is properly calibrated and you are looking at the correct torque spec when tightening the output shaft nut. Those threads sure do disappear quickly. So um, got any plans for that spare output shaft...
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Old 12-04-2013, 04:02 PM   #25
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Quote:
Originally Posted by Rob Farmer View Post
At the risk of saying Moorespeed again

Actually those gears are readily available here in the US. I have 5th intermediates with and without X, tall 5th with and without X, and stock inputs of all types at any given time. And, of course, the short firsts but they aren't helical.

And I am by no means the only one who has them.
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Old 12-04-2013, 05:13 PM   #26
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Originally Posted by AntonLargiader View Post
, tall 5th with and without X, and ....
Tall 5th with the dogs for the '74 gearbox...?
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Old 12-04-2013, 05:30 PM   #27
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No, no round-dog 5ths. I've asked about them but I don't think they are made. Just upgrade that stuff. It's actually not a '74-only gear, but as a general rule no one is going to tool up to make the '74-only parts. BMW changed away from them for a reason.
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Old 12-06-2013, 05:57 PM   #28
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Do you gurus have any pics of what you use to measure the distances for shimming. Not talking about plastiguage stuff either - your measuring devices.
thank you
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Old 12-06-2013, 08:38 PM   #29
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This for measuring from the machined plate to the top of the bearings. I don't have a pic of the depth gauge for the recesses in the cover.

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Old 12-06-2013, 08:51 PM   #30
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After not getting my box shimmed right with a conventional hand-held depth gauge (after 3 hours at a tech day), I ordered the compound from Cycleworks. Will report back after I give that a try.
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