the thrashed piece seems to be made of aluminum while the main body of the sprag is steel. This came out of my 88 700r4. The backside of the sprag has "GM4L60" stamped into it . It seems to be OK -it ratchets real nice and crisp and looks fairly new. Do you think its a 29 element unit? Why would the other piece be so flimsy? Ha ha... did you notice the spring? It didnt fare so well. Im surprised it ran at all. What would losing this spring do since I found spring pieces all inside the drum.

 

more pics

 

and the aluminum (I think) piece - Its awfully light.

 

Its not aluminum, its just weak steel. That is your overrun hub. That won't prevent it from moving, it will just cause a loss of engine braking. The only way to know if its a 29 element is to take the inner race out and count the number of sprags inside. I doubt its a 29, more than likely, its a 28 element which was used starting in 1987.

 

There did not appear to be any snap ring or other method of disassembly - like it was not meant to come apart.

 

There should be two snap-rings readily present. One that retains the overrun hub to the inner race, and one that holds that plate w/ springs (Overrun clutch return spring) to the input housing.

 

When I disassembled the trans the overrun hub and the sprag were not attached. The clip that held the two together had come off and had been chewed into non existence inside the drum. The sprag housing has no clip on it either. I hav a video showing how to remove this clip from the INSIDE groove on the sprag lugs - my sprag has no groove on the inside of the 6 lugs. Like I said before, It has GM4L60 stamped on it. I dont know if that means anything though. This piece looked dissimilar to the one on my video that can be disassembled. If my overrun hub was new I dont see how it could be connected to the sprag case since there is no groove, inside or out, for a snapring.

 

What you have is the Raybestos "mechanical diode". It is no longer available and was stronger than any Borg Warner sprag. As you see the overrun clutch hub is the weak spot (nothing available that is stronger here as of right now). If the mechanical diode looks good then I would reuse it, aling with a good used overrun hub.

 

how does ithe sprag attach to the overrun hub? When I disassembled the drum the hub and sprag were not attached and the clip (if there was one) was gone. It does not appear that ithe sprag will attach to the hub in the same manner that it normally would considering the snapring groove is not present. If you could shed any light on this It would help immensly since I have no point of reference as to how it should look fully assembled. Thanks again!

 

Do yourself a favor and get rid of it. I would use the 4L60E setup. This is the 29 element SKF Sprag and you should use the late versions of the whole assembly. It has been improved in a few key areas and holds up better than any of them. The Mecahnical Diode has not proven reliable. Ford used them OE on some truck units and has gone back to a regular Sprag in their heaviest duty unit. Every time we see one the whole drum is taken out by the failed diode. I had reservations about the diodes when I saw it at a Trans seminar and asked Raybestos about it. They gave me blank stares and took my name a number and said they would have an engineer get back to me on it. Still waiting.

 

Not to doubt you, Leo, but I have heard from many sources to stay away from the SKF brand sprags. This may be old news and they may have improved there product since then, but I have always used the Borg Warner 29 element sprags. Just wondering if you heard anything bad about the SKF (I guess not if you are reccomending them )

 

So the safe bet is to go with the borg 29 element unit plus I wont have to worry about how it connects to the overrun hub. Do the people that sell the sprags sell the whol sprag housing too? Any links would be helpful. Thanks.