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5057 Auxiliary information please
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By cerial - Thursday, March 14, 2019 5:22 PM
I have a 3 speed that I have been moving around for years and finally getting around to using.
I want to marry the thing up to a np205 transfer case and run it and the transfer case divorced behind a sm465 and engine making 300 ft/lbs moving around a 5500lb(max loaded) truck.

That being said I am not 100% sure what this is.

Mine looks similar to this one in this thread.

The thing has what looks like the 31-37 case with the side rails. But it has 5057 cast into the case with 5117 stamped into the large cover. To make this more fun I think this thing has 5531 gears inside.

The ratios are 1.54, 1, .72 and the gears are straight cut. No helical anything or needles that I can find.

The rails shift great, bearings, and seals are all good condition. The thing looks like it could easily be tore down when that time comes. But for now everything looks to be in great condition. The front input has had a pillow bearing added and has a 1410 flange input. The output has a mismatched flange so I am removing .013" from that shaft so I can slide a 10 spline coupler onto that for a tight fit allowing me to mate the 10 spline np205 input right to the 5057's output.

But I am a bit concerned about just how much torque to put into this thing.

I have a old H.S. Watson flier that has Auxiliary recommendations for GMC which list the 40 series in the 300,350, and 400. Then it list the 5531 in the 450 and 470 series. Then it goes on to the 6231 and 6041 with the 360/426 gas and 3-71/4-71 diesels. But I don't have any info on this 5057 case. If it was built this way or is something someone collaborated.

I am assuming back in the day the thing was placed behind a sm420 4 speed and engine putting out 250 to 280 ft/lbs in which me placing it behind a sm465 with and engine making 300 ft/lbs I should be fine because of the ratio difference in 1st between the 420 and 465. But I really do not want to break this case or snap a shaft.

Here are some pictures.

Rough gear measurement




Short video showing it shifting.
By Geoff Weeks - Friday, March 15, 2019 1:54 AM
My 2 cents is I never gave too much consideration for mfg torque ratings. It all comes down to the operator. If you are easy on stuff you can put double the rated torque, if you can break and anvil with a rubber mallet, running half the rated torque it will still break! I put 1400+ ft lbs through a 1100 ft lb trans doing heavy work 20 years ago and am still using that trans today. All my Big Cam Cummins run 14" organic clutches rated for 1100 Ft/lbs at over 1400 without a failure.
I'm not sure how he managed it, but one driver where I worked would break the shift handle off roadranger! He said " Pete doesn't make good shifters, this the 3rd one I broke!" It is a solid rod that tapers to 1/2" thread for the shift handle and he would break it below the threaded portion.
Lack of lube will kill anything faster than too much torque, but shock load can cause an immediate failure. If you can keep from wheel hop or wheel spin on ice that then hits dry pavement, it should be fine.
By junkmandan - Friday, March 15, 2019 1:53 PM
Cereal----You ain't gonna hurt that Watson with the combo of engine and trans you've listed. So I assume You know you'll use four wheel drive in direct only .