Gearbox

Dibbles

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I had the bearings replaced in the gearbox of my GS 100 a couple of years ago, about 25,000 kms ago (what ever that is in miles) and now they're gone again. The oil was changed twice or three times over that mileage using synthetic SAE 90 I think.
Why have they gone again so quickly?
Is it something I done or didn't do??
Surely they should last more than 25.000 kms.
 
Dibbles said:
I had the bearings replaced in the gearbox of my GS 100 a couple of years ago, about 25,000 kms ago (what ever that is in miles) and now they're gone again. The oil was changed twice or three times over that mileage using synthetic SAE 90 I think.
Why have they gone again so quickly?
Is it something I done or didn't do??
.
Click to expand...

You think?! Ewe'd better be certain of what grade you put it there! Using engine oil there is a get you home measure ... not somethin for 25,000 kms.

And yes a gearbox should go for many time 25,000 kms before needing overhaul. Does yours have the circlip installed on the output shaft? A few production years did not have that circlip ... the people who did the gearbox would be aware of it.
 
I think it was changed two or three times, I'm certain of the SAE 90, it's synthetic gear oil. I don't know about the circlip on the output shaft.
 
G/B

..no need for synthetic if changed regularly, but s/be SAE 90 GL5 for Summer, SAE 75/90 GL5 for Winter.
 
If the bearings were changed and you've kept on top of the oil with the right grade could be a failure to ensure correct end float on re-assembly of the box. The boxes are a little basic and over engineered but do need to be set up correctly.
 
I have ordered a new set of 5 bearings from a German tuning company, are these new ones on sale any different from the original bearings for the 81-84 models or am I being ignorant of the fact? :confused:
 
Look HERE post number 25 gives you the bearing sizes - aren't i good to you lot :D
 
End Float.

Would the lack of / excessive end float make the bearings eat themselves.
The last time this was done, the output shaft front bearing had eaten it's balls (they were almost square).

Maybe the best bet would be a exchange box?
 
Simple answer is yes, lack of any float could axially load the bearings and could cause rapid wear. Too much float could lead to vibration and same end result. Wrong amount of float would almost always lead to higher noise levels. Tolerances are always there for a reason. The box needs to be properly set up on assembly.
 
End float & bearings

Looser endfloat will be less harmful to the bearings than being to tight but it make sence to have this set properly.

Very important, big notice: BMW have got a SPECIAL bearing fitted to the front of the output shaft. This is the bearing that normaly fail in the gearbox and can cuase expensive damage to the box.
This bearing is a standard size bearing and can be bought from any bearing dealer but it will not have the specialy shaped inner race to aid the fitting of the circlip and it also will not be processed to be harder and smoother to give a longer life. I suggest that you get this bearing from the BMW dealers only and to check that the output shaft does have a groove for the circlip (as BMW thought this was not importand and mistakenly have stopped fitting this circlip for a number of years.) otherwise have this machined by an engineering co.
the part no. is 23 121 338 795
 
Got me bike with new gearbox back last night. I had the same guy build it as before. The front output shaft bearing was fooked again.
He thinks that oil baffles may have caused problems since last re-build. When he took it apart he discovered that one of these baffles was not where it was supposed to be. but needless to say it wasn't swimming about at the
bottom either.
So I'm hoping for a long service interval between gearbox rebuilds.
 
Hi Nud1e.
He's a guy from Warrenpoint in Co. Down.
His name is Francie Burns.
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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