R100GS gearbox endfloat

[tatters]

Just finished rebuilding the gearbox on my 1992 R100GSPD, new bearings/seals plus HPN lower 1st and higher 5th.

The closest l could get the endfloat on the three shafts was 0.08/0.12/0.15mm after many attempts and pulling my hair out trying to get around 0.05mm the bike runs fine with no nosies and gear changes are smooth would this excess clearance cause any issues or serousily shorten the life of the gearbox?

[FUTURE]

Really dumb question rleated to the topic. What is end float??? I have never heard of this till I bought a BMW myself and still don't understand what it is...

[BMurr]

My understanding of endfloat and the need to measure it is this- when you put the shaft and bearing back in the housing ( i.e. when you put the box back together)there will be a small gap between the bearing and the housing, if left as a gap the bearing can try to move into that gap when under load and put a strain on the bearing in a sideways motion thus damaging the bearing. A shim is a small piece of metal shaped like a disk which is used to fill that gap and thus preveent the bearing from makming that very undesirable movement. Only problem is that you don't see that gap as it is only until after assembly that the gap exists and then it is inside your gearbox invisible to yourself, so you have to estiumate it using a precisely measured plate which bolts on in place of the housing. This plate has holes going right throough it to accomodate the bearings, by using the measured thickness of the plate and by measuring how far beyond the plate the bearings will extend it is possible to ascertain what thickness of a shim you will need to fill the gap between the bearing and the housing in your final assembly.

Thats my understanding of it, I may be wrong as I am no expert and have never actually carried out this procedure.

[FUTURE]

Ok... I think... Thanks for that.... My gearbox was overhauled just before i bought the bike so hopefully I wont need to check any of this fro some time to come.

[dc lindberg]

Do you have the propper tools?...

There is just about no way less you have the BMW plate for axial play adjustment... Red-neck plates can be made from gearbox rear-end-covers.
Motorworks in England used to sell such - perhaps they still do.


IF you get the play too tight... you will need a new gearboxhouse...

If too loose is not as bad though, but wear will be more rappid....


IF one of the bearings breaks... the gearbox can litterally explode... Oak Oshlen have written about this, and an aquaintance of mine have experienced it first hand. When it explode it can rip off the lower leg on the side it bursts on.

[gsworkshop]

Better too loose than too tight.
A setting of 0.05mm is not really possible but to get the measurement between 0.05 and 0.1 is what you ideally should achieve. If the box is back together and the biggest gap is not more than 0.15mm I would leave it. A larger gap will most probably have a bigger influence on the shifting quality than bearing wear as the shafts can now migrate more freely forward and back.
Have you added the gasket thickness in your calculation?
I have found gearboxes with the end-float of over 0.3mm with no obvious damage caused by this but if even just slightly preloaded the bearings will start to wear excessive within the first 1000km.

Exploding gearboxes is not that dramatic but it does wreck havoc with the insides, shafts and gears, and almost always damages the gearbox cover. Repairs can be astronomical, so it is safer to have the gearbox overhauled before this appears. Check for metal filings on the magnetic pickup on the sump plug. Fine fibers that leaves your fingers dark grey and feels silky when you rub it between your fingers is normal but if you see and feel shiny flakes when rubbing the material on the magnetic plug between your fingers you can be assured that a bearing is on its way and it will be safe to say you should have it attended to in the near future.
You can also get a clear indication by turning the back wheel when on the centre stand and the motor switched of. A nasty rumbling noise that progressively gets worse when checked regularly is also a sure sign that the bearings is busy failing. Just make sure this rumbling is not part of the final drive which will mean you might have to service that instead.