Alternator cushion drive rebuild

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Msblu79
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Alternator cushion drive rebuild

Post by Msblu79 » Tue Nov 12, 2019 3:08 pm

Been a couple of weeks since I reported having issues with noisy bearings or something failing at the top of the motor. I pulled the alternator hoping it was it and not something more expensive inside. Once I had it in hand I turned the shaft and it was seizing up and sticking from a bad bearing. I separated the drive from the alternator and began tearing it apart. Everything was pressed together very tightly and took some careful hammering and a variety of tools and bits to come up with ways to hold and remove the gear and shaft from the bearings. I was taking pictures as I went but after a awhile the batteries died and I continued reassembling the drive after discovering I had no spare AA's around. I picked some up the next day and finished up the re-install of the complete unit back in the engine. The drive has two bearings stacked on each other with a spacer between them and held in with a snap-ring. After getting them both out I found the front one was coming completely apart and jamming up. There is a Viton seal behind the gear to keep engine oil from escaping which I ordered as well and had two on hand in case I effed it up. The cushion shaft was OK and not damaged by the bearing and I just emery clothed the area where the bearings sit to lighten the fit some and make it easier to fit the bearings. I pressed it all back together, installed a new seal and the gear and loctited the nut. I clamped the gear in some soft vise jaws to hold it while I tightened the nut so I wouldn't damage the teeth. Got it back in and it sounds much better, back to the normal clatter. :lol: Here are some of the pictures, click on them to enlarge. :D
DCP_3205.JPG
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2010 Black Patrol 92,000km's
Modtop airbox, 2013 branch pipes, Perch rings, Yamaha petcock, Drilled slides, Gossie needles, 145 mains, 45 pilots, insulated manifolds, Modtop pushrods, Dual FMF exhaust, PA Multi-spark system w/ VOES, Spin on filter conversion, 33mpg, Royal Purple fluids.

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Msblu79
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Re: Alternator cushion drive rebuild

Post by Msblu79 » Tue Nov 12, 2019 3:13 pm

More pictures from the drive:
DCP_3214.JPG
DCP_3215.JPG
DCP_3216.JPG
DCP_3219.JPG
DCP_3220.JPG
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2010 Black Patrol 92,000km's
Modtop airbox, 2013 branch pipes, Perch rings, Yamaha petcock, Drilled slides, Gossie needles, 145 mains, 45 pilots, insulated manifolds, Modtop pushrods, Dual FMF exhaust, PA Multi-spark system w/ VOES, Spin on filter conversion, 33mpg, Royal Purple fluids.

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Snakeoil
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Re: Alternator cushion drive rebuild

Post by Snakeoil » Tue Nov 12, 2019 5:35 pm

I tend to believe that a contributor to the failure of that bearing is the press fit of the shaft into the bearing. There is no reason for that as the assembly is captured when fully assembled. I went thru this process when I bought my Denso upgrade and still had major noises in the front end. It ended up being a bent crank and bad front main. But I thought it might have been the adapter and took it apart. This is when I ran into the same thing you did with everything pressed together. I modified mine so that the shaft simply slipped into the bearings. I believe that if you do not press everything together correctly and then tap the bearing inner races to assure you have no preloaded the bearings, they will fail.

Your decision to relieve the press fit a bit was a good one. IMHO you should have kept going until the shaft was a nice precision slip fit into the bearings.

Somewhere way back in the Greasy Wrench is a post about this from when I ran into it.
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Rob
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2000 Ural Tourist
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Lee Pape
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Re: Alternator cushion drive rebuild

Post by Lee Pape » Wed Nov 13, 2019 9:54 am

It is a little late for you now, but you should of cleaned out and re=packed the new bearing using Krytox grease.

Here are the search results for Krytox:
search.php?keywords=Krytox

I think I used DuPont/Chemours Krytox GPL 207—PTFE Thickener

https://www.mcmaster.com/grease
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Riding and working on Urals since 2000.

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Msblu79
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Re: Alternator cushion drive rebuild

Post by Msblu79 » Wed Nov 13, 2019 12:04 pm

Ooo crap, Lee, I plumb forgot about that Krytox grease, oh well, this will be a test of the bearing grease I guess, :lol: Snakeoil, I did just that and put the shaft in my lathe and sanded it down until the bearings slipped on. I really had to beat the daylights out of it to get the shaft out and didn't want to go through that again. It went together decently and should hold for a while till the grease fails, :( I made it easier to take apart so if it dies again it won't be so bad. Thanks guys.
2010 Black Patrol 92,000km's
Modtop airbox, 2013 branch pipes, Perch rings, Yamaha petcock, Drilled slides, Gossie needles, 145 mains, 45 pilots, insulated manifolds, Modtop pushrods, Dual FMF exhaust, PA Multi-spark system w/ VOES, Spin on filter conversion, 33mpg, Royal Purple fluids.

RC20
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Re: Alternator cushion drive rebuild

Post by RC20 » Wed Nov 13, 2019 2:24 pm

You done good and right.

Once a ball or race is damaged, its going to get worse though you might slow it down with more grease stuffed in and quiet it a bit.

The key to these is heat. Most applications if you heat the inner race up to 210 - 240 degrees, they slip right on the shaft (there are a few that will not). You can also put the shaft in the freezer and cold soak it and get more clearance.

While its nice to have a bearing heater, a small torch and a temple stick (crayon that melts at a specified temp) from the welding store works fine.

I put on 6311 size bearing with a torch though once we got the bearing heater we used that. I still used the torch for small bearings as the heater would not to a 6205 size and under.
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Msblu79
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Re: Alternator cushion drive rebuild

Post by Msblu79 » Wed Nov 13, 2019 3:43 pm

Oops, forgot to mention that when I started installing the bearings I put the housing in the oven at 350F for a while to heat it up and hope that the bearings would just drop in. I put the bearings in the freezer at the same time. Amazingly they just dropped into place with no effort. I then was able to lightly tap the shaft through and let it all cool off before installing the seal. Went together nicely and can only hope it gets me another 90,000 klicks. :cheers:
2010 Black Patrol 92,000km's
Modtop airbox, 2013 branch pipes, Perch rings, Yamaha petcock, Drilled slides, Gossie needles, 145 mains, 45 pilots, insulated manifolds, Modtop pushrods, Dual FMF exhaust, PA Multi-spark system w/ VOES, Spin on filter conversion, 33mpg, Royal Purple fluids.

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