The inside of my FD

patzx12 · Nov 28, 2008

06 GSA 17k miles.
this is what it looks like inside the FD.
All looks well but I can feel some play in the small pinion gear, it also feels whiney when I spin it.
I will be removing this once I machine up a special tool for removing the castle nut.

ebbo · Nov 28, 2008

Very interesting! any problems getting it apart this far?

Big Lee · Nov 28, 2008

Very interesting indeed :thumb2

Why have you stripped it down? What parts are you replacing?

Cheers

Lee

parkys100 · Nov 28, 2008

I would be intrested to know how you split the unit apart and rebuild just for future reference!

Pukmeister · Nov 29, 2008

Nice work Pat.

Any notable signs of wear eg lip seal scoring, crownwheel/pinion meshing wear marks, bearing play ?

Are you refitting the original shim(s) after replacing seals and/or bearings, or do you need to completely reshim things to set the crownwheel/pinion meshing ?

How difficult was it to get the rear disk carrier off the splines ? (any heat required ??)

I reckon you could make a few quid once you have made the required tooling, by repairing FD units by return of post. There was a lack of dealer support on this component, they seem to replace rather than repair these items and there is no shortage of concerned owners who have experienced FD problems (myself included).

patzx12 · Nov 29, 2008

No problem stripping the unit, I am an engineer but it is still an easy job.
Quite easy to pull off the disc carrier I made up a puller but you can buy bearing pullers.
I heated up the aluminium housing with a heat gun before knocking out the bearing.
Non of the bearings are worn but I will be replacing anyway. I think the problem with mine is the small pinion bearings.
ADVICE:
-Never power wash the rear of the bike.
-If you are changing the oil, give the pinion shaft a wiggle and see if there is any play. Change the RH seal at the same time it,s an easy job just remove the snap ring and remove the seal with a screwdriver or screw in some self tapping screws it pulls out easily.

Pukmeister · Nov 29, 2008

I look forward to the rebuild report. :thumb2

Any chance of knowing prices for the replacement parts required ??

bmwrich58 · Nov 29, 2008

Since you have the whole assembly apart,can you see or find any way the rear drive assembly breaths/vents itself??

patzx12 · Nov 29, 2008

I will have a look.

wilbjr21 · Nov 29, 2008

That's over and above something I would tackle myself ...... but very interesting. I'll heed your advice about the power washer. This is the second time I've seen this advice this week.

Old Man · Nov 30, 2008

Can I show my ignorance and ask why not use a power washer? Is it to stop water being forced into the FD?

patzx12 · Nov 30, 2008

Old Man said:
Can I show my ignorance and ask why not use a power washer? Is it to stop water being forced into the FD?

Hi, it's just my opinion but why subject the seals to high pressure force of any kind.

patzx12 · Dec 2, 2008

Finally got the pinion shaft out it put up quite a fight but I boshed it.
I had to make up the special tools. Don’t try this at home, this is not a DIY job. The pinion nut and sleeve is so tight it you tried it in a home workshop the nut would stay tight and the workshop would turn.
Remember my FD was showing only mild symptoms of failure but none the less it was banjaxed.
The FD was perfect inside but for the small needle roller on the end of the pinion shaft.
This is the last part to come out of the FD, no wonder BMW throw them away rather than rebuilding them.
If I continued to ride the bike the bearing would have disintegrated and released the needles into the gears OUCH.

DaveGSCymro · Dec 2, 2008

wilbjr21 said:
That's over and above something I would tackle myself ...... but very interesting. I'll heed your advice about the power washer. This is the second time I've seen this advice this week.

patzx12 said:
Hi, it's just my opinion but why subject the seals to high pressure force of any kind.

When I used to ride enduros we never pressure washed around any of the bearings even though they were replaced regularly and were easier and cheaper than this. Good pics and write up. :thumb2

autogs · Dec 2, 2008

good thread this,well done sir for getting it apart,i bet you were quite pleased to see the obvious wear after all that effort,to be proved right is what i mean.
do bmw dealers really not rebuild this pinion bearing,surley a chance to bill more labour than a straight swop?

autogs · Dec 2, 2008

just thought you must have to replace pinion as well as needle roller?
how much that then?

MattW · Dec 2, 2008

Wow - good job :thumb2

You most certainly are an engineer.

Looking forward to seeing the rebuild.

ebbo · Dec 2, 2008

Well done getting that apart, must have been unbelievably tight and what a state that pinion roller bearing is in!

sandyB · Dec 2, 2008

Brilliant project, but I think best left to the professionals if not got the same level of technical know how.
Just to add when heating something up to help it split, make sure you don't heat it too much as it might change the material properties a bit, I believe you can get Temple crayons/sticks that melt onto to the job once top temperature is reached. Just thought your better to know.

Looking forward to seeing the rebiuld pics, looks like good job done.

pogo · Dec 2, 2008

Hello ,

congratulations, nice job you did , especially the making of the tool :thumb2

Well , I guess the wear of the pignon and the needle roller did not only occured to your bike , but to most of the GS 12 , we just simply ignore that fact ,because we have no possibility to check that, unless we open the FD .

I am sure if I open mine FD with similar milage , I will discover the same issue....

A+ Pogo

The inside of my FD

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