Stovebolt.com Forums The Parking Lot Tons 'o Fun Transmission upgrade options...

Hi Gents,
I'm going to start restoring/upgrading a 51 chevy 1 ton dually and i'd like some opinions on a transmission upgrade. The truck has a good 235 in it right now, and I'm inclined to keep that in there. I would however, like to upgrade the transmission to get an overdrive.
What are you guys doing in these cases?

I know a T5 is a common candidate behind the 6 in cars and smaller trucks, but I'm worried about it's strength in this big truck. I dont plan on doing lots of hauling/towing, but I would like to know that I could if I needed to.
Are any of you guys running T5's? Are there any other options?

Also, as part of this, I'm not sure what the rear gear ratio of this truck is. Were there different options or did all 3800 dually's have the same ratio?

Thanks!
-Nick

5.13, 4.56 if you are lucky. T5's are adequate if not hot-rodded. Any other OD trans' are much more work to install.

You might consider a D60 or GM 14 bolt with modern ratios and brakes that will let you keep your existing 4 speed.

Ed

Thanks Ed.

Since my truck is a dually, and I want to keep it that way, would I need to look for a dually 14 bolt replacement, assuming I go that swap route?
I need to brush up on the dually anatomy so I know what I'm working with and how it all goes together.

Thanks!
-Nick

Easiest solution is swapping 4.10 gears into the original axle, once you find the used gear set or third member. We have a tech tip for that.
https://www.stovebolt.com/techtips/axles/1%20Ton%20Upgrade/
This gets you comfortably to 55-65 depending on health of brakes, engine, and tire diameter.

For swapping axles the GM 14 bolt from a Cab and Chassis truck is about perfect swap for the AD 1 tons both single and dual wheels.
These axles are same width as the original, did have dual wheels and will again accept dual wheels in the AD truck, or single wheels if you like. Ratios available to about 3.31 too fast, 3.54 which may also be too fast.
Or the more useful 4.10 or 3.73, and other slower ones.

I agree that the T5 is probably a little small for the 1 ton.
The reasonable OD transmission choice is the NV4500 and you can find adapters and or info on adapting one, probably more work and particularly expense than changing gears or even entire rear axle.

Grigg

Thanks Grigg.
This is a great writeup, and looks like a good alternative to an od transmission.
I'll be upgrading to discs in the front too.

For those of you who have a 6 cylinder in there, and the original 4 speed tranny, and let's say the stock size 18" wheels/original size tires, does 4:10 seem to be the ideal ratio?

Thanks again!
-Nick

Yes, 4.10 is a good ratio for an otherwise original 1 ton truck. At least here in the hills and mountains it is, and if using the truck as a truck at times.

4.10 gears in flat land and or if never hauling anything you'll sometimes or more often be reaching for that next gear after 4th; a clear indication you're geared to low.
In that case I expect 3.73 would be a good choice, and reasonably sure 3.54 would be to high, though I've not tried either in a stock one ton AD truck.

They could go faster with faster gears but the brakes begin to feel inadequate, and you don't quite have power to go that fast anyhow.

Perfect.
Thanks Grigg!

-Nick

I have a 4.10 rear in my 57 3800 with the original 235. It does ok on flat roads but driving on some mild hills gives the engine all it wants. My 235 is probably not tuned perfectly even though is sounds pretty smooth.

Thanks. I'm thinking of updating to HEI, and rebuilding the carb, but I've got an otherwise stock 235. Most of my driving will be flat though.

Now would be a good time to start searching for a 261 for your 1 ton.

Ed