help with pinion shaft thickness!!

[tranz am]

Im about to order up a set of gears for my 69 but it looks like 2 different pinion shaft sizes were used in the 12 bolt over the years. 1.438 in. & 1.436 in.
The rear end in my truck is a stock 1969 12 bolt. What size do I have? Thanks.

[tranz am]

Ok figured it out, I guess it depends on the carrier you have. I have a 3:40 or lower carrier so its the 1.438" pinion shaft or 3 series carrier. The stock carrier for my truck for the 3:90 was a 4 series carrier, thats the 1.436 dia pinion shaft. Thanks for looking guys, have a great one!

[71tahoe]

I only know car vs truck. 1.625 vs 1.438

[tranz am]

I find strange that the pinion shaft on a car 12 bolt would be thicker. It should be the opposite imo.

Originally Posted by 71tahoe

I only know car vs truck. 1.625 vs 1.438

[71tahoe]

Originally Posted by tranz am

I find strange that the pinion shaft on a car 12 bolt would be thicker. It should be the opposite imo.

It may not be based on the load that could be hauled but the relative gear ratios. Lower gears in trucks (higher numerically) likely apply a smaller torsional load to the pinion than a higher gear in a car.

[tranz am]

good point.

Originally Posted by 71tahoe

It may not be based on the load that could be hauled but the relative gear ratios. Lower gears in trucks (higher numerically) likely apply a smaller torsional load to the pinion than a higher gear in a car.

[Shaky]

Originally Posted by 71tahoe

It may not be based on the load that could be hauled but the relative gear ratios. Lower gears in trucks (higher numerically) likely apply a smaller torsional load to the pinion than a higher gear in a car.

Yeah, but .002 inch? That's probably within the tolerance on the diameter.

[tranz am]

yea .oo2 is hardly anything. that's thinner than a piece of paper.

Originally Posted by Shaky

Yeah, but .002 inch? That's probably within the tolerance on the diameter.