TonyBabiak

They were making some changes in the mid 50s so I'm not sure which version you'll have. Here's a pretty good video of the older style.

I just got on the forums so I went back and read your story. Great project you have there. Your bores have some wear. Piston clearance is the whole story though. Get some long feeler blades or micrometers and check that. I've read that you can go as much as .003 per inch of bore diameter. That's a lot in my book but I know someone who's done it. Ring life will be shorter due to the pistons rocking in the bores. I tore down a Pontiac 421 once that had over .020" clearance and it had broken rings in 6 of the cylinders. Proper finish on the cylinders is important to get the rings seated so make sure you hone them as recommended by the ring manufacturer. Just sticking new rings in a worn bore won't work. Usually I'd say that if compression is much below below 80-90 lbs, you have burnt or sticking valves (or those broken rings). Squirting oil into the chamber and re testing will narrow it down; if the compression goes up it's rings, no change means valves. You can also burn a lot of oil with bad valve seals and/or guides. I'd make sure the crank and bearing clearances are right. Don't skimp here. Normally when you spin a rod bearing the rod is junk. Hope this helps.

Thanks for the info, I'll try it again. I can feel the different loads against the adjusting screws in neutral vs. drive. The procedure described in the manual is similar. It describes using a tach to monitor engine speed to detect when the band just stops the drum from spinning and making adjustment from there. I'm convinced that my rear drum isn't spinning, no matter how much I loosen the band. That has me worried. I'll also try setting the throttle valve. Right now it's set to where it was when I pulled the trans. This truck spent most of it's life parked in a fire station and has under 20,000 miles on it. I'm pretty sure it's the original trans. My understanding is that trucks kept the old style Hydramatics years after newer versions were available in cars. GMC had them available into the 60s. Thanks again for the info. 😉👍

If you really want air shocks take a close look at the frame crossmember that the upper mounts attach to. I use to run them on GM A bodies without any problems. I ruined the floor pan of a very nice 76 Chevy Nova with them, no frame, no crossmember. Just re-enforced areas that weren't up to supporting weight, but then shocks were never meant to.

57 Chevy truck Hydramatic. Last October it decided to shed it's front band lining. After thinking it over I decided that since I had no experience and was short on space and time I would have a shop rebuild it for me. I pulled the trans myself and took it to the shop, 65 miles away. They were the only shop I could find anywhere in my area who would work on it. It's an established shop with a great reputation and some experience with vintage transmissions. I got it back $1200 later and reinstalled it. I'm 64 years old, work by myself and still hold a full time job so it took me a while. The shop didn't have the band adjustment tools so he told me to be sure to follow the manual for external adjustment. Front band, no problem. Just like the book. The rear band, no matter what I do, has no effect on the engine speed as described in the manual. I have reverse. It acts like it wants to creep backwards in drive. I can feel the different loads on the rear band adjustment screw in neutral and drive but no adjustment I make changes anything. I don't want to pull the trans back out. I'll get the whole damn truck towed to the shop if I have to but I'd rather avoid the $400 tow bill if I can remedy the problem myself. As you can see in the picture, access for adjustments is not a problem. Anybody have any ideas?