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

Thanks Ed.
I'll probably stick with the 235 for a while. If it ever gave me a reason to swap it out, I'd go with an LS.

-Nick

Just my opinion:
Since you are starting to establish your ‘minds eye view’ for your project I will put forth my view ( worth exactly what you paid for it),
our trucks were designed before the word freeway was invented, design top speed was 45-50 mph and slower for the bigger trucks, I see members discussing driving at modern speeds 65 and above and I just don’t see that as appropriate while staying with the original steering brakes shocks etc, even in fully restored/perfect condition.
You can re-engineer the entire truck and safely go with the flow on the freeways, or you can get the stock truck up to those speeds and white knuckle it (prayer is good), or you can take the path of enjoying the world at the slightly less stressful pace our trucks were made for.
No judgement, it’s your truck and I look forward to following your progress….. whichever way you go is the right way.


Chuck
Ps: btw, I have a fresh 235 with a T5 in my 46 1/2 ton, love the tranny, never use 5th……50mph I’m good….
PPS: nice shop!

An old thread I know but for the record both Spicer and Clark made 5 speed overgear transmissions with the GM bolt pattern. Some went in buses and had a tall shift tower and these are not so useful unless you find the correct tower. I've been told that Clarks are hard to get parts for. I had one but it was rusty inside so I abandoned it without looking for parts.

Tommy -- just my limited experience playing with Big Bolts, but those Clark 5-speed OD trannies are hard to find. The 5-spd non O/D are easy enough to find but, alas, no improvement as 5th gear is still 1:1

Been disappointed too many times in junkyards to spot a Clark only to rub the grime off the plate to discover its a non O/D ...

NP-540 series also come with OD(rare), problem is without two speed rear with a load, since 5th takes the place of third, there is a large gap between second and fourth, get stuck in second ‘til top of hill, really awkward. All 5 speed OD trans’ have this issue.

Ed

If your pocketbook can stand it a TKO 500 can take anything a six banger can put out and that's fully loaded on soft ground.

The T-5 will hold up well behind a 235. Ive put them behind 350 v-8's. Never had a problem. Just drive sensibly.

George

Nick,
I have a Chev 1954, 3800 flat bed with dual wheels, I purchased a GEAR VENDER overdrive. I still use the original gear box 4 speed
and the only thing major
to change was a new drive shaft. I installed it maybe 20 years ago and it still operates perfect.
Richard

To further kick a dying horse er.. thread:

My recent experience running at highway speeds (almost Canada to Arizona and back) tells me that a 4.57 axle ratio is about all you want to pull when loaded. I don't think it would be happy pulling a 4.10. These old trucks will haul a heck of a load and not complain but they just get slower and slower in the hills as they get heavier; I recently weighed out of the gravel pit at 12,500lbs. Last summer I changed from a 5.13 to a 4.57 to go with the 261 and so I could have some selection of tires and not be forced to use a 33in. 255/85xR16 of which there are about two choices, noisy and noisier, off-road deep lugs doncha know. But with the full load of the camper's wind resistance and weight I almost with I had the 5.13 back. With 2.65/75 R16s I'm running 2550 RPM at 60 in overdrive (17%) and 2850 was better for the cam I'm using. So I spend a lot more time in direct drive. I need a gear in between, maybe a 4.88 if I could find one. With a smaller load the 4.57 is great;

Since its an old thread and dying ....the point Chuck made about the speeds these trucks were made to operate at,45-50 mph, make me double think putting in a 4.10. ( yes I have one and a spare NOS ring/pinion set ). I find that 50 -55 is plenty of excitement as it is.

People tend to get spooky about running stovebolt engines in the power band where they were designed to work well. If an engine is HP rated in the mid-3K RPM range, insisting that it runs at a cruising speed a thousand RPM slower doesn't make good nonsense. Stovebolt crankshafts and connecting rod and main bearings are so over-engineered it's ridiculous, plus the forged crankshafts are tougher than woodpecker lips. With proper bearing clearance and good oil pressure, they will spin happily all day at speeds that would give most stovebolters a case of the screaming meemies.

My daily driver in college in the late 1960's was a 58 Chevy Del Ray coupe with a 235, a 3 speed, and a 3.70 rear axle. It also had 14" wheels. I routinely drove it 150 miles home on weekends at speeds from the mid-60's to the high 70's. It stayed together with no problems.
Jerry

Dusty,
I’m sure there are plenty of us 1-ton folks that would love to take them off of your hands, if your interested is selling them!
Mine was switched years back.
Jim