Your understanding is correct. I've disconnected the driveshaft and everything looked good while I disconnected it but I couldn't really see in there because there is not much room. Once I'm able to take the swing arm out, I'll know more and could have found the source of my problem. Either way, I want to read up on the clutch because it's been pointed as the likely source of my issue so I want to understand it better. Since the transmission magnetic drain plug had a lot of metal shavings stuck to it, I think that it needs to be opened up and looked at. I appreciate the help I'm getting; thanks!
Update: The output flange is fine and the transmission is out. The transmission is shot; when I turn the output flange, the input shaft turns. If I hold the input shaft and continue to turn the output flange, I can feel it slipping in any gear. I'll be opening up the transmission and update the thread with pictures. The question now becomes what do I look for in a used transmission?
I would rebuild your exsiting tranny instead of buying someone elses problem. With slippage it can be the gears, the dog ears or the bearings or a combination thereof. I have had both of my transmissions rebuild and only replaced what was broken. It saves in $$$$. Is this something that you can't tackle then there are plenty of folks that can and do it reasonable.
Sending it out is most likely the route I'm going to be taking but I expect something to be broken inside which is going to raise the cost of an overhaul. I'll open it up first to see the damage. I looked in the airmail an only saw one place that advertises overhauls and charges $625 for the basics. What are the recommendations if I send it out?
Please post what you find in the broken 1974 5 speed transmission. The 1974 5 speeds are unique. And I do mean that to say they are one of a kind. !974 was the first year of the 5 speed transmission. It is the only year that ordinarily has the kick starter. That is found later on some GS or G/S bikes I think but for most the kick starter was dropped after 1974. It is recomended if you have a working kick starter on a 1974 trans that you not use it because it can break. There is a gear that wears and can break leaving the trans unworkable or the kick lever hanging down lower than it should be where it hits your left leg. Riders want their kick starter because they think a motorcycle should have a kick starter but this one is a poor prospect because of it's faults. The electric starter is much more reliable. But this is maybe not really the problem of this trans. I can't say I visualize something like what you describe. There is a cushion drive part of the input shaft. This may have something to do with this trans problem It is most likely that you will have to replace the trans with something from another year because of the uniqueness of the 1974 trans very few of the internal parts are available. The gears are one year only. The shift forks are one year only. This stuff was redesigned for the 1975 transmission. Most of the time it is cheaper to use another trans and have that rebuilt if needed than try to rebuild the 1974 trans. Long input shaft 5 speeds are 1974 thru 1980. If you eliminate the problem year of 1974 that leaves 6 years trans that you can use for replacement. The /5 4 speed will also work in your /6 bike but most riders don't want a 4 speed. It will work and others think this is fine. We've been over this numerous times. Maybe I can find the link to the discussion last week. It is pages and pages of argument over which year trans works in a /6 bike. It is a long input shaft 5 speed.
I'm definitely in the market for a new transmission; the gear on the input shaft is completely shredded; said gear is $100. I can get a trans that's already apart (so I know what I'm getting into) for that price; I'm thinking that probably going to be the best way out. I'll post pictures later; I have not been able to get the output shaft and its companion. I did use heat but no it just didn't want to come out.
Replacing gears gets confusing. Most of the gears for a '74 trans are not available. If you buy the small gear on the input, new, it will most likely be the 17.5 degree gear. The 15 degree gears that all 5 speeds were built with up until March of '82 are hard to find. If they say it's the right gear ask them what angle it is. If you need a lay shaft, the middle shaft has no individual parts it is sold as one unit, they are next to impossible to find. If you are going to try and fix this '74 trans then the donor trans must have everything you need I think. Possible. But probably more work than it's worth. Questionable high mileage trans are sold for $250 roughly. One with a better pedigree will run about $350. +
Motobins has some 15 degree gears (new) and some other shafts as well... http://www.motobins.co.uk/bmw-parts.php?model=R Series 2 valve Twin
It's really easy to spend good money on junk when it comes to these older gearboxes. If you're buying a used transmission that isn't known-good, at least make it a '77-on just to improve your odds. If your '74 trans just needs an input gear, that isn't such an expensive repair. The problem is, it's likely to need more than that. I suspect that anyone advertising rebuilt exchange prices isn't figuring actual repairs into the price. If you send in a transmission with toasted helicals, that's $400 in gears right there. If you can find someone who will eat that in a $625 rebuild, go for it!!
Motobin will sell you an overhauled transmission for $500 provided you turn yours in as a core as long as you have someone to handle mail in the UK. I kind of wish I hadn't opened mine up and just done an exchange; I can't do that now in good conscience. Unless it's a reputable shop that can take the hit because they run through many transmissions, I wouldn't trust a shop that gave a flat quote before they opened the box.
Even then, why subsidize repairs for other people? Shoot, I could send in a non-shift kit, non-X gear, bad helicals, blown output shaft, shot splines, rusty bearings 5-speed and get a perfect one back for the same $500 that fixes your broken pawl spring. Actually, I highly suspect I wouldn't be able to stretch the deal that far, even if I were in England.
