Final Drive Play

[Beemerman59]

I'm struggling to try and understand if I have a long term problem or not with my FD. I have 16K on an '08 GSA and the FD has the well documented 6 and 12 oclock play in it which I'm guessing is at the 1mm mark there or thereabouts. I had it dealer checked a few months ago when the bike was in warranty but in retrospect I wish I had requested a formal check rather than a mechanic looking at it in the carpark. I was told all was fine.

Three months on there's no difference - same amount of play as far as I can tell, there's no bad noises coming from the FD when the wheel is rotated and there's no movement when checking the sideways play i.e 9 and 3 o'clock positions. There are no oil leaks anywhere. I have recently got hold of the recommended oil and will change the oil to see if there's anything showing in the old oil.

My question is, whatever it is thats allowing the 1mm of play which say for argument is fine and within spec, will this get any worse over time? Is it caused by wear or is it just a manufacturing tolerance. I'm sort of assuming that if the oil comes out nice and clean with no swarf or debris, then the 1mm movement I have will just stay 1mm for the life of the FD. From reading all the posts I can on here, there seem to be multiple issues with the FD which have required replacement and I'm just trying to understand whether I have one of these issues which may overtime become terminal.

The other potential problem that keeps nagging me is what the MOT tester is going to say when they feel the 1mm movement. Will they believe me if I tell them it's OK as its within BMW spec when cold? Has anyone experienced that conversation with an MOT tester?

 

[Slowdown]

Has anyone experienced that conversation with an MOT tester?

Yep - and his reply was 'They all do that mate - I do one a week and they're all the same - Don't worry about it.

And get a lamb feeding syringe of a farmer to do the FD oild change with - it makes it really easy. The first time I changed the oil what came out was black and stank. This time it was the same colour coming out as when it went in(light golden) and had no bits in it. The sensor didn't have any bits on it either - is the later model sensor not magnetic?

 

[GSmonkey]

Do you get the same movement if you apply the rear brake? If not, you know it's the paralever bearings and not the big ones in the bevel box.

 

[Spout]

Remember, the large nearside rear bearing doesn't run in the FD oil, so oil condition can't be used to assess this bearings condition.

 

[somclan]

MIne is the exact same

[By chance during a routine check on mine yesterday I discovered the exact same symtons... Will be watching this thread..

 

[misterman]

Got the same play with mine GS 2009 13k, took it to the dealer said it was in tolerances they all do that etc.
Said there was a slight rumble noise, it is booked in next week to change bearing.
Don't no which bearing it is.
Have checked wheel at regular intervals since i got it, did not have play before.

 

[Beemerman59]

The movement is the same with the rear brake applied. The disk carrier bolts are all tight as well. So which bearing is it that has this tolerance, is it a wear item and does it sit in FD oil?

I have the service manual but can't work out from any of the diagrams which item is causing this play. I'm not worried about it I just want to understand which bearing it is and whether its going to get any worse over the next 3 years/30K miles I'm planning to add to the existing 2 years/16K miles.

Many thanks for the words of wisdom.

 

[RickG]

The rear axle/crownwheel is supported by two bearings. On the wheel side is a large sealed ball bearing and on the other a roller bearing, the inner track of which is part of the crownwheel, not a seperate part. The latter bearing runs in FD oil.

As you've probably read in all the posts on the subject, some bikes have the play others don't. Provided your play is not in the hub carrier splines, 1mm at the rim seems not to be a problem.

I'd suspect the play was in the roller bearing rather than the ball, but that's a guess. As to it being a 'wear item' well I guess all bearings are, but how fast is of course the issue. If you mean can it be replaced, then the answer is yes, but only by buying a new crownwheel which after shimming and so on to get the mesh with the pinion correct is probably the price of a new FD.

In my experience the bearings that wear most are the ones that support the pinion shaft and not the wheel. Even when I have found these to be shot, no play has developed at the wheel, though once they start to fail all the clag can't do the one unsealed open wheel bearing any good - one more reason to do regular oil changes, if only to check for swarf.

 

[Beemerman59]

The rear axle/crownwheel is supported by two bearings. On the wheel side is a large sealed ball bearing and on the other a roller bearing, the inner track of which is part of the crownwheel, not a seperate part. The latter bearing runs in FD oil.

As you've probably read in all the posts on the subject, some bikes have the play others don't. Provided your play is not in the hub carrier splines, 1mm at the rim seems not to be a problem.

I'd suspect the play was in the roller bearing rather than the ball, but that's a guess. As to it being a 'wear item' well I guess all bearings are, but how fast is of course the issue. If you mean can it be replaced, then the answer is yes, but only by buying a new crownwheel which after shimming and so on to get the mesh with the pinion correct is probably the price of a new FD.

In my experience the bearings that wear most are the ones that support the pinion shaft and not the wheel. Even when I have found these to be shot, no play has developed at the wheel, though once they start to fail all the clag can't do the one unsealed open wheel bearing any good - one more reason to do regular oil changes, if only to check for swarf.

Thanks for this info - much appreciated. Next stage is to change the FD oil and as long as thats cleanish I will just do it every 6K with the engine oil.

 

[Beemerman59]

Just changed the FD oil which came out a 6 on a grey scale if 10 was black. Just a fine swarf and no particles of note but only measured 140ml that came out. The magnetic plug had a small amount of swarf with the consistency of moly grease. 180ml of Castrols finest gone back in so I will change every 6K from now on.

 

[obewan]

HELP please

Chaps, my 04 GS is in for new bearings right now. Just had a call to say the who diff needs to be rellaced as the wear in the bearings has also worn the pinnion. that £1000 thank you sir, on a 30k model

Then a call to say fear not. On the older GS1200 models there is a shim between the main crown bearing and the pinnion and a smaller bearing, and the garage believes that these are Ok it is only the crown bearing that needs replacing.

There is some movement in the shim but the movement is fluid, with no descernable notches or the like.

Does this accord with others knowledge. Please lift the dread and tell me all will be ok with just the crown bearings replaced. Got a Nurburg ring trip coming up

 

[patzx12]

Chaps, my 04 GS is in for new bearings right now. Just had a call to say the who diff needs to be rellaced as the wear in the bearings has also worn the pinnion. that £1000 thank you sir, on a 30k model

Then a call to say fear not. On the older GS1200 models there is a shim between the main crown bearing and the pinnion and a smaller bearing, and the garage believes that these are Ok it is only the crown bearing that needs replacing.

There is some movement in the shim but the movement is fluid, with no descernable notches or the like.

Does this accord with others knowledge. Please lift the dread and tell me all will be ok with just the crown bearings replaced. Got a Nurburg ring trip coming up

If you are in that far change the whole lot, bearings and seals.

 

[RickG]

Maybe there's a few things lost in translation as it seems a bit worrying if at one moment the pinion is supected to be worn, and then it isn't, and a shim will somehow solve that. Even if they are referring to the pinion bearings they aren't shimmed in a way that will allow play to be taken out. If the pinion shaft wiggles from side to side they are shot and will need replacing.

I agree with patzx12 100% that it's worth changing all bearings (2 x pinion and large sealed ball bearing on crownwheel while the thing is in bits as getting it in bits is the hardest job.

Call me cynical, but is the real situation that the garage hasn't actually got the kit to change the pinion bearings (check pat's thread on doing this job, it's a total and absolute sod) but can manage the large crownwheel bearing? Hence what they were offering is either a new FD ('solves' pinion bearing problem) or new crownwheel bearing (it's all they can do). May be worth a bit of investigation as it's difficult to tease out the story from your description, sorry.

Hope it gets sorted before your trip