The Stovebolt Site Forums The Shop Area Driveline driveline thoughts , help?

Hey gents, I am finalizing the purchase of a 1952 1/2 ton panel truck. it has a 1958 235 c.i. engine , stock 4:11 torque tube rear end , and a 3 on the tree transmission. unfortunately it has 15 inch wheels.. I would like to go back to the 16 's and try to get some 3.55 gears. I am also wondering if there is a positive traction unit that would bolt up to what I have described? I know nothing on the fine art of setting up a rear diff. and adjusting back lash and such . but I know it is critical to have it done right. I would welcome your insight.

What are your plans for the truck? Highway cruiser? Daily driver? Go to the show only?

daily driver/highway cruiser . I have tried to use an online calculator to figure out what it would look like with the set up I described, but I did not know my transmission ratios. so I was unsuccessful .

I think you’d be happy with 3:55 gears. There is an article in the Tech Tips section on the swap. Can be done over a weekend.

thank you Sweet.

A super neat Tip by Sweet.
My experience: (I guess that's insight)........More than a day, more than a weekend. A lot of work. If you get it wrong, bad news.

I did a 1960 GMC Dana 44. I would have never purchased the necessary hydraulic press (I don't like hammering stuff on, no control), a 250 Ft Lb torque wrench, an in-lb torque wrench, built a pinion yoke holder, chiseled off the wheel bearings, purchased wheel bearings, wheel bearing seals, pinion seal, gasket, spider gears, pinion gear, ring gear, two sets of carrier bearings, two pinion bearings (one for set up, one for final), dial indicator, indicator holder, marking grease, back and forth balancing end play, backlash, pinion torque and contact pattern; and done all the lifting and grunting by myself if I did not have a 4X4 that needed a matching 3.92 Dana 44 rear diff. THAT I COULD NOT FIND FOR A GMC after 6 months of looking all over the USA and then got local rebuild quotes of $950 from folks I wouldn't trust.
The money I spent was less, I got more parts, and kept all the tools. It was a great learning experience that I now have but don't have anymore desire to do it than I did before. I've probably been lucky with the donor diffs I've used.

Up until then I have always found a complete donor rear end for $150-$250 with the ratio I wanted and Posi if I wanted that.
All I can say is Sweet makes it look semi easy, I did not find that. I believe he did find it "easy", with help and his experience. I did not study his TIP carefully and maybe the dropout diffs are easier. I am very mechanically inclined and I don't recommend doing it. I commend his good work and very nice truck.

I recommend switch to open drive shaft and getting (up to) a 3.73 that fits the width. Should be plenty out there. If someone is parting a truck that you can try out, all the better. If not, always open it up and look inside. To read the ratio stamped on ring gear and check all the teeth of all the gears. You still will want to double check wheel bearings.

Wendell, you're a planner aheader for sure. I would be just wanting to crawl around it and clean it up and such. Not thinking of diff swap at this point. I'm slow I guess. Anyway I know my thoughts are 180 from Sweet. But that's what you want. Yin and Yang.

Bartamos thank you for your input, I appreciate your wisdom.

I have done two 3.55 conversions with a knowledgeable friend (who had never worked on a torque-tube).
I had never been inside the torque rear-end at that time & I had never done anything in any differential.
My experienced/professional friend had done R&P changes in modern rear-ends (he had never seen the insides of a torque-tube rear end).

We had the complete installation kit.
We had all necessary tools (in a vehicle demolition/recycling-yard garage) and gauges (from Harbor Freight) and Prussian Blue (from NAPA).
We custom-made a few pipes that served to remove some seals/bearings/gears (as I recall).
We studied Patricks installation-procedure sheets several times (it was barely legible).
We did not have the benefit of Sweet's excellent Tech Tip.

The first time took us two long nights (which included cleaning all parts inside and out).
The second time took one long night - the outside of all parts had been cleaned in advance, and we knew what we were doing.

I am 100% pleased with the results.

I would not have tried doing this by myself, either time (or, in the future).