Final drive change - warmed up or not?

BMW recommends changing the fd oil on a warm bike. Doing oil changes warmed up usually makes sense because the oil is thinner and runs out more easily. For the fd it also means having to deal with the hot exhaust though.

I am wondering if one could just warm up the fd with a hair dryer to get the oil to thin.

Last time I changed mine I had some of that black, greasy stuff come out that many reported on here also. Wouldn't it be better to allow that to collect on the bottom before draining, i.e. not drain the oil after riding but after having the bike sit?

Maybe it all doesn't make such a big difference. Thoughts?

Hair dryer heats from the outside in and won't heat up the housing enough to warm much more than the outer housing. Running the bike heats the oil up from the inside do to friction of the gears.

This may be contrary to what others do, but you could do it from cold. Pull the plug let it drain, and go off and do something for 30 minutes, or let it drain overnight if you want. My thoughts are to change cold and let the oil and debris settle, instead of mixing it up by heating it up.

If I saw black stuff coming out of my rear drive - I'd assume this is the first time it was changed.

That's what is reported coming out at the 600 mile oil change. I've heard of a bit of black stuff showing up at the 2nd change - but after that change it should all be gone.

If it suddenly reappears - that's a sign a grease seal on the pinion bearing has gone bad, and the grease is washing out of the bearing (bad thing..) That's the only sealed bearing AFAIK that is exposed to the oil (the needle bearing at the outside axle end isn't sealed, and the big bearing at the inside axle mounting is outside the drive.

Oh - back to what to do?

IF I saw black stuff coming out (say it was the first oil change) - I'd fill the drive, run it until it's warm (you can run it right on the centerstand with the wheel off..) then drain it and fill again. I'd repeat this until no evidence of black stuff came out with the oil being drained. My WAG - this will just take a 2nd draining to take care of.

Also - the hot exhaust isn't a big deal. The rear muffler actually doesn't get all that hot, and in my experience, cools down rather quickly.. where the mass of the rear drive helps it retain heat, especially heat generated by having the gears inside warm.

I ride my 05 to warm it up, but by the time I get it on the stand, strapped, remove the exhaust and wheel, drop the drive, it is certainly not "hot" anymore. Once draining, I like Richard leave it drain while I change my tires, so that's a good hour or more and it does drain well and completely in that time.

So ride and drain shall be it. I also plan on changing my tire with it. Thanks for the responses.

The only time I changed the fd oil was at 12k, a little more than a year ago. Whether that was the first time or not I can't know for sure, although the previous owner told me it was done at 600. When I changed it there were flakes of that black stuff in the oil. Not enough to freak, but enough to see with the naked eye. It didn't look like something that would suggest a failure, and I decided to not worry about it.

Hey Harald, I just noticed it was you. Hope all is going well.

Rob

The primary idea behind changing oils hot is that you want the oil to have been freshly circulated so that any debris contaminants that might settle out after some period will still be insuspension (and thus will come out of the drain).

Yes, the thinner oil comes out easier, but the difference is amount as compared to cold oil is trival if you give the oil enough time to drain completely -- point is, oil drain quantity is not a reason to get the oil hot.

Getting burned in order to get that last bit of contamination out of what is already a pretty clean environment never made any sense to me. My suggestion:

Warm up the bike by riding it to get the tranny and FD fluids to fully circulate (not just standing idling, which only heats the engine oil). When the fill and drain plugs are accessible without danger of burning yourself, drain the oil and call it a day. The amount of crud removed from freshly stirred and still warm oil will be just about the same as from freshly stirred and painfully hot oil.

Thanks for all the suggestions. I did ride the bike a bit before changing the oil, and I had no more of the black, greasy flakes coming out. Given that it is the cool season, the exhaust was touchable with a towel after removing the rear caliper and loosening all other bolts.
I also changed my rear tire, but that's a different story altogether. First time doing it with a new Cycle Hill tool...

deilenberger said:

If it suddenly reappears - that's a sign a grease seal on the pinion bearing has gone bad, and the grease is washing out of the bearing (bad thing..) That's the only sealed bearing AFAIK that is exposed to the oil (the needle bearing at the outside axle end isn't sealed, and the big bearing at the inside axle mounting is outside the drive.

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Does anybody besides me notice that after a ride of several miles or more, the rear rim always has a film of black grease/oil on it? Not a lot, just a slight film that easily cleans off. Is this normal or do I possibly have a seal failing?

