Rear axle offset question
 

I was looking at the axle on my old 71 big block 157 in wheel base DRW C30 comparing it to a standard 3/4 ton axle. What is the reason the one ton center section isnt centered on axle meaning one axle side is longer than the other. Looking at the 3/4 ton the center section is centered on the assembly like all 3/4 and half ton Chevy trucks I have looked at.

Re: Rear axle offset question
 

The driveshaft and pinion gear of most differentials are centered.. This puts the ring gear offset to one side, making one axle longer than the other.. I can't see your C/10 from here but I can see my '71.. It's not centered...

Re: Rear axle offset question
 

I just assumed on the 3/4 ton the axles were the same on each side. I’ve never taken a rear end apart, beyond my capability. After reading your post I sort of understand a bit better. Still unsure why the one ton is so much different.

Couple pics, one ton axel is nice and clean, 3/4 ton is “weedy”

Re: Rear axle offset question
 

The HO52/72 from your 1 ton are off set like that. The dana 60 in your 3/4 ton is centered. Just a difference in axle designs. Also noteworthy here in my observation, most 3/4 ton Chevy’s got the Ho52, and GMC’s seem to have gotten more of the dana 60’s but this isn’t cut and dry.

Re: Rear axle offset question
 

Any idea on why it was designed with the offset?

I believe the 3/4 ton started life as a 72 Cheyenne Super that I sold the guy that owns it now. He parted it and this is all that’s left

Re: Rear axle offset question
 

There are 2 different types of drive shaft angles.
It helps with u-joint rotation and vibration.
Too much or too little angle cause accelerated wear.


U-Joint Operating Angles:

{The u-joint operating angle is the angle formed by two yokes connected by a cross and bearing kit. There are two kinds of u-joint angles.

The simple one plane angle found in most installations has all driveline slope confined to one plane, usually the vertical plane. The other type of driveline angle is compound angle in two planes. This is found in driveline designs where offset exists in both the vertical and horizontal planes.}

1 plane set-up

Attachment 2391081

2 plane set-up

Attachment 2391082

Re: Rear axle offset question
 

Interesting stuff. So maybe because the C30 has the 157in wheel base it required a different drive shaft set up than the shorter wheel base trucks.

Re: Rear axle offset question
 

I don’t think it being a long wheel base 1 ton is the whole deal, like I said, a lot of the 3/4 ton trucks came with the HO52 which is basically the same setup as the HO72 from your 1 ton. Part of the reason that the yoke and center housing is offset is because of the design of the removable 3rd member from that design of axle. In order for the third member to be removed the ring gear has to be able to clear the housing when coming out. The axles without a removable third member don’t have to deal with this so the pinion can be placed more centered in the housing if that makes sense. 14 bolt FF axles for instance (and likely the dana 60) just like your HO72 actually have a left and right axle shaft because of this, the driver side axle is shorter than the passenger, with the pinion being more centered it moves the ring gear and carrier further to the drivers side of the truck. The gear housing where the third member bolts up on the HO52/72 is more noticeable with this in my opinion with the big ole round center section on display. Heres a picture of a 14 bolt with the cover off and pinion yoke visible to illustrate this, which will be basically the same as the Dana 60 you posted above.

Hopefully that kind of makes sense. The HO52/72/110 can trace there roots back to the late 30’s/early 40’s, a lot of what you see in the later axles are just refinements and changes over time. I like removable 3rd member axles my self. They are pretty convenient for gear swaps and rebuilds. And they are tough as nails.

Re: Rear axle offset question
 

Ok thanks, more great information. Im just not that versed on this kind of stuff so I appreciate your input and the others.