The Stovebolt Site Forums The Shop Area Engine Shop Towing capacity of a 235

What is the towing capacity of a 235? I have a 3 spd tranny (w/OD that can be locked out) and a 3.90 rear end.

up hill or down?

Bill

Uphill, both ways.

then very little!
might pull a small aluminum boat on a light trailer, but the 235 only pulled med-heavy loads in the bigger trucks w/ 4.57 or 5.14 rear gears, and then pretty slowly - my 57 w/ that gearing hauls 3/4T or more in the bed, but not at highway speeds, and I avoid the ups

Bill

The 235 barley hauls itself. Mine has trouble moving my 62, 3/4. If you hit a headwind and have a slight load, you will soon find yourself with no more pedal left. It's a sinking feeling. lol.....

I have a 62 longbed with a 235 w/ a 4-speed and a 3.90 rear end. I pull a 1959 Glasspar G-3 (14') and trailer. The combo weighs just over 1000 lbs. It does just fine until I hit the hills. I can go 35 in 3rd gear on the real steep grades! I haven't towed the boat since I installed a set of fentons - there's one familiar hill I can't wait to test it on. By the way, What are you thinking of pulling?

You'll find the limiting factor to be your brakes. Not many hills here in southern Kansas, but right now I have two tons of dirt in the back of my 52 3/4 ton, 4.10 gears and 31" tires. She will run 60 with that load on any hill around here, but with that much of a load I don't run over 40 cause she doesn't like to stop. The 1/2 ton has even less brakes.

I have a GMC 270 in my '55 1st 1/2-ton, so I have another 35 cubes than your 235. The truck has an SM420 and 3.08 gears and modern 11 inch drums on the rear and 11 inch disks on the front.

I once pulled an 1800 pound trailer with two stripped car bodies sitting on it. I certainly felt the load both accelerating and stopping. It worked but wasn't fun.

I need to haul a 2000 pound load on the same trailer sometime in July and I'll be using a truck with a V-8 this time.

Looks like I've had more success with my 235. I've got a 3/4 ton GMC (1952) with SM420 and 4.56 rear end. I put a class 5 hitch on it and towed a U-haul flatbed trailer at a mile in altitude over dirt roads with a lot of washboard with a 2000 pound, engineless car on top. On the hills, I'd slow to 50, on the straights, I'd speed up to 60, so overall, I was able to average 55 in those rough conditions.

I don't think the 235 is capable of very serious towing either, but I was pleasantly surprised by how well it handled the U-haul car hauler.

Dad I'd bet much of the difference in our experiences is your 4.56 gears compared to my 3.08s. My motor isn't spinning as fast at 70 as yours does at 50.

Is it a Canadian GMC or a replacement motor? My '52 GMC came with a 228.

Yeah, no doubt. I don't have much top speed, but the torque is decent for an I6. No, it's not Canadian as far as I know. I bought it up in Wyoming and drove it down to Colorado. It had a GMC motor, I don't remember the size, but it had a screwdriver stuck in the piston when the guy tried to get it rebuilt. The screwdriver destroyed the original motor, so he found this 235 to rebuild for it.

I pulled a 2500# Datsun and 2500# of tools and car parts with my 48 Chevy 1/2T from San Diego to Seattle with the 235, SM420 and 4.10 gears with 235x70x15's. Top speed was 55-60. And the hills meant 3rd gear at 35mph (up and down hill, didn't trust the huck brakes with that much weight). Gas mileage was 11-12 mpg the whole trip, and she didn't drink a drop of oil, even through the Sacremento Valley in May when temps were around 90-95. Made the trip in 2 1/2 days, but my 48 has twin tanks (the 48 under bed and a 50 behind the seat), so gas stops were not too often, just a bit more pricey. :-)
Hope this gives you a few ideas. I would get a SM-420 for any towing duties, as a friend had a 60 with 235 and 3 speed that he blew up 4 3spds just pulling a 2200# utility trailer around WA state and that was with a bone stock 235...
Garry K

I have a picture of my 48 3/4 ton with a tired 235, loaded with a ton of hay in back. I am geared low and I dont even have to shift down on corners from 4th. Hills are no problem either, just slow. I have pulled my 16 foot horse trailer as well and it did fine in its speed range. I would not get on a major road with or without a load with my low gearing. These engins have loads of torque for pulling, but lack the horsepower to pull at modern speeds.
Ralph

I want to dump this 235 and replace it with a small diesel. We had a good discussion about this not long ago.

I have towed a 16' empty flatbed trailer 250 miles at 65 MPH most of the way with no problems. There were a few hills, but nothing significant. I need to buy fencing materials like 8" wood posts, 4" posts, t-posts, barbed wire rolls, etc., and the vehicle that I usually use for towing may not be available. Depending on how much I buy at a time, it could be a heavy load. However, I usually won't have to go but 10 miles with the load.

Pardon my ignorance, but what is a SM420??

Kels

SM420 is the 4 spd transmission that was used in the 1/2 ton thru 2 1/2 ton trucks from 1947 thru 1967. It is a desireable tranny for the off-road community due to the 7-1 granny low first gear. I think that it is just about the lowest 1st gear tranny ever built for a production truck. Hope this helps.
Garry K in Port Orchard, WA

Do you have a pic of that SM420? I want one.

I have 3 of them lying around the place Tab. I will try and get a picture of one tomorrow and e-mail it directly to you. They are still a 1:1 final drive transmission like the standard 3-speed, the only difference is they have the granny gear.
Ralph

My 48 1 1/2 ton can haul as much as you can get on her in granny gear, about 8 tons in second gear, Around 6 tons going flat or downhill in third, and not much more than it's self in forth gear. My V-8 1 1/2 ton truck will haul anything at any speed all day long,
Scott

Thanks Oldtmy! The 1:1 ratio kinda sucks but they have to be better than the crappy 3sp with no syncro in first. Are all the gears syncro? Will it bolt up to my 62, 235?

Tab - if it's syncro you want just get a later Chev Saginaw 3spd [67+] that has all 3 sync'd - what I've got in my 57 and 58 - same size case, same shift levers, same ratios

Bill

tab,
No, 1st gear is still non-synchro in the SM420, and usually we just start in 2nd, unless hauling heavy loads. But it will let you go with higher gears in the rear, Like 3.08's and still be able to get going off the line, and be able to cruise free way speeds, but I like my 4.11's. May swap up to 3.9's from a 55 gmc later, but for now I will just drive her.
Garry K

Garry I've got an SM420 and 3.08 gears, and I still start off in 2nd almost all the time. Of course its a 1/2-ton truck and rarely carries more than just the driver.

Of course I'm running a GMC 270 instead of the 235 and those extra inches do make a difference.

Tab, I just sent you a couple of photos of the SM 420 tranny via e-mail. Hope that helps.
Ralph