Boxerworks.com

Howdy everyone,

I am fairly new to airheads, so please bear with me if I'm asking a stupid question:)

I am in the process of rebuilding an '84 R80 motor in order to transplant it into a ural sidecar rig. Part of that involves replacing the clutch-carrier/clutch setup with a pre-1977 flywheel and clutch. According to everything I've read, there should be marks on all the flywheel and clutch parts that need to be offset 120 degrees when all the parts are installed, but none of the parts I have have any marks on them that I can find.

Can any of y'all suggest a way for me to figure out how to orient everything as I re-install the clutch and flywheel? Any help will be much appreciated.

Thanks,

Matt Pearsall

Welcome to the forum.

Usually the clutch components have a blob of paint to identify the heaviest area, and the idea is to have these three blobs saced at 120 degrees to maintain balance. In practice however, the accuracy of modern balancing means that these components can often be assembled without too much concern that the bike will suddenly become a big capacity vibrator if they aren't assembled "correctly".

YMMV etc

If the pre-77 clutch/flywheel assembly is NEW, there might not be any marks. If used, the person taking it off whatever it was on should have made marks.
I bought new clutch parts for my '78 R100s a few years ago and there were no marks anywhere around the edges. Doesn't seem to be a problem.
JUST BE SURE you get the timing marks on the flywheel in the right place!!! You have 4 out of 5 possibilities to get them wrong!!
Use new hardware...it's cheap.

Can this be done without also making changes to the transmission?

Kurt in S.A.

Kurt in S.A. wrote:Can this be done without also making changes to the transmission?

Kurt in S.A.

The input shaft of the trans is a different length before and after 1981.

Which transmission are you planning on using?
Some of those russian bikes had dual clutch discs and a completely different spline pattern on the transmission input shaft.

Garnet wrote:

Kurt in S.A. wrote:Can this be done without also making changes to the transmission?

Kurt in S.A.

The input shaft of the trans is a different length before and after 1981.

Hence my question.

Kurt in S.A.

Kurt in S.A. wrote:

Garnet wrote:

Kurt in S.A. wrote:Can this be done without also making changes to the transmission?

Kurt in S.A.

The input shaft of the trans is a different length before and after 1981.

Hence my question.

Kurt in S.A.

One presumes some degree of awareness on the part of the OP to check that the clutch splines will match his gearbox of choice. We await his response with interest . . . .

Thanks for the quick replies! I am using a mixture of new and used parts, none of which have any markings on them. If it's a matter of finding the heavy side of each part, I could spin it on something and see what end faced down, like I'm balancing a tire--it sounds like this isn't super critical, so getting it in the ballpark should be fine.

As for the splines & transmission, I am using the original Ural transmission. It has the same splines as a /2 BMW, so I am using a /2 clutch plate in the /6 clutch that I am putting into the '85 R80 motor. From what I understand, all of these parts interchange, and other people have done exactly this. I have yet to actually do it, though, so I'm still holding my breath a bit.

Once I have that done, I will need to have a welder move the mounting points on the ural transmission so that they match up with the points on the engine. Then, (if all goes according to plan) the engine should drop right into the ural frame using the same engine mounts.

If y'all'd like, I can post pictures as I go through the modifications.

Thanks again,

Matt Pearsall
'94 KLR 650
1989 Dnepr/BMW (under construction)

If y'all'd like, I can post pictures as I go through the modifications.

you kidding? We live for that stuff. (no cut-off pictures, though! )