1200gs final drive

[mikeyboy]

hi all,i was servicing my gs recently ,when i changed the final drive oil there were metal shavings in the oil.on reading the many posts on this issue i decided to strip the unit to inspect it in more detail.i am a motor engineer and have been in the industry for 26 years.once the unit was partially dismantled it became apparant that the pinion nose bearing has slight wear.bmw has made the final disassemby of the unit very difficult but reading other threads ,not impossible,i have some very good engineering contacts and have handed the unit over to a good mate who is going to investigage the possibilitys of reconditioning the units.my question really is. is there a market for us to tool up to offer this service????.does anyone already do this??..second hand drives would appear to be a waste of money given that so many owners have experianced problems. one final thing ,i would encourage owners to change the oil on these units every service.

 

[harry]

That really depends on the cost of tooling up. As the 12's get older I think there would be demand for the service.

Good luck with it, should you go ahead

and welcome to the site BTW

 

[Ash]

I agree with the most honarable member above

 

[elefantman]

It amazes me that none of the aftermarket big players offer an upgraded alternative to the standard unit,there would appear to be a market for it

 

[Spout]

It amazes me that none of the aftermarket big players offer an upgraded alternative to the standard unit,there would appear to be a market for it

 

[elefantman]

I'd buy one of them tomorrow,you come up with a kit and i'll write the cheque,
how do they do it on car engined bikes like the boss hoss?

 

[Pukmeister]

I'm a former marine engineer and toolmaker, I tried to make my own tooling to undo the castellated input pinion nut but couldn't make a strong enough fixture to hold the casting whilst I undid the nut in my home garage vice.

I believe that PatZX12 ended up bolting his final drive down to a milling machine bed to undo his, and it was still a bit of a mission to undo it.

Your mate better have some good tooling and a very strong vice and breaker bar/scaffold pole to hand. If he can strip and rebuild these units he will be in line to earn himself a few bob now and then as word gets around and owners come asking. Be aware that not all final drive internal parts are interchangeable between early and late R1200GS/A bikes so be careful when ordering replacement components.

 

[Chris Terry]

Isn't that one of those grease flinging things they used to fit to old bikes?

 

[jpooch00]

I'd buy one of them tomorrow,you come up with a kit and i'll write the cheque,
how do they do it on car engined bikes like the boss hoss?

Believe it or not, they use a toothed belt, like a Harley!

 

[midnitemo]

yeah 350 bhp through a lassie band

Believe it or not, they use a toothed belt, like a Harley!

Seems to work though...mate just bought one(20k for a 10 yr old one...wtf!!!!) not sure it'd take my hamfisted launches though
maybe that's why he's so reluctant to give me a go!

 

[elefantman]

how hard would it be for some engineering type to make an adapter to allow a chain or belt conversion with a swing arm

 

[mikeyboy]

update

it would appear that the castlated nut securing the pinion bearing is the main problem.im not prepared to damage the unit three weeks before my italy trip so i have just replaced the crownwheel bearings for the time being.im going to try and get hold of some old units to play around with!!I WILL NOT BE DEFEATED. mike.

 

[jpooch00]

how hard would it be for some engineering type to make an adapter to allow a chain or belt conversion with a swing arm

The problem is that you'd still have to have a right-angle drive to run the chain or belt. Plus, you'd still have the clutch and tranny issues, leaky seals, dropped valves, electrical glitches, fueling problems, warped rotors, corrosion, etc. etc. etc. to deal with.

 

[Demongroover]

I'mgoing to try and get hold of some old units to play around with!!I WILL NOT BE DEFEATED. mike.

I was thinking the same myself but you are far more qualified than me by the sounds of it!

I'll buy one if there is an exchange reconditioning service!

It seems the FD unit / bearings are a consumable cost no one can afford at the mo! We need an alternative!

 

[ebbo]

it would appear that the castlated nut securing the pinion bearing is the main problem.im not prepared to damage the unit three weeks before my italy trip so i have just replaced the crownwheel bearings for the time being.im going to try and get hold of some old units to play around with!!I WILL NOT BE DEFEATED. mike.

Read this thread Micky, right up your street mate:
http://www.ukgser.com/forums/showthread.php?t=166875&highlight=bearing+drive
Good luck

 

[Steptoe]

.im going to try and get hold of some old units to play around with!!I WILL NOT BE DEFEATED. mike.

That's my plan.
I have an enginering man who rebuilds all sorts of un-rebuildable units but so far i've not been able to get any failed units.

BUT, if the design is flawed to start with it won't be a cure, just a fix until the next time it fails.

 

[Slowdown]

...
BUT, if the design is flawed to start with.....

But that's the rub, isn't it - not all final drives fail. Some bikes eat them as if they were Jaffa Cakes and some bikes don't. And there's some in between.

Does anyone know if it's just cheap bearings that may be the cause? Or is it more likely to be what Steptoe's speculating?

 

[KAYCEE]

I know this might sound a bit strange, but could the problem with the final drives relate to the bending stresses that are induced through the unit because of the single sided swingarm arrangement on the GS (and othe BM's)?

And, that if this is the case, could there be a way of converting the swing arm to be two sided, thus giving the wheel and hence the FD more support?

Sounds like an expensive solution, but just thinking out the box.

Kaycee

 

[Steptoe]

I know this might sound a bit strange, but could the problem with the final drives relate to the bending stresses that are induced through the unit because of the single sided swingarm arrangement on the GS (and othe BM's)?

BMW have used a similier single sided set up since the K series bikes in 1984, and they rarely ever gave these sort of problems.

It maybe a quality control issue wherever the final drive units are assembled

 

[skywalker]

More like accountants intervening