1936-1940 Main Races Knucklehead

[willardsmarts h-d parts]

Has anyone ever seen a tool to lap the case races with the blind race? For 1936 to 1940 Harley-Davidson Main Shaft & Pinion. Jeff AMCA 9583

[koanes]

Sunnen offers a blind hole mandrel from their industrial division for use with a precision honing machine. It would be nice to be able to size the race after installation, as most of the time the hole in the case is not perfectly round or slightly tapered and there is always a little distortion of the I.D. of the race to follow. It is tough to get the race holes as true as you can with a through lap or hone. I usually try to true up the race with my line lap tool. I have modified a couple of lap heads (one for star hub drum side) by removing the bevel so it will bottom and truing the lap head in the lathe as neccesary.

[willardsmarts h-d parts]

Sunnen offers a blind hole mandrel from their industrial division for use with a precision honing machine. It would be nice to be able to size the race after installation, as most of the time the hole in the case is not perfectly round or slightly tapered and there is always a little distortion of the I.D. of the race to follow. It is tough to get the race holes as true as you can with a through lap or hone. I usually try to true up the race with my line lap tool. I have modified a couple of lap heads (one for star hub drum side) by removing the bevel so it will bottom and truing the lap head in the lathe as neccesary.

Thanks I Have the Stock H-D Tool for the 41 Up and I use it all the time. When I was doing one of my 39,s I had it come into my head what it might look like, you Know the tool. Thanks Again Jeff AMCA 9583

[Chris Haynes]

Most builders remove the block and install the later bearing race.

[willardsmarts h-d parts]

Most builders remove the block and install the later bearing race.

Hi yes I did on a 40. My and 36EL 3 39EL thay all were in great shap. It was the tool, and if thay H-D, had one for that for tha app? Jeff AMCA 9583

[T. Cotten]

A lapp is a crude "field repair" tool.

I is un-imagineable that the Factory could ever have produced the numbers of machines that they did by fitting them with a time-consuming lapp, and the inferior mill-profile surface that they produce.

Most likely, the races were pre-sized and crammed in, dismissing the distortions that resulted. (It is my opinion from observation that the other major American marque did the same.)
Face it: the split pinion generated much more error in truing the crank than a sloppy "running fit" on the rollers produced.

Today, professional restorers, who sincerely wish to achieve an "ideal" assembly to survive duty on modern roadways will grind out the blind ends of the case housings and install later races with snap ring grooves (or as I did: use a 55-57 Pinion Shaft to dispense with the split-pinion nightmare.)

With the blind ends of the races relieved and updated races/pinion shaft, both cases can be torqued together to allow both races to be line-honed on a proper honing machine mandrel, to an exquisite fit that will probably out-mile the original design.

...Cotten
PS: Liberty does not offer motor services at this time, so don't ask.

[Paps]

Cotten....I have the exact same machine ! Where do you get your replacement belts ? Paps

[Carl Olsen]

Paps,
Go to the autoparts store and buy a serpentine belt of the same length.

Cotton,
I bought a special long arbor for doing both case races at the same time a few years back, it was expensive, but I can now be 3-4 times more productive and my back is not sore for a couple of days afterwards.
Carl

[Paps]

Thanks Carl, but how can a sepentine belt stay on flat pulleys ? Or are you saying to flip the serpentine belt inside out, so as to have a flat running belt surface ? I had thoughts of using a stapled belt but decided the staples would cause chatter in the honing process. Not only this, the staples would quickly wear out the all aluminum pulleys. Paps

[T. Cotten]

I need a new belt too.

The mandrel shown is a simple two-shoe version (P28?), but I can cut on only one race or the other by replacing the stone within the race that I do not wish to cut with one that I have attached a nylon face upon. With a selection of these nylon wipers of different heights, I can accomodate the wear of the cutting stone and keep them close to equal. By swapping the stone and wiper, I can then stroke from the opposite side.

This allows me to set up the mains with different sizes of rollers when necessary, and still cut piloted by the opposite race.

Occasionally a fresh race may have a constriction in it that makes it necessary to file a stone quite short, so it can be stroked in only one region of the race. (Some Left-coast Indian sprocket mains were notorious for this because of an exaggerated external knurl). Since the opposite race is not being cut, they won't be blown out beyond the largest roller before the tapered race comes true.

The worst case scenario (pun intended) is when weld repairs, or installation of an oversized race, have skewed the alignment slightly. For H-D pre-Timken Big Twins, I am fortunate to have a Sidley Diamond "lapp" preset to .001" oversize rollers. It cuts without compound of course.
One set of cases was so bad that I had to place the tool into the cases without the studs tightened, and a gap between. As I would turn the tool, I slowly tightened the studs until the cases could be brought together.
Apparently, gear mesh in the cam chest can accept a great deal of error!

Liberty is still looking for experienced professionals to re-open its motor, transmission, and chassis service departments:
http://virtualindian.org/5deallib.htm

....Cotten

[willardsmarts h-d parts]

Cotten Ive been in bed for a long time thanks for your help and yes this looks like the way to go thanks Jeff AMCA 9583