The Stovebolt Site Forums The Shop Area Driveline 59 1/2 ton rear swap?

Hi everyone, driving the old Apache around this week led to discovering a brand new noise when I get above 30 or so. Actually it's more of a roaring vibration that gets more intense the faster I go. Come to find my pinion bearing is getting nice and hot, so I could do a bearing swap, or I could use the opportunity to finally get a rear end with a better ratio than the stock end I've got. I'm a bit new to rear end swaps and I'm not really sure which years/models would have the same width and preferably 6-bolt pattern to match my truck. All I know is I'd like to be able to cruise at highway speed. Budget is a bit tight so I may just go ahead and replace bearings for now, but either way would like to start looking around. Any suggestions for what I'm looking for would be appreciated

A late 90s 4WD S10 rear axle is the right width and has the same 6-bolt pattern.

You will have to change the spring mounts on the axle, but it will work otherwise. You can find them with disks or drums to suit your fancy.

Make sure you get one from a 4WD though. The 2WD axle is 2" narrower.

If the pinion bearing is making that kind of noise and is hot, I would also suspect that metal debris has found its way into the rest of the differential, I think an axle swap is in order or at least pull the pig and inspect carefully.

I have yet to find a 6 lug s10 4wd axle. If they existed, they were a rare bird.

I think 6 lug wheel was used on later Colorado / Canyon 4 x 4 rigs.

Yes the Colorados are 6 lug. I’ve looked into that swap myself. I think it would work pretty well. Several different gear ratios. Limited slip easy to find.

The Colorado and Canyon pinion is located 2 inches to the right of center. You will be working with 2 separate drive line angles.This can be a problem. I know.

Doesn’t the left to right offset just take care of itself? Trans output and pinion are parallel by definition.

Hmmm....hopefully so but you might cause a single plane angle situation and you may cause a compound angle situation. You'll need to use an angle chart for the single plane angle situation and you'll have to calculate the true u-joint operating angle for each of the u-joints for the compound angle situation. Aside from that, no big deal.

You can read about them here: https://www.waterousco.com/media/pdfs/J3311-1-DSSP.pdf

I read it. Still confused.

I know that offset pinions are common. And commonly not associated with an offset powetrain. I can’t quite get my head around how they explain what “good” looks like in terms of verifying the angles.

Totally familiar and comfortable with the pinion angle concept from a “side view” perspective.

Let me try this. What you need looking top down are equal opposing angles at each side and generally something between 2 and 3 degrees will be okay. Less is much better. If you get past 3 I think I'd start to be concerned as I don't expect it will work smoothly for you. Looking at the side view, you need opposing angles at each end but you'll generally need an extra 1 degree (or maybe a bit less) to compensate for spring wrap-up. A lot of the stuff on the internet falls into two categories: YouTube videos which I don't pay any attention to. These can be awfully bad, actually. And non-video stuff written for either dragsters or off-road vehicles (which you don't have and which will have notably different considerations).

As for left to right offset and up/down offset taking care of themselves as I said hopefully but there can be complications. If you could see the driven u-joint going through the operating angle (assuming you have an angle and that the u-joint isn't running straight with no angle), you would see it travels in an elipse...which will have 4 quadrants. The driven joint will be accelerating and the receiving joint will be more or less decelerating at the same speed. And when that happens you have a nice smooth transfer of power. If it doesn't work that way you will have one joint arguing with the other and then you'll have noise, vibration, etc and the u-joints will wear out. In my experience it does not take much to mess things up. An up/down (side view if you prefer) coupled with allowance for spring wrap-up will usually produce at least for a while a compound angle and for that you need to figure out the operating angle for each of the u-joints. They'll be different. I've seen some offset situations where the spring wrap-up was just omitted, but you know all that does is to transfer that angle to the top side (if you follow that explanation). Point being if your rear end (and this is really a given with the setup in the AD truck) wraps around under torque, it will flex the springs and allow the pinion angle to change...if your bed is off and you're a passenger you can easily see this happening as the truck is driven. You want that 1 degree allowance to bring the pinion angle into agreement with the angle of the u-joint at the other end (at the transmission). When that happens, things will be Jake. But you will have a compound angle there...either by virtue of having added a degree more offset or by allowing your drivetrain to add a different one for you. And during travel you won't always be applying enough torque to try to wrap your rear end as much.