The Stovebolt Site Forums The Parking Lot Big Bolts 2 Speed Rear End

So just out of my own curiosity, does any now know what numbers on this ring gear mean. I know the first set it the part number but what about the rest of the numbers?

1956 Chevrolet two speed vacuum shift rear differential

3702244 GM = Part number

5-32 1 56 2 = ?

5-32 is the gear tooth count of the pinion/ring set (equates to a 6.40 ratio).

1 56 2 IMHO is most likely the date of manufacture (possible January 1956 - 2nd shift???).

Someone with more knowledge about the factory dating info will hopefully come along and confirm or correct my offered info.

Usually the stamped ratio is the high side!

Ed

5-32 will be the tooth count for the ring and pinion gears. You can confirm that by doing an actual tooth count since you can see the gears. Low range is accomplished by inserting a planetary gearset between the ring gear carrier and the axle shafts, reducing the overall reduction ratio to 8-something in most cases. "Slow"- - - -and "REALLY SLOW!"
Jerry

Multiply HI gear by 1.36 to get LO gear ratio. So 6.40 HI will have about an 8.70 LO.

Mike B

All of the responses are correct. Per the GM Heritage site, the high side 5-32 is 6.40 :1, the low ratio is 8.74 :1. I'm real happy with doner 2 speed that DougH6100 was able to part with, same ratios and a direct fit in my '57 LCF corporate axle. Before the transplant my truck would top out at 51 mph at 4000 rpm, now it can do 62 - 63 mph. It's pretty happy at 55- 60 mph around 3700 - 3800 rpm. Tire diameter will make a difference also, my drive tires are 10R-22.5, they are taller than the old 10.00-22.5 but I have not researched the diameter.

Your 10R-22.5 tires are 40" tall...

Mike B

Thanks Mike, they are a little close to the wheel wells in the rear but as long as I don't load it with 9000lbs. of beans or shelled corn it'll be fine. It was ok with 110 bales of hay but that's only about half of the capacity of it's payload. I took it to Church a few weeks ago, had thousands of deposit pop bottles in bags in the box, after unloading them for the youth group for their bottle drive, the young boys were excited to look at the truck, I offered to let them drive it, they and I had a blast going around the parking lot. The parents were thrilled that I let them drive.

That's awesome!!

Thanks for the info and yes the ring gear has 32 teeth, not sure about the pinion, didn't take it out.

Mike you are correct on those ratios. Counted revolutions of the pinion compared to the end of the axle. Slow and even slower.

Have you shopped for tires yet? I think I gave you the info for the shop in Ypsilanti, wouldn't hurt to check it out even before you get to the point of needing them. The big drives I have on mine make it "slow" and "not as slow".