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80" Flywheels Out of True

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michigander52
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80" Flywheels Out of True

#1

Post by michigander52 » Sun Jul 15, 2018 2:53 am

I have some questions on a set of 80" flywheels that I'm working on that I recently purchased off eBay. After splitting the wheels the first thing noticed is the big time wear on the thrust washer on the pinion side, there is a grove almost into the casting of the wheel itself. So I'm wondering why only on the pinion side?
I centered the sprocket shaft with it's wheel attached and the pinion shaft with it's wheel attached with the dial indicator located on the bearing surface and no run-out but when the dial indicator is located on the face of the wheels it is showing run-out. Kind of like the sprocket shaft and the pinion shaft are not square to the flywheels/tapers? I guess I didn't think I would have to worry about the sprocket and pinion shaft being trued to each wheel also? I want to remove/loosen the sprocket and pinion shaft to true them but noticed the torque on the sprocket shaft is 400 ft lbs. Wow, that seems like a lot? My torque wrench only goes up to 200 ft lbs. Guess I need another tool purchase.



RooDog
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Re: 80" Flywheels Out of True

#2

Post by RooDog » Sun Jul 15, 2018 4:20 pm

When I was building my 4-5/8 S&S wheels they too called for those big torque numbers you are dealing with. I clamped each flywheel and its shaft in a solidly mounted bench vice and with the four foot handle from my Lincoln floor jack slipped over the handle of a 1/2" Snap-On breaker bar I pulled until the bar started to flex/bend and that all the torque I was able to apply. I have no idea how many ft lbs that was but it was all I could apply. Never had any problem with that stroker crank.
As far as to the rods running to one side: I too had that problem and determined that my jugs were not setting square with the crank center-line, so I removed the studs and had my cases squared and trued parallel with the CS CL. I do hope that was the fix, I'll have to wait til the next tear-down to find out...... RooDog

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Re: 80" Flywheels Out of True

#3

Post by RUBONE » Sun Jul 15, 2018 4:37 pm

Several different scenarios can lead to excessive wear on a rod thrust washer. The most common is rods being slightly tweaked and pistons not running square to bore, which causes side thrust and forces rods to one side or the other. Another can be the location of the crank in the left main putting the centerline of the crank too far left. It is easily corrected with shims between the flywheel and inner bearing on the crank. H-D had shims for the bearings that work well in this application. On early engines different thickness washers on each side will move the crank to a center point. In the early '70s many Sportsters had cylinders not bored straight, which caused lots of issues, one being rods running off-center. If your cylinders have been bored be sure to check them as to true perpendicular running. RooDog's issue seems a bit extreme, but yet another one to look at.
Good luck.

michigander52
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Re: 80" Flywheels Out of True

#4

Post by michigander52 » Sun Jul 15, 2018 5:21 pm

One of the first things I noticed was when turning flywheels while on centers the front rod would hit on the inner face of the right wheel. I first thought this was due to the wheels being out of true. I'm not sure that was the case. The rods don't have up and down play but the front rod has 0.100" side play when measured at the small hole in the rod.

Also once I split the wheels I measured the run out of each wheel at their face while mounted on centers each one has run out. Is it correct to measure for run out at the face of the wheels?

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