View Full Version : Clutch engagement - South Bend 9A

10-18-2011, 04:51 AM
In both longitudinal and cross-feed my clutch will disengage after a few secs, more so under moderate to heavy load, unless I tighten the start knob about as much as I can by hand. I re/re'd and cleaned the apron a few months ago and all parts looked unworn and it has remained clean. It doesn't engage until the star wheel is turned almost all the way in and I can make it slip by holding the cross feed or handcrank wheel unless it is very tight. Oil sump is full. Any ideas?

10-18-2011, 09:59 AM
Did you take the clutch apart? The two times I've had the apron off my lathe for cleaning, I've looked at the clutch and decided to leave well enough alone.

Did the clutch have this behavior before you took the apron off?

If this is new behavior and if you disassembled/reassembled the clutch, based on my opinion of my own lack of ability to do that job successfully, I wonder if you got the clutch back together incorrectly.

I don't mean to suggest that you are as incompetent as I am, just that I think that getting the clutch apart and back together correctly again might be difficult.

10-19-2011, 01:23 AM
Yes, I did take it apart (just the 1/2 nuts and clutch), it was full of swarf and required alot of tension to engage. After I reassembled, it was better, but still did not seem quite right. Maybe those 1/2 moon discs are worn, no idea where to find the original dimensions. Guess I'll have to take it apart again and have a better look. It's not that difficult to reassemble and only appears to go together one way. I found some good photos of the procedure here:

10-19-2011, 08:55 PM
OK, took it apart again. I think there are a few wear areas contributing to the problem.

1. The outside of the shoes are showing some wear but feel smooth in the direction of rotation. (Maybe some roughing up will help improve friction for a better grip)

2. The butterfly leaves that expand the shoes are worn on the edges but not the middle. (reversing them may help)

3. The inside of the shoes have a groove worn where the middle of the butterfly leaves ride. (doubt this has much affect)

Here is a pic of a similar assembled clutch - forgot to take mine 1st:


I think the easiest fix may be to fabricate some new butterfly leaves but I will try some emery cloth on the outside of the shoes first. Well, maybe not so easy with no mill and my only lathe in pieces!

10-19-2011, 10:12 PM
Re: Post #3

Great link! Thanks.