Because of an ongoing issue, tranny came out (again). Question for you transmission smart types out there:

What is the tolereance between the OD of the Main Drive Gear Bearing and the tranny case ID?? Mine mic's out at .020" difference, ie the bearing is .020" smaller than the bore it's supposed to fit into. That seems like a lot of clearance! (and may well be the cause of my vibe/tapping issue!)

I ain't real smart, but a press-fit bearing OD should be going into an ID that is virtually the same size.

Anybody have the spec dimensions for the ID of the tranny case?

How many out there have found this problem with the newer (09-up) cases? Is this an ongoing, but non-acknowledged MOCO issue?

Thanks for any help!

 

That is too much for a outer race to case clearance. Do you still have the original? did it spin in the case?

 

By definition, a press fit means the bearing is marginally larger than the hole it fits into. Something seriously wrong with yours.

 

It didn't spin in the case, but it does look like it shifted a bit. Small diag. "chatter" marks on case bore.

Agree on the definition of press fit. Worked on helicopters for 20yrs and I've never seen a bearing fit that loose. Well, fit that loose and be right!
But it's HD and their "special" tolerances, haha. (.013" run-out on a crank....Seriously?!!??!)
Just need some technical advice from those who've worked on them.

I didn't even need to use the press tool to get the bearing out of the case, just gave it a good push with my fingers and PLOP, out on the floor it fell!!

Oddly enough, the gear pressed out of the ID pretty easy too, didn't even break the bearing. Is that unusual? Or does it happen occasionally?
The first time I pulled the tranny, the bearing seperated as expected. This time, the gear slid right out of the bearing.

I'm thinking a new tranny case is in my near future........

Anyone know if HD had a problem with overboring the cases for a few manufacture runs???

Thanks for the help!

 

Don't get sidelined by all the nonsense you read about crank runout!

Your bearing should be a tight fit in the trans casing and isn't. I don't know what the solution is, but suggest you talk to a dealer or indy about it and if there is a solution available, to correct it.

 

Update!

RTFB! Read The F#$%@#$ Book! Found the tolerances, .0003 to .0017. Which is less than what I have going on! And after some better measurement, is really about .002 to .0025, still too much though. Sheesh....

Here comes the new case. Oy, will the spending ever end. HAHAHAHAHA

And certainly not sidelined by crank runout. Just a statement about the moving target that is HD tolerances.

20yrs as Test Pilot on helicopters, I know a bit about vibrations and "wobbly shaft" acceptable limits. Only one kind of shaft I know of that the user would be happy with more "wobble"!! And engine crankshaft ain't it. ;-)

 

I did look in my much older book, but with no joy. Early in my career I had a hand in manufacturing helicopter engine compressor and turbine rotors - balance of those takes on a very different meaning! Glad you found the problem, but I'm not sure there is a suitable repair solution available. I doubt if a dealer will understand, but a local indy might just!