Questions About Timing Chain Parts

[Jeff in W.C.]

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 The timing chain has been superseded.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 #7 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

[gspd]

The hard parts, bearing and chain, should be fine.
If i'm not mistaken, the difference between the 2 chain part numbers is that one is an endless chain and one has a master link. I have vague recollections of some early bikes coming from the factory with endless (no master link) chains. All the replacement chains had master links.
There may be a service bulletin about this.

The seal is the one around the alternator rotor, correct?
If so, it's easy to replace if it leaks later, but they rarely do.

As for the slide rail, it can't be any worse than the 35 year old one that's in the bike now.
It should be OK.

Do you have a new tensioner arm? That probably should be replaced while you're in there.

[Rob Frankham]

1) The 'old' chain part number (934) was certainly current in 2006 with no mention of the 'new' number. It's probably just a change of supplier.

2) If the seal is unused and has been kept out of sunlight in a stable temperature, it'll be fine.

3) All of the sources for the nose bearing I can access give the same number (07 11 9 981 722) the other number doesn't even seem to be a valid BMW part number #7 10 1 468 882 (doesn't have enough digits). Where did it come from? In any case, the '722' number is current in all of the parts lists I have access to so it will be fine...

Rob

[Jeff in W.C.]

Thanks GSPD and Rob,
The chain is not endless. It has a master link. My guess is that it’s a different supplier. The photos on Max BMW’s website show the chain I have which is black and the newer one which is metallic in color (unpainted). I’m just going to run with the one I’ve got.

The seal is for the one around the alternator. The seal has been out of sun light, but in my garage, which gets above 100 F or 38 C several times a year. Right now, we’re have a heat wave 105-110 F. For ±$10, I’m tempted on just getting a new one for the peace of mind.

The nose bearing was purchased from a BMW dealer, is in a BMW box with label and logo etc. My bad though-I accidentally left out the first ‘0.’ The full number is 07 10 1 468 882. The bearing itself is manufactured by SKF in Italy and has the following written around the bearing: SKF, 16007, Italy B, **C (*=dots), Explorer. My memories coming back a bit and I think the parts guy said it’s the right part, but different part number on the box. If I can’t determine it’s a C3 bearing, I’m just going to get a new one. A new bearing is about $20, so it’s not terribly expensive to make sure it’s the correct part.

Yes, I have a new tensioner arm and spring. Should the Timing Chain Piston (11 31 1 335 579) also be replaced? The timing chain kit from EME includes one.

[gspd]

I would have no qualms about using the seal and bearing you have.
Especially if it's a SKF bearing.
These are non-problematic components that usually last forever less a day.

FYI - piston and spring replacement.
The piston and spring should be replaced as a preventative measure but never seem to actually wear out or fail.
The spring's purpose is obvious: it applies a pre-determined degree of tension to the chain to prevent it from slapping around.
The piston is actually a hydraulic damper, something that never seems to be mentioned, and therefore ignored. It gets filled with oil that gets splashed into a funnel just above it via a tiny hole while the engine is running. Once full, semi hydraulic lock prevents the tensioner from being pushed back by chain fluctuations.
It's the same principle that's used for hydraulic lifters on automotive valvetrains.
Be sure the feed hole at the bottom of the funnel is not blocked with debris and if you want to be really fussy, you can prime this funnel with oil before re-assembly.

Also, a final tip (that many won't agree with): Just use grease on the gasket, not sealer.
And again, don't forget the two top washer gaskets (common omission).

[Jeff in W.C.]

I asked over at BMWMOA site if anyone could identify the bearing part number I have. Someone responded that the parts fiches show the 07 10 1 468 882 number as superseded by 07 11 9 981 722. So, it seems like it's an old part number that was superseded. Granted, I'm not sure what parts fiche he was looking at, but it makes some sense that it's an old part number.

[Rob Frankham]

Agree with GSPD, all of those parts should be fine for use... but it's your bike your pocket and your peace of mind.

Never seen any significant wear on the timing chain piston but, if you have a new one, by all means replace it. Personally, I'd be more interested in replacing the spring but I've never seen any suggestion that they fail either. I guess, if the timing chain has been allowed to get very worn, these components could become worn out.

The person on BMWMOA probably has access to the current parts ordering system. The change in number must have happened very recently. Supercession doesn't mean there is anything wrong with the 'old' part, just that there has been a detail change, probably due to a change of manufacturer or the old part becoming unavailable. It's even possible that the part with the original number was marginally better than the new part. I certainly wouldn't have any qualms about using a SKF bearing.

Robin

[SteveD]

I asked over at BMWMOA site if anyone could identify the bearing part number I have. Someone responded that the parts fiches show the 07 10 1 468 882 number as superseded by 07 11 9 981 722. So, it seems like it's an old part number that was superseded. Granted, I'm not sure what parts fiche he was looking at, but it makes some sense that it's an old part number.

www.realoem.com has the superceding info.

[Rob Frankham]

Quite right, it does... didn't go deep enough.

I've also just noticed that the parts list they use is dated 2019, which is information worth knowing.

Rob

[Jeff in W.C.]

The part number would have been superseded a while before purchased it 10-15 years ago and not recently. I do not know where the individual got his information from. I have Googled the part number and it did come up on two sites as a 16007 bearing, but no comment to it being a C3 bearing. Given that the part number may have been superseded a while before I purchased it, it's unknown how long the bearing's been around. It could be in good shape, but maybe not. I was reading on SKF's website about storage and open they typical only a few years shelf life--up to ten in an environmentally controlled storage area. They have no guidelines regarding unopened--in their original wrapping undisturbed. The wrapping does not appear to have been tampered with. Also, I can't 100% tell if it's a C3 bearing. As such, I'm leaning to just buy a replacement one for $20-25 than worry and wonder.