Crank assembly help
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Intermediate
Joined: Dec 2022
Posts: 38
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From: Lakeside, ca
Crank assembly help
I started to build my crank but if I tighten the crank pin nut down just a little the rods lock. Something is definitely wrong here. I dont know if the trust washers, pin, or bearings are wrong. I used a crank pin from vtwin, p/n 10-0131 (1940-52 big twin UL). Ive tried two different Sets of trust washers vtwin p/n 10-1284 (they say standard but the eastern p/n says .055) and vtwin 10-1217 which is labeled .005 while the Eastern label says .060. The bearings are standard size S&S p/n 493878. Rods have been honed to proper size. I cant find the standard thrust washer thickness anywhere. Maybe Vtwin mislabeled them? Just for reference the left case is a 37 and right case is 48. I also could use some help finding the correct sprocket shaft seal. Thank you!
Club Member
Joined: Mar 2009
Posts: 66,115
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From: Niles Canyon Ca.
Taper in the wheels themselves could be oversized, run into that with older flywheels occasionally. Using just the new crankpin, install, torque then measure the gap between wheels with the new thrust washers installed, then check the big journal rod end width. That's where I'd start with this.
Thread Starter
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Intermediate
Joined: Dec 2022
Posts: 38
Likes: 14
From: Lakeside, ca
Taper in the wheels themselves could be oversized, run into that with older flywheels occasionally. Using just the new crankpin, install, torque then measure the gap between wheels with the new thrust washers installed, then check the big journal rod end width. That's where I'd start with this.
Seasoned HDF Member
Joined: Jun 2015
Posts: 8,055
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From: Canada
I ran into some challenges doing my flathead crank. The aftermarket pins were the problem, wrong angle on the taper, wrong length pin, wrong size big ends on the rods, wrong side clearance and on and on. Took a lot of messing around and fitting the rods to get side clearance and bearing clearance right. You should measure the old pin vs the new one and check the depth the pin protrudes on the nut side on both. Then get ready to make things work together.
Seasoned HDF Member
Joined: Jun 2015
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From: Canada
Flathead had different rods and rod ends. Why they did that I dont know but changing the pin to a larger journal will send you down the garden path as you're finding out. Its what happened to me and I came close to just pulling out the plastic and ordering a T&O rotating assy to get away from the drama and down-time.
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Intermediate
Joined: Dec 2022
Posts: 38
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From: Lakeside, ca
Flathead had different rods and rod ends. Why they did that I dont know but changing the pin to a larger journal will send you down the garden path as you're finding out. Its what happened to me and I came close to just pulling out the plastic and ordering a T&O rotating assy to get away from the drama and down-time.
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Club Member
Joined: Mar 2009
Posts: 66,115
Likes: 51,405
From: Niles Canyon Ca.
Check this guy out.
Crap won't let me post a working link, Pacific Mike Youtube , had a vid on flathead wheels and the various parts for them
Crap won't let me post a working link, Pacific Mike Youtube , had a vid on flathead wheels and the various parts for them
Last edited by TwiZted Biker; Apr 25, 2023 at 06:24 PM.
Thread Starter
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Intermediate
Joined: Dec 2022
Posts: 38
Likes: 14
From: Lakeside, ca
hahahaha. Ive watched his videos. I think the crank pin was the issue, new one on order. I wish he would have referenced part numbers when he was making that video.
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