• Welcome, Guest! We hope you enjoy the excellent technical knowledge, event information and discussions that the BMW MOA forum provides. Some forum content will be hidden from you if you remain logged out. If you want to view all content, please click the 'Log in' button above and enter your BMW MOA username and password.

    If you are not an MOA member, why not take the time to join the club, so you can enjoy posting on the forum, the BMW Owners News magazine, and all of the discounts and benefits the BMW MOA offers?

  • Beginning April 1st, and running through April 30th, there is a new 2024 BMW MOA Election discussion area within The Club section of the forum. Within this forum area is also a sticky post that provides the ground rules for participating in the Election forum area. Also, the candidates statements are provided. Please read before joining the conversation, because the rules are very specific to maintain civility.

    The Election forum is here: Election Forum

5 speed transmission

R100RTurbo

New member
The transmission is s/n ZSA079719:
a) regarding the output shaft circlip usage, anyway to know its in there other than a disassembly? (no issues or symptoms and clean magnet plus yoke rotates smoothly with no sounds)
b) what is a reasonable input shaft "free play", with regard the torsion spring and ramps built into the front gear and such? (again no symptoms/ problems but roughly 80 degrees rotation noted to a feel of contact).
Technical detail not immediately found in the better known sites and expert documents, so help appreciated.
LW
 
If I understand Snowbum's site, the "79719" seems to fall in the 1984 timeframe. He has yet to find any '84 transmissions that are missing a circlip.
 
There have been plenty of '84s without the circlip. You can't tell without disassembly.

The rotational play you mention isn't in the input shaft but rather in the gear dogs. If you have a broken input shaft spring, though, you will get more of it; I will try to remember to check a few of them this coming week to see what is normal. Normally the shaft has no play under hand pressure.
 
Anton -

Have you provided the specfics of 84s w/o ciclips to Snowbum? As you know, he has asked the Airhead community to provide these details and he will gladly publish on his website. It sure would be good to expand his information w/ yours.
 
Hand Pressure

There have been plenty of '84s without the circlip. You can't tell without disassembly.

The rotational play you mention isn't in the input shaft but rather in the gear dogs. If you have a broken input shaft spring, though, you will get more of it; I will try to remember to check a few of them this coming week to see what is normal. Normally the shaft has no play under hand pressure.

Thanks for the help Anton and Kurt.
The play that exists between the "dog ramps" is very free and without having the component apart to witness, certainly lends the impression of perhaps a short torsional spring. (do they loose tension?)
It is pretty much close to a quarter turn between obvious mechanical contact between those surfaces inside.
There is no previous or current metal on the magnet but pending your advice on comparative units, plus the random potential of no circlip residing within, I will be adding one more job to this winters list. I noted Bob's request for feedback (@ Snowbum) on these years of bike trannies in regards to the circlip, and judging by what is shaping up, will be able to offer one more "yea/ nay" to his records.
LW
 
Have you provided the specfics of 84s w/o ciclips to Snowbum?

Yes. I've only found one or two, but I've talked to others who have also found them. There aren't many, and they have circlip grooves but no circlip. Come to think of it, I might have just had another one in the last few weeks.

Anyway, I have a hard enough time keeping my own website up to date without worrying about someone else's!
 
Shaft Rotational Play

There have been plenty of '84s without the circlip. You can't tell without disassembly.

The rotational play you mention isn't in the input shaft but rather in the gear dogs. If you have a broken input shaft spring, though, you will get more of it; I will try to remember to check a few of them this coming week to see what is normal. Normally the shaft has no play under hand pressure.

r90s_shaft.jpg

Ignoring the worn condition of this borrowed photo of an input gear assembly (photo from Jorg's tutorial), it would "appear" the flat nature of the gear dogs have some room to rotate freely between the spring seat dog radius "ramps".
Shail's is just down the street, may drop by after work to see if he has a unit on the floor I can give a "twist".
LW
 
Under engine power, yes. Under normal hand pressure, no.

In first gear, 80? input shaft rotation matches what I see on a transmission I have here. It varies depending on the gear you are in.
 
That photo posted above is not accurate to my input shaft assembly, I took a look at one removed from a similar vintage transmission and concur with Anton's recommendations. The play I note is most likely the gear cogs which have generous slots to reside within when shifted.
Hence, the old adage "if it ain't broke then don't fix it" and I'll leave the box together at this time as it has no known issues and is removed for a spline lube and clutch rework** (wouldn't mind pulling it down perhaps next season but will budget for some fresh internal items so that I don't resort to the reusability philosophy so heavily).

** working with a couple of paddle disc's, one is a 3 puck arrangement, the other is a 4 puck on a softer ceramic material - and a test cell to confirm torque holding characteristics. I haven't gone far enough to post any detail on that yet but will.
 
Back
Top