The Stovebolt Site Forums The Shop Area The HiPo Shop Crazy transmission talk

I'm thinking about running a 700r4 in my '54 GMC 1-ton to get the overdrive. If I do, I'll run a 454 in front of it.

Here's the problem and why I'm thinking I can get away with it. I'm going to use this truck to pull my 18 foot car trailer. I believe GM did not put this transmission behind the big block and while it is used in 3/4-ton pickups (I have one) even there they do not recommend pulling a trailer in overdrive.

While I enjoy power, I don't generally hot rod while pulling a loaded trailer. I'm thinking I can enjoy the OD when unloaded, making the truck much more usuable, and then just drive gentle in direct when its got a loaded trailer behind it. Even pulling hard up a hill the application of power is smooth and would not be like drag racing or that kind of harsh load.

The one other detail that makes me think I can get away with this is that I own numerous vehicles, and don't drive most of them very far each year. This one may only go a few thousand miles a year and may not go even go a total of 20,000 miles once I finish it.

The alternative is to run a TH 400 or TH 475, both of which I currently own. I could run a Cadillac 500 instead of the 454, but don't want to run that in front of the 700r4. Until I started thinking about adding overdrive I was planning to go with the Cadillac.

Do you think a 700r4 will live 20,000 miles behind a mild big block in a 4000 pound truck pulling an 8000 pound load? Or is this just crazy talk and I should go back to the Cadillac and Turbo 400?

No what you should do if you are serious about this combination is not use the 700R4 (which you would have to build the [censored] out of to make last up the first hill you came to) and buy a 4L80E and a controller (many companys make plug and play controllers to adapt this transmission to carbureted vehicles). This transmission WILL handle what you plan to throw at it and it will last as well.

Joe your experience matches my expectations. Buy a new rebuilt 700r4 and maintain it right and I'd expect it to work. And I have pulled a trailer using a small block and 700r4 and done okay. It will hit 190,000 in the next few days.

Running an overdrive automatic behind the Cadillac would require an adapter plate and I don't want the trouble or expense. The 454 needs to be moved and the Cadillac doesn't...

38 I don't want to pay for a 4L80e. Just the control box by itself will cost me what I expect to pay for a 700r4. The transmission will be thousands more. I have priced this option.

I'm building this truck on the cheap and while I won't skimp on safety and control aspects, this seems like a place where a realistic look at my needs means I can get by with a cheaper option.

Which part of the greater Seattle area are you in? I'm on Bainbridge Island.

a trans cooler on any vehicle that is being used to tow a heavy load or on a regular basis MUST have a trans cooler. Heat is what kills transmissions.
the fluid chemically breaks down and loses its critical friction and lubrication propertys which is when the trans starts to slip.
running full synthetic transmission fluid is also recommended (dextron Six, redline ATF)

http://www.transmissioncenter.org/compushift_4l60e_4l80e.htm

Yes the controller is expencive. a new transmission is more. how many times are you going to replace your transmission because it cannot hold the load your putting on it?
I was a builder for quite some time and the transmission i saw the most of was the 700r4/4l60e.
You CAN build a 700 that will hold what you want to throw at it if your REALLY easy on it for a while for about $2000. just make sure if you do go with a 700 that you adjust the kickdown cable right as this is the most common cause of premature failure.

a 700r4 is limited to hold about 450hp. they can be built to hold more but at a heavy cost and they are designed for drag racing, not constant towing. they are not ment to be used as frequently as it sounds like you want to use yours.

if the guy building your transmissions toomany3count and they only lasted 50k then he is not a builder, he is a backyard mechanic.

The motor I'm planning to run is a stock late 80's TBI 454. It probably does not make more than 300 horse. It would produce a fair amount of torque.

I have a '91 K2500 with a 350 and a 700r4 which I have used to pull my trailer. I'm not impressed by the performance but it has almost 190,000 miles on it, so I am impressed at the longevity.

The project truck will probably do most my trailer pulling once its done, but would rarely leave the yard, so its not like it will see a lot of use. I just can't see spending $3,000-$4,000 on the transmission when I won't have that much in the rest of the truck all together...

well i have to say too many 2 count is a smart man actually changing the trans fluid BEFORE they burn up their tranny. I assume the fluid will remain in the transmission for 100k miles all the way up to the life of the transmission with the exception of what leaks and is replaced by topping off.

I had one customer a week tops to have the fluid flushed or simply a filter change even who was not an existing customer who had bought that transmission from us.
as in... until they burned the thing up they forgot all about it or were just uneducated in the basic maintenance needs of automatics.

Yes changing the fluid on a regular schedule increases trans life greatly and SHOULD be done anyways.

I am a fan of the full synthetics because they withstand higher temperatures and are rated to be good for 100k miles. I've noticed better shifts as well from the improved friction modifiers.

if you are just running dextron III then LUBEGUARD is a great product. it is an additive. the black bottle is the one to run in GM's I believe but its been a few years sense I've used any fluids that i'd want to add it to.

I've done some more calculations and increasingly I'm not convinced I can save enough fuel to justify spending money on any overdrive transmission, when I already own the TH 400 and TH 475.

I may give up this whole line of thinking and just go with what I've got.

Does my brain hurt? Yes. And my back and my feet too. When my fingers start hurting I'll stop posting...

I think I just scored another Cadillac 500 with TH400. That may be the end of this story right there. I can drive this one into the shop and move it into the truck.

>The motor I'm planning to run is a stock late 80's TBI 454.<

I believe the 4L80e has been around since about '93. Get the 454, 4L80e, wiring and computor from the same truck. The price difference between a '93 and say an '89 is not going to be that great.
I hope you didn't expect to do this for pennies. You've got to deal with the extra weight, bigger brakes and steering $$$$$$$$$$$$ A couple of extra bucks for the drive train requirements you listed, is the least of your worries.

Richard I've not spelled it out here, but I already own all the motors I'm discussing here. The TBI 454 with Turbo 400 I've proposed using are in a wrecked '89 K3500 sitting behind my shop. The q-jet 454 with TH 475 are in an old P30 motorhome setting in my back lot, and the Cadillac 500 with Turbo 400 are sitting in the back corner of my shop. And actually there is a second Cadillac 500 with Turbo 400 setting in my yard, and though today it belongs to my son, within two weeks I think it will be mine.

This post was just about the the overdrive transmission issues. If you search on my name you'll find I've been dialoging on numerous other aspects of this truck project.

I would point out though that extra weight isn't really an issue. Any of the engine transmission combinations I've considered will not weigh enough more than the stock GMC 248 and Hydra-Matic to make a huge difference. And the truck I'm starting with has a GVWR of 8800 pounds which is only 100 pounds less than the '89 K3500.

While pennies isn't realistic I do intend to do this on the cheap. My intent is to keep the total budget under what a 4l80e plus controller would take new.

I agree to a point. He has the motor. I say go buy the Transmission, Computer, Throttle body off a 4L80 truck and use one of his motors. If you have a little negotiating skills you could probably walk away from that one with all the parts you need if you pull them yourself for cheap.