Noob trans question

I've located a "running" engine and trans for my bonneville for cheap. ...and said he would throw in a 4 barrel manifold with it.

It's a 389 that came out of a 65 pontiac. The guy said the trans is a turbo hydramatic. ...I am probably way wrong but I thought the hydromatic was only in 59 and 60s.

...am I wrong?

Okay let the bashing begin. Haha

The term "Hydramatic" was used from 1939-1980's. However, they're NOT the same designs as they changed throughout the years. The one that originally came in your '59 was a 4 speed version that used 2 torus' (dual coupling), rather than a torque converter like the 3 speed versions from '65+ models.

BTW, the 389 from the '65 is not a direct bolt-in as the motor mounts are placed differently. The trans from the 65 is also no bolt-in. You'll need to do some fabrication to get that combo to work, along with some custom driveshaft work. This is why most of us keep everything stock so there's little to no custom work involved.

Damn... Thanks. I don't know jack about transmissions and for some reason I thought hydromatic transmissions were a 59 and 60 gm thing.

I guess my best bet is to rebuild the original engine... Don't have that kind of cash right now.

...maybe I can find a 59 or 60 donor car.

I believe that you are incorrect about the motor mounts. I'm pretty sure that all 389/400s have the same motor mount bolt pattern on the block along with the 350s and most of the 455s. I know one of the motors for a few years has a different pattern but I'm fairly certain that a 65 389 will have the same motor mount bolt pattern. I'm fairly certain that you can use '59 motor mounts on a 65 motor and it would bolt right in. I have no idea what the actual mount looks like on a '65. I believe the motor mount change was in the 70s

Most people don't call 64+ TH350s/400 "hydramatics" but the TH stands for "TurboHydramatic." Most people call them "Turbo 350s" or "turbo 400s." The early 60s "Slim Jims" were Rotohydramatics.

I still got that '63 389 and slim jim 3 speed if you're interested...

I'm positive a 55-64 389 will be a direct bolt in not including the trans just the motor.

And keep in mind that 55-60 motors use the same trans bolt pattern and 61-64 use the same bolt pattern and I believe that 65+ are all the same and interchange with Olds, Buick and Caddy. So you couldn't use your trans with the 65 motor but they do make adapter plates

Ok I read your original post again. You said you don't plan on keeping it original, so whats the big deal of making a 65 389 and trans work?

OK I looked on ebay, 65 motor mounts are the standard 2 bolt Pontiac pattern so you could use '59 motor mounts on a 65 block and it would drop right in. The Th400 behind the 65 motor will be smaller than your hydramatic so you won't have to hack up the tunnel or anything. Not to mention the TH400 has millions of aftermarket parts and are cheap and easy to find people to rebuild them. BUT it won't be as quick off the line because I believe the 400s usually have a 2.4ish first gear while your '59 hydramatic has a 3.8:1 first gear! You could really use that low ass first gear to get your big old boat moving but it would be better than running say a 4.10 rear end gear because you could still cruise at 2300 RPMS down the highway instead of turning 3200 with 4.10s. If I would have stayed with an auto I would have kept the original hydramatic.

I'm not sure if a TH400 is shorter or longer (or maybe the same) length as your hydramatic but the output shafts should be the same. I believe all 400s used the big out put shaft as does your original hydramatic. TH350s used the smaller output shaft. If you just need yourdrive shaft shortened, I paid Driveshafts Unlimited $109 to repack the carrier bearing, put in new U joints and shorted my d shaft 2" and it took them about 45 minutes to do it. I'm sure you could find a similar deal

The only other thing you might need to do would be modify the cross member which is not that hard if you have a grinder and a welder. I made a 1" long adapter plate to make my stock cross member work with my Muncie. no big deal

Thanks for the info. I found this 65 389 with tranny locally for $300 and it's suppose to run. I appreciate your offer though.

I have no problem with the idea of putting a later model engine in but the only problem is the fabricating part. I don't have a welder and haven't done a lot of welding. I have a guy locally who can cut the driveshaft no problem.

Maybe I will give it a go.

Thanks again.

By the way, your starcheif I damn cool. I've always liked the gm flat top cars. Thought I was gonna buy a 59 Buick flat top a while back.

I think all 59/60 GMs were the most beautiful cars ever built hands down, especially the Buicks and Pontiacs.

There wouldn't be any real advantage of the 65 motor other than the ability to bolt up a more "modern" transmission such as the TH350/400/700R4 etc etc. The 59 block is actually A LOT thicker and stronger

If you had a buddy that could weld I'm sure he could at least tack up a modified crossmember to work.

Actually, the stock crossmember is a pain in the ass. The X frame on our cars makes it a pain in the ass to line up and the threaded holes in the frame are fine thread so it's damn near impossible to get the bolts started. You could probably come up with something better if you put some effort into it.

I wish you were closer so I could help you out

Thanks, I love my Star Chief. I've bought and sold a good amount of old cars but I'll never sell that one

Thanks. So far I haven't owned a car that I wouldn't sell for the right price. Maybe that will change with the bonneville.

I'm weird about 59 buicks and cadillacs... Flat tops and coupes. I'll own one of em someday.

My best bet would be to get everything in line for welding all at once. Floor pans, trunk, ...possibly crossmember. I should probably go ahead and pick that engine up. ...don't know the likelyness of finding a 59/60.

I just sold a '60 block and I've been looking for a '59 block. If you get that other block I'd buy your '59 block from you or if you want my 63 we could work out a trade. If it's a decent motor I'd pick it up if he only wants $300. I wanted $400 for mine. It's an original 80K mile motor that's pretty damn clean. I was going to re ring it and re bearing it and throw it in my 62 Gran Prix but lately I've been more into my Dodge trucks so I'll probably sell that 62 soon

Keep us updated on your progress

There it is after I cleaned it up