Opinions on that Airhead higher 5th gear?

Called the rebuilder... Draining out the Redline milkshake. It was less pronounced today, but this transmission was always silent. Diving back in.... Ughh.

Rebuilder opened it back up. Said everything looked fine, it goes back in today. He did say if it made any noise at all he'd come listen to it at my location. (I like that level of attention)

Anyone think of anything that might have gone wonky putting it all back together that would not be the Transmission for the noise.

I ran the bike in gear, heard the noise. Clutch lever pulled, still noise. Turned engine off, still noise. So only wheels and drive train moving for the noise to be coming out of. No rubbing at the rear wheel. Still sorting it out.

Picked it back up from the shop owner said he took a thousandths off a shim or two. Ended the conversation with, "if it's not right, call me I want to come listen to it." You have to appreciate that he'd be willing to come to me to make it right.

Put back in and it's RIGHT AS RAIN. Hot Damn the "white bike" rides again.

That's a touchy bugger if it only took a couple thou of preload to get it to sing.

...and that is why we send them to the pros!!

...and they lived happily ever after.

I'm dreaming on a six speed on my G/S
I found the gearing perfect for small or montain roads, city etc, but too short for highway

I could probably hook you up for around $2200.

Yep.. took it out for 160 miles today... smooth shifts, very nice. Can you tell I've not had a moto to ride in a little over a month?

While out, stopped off for a soda at a junction, an Airhead rider with a R90/6 was there too. He'd had his transmission done by the same guy and was equally happy.

Bumping an old thread rather than starting a new one.

Lets say I decide to install a higher 5th gear in the box from my early (feb) 1981 G/S:
without going full rebuild (the box works well) what are the other easy to do things that I might as well do 'while I'm in there'?
Full gasket and seal kit I am guessing?
The updated shift kit thing? In the small amount of riding I did on this bike before I started pulling it apart I did hit a fair few false neutrals- however the whole shift linkage is completely loose and worn out and I am pretty sure this was contributing.
The metal K roller thing?
What about bearings, anything I might as well do that is not too hard?

I've never opened one of these boxes before and the closest relevant experience I have is doing a full rebuild (all bearings, seals, gaskets and full internal gear and shaft swap) on a 40 series landcruiser ('split')transfer case.
I don't want to go too deep into the G/S gearbox but I would want to do what I 'might as well' do.
I can probably get access to a press, and buy a puller or two, but I'd like to avoid complex shimming and preload type details if I can. However this bike will probably do a bit of international riding so I need to consider doing the best job I can on it.

If it has any relevance I am currently putting together a big motobins order and am dangerously considering the siebenrock 1000cc power-up kit in combo with the higher 5th gear. All these parts would be purchased from motobins stock.

thanks,

I wouldn't install the steel roller, supposedly there's a possible problem with that mod, but don't recall specifics. The stock rollers hold up well, so don't bother.

The shift mechanism is a good idea and easily swapped. Your bike is right around the time a lot of those things were changed - are you sure yours doesn't already have it?

Besides the false neutrals, how does your shift? If clunky, it should be shimmed anyway. And if you replace the large front output shaft bearing you should, at least, check the shimming. And if you're planning on taking the bike on tour to rougher roads far from home, I'd recommend replacing that bearing while in there, if nothing else. Since I can fix my own, I don't worry about the bearings and re-use them if they look and feel good. But that bearing is most likely responsible for most tranny rebuilds, so to be safe, replace it while you're in there.

Have you read anything about working on these tranny's? There are a few sites that go into detail, and I'd recommend it.

I don't think it is reasonable to expect that you can open any of these transmissions and not have to shim the shafts when you put it back together. Supposedly you can only replace the bearings that either feel notchy or loose but those have to be shimmed and since that is happening you should shim all the bearings. It is also reported that the factory did not do a very good job of shimming these boxes so if you are opening one you are advised to be ready to shim it before you put it back together.

Now you are replacing one of the gears? You have to shim the whole box. Period.

How many miles on this trans?

Charlie

Forgot about the new gear. Yep - shimming is in order. And I agree with what disston just said - and we're not talking about bmw, these trannys were built by Getrag and shimmed by them. It's been said they didn't do a very good job of shimming, but at least they were usually shimmed loose rather than tight. And frankly, every time I've opened one up, the shims have fallen out or gotten confused, so didn't know which went where.

OK,

No, I am not sure. Is there a way to tell without cracking open the box?
I think it was in this thread (could have been one of the others I read) that Anton said (loosly paraphrasing from my memory) the later shift mechanism started on some bikes half way through 1981 and was in most bikes by 1982. Mines a Feb 1981 bike.

Clunky is a bit of a relative term on these boxes isn't it? Gearbox shifts reasonably well and is less clunky than many other airhead 5 speeds. Seems fine to me.
I'll look into the front output shaft bearing.
It looks like my want to avoid shimming is completely unrealistic- fair enough I'll have to shim it. Shims are cheap so maybe one of each,
.2mm, .28mm, .38mm, .5mm?

I'll hit google again tonight after work.
Thanks.

Ok, shim I will do if I go through with this. Sorry for the unrealistic want.
the miles are completely unknown for the bike and the box.
For the bike, at least this when the speedo seized a while before I bought it

My engine number (6251767 ) doesn't match my frame number (6252171), which I originally thought meant an engine swap but was told a while back that bikes of this vintage didn't necessarily have matching numbers in the first place.
The previous owner couldn't remember much about details like this and didn't do his own work on the bike. I know the guy who sold this bike to the previous owner, and he is our local airhead parts guy/guru, but it was a while ago and as he sells a lot of bikes, so he can't remember any specifics other than 'if it needed anything done I would have done it before I sold it'. He remembers it coming in for a few services and minor repairs over the previous owner's ownership.
It looks like I any more info about this bikes history is unavailable to me.

