It’s time to start on my rear axle for my ‘60 El Camino. I’ve got a 59 3.08 posi and a 64 3.36 posi. I took the 3.08 out of a 348 parts car that had set since ‘75 in a damp field. I got the 3.36 from a house flipper cleaning out an old biker’s lair. Confederate flag floors and every inch of the walls covered with easy rider centerfolds. It was hidden under a bench. I hope to put the 59 in my ElCo and save the 64 for my 63 SS in the future, but I’ll use whichever works now if I need to. I’ll probably use a 3.55 or 3.70 gearset. I’ve got a 350 with an M20. I’ll run 14” wheels and not too much tire. I’ve never gone through a differential before, so I’ve got some learning to do. It’s either learn on this one or putting lockers in my OT Jeep. The 59 reared was leaking like crazy so I figured I should reseal it. So I might as well put bearings in. And clutches. And re-gear. I think the 59 posi is virgin, but there’s pitting from sitting. The 64 has been messed with and has loose fasteners. Is there anything to watch out for that’s not in the factory manuals? Who’s the go to supplier on this stuff? I learned the hard way that I should have gone to 5speed Paul from the start when I did my Muncie. Is there a similar vendor for old posi stuff? What’s irreplaceable aside from the “P” case and the carrier? Both carriers have some bluing where shafts come through the body. Is that normal or is that heat and disaster? Pics: The bluing for lack of a better term: I’m spending money on power steering right now, but I’m trying to get a plan together for this next. Thanks.
Just check for normal worn out parts. Gut out your micrometers and measure the cone and flat plates, and compare that to the manual dimensions. The flat plates "are" still flat. No burn parks on any of the plates. Remove all of the rust. The inside of the case where the inner side gears rind, there's no galling on the case or gears, or on ANY other surfaces. No obviously worn parts, like the cross bars, where the side gears ride. Etc., etc. Clean well... Oil everything and put good parts back together, torque properly. No real magic other than just proper care and feeding, per the manual. Mike
M20 is a wide ratio Muncie isn't it? I have 3.36's in my 61 Impala and a 2.52 ratio first muncie and it works great
I wouldn’t run a bearing with a blue color. Indicates overheating, lack of oil, etc. But the shafts I wonder about, they don’t have the stress of a bearing on them. Guess I’m saying “good question”.
Thanks, this is super helpful. Yes, wide ratio. The more I look at ring and pinion prices, the better that 3.36 looks. 3.55 is appealing though. The fact that they’re both discolored in the same spots is reassuring, but it does make me nervous.
The bluing, if I'm looking at the right spot, might be where some used torch to heat the cross pin, to get it out? Maybe. Maybe forgot to take the locking pin out first, and was wondering why the cross shaft was stuck.
Note there are differences between early and late units. Early had fewer plates. https://www.trifive.com/threads/57-chevy-rear-axles-posi-vs-non-posi.197854/ "Below is a comparison of an early(left) and a late posi units. Notice the difference in the V in the case halves and cross shafts. As can be seen, the shallow V of the early posi unit will allow the cross shaft to slide up the ramp somewhat easier than it does on the late unit. As the cross shafts slide up the ramp, more and more pressure is applied to the clutch pack of the side with more traction."
The Jalopy Journal
