The Stovebolt Site Forums The Shop Area Engine Shop hydramatic

1957 rusty stock 57 3600. Sat for 20 yrs, got motor back in action, but the old hydramatic wouldn't upshift or drive in reverse. I know many people think I'm an idiot for having the original hydramatic rebuilt rather than swapping it out for TH 400,700, but with the original 283 motor I think the truck will thank me later. The next step (possibly)is to change out the rear end. Which brings me to the question of the high end speed limit of the original rear end. I've heard sixty? What's safe? This decade of cars is new to me so if any one has any suggestions about any aspect of this restoration from past experience, please bombard me with direction.
Thanks,
New Guy

how about this suggestion- don't quit your day job!

The 283 is a good motor and that is what I am putting in my truck. The stock rearends are not noted for going fast. Sixty could have the rpms up. If you want to go faster you can 1) put taller tires on the truck 2) change the rearend ratios to something move highway friendly. 3) put in an overdrive transmission.

Figure out how you are going to use the truck and have fun. Good luck, Wayne

Thanks for the info ZB3,
I've heard that the hydramatic (and it's being rebuilt as we speak for a small fortune) will go one hundred mph no problem, it's just the differential that's geared low, so I'll take option 3 for 1000 Alex. What would you recommend as a good replacement to let this stock motor and tranny show it's true abilities? And by the way, I was hoping to keep the truck simple- Farm truck, with drag potential.
Thanks Again
RT

Sorry ZB3 I mean option # 2. Replace rear end, just wanted to clear that up.

You might look for a 3rd member from a '67-'72 3/4 ton, they have more rpm freindly ratios, 4.10 is common, and will go right into your existing rear end housing. The turbo 700 would be a good coice if you change the trans, it has a deeper 1rst gear than the th350/400, plus the overdrive. Just get the later version, the '85 and earlier have weak pumps.

If you want to drag, you don't want cruizing gears. Accellerating is what wins drags and you'll accellerate slower with higher (numerically lower) gears.

Glad to hear you're keeping the hydramatic. They have a reputation for being bullet proof.

Check out the old GMC trucks site. Several hydramatic fanatics hang out in the discussion forums. Yes they let Chevy owners in. Lots of good info has already been posted so do a search for "hydramatic".

Depending on tire size a 3.43 would give you decent highway speed and some pull when you need it. If just highway cruizing then a 3.08 or 3.23 or so would be fine. For drags then a 3.73 and higher. Everything is a compromise between acceleration and towing versus top crusing speed and economy. Have fun, Wayne

Thanks for the feedback guys,
I guess I'm hearing that with the stock rear end I would get more torque but couldn't get too far over 50 mph. Hmmm. What to do. Switch it out with a 4.10 or I'll just leave it alone- burn rubber then drive like AARP on the freeway. Oh and thanks for the vote of confidence in keeping the hydramatic- it is a very unique piece of mechanical history.

Thanks for the #'s Wayne, I'm going to see what I can find in the bone yards. I don't know the ratio on the current rear end but it seems to have alot of torque. Thanks for your help,
RT

Just don't get going to fast and out run the brakes!!!

Good point. I rebuilt the original single master cylinder, but should replace with the dual. Disc brakes in front might not hurt either.

ugly,

Where are you having your hydo. rebuilt and what is the damage?

The HydraMatic is supposed to have 100% efficiency as opposed to about 95 on a modern auto trans. Final drive ratio will be 1:1 so it is same as any manual trans that does not have overdrive. 1st gear is real short and just to get truck moving. After rebuilt, the HydraMatic is supposed to be bulletproof. I think you made a wise choice. go to www.areds.com and check with Leon

The hydromatic was a good transmission. I have a version of that vehicle with a dump bed and a 4 speed with a pto.

It seems odd that you want to race a truck that big, especially with a 283, unless drag means drag a trailer behind it in which case you may well want to keep your rear end gears and obtain an overdrive for it for more comfy freeway driving and fuel economy. With that trans you may be able to bolt on an aftermkt overdrive. Mine has the drum E brake behind the trans so I would need a stand alone overdrive (cost about 3k).

Good luck trying to find higher gears for that rear end. There are alot of guys in that same boat and finding even a 4.11 is hard. The original in mine is a 4.57 and believe me, at 50mph that motor is screamin'. To help mitigate the problem I added 19.5 inch wheels which raised my tire height from about 29 to 33 inches. That helped by about 10mph or a few hundred rpm's. This places me at roughly 2600 rpm's at about 60mph. I'd like to get closer to 2k for sound, comfort and fuel economy.

Now regarding brakes. Good luck. There is no off the shelf disc brake kit for a 3600. See the discussion regarding this in the hipo section. When I have this solved I'll be letting everyone know.

Mine was ugly but now its...less ugly.

Hey guys,
Thanks for the votes of confidence on the old cast iron tranny. I like that bit about dragging a trailer. I'll be lucky if it will considering it's current condition. All I could get from that hydramatic was first- but it would throw enough dirt to bury a honda. So- I'm hoping this old timer rebuilding it makes it as good as the tag phrase "bullet proof". This truck really is too big to competitively race, but I think it could do a pretty quick start. Thanks for your info- I need all I can get.

Rodger that RTV. Keep me posted and I'm in your area as well...