R80 crankshaft end float

[davnjud]

Rebuilding my 86 R80 engine. Had the crank out to check main bearings - all very good. Reassembled and when the flywheel is tightened down it is somewhat harder to rotate than before tightening and a bit stiffer than I would like. Con rods / barrels. are off. checked and rechecked and rechecked that the inner thrust washer is still on its pins - in fact it seemed conveniently quite solid on there from the start so I never removed it.

What concerns me is that I can’t detect any end float at all albeit with the thrust contact surfaces coated in assembly lube. I didn’t do anything to the rear main bearing and only removed and replaced the front main bearing carrier without touching the bearing so my thinking was that the end float should not have changed. The crank movement is smooth and I can rotate it quite easily by pulling on the flywheel ( when fully tightened with cam shaft , oil pump and chain also being rotated ) but not using one hand only on the smaller diameter cam gear. With the flywheel off I can rotate using one hand on the cam gear. Does this sound normal ?

 

[mikeyboy]

I think I’ve go the gist of your comments.
To check end float,go to the right side of the engine,through the cylinder aperture you will see the thrust bearing and crank,turn the crank so the the throw is out of the way,then you can try and get a feeler gauge between the thrust bearing and crank journal.
You may well need to lever the crank forward to get maximum clearance.
IIRC the minimum is only 0.1 mm or 4 thou ( but check manual)

 

[davnjud]

Thanks I’ll have a look, maybe use a puller to get the crankshaft fullyforward

 

[DrFarkoff]

Thanks I’ll have a look, maybe use a puller to get the crankshaft fullyforward

Just do as Mikey says and lever or get someone to lever through the other side BUT protect the circular cylinder aperture from damage

A puller may be too much and awkward to operate

 

[davnjud]

Yeah couldn’t see how to get a puller to work. Couldn’t get a .06 feeler guage in and oiled min limit is .15. No movement visible at all when levering with screwdriver.( keeping clear of barrel joint as mentioned). I’m not the first in here judging by the damage to the bearing carrrier outer ring presumably due to an incorrect forced assembly attempt. It’s all going to have to come out again and a proper effort to select correct thrust washers. Day wasted putting in camshaft oil pump and front sprocket. Is this feeler gauge method ok for setting the end play ( dry) as I don’t have all the dial guage mounting stuff?

 

[davnjud]

Very surprised to find one of the washers marked and stamped as red 2.48 - 53 actually measures at 2.56 which is in the blue range 2.53 to 2.58. That might contribute to the apparent lack of endfloat. The other one,green, measures up bang in the middle of its range.anyone seen this before ?

 

[davnjud]

I bought a dial gauge stand and found that with the crank installed dry I could get about .07mm endfloat versus spec of .08 to .15. The assembly oil had filled this gap so I couldn’t detect/ measure it before. Apparently quite common for factory shimmed engines to have low endfloat. No evidence of overheating on the thrust washers. Contrary to expectation FYI I found the front bearing holder could be reinserted just by freezing and no need to perform the tricky heating of the engine casing. .

Thanks to this exercise in putting my mind at peace I have had to damage and remove a brand new main seal. Motorworks describes their rear.main seal as viton. Do they mean Teflon which is not the same. I think Viton needs the lip lubricating whereas Teflon doesn’t.

 

[DrFarkoff]

I bought a dial gauge stand and found that with the crank installed dry I could get about .07mm endfloat versus spec of .08 to .15. The assembly oil had filled this gap so I couldn’t detect/ measure it before. Apparently quite common for factory shimmed engines to have low endfloat. No evidence of overheating on the thrust washers. Contrary to expectation FYI I found the front bearing holder could be reinserted just by freezing and no need to perform the tricky heating of the engine casing. .

Thanks to this exercise in putting my mind at peace I have had to damage and remove a brand new main seal. Motorworks describes their rear.main seal as viton. Do they mean Teflon which is not the same. I think Viton needs the lip lubricating whereas Teflon doesn’t.

You don;t need those pricey things

Linky 100 x 80 x 10 Double Lip Oil seal I checked before, the Nitrile Rubber is fine for up to 120 degrees (probably more allowed for a safety margin) or you can go to Viton with 200 degrees ish

 

[Gelandestrasse]

Thanks to this exercise in putting my mind at peace I have had to damage and remove a brand new main seal. Motorworks describes their rear.main seal as viton. Do they mean Teflon which is not the same. I think Viton needs the lip lubricating whereas Teflon doesn’t.

Some reading material on this point here... https://bmwmotorcycletech.info/flywheelremovalwarning.htm

 

[davnjud]

Motorworks checked with seal supplier and confirmed that oiling of the Viton seal lip is preferable. Snowbum article above also refers to light oiling of a ‘ Teflon like ‘ seal. If it leaks I’ll update but fingers crossed. Won’t be worrying about seal damage on first start up now.