BMW Gearbox help, please...?

[Enn]

I've got a 1981 BMW R100RS. The gearbox is 'clanking' when it's hot, goes away when I pull in the clutch and is noticeably getting worse. I'm hoping that someone on this forum can offer me some advice, and perhaps recommend a mechanic with specific experience with BMW's. As I live in the South Island, someone not too far away would be good. (I'm starting to look like my avatar!)

Cheers, Enn

[Paul in NZ]

You would have to ask someone more expert on BMW's but.... They have a certain reputation regarding gearbox's.. And it's not for endless reliability.. Bearings from memory.

I'd ring your nearest BMW dealer, I'll bet they have done a bunch of em..

Paul N

[dangerous]

Contact beemer89 hes just done his gear box up after blowing the arse out of it, he might be able to help.

[rudolph]

My old R90 got a bit clunkey when taking up drive then snaped all the flywheel bolts and bent the exhaust vealvs

[Motu]

The dreaded spline problem.

Where's Milky??

[Posh Tourer :P]

Splines (I assume you mean crown wheel) wouldn't be this. That is clanking and snatch on take off. Unless they are razor sharp maybe. Take the back wheel out and check how thick the drive splines are.
Other than that Milky'd have to consult.
Where in the SI are you?

[Motu]

I was thinking clutch splines Maarten.

[Ixion]

Eeek. Eeek.Eeek. Runs and hides. BMW gearboxes are always crap.s yours more crap than average? If so its the big strip down. Oh shit (sorry I'm pissed I'll post something more coherent 2mrw)

[Enn]

Ok, here goes, Bikes got 70,000 km on the clock, clutch works fine, takes up progressivly as the clutch is let out, no snatching or grabbing...
Few rumbles in the gearbox ,as it warms up starts to ''nack'' (nackered!)
Used a bit o wood as a stethiscope and can hear ''the nack- clack- noise the best arount the rear clutch rod boss...
hard to tell if it is coming from the front.....
No nastys in the oil small amount of grey fuzz on the magnetic bung , no feelable lumps or wires....
Havent checked the rear drive splines, but had a new rear tyrer fitted (cycle treads) and the chap did not say anything about it, but i gotta check any way...
So got a maintainance go over to do any way so nows the time.....
Ready for lotsa rides ... when i get time.

thanks all for the advise, it is appreciated.
Found a good BMW site www.motoren-israel.de or siebenrock lotsa BMW go goodies, makes ya want to do a lot of overtime tho......

[Enn]

Oh yeah i forgot to mention im in Greymouth sunshine capital of the coast......

[Kiwi]

Hi
try an other gear box oil - Castrol MTX 75W 140 - works in my R100GS pretty good

cheers
Kiwi

[Milky]

not too sure on the getting worse thing, but i hear that the pushrod for the clutch sits nside the hollow input shaft on the gearbox, and this often makes clicky noises as it rattles around in there when the clutch is not pulled in. Obviously goes away when the clutch is pulled in as there is force on the rod. 'tis possible that this is the noise that you are hearing. There is an adjuster on the lever on the back of the gearbox afaik, and re-setting this to give the right offset/movement range to the clutch is a possible solution. Is the noise just in neutral, or when in gear as well?

On the oil thing - EP90. Works a treat, and shouldnt be the cause of any troubles in that department

[Enn]

[. Is the noise just in neutral, or when in gear as well?

On the oil thing - EP90. Works a treat, and shouldnt be the cause of any troubles in that department[/QUOTE]


In neutral as well as in gear .. i think.. i get back to you on that one..
Thanks..

[Enn]

Ok put the bike on the centre stand and proped the rear wheel up, ran through the gears few rumbles but no clacking, only in neutral
Adjusted the clutch no change.
noted that the 'noise' stopped when the clutch lever on the g'box was 3/4 in towards th g'box.

Well heres an update,
Spent a couple of hours on the net and in paticular the ''airhead'' list & came up with a few replys on the same problem..... consensus was that 'it is normal for bmw r bikes to have this noise' & that the later models with the lighter flywheel and clutch assembly were the worst, bad carb sync makes it a lot louder.......also a clutch spline lube needed symptom.
So looks like ive got a bit of maintainance to be doing to eliminate some probable causes....worth checking out before ya start shelling out big bikkies for a g'box overhaul.. gives me hope yet!

[Paul in NZ]

OK.. I'll have a go at a sensible reply.

You did the right thing by getting on the airheads list. Someone there will be able to give you a more accurate diagnosis because I know shit all about BMW's other than I'd quite like an R90S.

If you look at my Moto Guzzi, it's roughly similar (except better looking and the owners are sexier) in this regard. Getting the carbs snyched is vital to achieving a decent ride. Naturally, being Italian the carbs have other ideas and in fact possesed by demons, always on a break, half pissed or trying to shag the battery.

When the bike is idling, the slightly uneven power pulses will cause all sorts of clanking and clonking in the drive train. Moto Guzzis have a flywheel that could be used on a mack truck in an effort to damp some of this out but it remains and is amplified IF the carbs are not right at idle.

This is especially true on older Moto Guzzis with shallow spline clutches (like mine) where everything tends to rattle about a bit.

Pulling the cluch handlebar lever in at idle will make a lot of this noise go away but will substitute a new noise (the intermeadiate plate rattling on the splines). This is pretty normal for bikes with dry clutches. A Ducati with a dry clutch sounds like a lawn mower sweeping up at a bolt factory after and earthquake.

Running the bike in gear on the main stand is not a good thing (on a Guzzi) as the drive shaft is at an extreme angle and often the cardan joint (U/J) will bang on the housing. Even if it doesn't, running the wheel without a load often makes some funny noises. Not so bad on older models with 5 dog gears but the later ones with 3 dogs can have a lot of back lash in the drive train and sound terminal in this situation.

OK.. So you expect noises, but how much is normal? Well thats hard (read impossible) for us to judge on the internet.

My plan would be to change the gearbox oil AND the rear drive oil into a clean container (like an ice cream one) and check for any debris. Bit's of hardening, bearing etc. If it's clean, bung in some fresh oil (of the recommended type) and then check your universal joint for wear. If thats OK, ride it carefully for a bit.

If the noises get any worse, pull the wretched thing out and get it rebuilt. It's a LOT cheaper to do this early than late.

Hope this helps.