Checking Crank End Play?

[pommie john]

That says 2 thou.
According to this site, the correct clearance is 3 - 6 thou . http://bmwmotorcycletech.info/crank.htm

[lucky23]

That says 2 thou.
According to this site, the correct clearance is 3 - 6 thou . http://bmwmotorcycletech.info/crank.htm

Thanks! I knew it said 2 thou of an inch, but my confusion is that the manual says crank endplay should be between .0032-.0059...Do you you always round down if it's less than 5 and round up if its more than 5?
Also, my thrust washer thickness appears to be .1015, do I need a thinner one such as a "red"?

[crazydrummerdude]

Originally Posted by lucky23

the manual says crank endplay should be between .0032-.0059

That's pretty damn specific. While there are instruments/dials/etc that measure tenths, I'd just call it .003-.006.

[lucky23]

Bear with me, Im new to building a BMW engine in this capacity...but hell, not only am I building a motorcycle, I'm learning remedial math to boot!

[wirewrkr]

This job can also be done with feeler gauges.
Not as accurate as a dial indicator, but accurate enough and a whole helluva lot cheaper.

[disston]

When you made your measurement were the bearings and the steel surfaces all clean and dry, no oil? I have trouble accepting that this is the way it's done but the Gurus or at least people smarter than me say it is so. I think some will disagree with this? If you had oil, even light oil on those bearings your measurements would be off.

[Wirespokes]

I'm thinking the reading may be more like .0025 rather than .002 due to the angle the photo was taken at. In that case I'd be tempted to leave it.

The reason your specs say .0032 and .0059 is because someone did the conversion from the metric spec and didn't have the understanding of what it takes to make such fine measurements.

[lucky23]

I'm thinking the reading may be more like .0025 rather than .002 due to the angle the photo was taken at. In that case I'd be tempted to leave it

The case is emptied of oil. It had been sitting on a shelf for about a year. You think .0025 is safe? What would likely happen if I left it at .002?

[disston]

And I think the true reading is 0.0015 if there is oil on the bearings. That needle is not at any great angle. The current reading is about 0.0021.

I suppose the problem is that this engine came assembled? Did you buy it with an assurance that it was xxx miles and a good runner?

I think I'd try and make it fit the loose end of the spectrum. You can take a micrometer to the parts counter at the dealer and try several bearing while there. if they stock Airhead stuff, I guess.

[lucky23]

Yeah, he said it was good runner. I ordered a "red" thrust washer since it was the next smallest . My current one is .1015 thick it seems.

[disston]

OK, when you get it measure the actual thickness of the bearing you get. Then do your measure of the end play. The thrust washers are not a standard size. According to Snowbum the red bearing can have a variation of 0.0018" . Here is his list of bearing sizes;


Here is the real values of the thrust spacers:
RED: 2.483 mm to 2.530 mm (0.0978" to 0.0996").
BLUE: 2.530 mm to 2.578 mm (0.0996" to 0.1015").
GREEN: 2.578 mm to 2.626 mm (0.1015" to 0.1034").
YELLOW: 2.626 mm to 2.673 mm (0.1034" to 0.1052").