Questions About Timing Chain Parts

[88bmwjeff]

I was doing an inventory of parts I had purchased about 10+ years ago to replace my timing chain. Never got around to it for several reasons. FYI, the bike is a 1988 R100 RT. Anyway, I have a few questions.

1. The timing chain has been superseded. I have part #11 31 1 335 934. Current part #11 31 1 335 580. My guess is that there's no real improvement to buy the current version. Any thoughts on this?

2. I have the shaft seal for the timing cover (part #11 14 1 337 654 is the current part number); however, it's 10+ years old. Does it make sense to buy a new one, since the rubber is 10+ years old. What's the likelihood a new one could have been sitting on the shelf for as long?

3. I have the nose ball bearing with part #07 10 1 468 882; however, according to the parts fiche the part number is 07 11 9 9 81 722. The parts fiche indicates the bearing is a 16007. The bearing I have is stamped with 16007, so it looks like it's the correct part and was purchased through BMW dealer. Is this correct? I can't find the part number I have on the fiche.

4. The slide rail appears to be part hard rubber. Would the hard rubber degrade too much in my garage for 10+ years?

Thanks,

Jeff

 

[20774]

I would be inclined to replace rubber parts. Sure they might be sitting on a shelf somewhere, but I would think the current parts suppliers hasn't been there for 10 years like yours.

As for the nose bearing, Snowbum lists the -722 part number on his website. He cautions that the bearing must be of the correct grade which is says is FAG16007-C3, specifically the C3 callout.

https://bmwmotorcycletech.info/timingchain.htm

 

[gtgt_bangbang]

my timing chain done too far back to recall the specifics,
but seem to recall some thing about chain revisions; from an 'endless" version ( little harder to install) to master-linked style ?

I 2nd the 20774'th motion; 10 years of ozone on rubbers part is not ideal ( got any electric motors running near your parts stash? those are 03 generators ... ).
I'd pop for new seals unless wildly expensive.

The hard rubber tensioning slide is another issue; doesn't depend on softness/compliance to work .
Unless any areas were looking frosted ( oxidized) I'd run the shelf part.

The C3 designation is a tolerance / clearance spec.
Some bearings applications need/tolerate some slop (affects shaft ' stiffness ' while in use) , other apps require tighter specs.
C bearings are tighter spec