Impending Sprag Failure

[d55dave]

I am in the middle of rebuilding a '65 727 for a friend. He is putting together a big block '64 fury and wants a slip yoke cable shift transmission ('65 only) to retain the push buttons. He supplied a big block cable shift case and I found, from another friend, a small block '65 727 to harvest some internals from.

The small block trans came from a fury that had been parked (was running when parked) since the late 70s or early 80s. Everything in the small block trans looked great until I got down to the sprag clutch. I was really surprised to find that one of the sprags had rolled into the adjacent cavity, and a few of the springs and fingers on the retainer were deformed. Also there is a crack in the case directly above where the dislodged sprag was. The inner race is all brinelled as well.

I have often wondered what fails first in the sprag, does the outer race tear loose? I would say not based on this transmission. It appears that there is enough flex in the case allowing the outer race to move away from the inner far enough for the rollers to jump into the next cavity.

Man.... I dont think this trans had much time left..... and yes, I am putting a new bolt in sprag from A&A into the big block case.

 

[TrailBeast]

In the business we called cases like that scrap.
I'll bet you find that outer ring is split.

 

[d55dave]

In the business we called cases like that scrap.
I'll bet you find that outer ring is split.

I kind of thougt the same about the outer race, so I knocked it out tonight. I cannot see any fracture in it but it does have a pretty good groove worn where every roller sits.

I agree about the case. Good thing it is one part that I dont need from it!

 

[threewood]

If you are getting a bolt in sprag, get the ultimate sprag as it has a few more rollers. The standard bolt in does nothing beneficial unless the outer ring is loose in the case. You can see that if it jumps it will swell and split the ring and case. Worse case it will blow apart. Some bolts aren't going to stop it.

 

[TrailBeast]

I kind of thougt the same about the outer race, so I knocked it out tonight. I cannot see any fracture in it but it does have a pretty good groove worn where every roller sits.

I agree about the case. Good thing it is one part that I dont need from it!

Cool.

 

[jockeyshift]

Had to reread

 

[67Dart273]

I kind of thougt the same about the outer race, so I knocked it out tonight. I cannot see any fracture in it but it does have a pretty good groove worn where every roller sits.

I agree about the case. Good thing it is one part that I dont need from it!

Looks to me like it's split just CW from the doubled up rollers.......in the photo