sst45 Crankshaft

[jimi1]

The APBA rules for SST45 state "...The crankshaft for the SST45 was prepared for racing by hand grinding a radius on the topcrankpin hole....When using a replacement production "fishing " crankshaft it is advisable toduplicate this feature."

https://www.apba.org/sites/all/files...tion022515.pdf

My question is "is this what they mean by the top crankpin hole"?

[powerabout]

yes thats it
That design crank has been around a long time so i'll bet there are a few different forgings ( it was cast in the old days do you know what model yours came from?)
If its large spline its forged

[jimi1]

It's from a replacement head I bought in 2014. Pretty sure it was a mid 80's as it had the nice xxx100 block.

The spline fit the existing drive shaft in the 45ss midsection so I never took the time to figure out which size the spline was. Here's a picture.

[jimi1]

Any idea why they (ABPA) would suggest radius'ing the top crankpin hole? Was it the only one that failed?

[powerabout]

It would have been OMC when they did some testing at 7000 and found some cracks so they ground it at the factory.
Same with the rods, so they didnt drill the cap oil hole but since you cant get either part any more the class needs to tell you what to do.

[jimi1]

Based on the photo I posted of my crank shafts bottom end, does it look like a large spline or small to you?