1937 transmission

[ldfly112]

My 1937 UL 4 speed transmission has been showing signs of needing repair. The trans. was rebuilt about 6000 miles ago new andrews gears. The transmission seemed to be operating fine after rebuild then I noticed that going down from 3rd gear to 2nd gear it would grind a bit. not at all going from 2nd to 3rd or any other gear. I removed the transmission from the bike and removed the lid thinking I would find a slightly bent shift fork . Nothing looked wrong at all in the transmission after studying it for a while I noticed that while spinning the main shaft it would have a small amount of resistance nothing consistent at all. I am hesitant to put it back together not finding anything wrong. Anyone have any ideas THANKS if can help

[duffeycycles]

I've seen a few bent mainshafts in customers bikes,overlooked by previous "best mechanics" had been thru them. If you used the Andrews shift forks I always grind relief to the the leading edges to Andrews shift forks.

[dukekleman]

My 1937 UL 4 speed transmission has been showing signs of needing repair. The trans. was rebuilt about 6000 miles ago new andrews gears. The transmission seemed to be operating fine after rebuild then I noticed that going down from 3rd gear to 2nd gear it would grind a bit. not at all going from 2nd to 3rd or any other gear. I removed the transmission from the bike and removed the lid thinking I would find a slightly bent shift fork . Nothing looked wrong at all in the transmission after studying it for a while I noticed that while spinning the main shaft it would have a small amount of resistance nothing consistent at all. I am hesitant to put it back together not finding anything wrong. Anyone have any ideas THANKS if can help

The small amount of inconsistent resistance you are feeling could possibly be the loose needle bearings found on each end of the countershaft and on the main drive gear.

What commonly happens with them , usually due to condensation moisture in the oil, is that they begin to pit the needles and the races.
This will cause the needle to skid, verses roll. Perhaps the small resistance you feel occasionally.

Hope this helps,

Duke Kleman

[Rubone]

Make sure your clutch is perfect before you get into the gearbox!

[exeric]

I had shifting issues that (I believe) were due to resistance in the shifter drum paths, and possibly the top-hats so I replaced them, and carefully dressed the drum paths with a diamond file and checked clearance with a gauge pin. Prior to that, I checked a number of main shafts on a surface plate, and replaced some gears and generally chased my tail. After addressing the shifter drum and top-hats the problem went away so maybe it was a combination of many things that needed attention.