Tom
R1200RT

thundley said:

Does anybody besides me notice that after a ride of several miles or more, the rear rim always has a film of black grease/oil on it? Not a lot, just a slight film that easily cleans off. Is this normal or do I possibly have a seal failing?

Tom
R1200RT

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OIl/grease would be unusual.

Black dust from the rear brake pads, however, would not. This dust has a fine feel, like graphite lubricant -- easy to mistake for oil.

I don't know if my rear has more of the 'film' than the front, but no it is not unusual if it fits the description Mark gave above.

Last year we were in British Columbia, camping. One morning when I got up I thought I had a final drive leak. The wheel had what looked like an oily puddle on it. Upon further inspection I discovered that the puddle was composed of a fair accumulation of brake dust and a very heavy dew. I cleaned the wheel up and had no further concern about a leak.

It sure did look like gear oil with moly in it.

thundley said:

Does anybody besides me notice that after a ride of several miles or more, the rear rim always has a film of black grease/oil on it? Not a lot, just a slight film that easily cleans off. Is this normal or do I possibly have a seal failing?

Tom
R1200RT

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Just make sure it's not the "dust" that's produced when the splined wheel flange wears against the axle tube. To be sure, I'd check for play in the rear wheel: bike on centre stand, then grab at 9:00 o'clock and 3:00 o'clock and give a wiggle, then repeat at 12:00 o'clock and 6:00 o'clock. The first indication I got when my wheel flange was disintegrating was when I noticed what looked like brake dust appearing on my rear wheel, then confirmed with the noticeable play in the rear wheel. The fix at the time (summer 2007) was a complete new final drive, along with rear brake rotor and lug bolts. I wouldn't freak out, but I would check. I have 100,000+ kms on my R12RT and I really don't get much in the way of brake dust on my rear wheel. The"dust" from the wheel flange was almost black and was quite noticeable.

I generally drain my fd and engine oil in mid to late November and let it drain/drip until May when I put in fresh oil and get it ready to ride.

That's probably enough time!

thundley said:

Does anybody besides me notice that after a ride of several miles or more, the rear rim always has a film of black grease/oil on it? Not a lot, just a slight film that easily cleans off. Is this normal or do I possibly have a seal failing?

Tom
R1200RT

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Yes, I notice that also, but I think one would see an exit point somewhere if there was a leak. There is the thought of brake dust, but that would indicate a lot of brake wear. I think it may mostly be road dust.

Whenever I ride on a gravel road I have lots of dust on the rear rim, very little on the front. It seems that whatever the front wheel kicks up sticks to the rear. In normal driving that should include whatever rubs off the front tire and the road. Rubber and asphalt both include oils, hence the greasy film.

One comment on the brake dust (which is also tied into rather rapid wear of the rear pads..)

IF you see a lot more brake dust on the rear wheel then the front on a hexhead with linked brakes (and you're using the brakes as designed - primarily front lever only) - that's not normal. And if your pads wear out rapidly - that's not normal (I was getting 15k miles out of a set..)

I had both on my R12R.. and I noted a few local club members with hexheads also had the same. Another clue to abnormal behavior is a very hot rotor when you haven't been using the brakes a lot.

The cause - the sliding caliper on the rear brake isn't sliding as easily as it should and causing the pads to drag on the rotor.

Fix is pretty simple. Remove the pads so you can slide the caliper back/forth (or do this as I did when changing pads) - then put a tiny dab of high-temperature grease on the pins the caliper slides on (which are under the little rubber accordian like boots), and slide it back/forth until the grease is well distributed. You want to have a barely visible coating on the pins.

Reassemble - and you'll find the brake dust now is the same or less then the front rim, and the rotor no longer is cooking (and that helps keep the rear drive cooler.)

Oh - one additional comment - the bikes seem to come this way from the factory. A club member's brand new R12R had a rotor so hot it burned my hand when I brushed against it. The bike had just come from it's 600 mile service... apparently the vendor for the rear caliper assembly isn't greasing the pins correctly (there is a specific grease made for this for BMW cars..)

With clean rear-rim in NJ... and the pads I put in at 30k still look almost brand new at 45k..

deilenberger said:

Fix is pretty simple...

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Is this only an issue with the rear or should one apply grease at the front also?

hjsbmw said:

Is this only an issue with the rear or should one apply grease at the front also?

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The front doesn't use a sliding caliper design, it uses opposed pistons - no place to put any grease..