82 5 Speed Trans post Mortem

[Ray from Indiana]

I originally mis-posted this under "BMW Motorcycles" so re-posting here


Well I got my gears ( 1982 5 speed ) cleaned for inspection. Its not good. Can't stick my bearings on just yet.

The input gear is buggered with pitting which from what I understand is typical for an 80s 5-speed. The mating layshaft
gear is less pitted but is still slightly pitted all the same.

Now Moto Bins sells the 5th gear for the layshaft. The question is, can this gear be removed with a hydraulic press or is it heat shrunk on the shaft? I really should ask the people selling the gear shouldn't I.

Just wanted to ask anyone who has fixed such a problem. I know the standard answer would be to replace the layshaft.
But hey, I only paid $1k for this bike 10 years ago.

[Toga]

Hi Ray,

When my 82RS was done the first time, I was present and remember all gears were heat treated then pressed to fit... I dont recall how they were removed to be honest.
Definately get the suppliers recomendations imo.

Cheers
Joe

[Ray from Indiana]

Well Moto Bins says just use a hydraulic press for off and on. I have a press but I haven't taken a decision ($300 in new gears required ) on my course of action. Thanks for the reply.

[Duane Ausherman]

I am always a bit nervous using a press. After doing a job many times I kind of know the pressure required and can then relax.

Just before you press it on, there is nothing wrong with freezing the shaft and heating up the gear to boiling temps. If the set up doesn't allow one to move quickly, then it is a waste of time.

[Ray from Indiana]

The stored potential energy in presses is something that makes me anxious too. Not worth dying over a trans.

here's a pic of the gear that mates the input for 5th gear, with more minor pitting.

[URL=http://s1313.photobucket.com/user/ ... .jpg[/img][/url]

[DonW]

Two things-

I used a press (by myself) for the first time recently. Pressed off, and then back on, gear sets and bearings on 3 transmissions. Had seen others do it in the past. It was absolutely no problem. Go slow, make 3x sure everything is lined up, and think before hand how far things are going to move so you'll have adequate clearance. We used various metal blocks, and regular old impact sockets to "push" and "hold".

Second thought- I will never rebuild a transmission again. For $5-600 you can buy a good used one, and even if it only lasts 30-40K miles, it's a better deal than a long challenging fiddly job that you're never quite sure is right.

BTW, I have an excellent tranny from a '82 R65- I replaced the gears with newer "x" gears from a '92 box, but it has the older circlip style shafts and older shift cams... PM me if interested.

Don

[esman100]

On my screen the gear looks very serviceable. If it's just minor surface pits I would clean it up an reuse it.

[Jean]

I agree with esman100 as far as I can see. How long did the bike sit before you bought it? looks like either the oil wasn't right or it had water in. Be sure the oil you put back is the right sort for a gearbox. Maybe something with a moly additive, but it should be identified as "extra pressure" to protect the teeth.

[Ray from Indiana]

The pitting is worse under the eyeball than the picture shows.

Near as I can tell this bike sat for about 5 years unused before I bought it 10 years ago. Its only got 48k miles on it. yeah your math is right, I don't ride it very much

This pitting is also not due to corrosion and I doubt it was due to lubrication problems-at least for the gear faces, its due to misalignment of the shafts ( bad bearings which could have failed early due to improper lube by PO ). How do I know this? I've seen it on industrial gearboxes that were run with bearings going bad far beyond our recommendation based on vibration analysis....most times on helical gears the bearings led to mislignment and tooth interference---> resulting in gear face pitting.

Ive decided not to use that gear on the layshaft

[Major Softie]

I don't doubt your knowledge about gears in general is superior to most all of us, but don't discount people with specific experience with this gearbox. I'm sure the industrial applications you are experienced with dealt with many times the torque, as well as many many times the revolutions between servicing.

Nothing wrong with making sure you're doing it right, but you may be overdoing it just a bit (not that there's anything wrong with that).



...apologies to Seinfeld...