Just found this forum, and I'm really impressed with the knowledge here! I have a '91 4L60 and I am threatening to rebuild it. Limited experience: with help, I did an old '65 Rambler trans back in the day, and I've done one TH-350 on my own, with success.


It is a "K" case, will bolt to a V-8, and it's stamping is 1SHM067C (9='91, type "SH" [whatever that means], M=4L60, 067=Julian Date, C= made on the second shift). The guy that owned it before me said it was out of an S-10, but I don't know which engine was in the truck.


The application is a street use, 400 horse, 383, 3500-lb. car. 4:11 rear.


So the basic questions are: 1) Is this a good core to work with? 2) What hard parts will I need THAT I WOULDN'T NEED OF IT WERE A V-8 TRANS? (I've been reading, so I know about the Corvette servo, boost valves, accumulator kit, and B-W fwd sprag).

Note: I've searched for about an hour, but did not find this topic addressed.

Thanks, Bob

 

Pardon me for answering myself, but it may help someone else. Here are my findings:

The "SH" in 1SHM067C translates to "S10, 4.3 V6, 2 wheel drive".

Also, the hard parts in this V-6 trans are identical to the V-8 (Incorrect. See post #4.), with the possible exception of some valve body small parts. A good shift kit like Transgo's 700-2&3 should fix any of that. Exception: I have heard that the "TV Modulator Downshift Valve Spring" is different in the V-8, and will not be found in the shift kits. I need to scrounge one from a V-8 valve body. The V-6 one may cause unwanted partial throttle shifting between 3 and 4.

Bob

 

towards bottom of the page. http://www.montecarloss.com/SSThunder/drivetrain.html

 

Eureka! The needed info is in the section entitled: "700R4 Overhaul Tips", after the picture showing which holes to drill in the separator plate. For future readers, here's a summary:
1) Replace the 3-4 apply fingers in the aluminum drum with the V-8 version (allows 1 more clutch & steel).
2) Remove the aluminum plate & top overrun steel plate from the forward clutch and replace with V-8 version (allows 1 more forward clutch & steel).
3) Replace the reverse input piston with a shorter V-8 version (allows 1 more clutch & steel).

 

I have found that the above three suggested mods do not apply to a '91 4L60 from a 4.3L. I believe they apply to 4 cyl and smaller 6 cyls.