Acceptable start shaft run-out

[Jeff H]

I've been chasing a high speed vibration for a while. Besides finding out that my fan is .003 off of being flat (checking the face of the fan) (I swear it was closer than that when I installed it :D )I pulled the start shaft , stuck it in the drill press and wow, even at 600 rpms you could feel a little movement. Indicated somewhere between .006-.008 on several attempts. Seems like alot to me, but then again, the shaft is long and well supported.
What do you think?

BTW this is in a CT

[DavidH]

Jeff,
I would recommend getting the fan run out down under .002 . I check the run out on the inside of the hub where the delrin ball rides. I am not that concerned about the top of the hub being flat. The gap between the clutch and the fan hub will take care of any of that movement. That gap should be in the range of .030 to 035

As for the clutch shaft into the clutch, those shafts are pressed in. It is possible that the shaft may be tweaked some. MA presses the shafts in the clutches. I have seen the process and and checked a few of them right after assembly. The ones I checked were always in tolerance ( less than .002). But it is possible for the shaft to be banged around and maybe get tweaked outside that range.

If the clutch shaft runout is not within tolerance, you can try to get it back in range yourself. Or you can send it to MA and have them do it.

David

[Jeff H]

I check the run out on the inside of the hub where the delrin ball rides
I wen't back and checked that and it was .0005 , so pretty darn good.

As far as the start shaft is concerned, I was only talking about the shaft. There seems to be .006-.008 runout from the top of the shaft and the bottom. The clutch shows the same runout.

Must have got bent in one of by better landings :D

Anyway, I'll try to straighten it , my guess is if there is a bend, its gonna be below the bearing block. Any tips for straightening it?

[DavidH]

Jeff,
If the clutch shaft is actually bent and not tweaked in the clutch. The only thing I will recommend is sending the clutch back to MA to have the shaft replaced. I believe that MA charges less than $10 to replace the shaft in a clutch.



David