snapped pinion shaft

[Dooner]

pinion shaft snapped inside gear case, just behind the pinion gear. anybody who might have a reason for this.

[Jack_Hester]

In the old days, H-D mechanics were taught to strike the flywheels on the truing stand, when aligning them. This caused two major problems. It eventually damaged the centers on the stand. This is not what stopped the practice. It also fractures the pinion shaft, as it is the longest, and supports the most weight, on the truing stand. You can look in any old manual, and see a picture of this practice of alignment. I had the opportunity to learn as a kid (from some old wrenches), the right way, and not cause either damage. Most people who don't know, learned the wrong way from the manual.

This being said, most of the time, the fractures occur near the flywheel. But, they can show up at any weak spot on the shaft. I have no idea if this is the cause of your problem. But, it's a thought to consider.

Jack

[Cotten]

There was a rash of pinions that would shear like that on late '70's Chubbles.
We are talking Panhead here right?

I wouldn't blame anyone for sneaking in a Chubble question occasionally, the Chubble forums basically suck.

Still, a late Pan could have had such a shaft installed, although I think they were end-oilers.

And yes, the Manual instructions showing pure abuse is testimony to how forgiving these implements are.

[Dooner]

What ta hell is a chubble? I did forget to mention it pan right, shovel left.

[Jack_Hester]

Chubble = Shovel

[Dooner]

First of all thank's for the replies I need all the help I can get. Now, is this a common problem with a Pan-Shovel. Should the case's have been line bored?

[Jack_Hester]

Though it is not a common problem, I don't believe that it is unique to any particular configuration of twin. It could be due to a defective shaft. Or, due to the aforementioned method of truing. Very difficult to determine on a forum. I would say just plan a thorough rebuild, with a reputable builder, who will take care in assembling and truing your wheels. And, who will be just as thorough, and careful, with the rest of the engine.

Jack

[65FLH5326]

One possible cause would be that the flwheels are out of true causing stress on the shaft, that is a bending stress between the right main bearing and the pinion bushing. Or a cam cover that the pinion bushing has not been line reamed using the right case as the guide.

Don