Crankshafts

[willedoo]

This bloke does some good video presentations. This one gives a good explanation of what happens when hoons ride Harleys:

 

 

[nomadpete]

This can be a problem with Rotax 912's or any pressed crankpins.

[facthunter]

Hang on You are not allowed to criticise Rotax's. That Bloke's just trying to sell his product in super dumbspeak. Years ago Harley went to Splined Pins that Broach the spline in the wheels, when pressed in and it cannot move by twisting but it's a Once only thing, done at the factory with special alignmment presses. The whole shaft and rods assy must Be replaced but at Much the same cost as a normal rebuild. The usual term for that type of rod is Fork and Blade. A couple of small weld runs won't last Long as a repair. The Flywheels are steel forgings with the Mainshafts integral..The assembly HAS to be built up as the Big end Bearings are caged Rollers.  Nev

[onetrack]

I thought of splined pin design as soon as he started talking about the twisting problem. I wonder what welding does to the heat treatment of the steel.

The pin has to be hardened to exceptional hardness to meet roller bearing hardness levels. Arc welding puts a lot of concentrated heat into the items being welded and creates localised stresses.

Another anti-twisting technique would be to install a rectangular plate bolted into the end of the pin, which plate would lock into the flywheel plates via a recess, or via blocks on the flywheels - provided there was clearance for the blocks.

[facthunter]

They used to employ Nuts each side with Tapers, but it's better to Have More metal to press into The spline thing has been used for years now with No problems. Later Harley bottom ends are used for a lot of performance Specials. High interference Press fits cause distortion in what you are pressing into and you end up with unsolvable run out issues.  Nev

[facthunter]

 Press fits also Induces high stress in Parts before any extra load even comes into the Picture, from an engineering point of view..  Nev