Thanks a lot for the respones,
gotta run to work now.

If you are going to do this yourself there are a # of tools needed. If you only ever do one gear box in your life it will be hard to break even. If you see yourself learning a little more and doing at least two then you can break even or even come out ahead a little. The pros that rebuild these boxes also do a better job the first time. What I'm trying to say is it won't save you any money to rebuild this box yourself. But if it's want you want to do then there are people here who will try to help.

You need access to a press and the tooling common to those. Particularly a small size bearing splitter. I used a press once the guy not only didn't have any bearing splitters but he didn't know what they were. Don't know what he did on that press.

You need the output flange remover tool from Cycle Works and the measuring plate from them also and get a package of the assorted shims. With the ones in the bike now and the assortment you should have plenty. I also like to use the parallels in addition the the plate. And you will need a depth micrometer.

You may want to wait till you have it apart or just get all the bearings now. Ted Porter will sell you all of them and gaskets and seals and a few other things. But I don't know if we have the lower price yet on the shift kit in this country. It is being sold by MotoBins in England for less than I've seen it here. You can wait till you have it apart to see if you need the kit of course. Once you have it out it is recognizable by several parts that look different, particularly the pawl.

I don't know of anyway to tell for sure if your bike has the kit or not except to look at it. I did notice when I installed one the shift throws were longer but it's not something I measured or think anybody else has either. I think because you report there are false neutrals now it might be a good idea to assume you don't have the shift kit. The kit is supposed to help fix this problem, ain't it?

About the bearings; it is pretty standard to replace them all if you want a really fresh box but the front input shaft bearing is not always replaced. You can also take the path of just replacing the ones that feel ruff or loose and again the front input shaft bearing is usually left in place. It can be replaced but it is a proprietary and is only available from BMW. It is not a ball bearing but a needle bearing. I guess this is why it lasts longer.

Another thing about bearings. They are not the run of the mill generic bearings you might get from several sources. You will have to buy parts and bearings from suppliers that sell the right thing. All I remember about this is if we get into it the term "C-3" will be thrown around a lot. And some people will advise to only use "BMW" bearings. But if you stick to C-3 most will leave you alone.

Charlie

Looks like that speedo needs some help!

Charlie laid that one out pretty well. Working on these trannies isn't just about the expense of the tools, it's also something of an art. We're talking about tolerances that aren't easily measured, along with shims that might not be the same thickness at all points, variations in temperature that changes tolerances, compressability of gaskets, and on and on.

That's not to try to discourage you, just be aware these things aren't a walk in the park. Getting the tools is only the first hurdle.

The updated shifting mechanism has more defined and bigger peaks that help prevent the roller from hanging up between gears. I could tell by looking at the ramps which one it is.

The longer 5th and the 1000 kit - perfect match for the G/S.

You don't need it but you want it

Once you got it, you would not have it any other way.



I feel dirty, I'm gonna wash.

My ODO went last weekend was doing crazy things looping the loop but my speedo remained the same - that being ever optimistic.

Thanks Charlie, a very helpful post.
I guess this was the crux of what I getting at- wondering about going in there to change the 5th gear and while I'm there grabbing any other 'low hanging fruit'.

I've just read through largiader's, most of Duane's and all of Joergs pages on gearbox's and rebuilds.
Joergs was particularly helpful to me.

I suppose if I was going to do it, I'd just do it right and replace all the bearings (possibly excepting the input shaft bearing).
I've just made a phone call and have determined that if I want to I can borrow most (all?) of those specific tools required for rebuilding the box (the flange puller, the measuring plate, etc) that a friend and parts supplier has had for a while but doesn't really use (he outsources rebuilding of his gearboxes)
I can probably access a press if required and would try to track down an appropriate depth gauge to borrow.
Ie I would probably not have to buy or make any tools.

About bearings and stuff, yes, I would be sourcing all this from Motobins.

I've fixed the speedo already,
came to me like this, wet, rusted, seized and stripped...



and now, with a few parts from a donor R65 speedo and some bloody minded persistence and ingenuity repairing the other bits, it looks like this and is working perfectly (so far)

Thanks, I do appreciate the advice and the warnings. After reading through Joergs pages quite closely it all actually seems quite doable to me- not saying I'm confident I would get it right, just saying that nothing in the process scares me too much and I'd be willing to give it a go- especially as I could borrow those few specialty tools.
I very much enjoyed completely rebuilding my 4x4 transfer case. At first it was a bit overwhelming, but after a while I really got into it and enjoyed it like a big complicated metal jigsaw puzzle. Dealing with these sorts of things I really like and have a slightly better apptitude for compared to say anything auto electric:eek1

Will I do it? Eventually yes. I want to be able to deal with gearbox rebuilding myself WHEN it is required (as I plan on keeping an airhead for a long time, and I am not all that kind to my gearboxes).
Will I do it now for this purpose?... I'm not sure.
For starters I'm going to do up a pricing list for all the bits and bobs required and have a bit more of a think about it all.

Reading Duanes page on gearboxes has gotten me inspired to bench test my two spare gearboxes to see how they feel.
Anyway, thanks again,

P.S. No doubt I'd be doing a fair bit of this kind of thing during a gearbox rebuild- my projects tend to invade my life a little like that and the coffee table is where I get some of my best garage work done




and as I previewed this post I missed another one,

arrghh.. between you and Rucksta I am going to get into some serious trouble.
Do you have the 1000cc and the longer 5th? Tell me more?

Now there's a man who knows what he's talking about, spot on, well done, you've saved me the trouble!