Spacer/Washer for Timing Chain Guide Rail?

[justabill]

Hey folks,

In my teardown of my '85 R80RT, I have run into a (hopefully) small issue. The timing chain guid rail was mounted with only one backing spacer. The one on the stud was missing. Consulting with the appropriate parts fiche, I don't see these spacers in any of the diagrams, though I note that they are present in the videos from Brook and Boxer2Valve.

I also don't seem to see any clearly correct spacers on any of the usual parts sites. Searching for washers/spacers of similar specs is also a disappointment.

The one I have has these measurements:

OD: ~15.75mm
ID: ~8.25mm
Thickness: ~1.85mm

Anybody have a part number or one or two laying around I can exchange for a 6-pack?

 

[justabill]

Ok. I am going to assume it's #14 in this diagram. The fiche notes that 4 are required, though only 1 is illustrated. On Max, I see that this is a thicker washer. What I removed was one thick washer from the back of the guide rail and two thin washers from the front. I figure it's worth a try...

 

[20774]

The one in your picture doesn't necessarily have anything to do with spacing...most likely to hold the bolt head in place after torquing. Any spacers on the other side would move the rail out. Wouldn't the number of spacers be defined by how the rail lines up with the center of the chain??

 

[52184]

I don’t think those are the washers you need. The washers under the fixed guide are special and I’m pretty sure they are NLA from BMW. They are mentioned only briefly in Snowbum’s article on cam chains. They may have been called out for size & thickness on the airheads list; I’ll dig through what few archives I have and see if I can find anything.

In the meantime, be aware that the only reason for the washers under the guide is to properly align the rubbing block of the guide so that it is centered on the chain and is aligned parallel to the chain. In the end, you may end up having to experiment with washers and shims to achieve that goal.

Best,
DeVern

 

[drost]

I took pictures of my engine during rebuild for reference during reassembly. My engine was never apart. #14 washer may be correct, the front bearing carrier diagram shows the wave washer. The order of washers are stacked up wrong on the parts diagrams. Hope my picture helps.
Doug

 

[justabill]

I took pictures of my engine during rebuild for reference during reassembly. My engine was never apart. #14 washer may be correct, the front bearing carrier diagram shows the wave washer. The order of washers are stacked up wrong on the parts diagrams. Hope my picture helps.
Doug

This definitely helps. Thanks! What year is yours?

Yours looks like the R80 in both Brook's and Boxer2Valve's videos. 2 spacers and 2 wave washers. The parts fiche item for #14 is definitely not a wave washer and calls for a count of 4, so I am thinking that the intent was to use 4 of these instead of 2 & 2 wave washers. Somewhere along the lines, they may have switched. At least that's my best guess. It's an odd over-simplification in the diagram, if that's the case.

My engine was clearly apart to a point. I don't think anybody got as far as removing the cam and followers before, but there were a number of signs of previous work. I found a few notable non-BMW fasteners on the front, and plenty of over applied silicone sealant to deal with.

My guide rail was missing the spacer on the top, and the bottom felt a bit over-torqued. It also had flat washers rather than wave washers. I have about 200 photos, but managed to miss snapping an image of this area at the right time to compare.

 

[justabill]

The one in your picture doesn't necessarily have anything to do with spacing...most likely to hold the bolt head in place after torquing. Any spacers on the other side would move the rail out. Wouldn't the number of spacers be defined by how the rail lines up with the center of the chain??

I think it's notable that the diagram appears to be incomplete. It omits any spacers behind the guide rail and also the nut and washer for the second mount. So I am guessing it is not as reliable as I would hope.

 

[drost]

My RT is a 1993 with 123,00 miles. Cosmetically it was ugly but well taken care of mechanically.

 

[justabill]

My RT is a 1993 with 123,00 miles. Cosmetically it was ugly but well taken care of mechanically.

Mine had 163K on it when I got it almost a year ago. It was a good looking bike at 10 feet away, and solid in all the areas that matter most.



I also see a lot of signs of regular maintenance. Nothing scary in the oil pan, carbs had been rebuilt, valves/top end done at some point, gearbox had nothing bad drip out (still have not opened it up, so fingers crossed), and the final drive checked out very well. I just also see that it was likely worked on by someone who cared less about the smaller things. Random bodged fasteners, ruined main fairing to install an aftermarket radio system, way, WAY too much silicone sealant throughout. Mechanically, the only thing that was a scare was the cam followers, but the cam itself measures in spec, so all good there. The oil pump needed to be replaced and had more scoring than I would like, but I have not found any evidence of other excessive wear.

The missing spacer in the timing system and generous silicone are the only WTF items. As I am converting it to an S bike, it's a solid starting point.

 

[drost]

Mine is identical in color and am doing the same conversation. Taking a brake on working on it now that riding season is here.

 

[justabill]

@drost: We should meetup sometime. Would love to see your project.

Regarding the spacer, I ordered 4 of these from Max. 07119931684 is #14 in the diagram.

In the end, I only used the two on the back and am not sure why they list 4 as required. They do seem to be the correct part for that spacer and the guide rail appears to be lined up correctly with the timing chain.