I rebuilt the 1997 flhtcui due to a twisted crank .012 pinion shaft run out. It is now 1 year later with a S&S trued and balanced stroker crank with less than 5000 miles and guess what, pinion shaft is .012 run out. Any idea what is causing this?

 

Wow! This is the first I have heard of a S&S Crank twisting like that! Was the crank new from S&S or had it been worked by somebody else? What did the Crank measure when it was first installed ? The first thing comes to mind is locking up the rear tire without pulling in the clutch...
Following to see what the experts have to say...

 

Evo cranks are not the same as Twin Cam cranks.

As far as the crank twisting, how is the bike ridden? Burnouts, down shifting without rev matching, hard roll off full throttle before pulling the clutch in, etc. puts a lot of stress on the crankshaft.

 

No abuse of any kind given to the engine, I even upped the idle speed so I wasn't lugging the engine. The crank was purchased new and trued and balanced by Revolution Performance. Yes it is under warranty, but who wants to tear down a new engine. Short from launching the bike on a drag strip I don't understand why these cranks can't take normal quick acceleration. It's not like I'm putting out 120+HP.

 

Someone other than S&S Cycle worked on the cranks before they went into your motor, putting the blame on S&S Cycle is unacceptable. Most people on the Internet have very poor reading comprehension skills and tend to make their minds up mid-sentence.

Was the cases inspected for damage after the first crank (stock?) was twisted before putting a new crank in?

Was any of the hardware (bearings, spacers, etc.) reused while putting a new crank in?

Who did all the engine work? Could they have made a mistake?

 

Pinion bearing fitment correct?
Timken and pinion bearing bores/races in alignment?
Scott

 

I guess somebody already misread, misunderstood, or assumed I was blaming someone. I'm looking for answers why this would happen and how to prevent it. This crank can't be welded so how can I make it bullet proof. I mentioned it was a S&S crank so people knew I didn't install a pos crank. I sent the cases to Revolution Performance and had S&S drop ship the crank. They installed the crank, after balancing and truing it, replacing all bearings.

 

People pin the rod throw to the crank cheeks with great success. Call Scott at Hillside.

 

These guys build all out bullet proof if you must and have no fear what the results may do to your body.

https://www.hdforums.com/forum/engin...flywheels.html

 

If the bike isn't seriously beat on about the only thing that will cause the older tapered crank pin fylwheels to twist is the crank pin nuts were not torqued down to spec or the holes weren't true when assembled. I have seen non harley flywheels where the tapers were out of spec new.