3rd gear bushing fit

[Omarttentmaker]

Can't seem to find a tolerance for the fit between the bushing i.d. and the mainshaft for a 3rd gear in a big twin transmission. I know the manual calls out the bearing fits, but I guessed that referred to the needle bearings in the countershaft and the main drive gear. Does anybody have that elusive bit of info?

[Rubone]

What year book are you looking at? The info is in the specs in the Panhead service manuals. From '59 up the bushing was eliminated on 4 speeds so late info won't show it. .001-.002 to shaft.

https://www.hydra-glide.net/joomla/i...ission-general

[Omarttentmaker]

I was looking on the page in the knucklehead manual. There didn't seem to be a lot of info there. And I do have a '59 and up gear, but not the matching cluster, so I'm using the gear with the bushing in it. Thanks for posting the answer. Gotta wolf down some bird and then get back to work!

[Jerry Wieland]

Third gear is probably the highest stressed gear in a HD 4 speed gearbox due to it's offset. I always try to stay below .0015" for clearance.

Jerry

What year book are you looking at? The info is in the specs in the Panhead service manuals. From '59 up the bushing was eliminated on 4 speeds so late info won't show it. .001-.002 to shaft.

https://www.hydra-glide.net/joomla/i...ission-general

[T. Cotten]

What I found most important, Omartentmaker,....

Is to lathe bore the bushing true to its outer circumference.

Just poke-reaming or honing the bushing can make it whine.

...Cotten
PS: Idler gear shown bored similarly.

[larry]

You might consider finding the late cluster. You already have the late gear. Harley upgraded for a reason.

[T. Cotten]

You might consider finding the late cluster. You already have the late gear. Harley upgraded for a reason.

Don't look now, Larry,..

But the bushed gear was used for handshifts through at least '65.

Don't know why, as I got away with both designs on handshift machines.

...Cotten

[larry]

Interesting.

[Rubone]

It was used on 3&R boxes through the '60s, the updated gears for 3&R are -70 part numbers. Apparently not enough out there for an earlier update. If you have a '59 low cluster the bushed third gear won't work due to the depth of the recess in the cluster. It only works with the early one. And vice versa as you have discovered. The longer sleeve on the '59 up gear was to help with the premature wear and whine in the bushing type.

[Omarttentmaker]

Thanks to all for your input. May be I will hunt for a later cluster. And Cotten, you're right about boring the bushing, but my old clunker of a lathe doesn't have a three jaw that runs true enough to bore like you show. I'll have to put up a 4 jaw, and put 4 dowel pins at 90 degrees in the teeth, indicate the bushing and bore to size. My thought with using the dowels in the teeth is that it might cut down on the whine, as the gear's pitch line will run truer if I use that as the indicator datum.

[BigLakeBob]

Instead of using a 4 jaw, sometimes I put a piece of shim stock or feeler gage between the jaw or jaws and work piece to make the part run true.

[larry]

Your 3 jaw chuck can't be adjusted?

[T. Cotten]

A four-jaw is most proper, Omar!

I'm just lucky to have a very precise Cushman three-jaw.

(Not the scooter brand, I believe.)

Shimming or dowels is the only way it could be adjusted.

....Cotten
PS: All three of my hand-shift 1965 transmissions with bushed gears are four-speeds.
Just as I found them; one a Kansas City PD machine that was only ten years old.

[BigLakeBob]

A four-jaw is most proper, Omar!

Nothing wrong with using a 4 jaw, but I machine for a living and time matters. If it is only one piece, and for example, it runs out .004 and you can locate how the part can be persuaded to run true, there is nothing wrong with putting 'say a .002 shim' between the work piece and a jaw to make it run true. This is a lot quicker than removing the 3 jaw, putting on the 4 jaw, then indicating the part true as you could have done in the 3 jaw with a shim but quicker. On my 18" swing lathe, I have a 12" chuck. Putting a piece in the chuck it usually runs within .002 TIR (total indicator reading). I know the #2 jaw in wore some, where it meets the scroll. So, if I need the part to run true I know usually which jaw needs the shim, plus a little tapping on a jaw with a plastic hammer brings the part right in. Once you learn where your chuck is off, unless it is totally worn out, adjusting for one piece can be quick and simple. That's all I was saying.

P.S. Now for the last word.

[T. Cotten]

My "Last Word" is a Starrett, Bob!

....Cotten