The Stovebolt Site Forums The Shop Area Engine Shop Automatic Transmission Rebuild

Im tossing ideas around in my head about automatics and wanted some help. How difficult is it for the at home mechanic to rebuild a th350, 400 or 700???

I really dont mind buying any particular tools, manuals, etc, that I would need. Being pretty darn particular about how things are done I would rather do the job myself. Not something I plan on doing anytime soon, but I do plan on doing it myself eventually, regardless. Being mr anal compusive I figure no ones going to do a better job then me, and besides its fun learning and working on new stuff!

Ive never been a big fan of automatics but I have a project (actually my wife does ) coming up and a 327/th700 combo really catches my interest. I have an article (somewhere...) out of a magazine thats probably 10 years old about rebuilding a th350 and it seemed pretty straight forward, just making sure everything was assembled and aligned properly seemed to be key.

Thanks! Jeff

Jeff,

My unprofessional opinion. I do lots of mechanical stuff all day long but the one thing I wouldn't do is rebuild an automatic transmission.

My cousin had a transmission rebuild shop for 35 years. I worked for him when in high school as a flunky, and hung around a lot in my adult years (still a flunky).

There were some special tools, but the real special thing was the experience. The ability to see a thrust washer and know it was worn and wouldn't work, or the proper way to install a quad ring and know you hadn't pinched it.

Maybe I am over 'mystify' this profession as I have always thought this too technical for a shade tree mechanic. I would put my finances and energy into the more mundane aspects of the hobby and leave the automatic tranny to the experienced tranny man.

Maybe I'm too old and not as adventurous as some!

Stuart

I assisted with my first automatic trans rebuild in 1958, at age 12. My father was one of two mechanics in Nashville, Tennessee who started rebuilding automatics after WW II, so it's sort of been in the family ever since. Any kind of hydraulic system work is terribly unforgiving of mistakes, so I'd suggest enlisting the help of someone who is very familiar with the trans you're planning to build. A Turbo 350 is one of the simplest automatics to rebuild, and it's got at least 20 places where an inexperienced rebuilder can make a serious mistake. The Turbo 700 is worse, because of the way a series of interlocking clutch disks have to align with a set of progressively smaller splines. Just miss the engagement on one clutch disc, and the end play is wrong, resulting in a locked-up input shaft or rapid, massive wear if you force it together.

I think you need to find a pro willing to let you observe his work, at least for the first several rebuilds!
Jerry

Stuart is absolutely correct about having experience.
A few years back, I rebuilt a C4 auto as part of my ongoing restoration of my '65 Mustang 2+2 fastback. The rebuild was a success, I think. (car still hasn't been driven except up & down the driveway). After I got into it I quickly realized I couldn't tell what was acceptable wear on a few parts. And the rebuild kit didn't come with all the parts that could possibly be worn, such as that aformentioned thust washer.

I had fun doing it, but I am fully aware of the possibility of transmission failure.

So if you want to do it for fun and are ready to accept the possible bad outcome, I say go for it. You'll be proud as a peacock when the rebuild is a success.

The worst thing that can happen is Ill screw it up! Its only time and money, more will always come along. I appreciate the input so far, keep it coming. I like the idea of seeing someone rebuild one and I think I know a shop that may let me sit in.

It runs in the family but Im your typical norwegian, stubborn as a mule and theres nothing like telling me 'you CANT do it' to make me prove them wrong!

Thanks, Jeff

went to a vocational school my last two yrs. of high school. they had a dump truck load of motors and trannys come in at hte start of school. we unbolted the trannys and put them in a storage room. and spent the first 9wks. pulling apart engines and putting them back together. when we finally got to the trans phase of the school yr.our instructor had us sit in a circle and start tearing the trans apart and throwing the parts in the middle of the circle because and i quote"no way are you dumb sob's gonna be able to put them back together".......dave

Somewhere I have both a book on rebuilding a Turbo 350 and a rebuild kit. I've had the kit more than 15 years...

I can't claim any expertise and this is something I've not even tried before. Based on what I've read I do not think I'm afraid of a TH350 but a 700r4 would scare me. I've got a couple of TH350's around here and might someday actually do it.

I built a TH 350 about 20 yrs ago, never having seen inside one before. I had an excellent manual, & did it page by page. It worked fine. Don't think I would try a 700 at home tho.

I rebuilt my first THM350 in 1970 at the GM Training Center in Tarrytown NY. At the Chevy dealer in the late 70's, I did 87 THM350 rebuilds under a torrington bearing to case recall. Then came the THM250,375,400,425,700R4 and many others. Save your money, in a long run you are better off having a good trans shop do up a THM350 with a shift kit. Just my 2 cents.

I think you should give it a try. Learning how to do one unit is not that hard as opposed to having to do all different types. Feel free to ask me questions. The 700R4 is not that bad to work on.

Been doing them for years, not that bad with a bit of common sense.most kit's don't come with all the part's,like band,thrust washers and such.For the most part I tell people that if they drove it till it just wouldn't move anymore they may need a second tranny for part's.This way i have usally what I need for spare parts.Also I highly recomend replacing the torque converter or having it checked by a quality shop.Some failers are a result of a bad converter.Tom