rear axle

[climberman]

I thought my powerglide was going out it was making nose found out it is the rear axle. It will cost around a $1000 to rebuild but the mechanic told me to get a new one that has disc brakes and then buy a kit to change the front to a disc brake. I like the idea but not sure which rear axle to look for. Thanks for the help I have a 1966 Chevy truck step side short bed


Rocky

[The Rocknrod]

Easier to keep the truck 12 bolt, buy the drive parts from Quick Performance.
Find an inexpensive rear brake setup on eBay, like a Cad or Riv (I think) with e-brakes.
Someone had a killer deal on a 9 inch (with C10 pads already welded) housing recently but I forget who. So you'd still have to buy all the inerds for it, It would cost you over a grand more total.

[jayoldschool]

Or, pop the cover off your rear end, have a look at the damage, and simply replace the broken parts. You probably only need a ring and pinion. Maybe a centre section. Either will be a lot less than 1k! The truck stopped for over 50 years with drums, it will be ok for a few more years. Of course, if you are building a high HP truck that handles well, yes, consider a complete rear rebuild and disc brake upgrade. On a stock-ish truck, just fixing it is fine.

[MikeB]

There's absolutely nothing wrong with 11" rear drums and a good quality front disc brake kit. I have owned and worked on several trucks with this combo and it works very well, even with a load and no power assist.

Yes! Keep the 12-bolt truck rear end, and simply fix what's wrong with it. Parts from many sources are readily available.

What are the symptoms, and exactly what did the "mechanic" say is wrong with it?

[nxtruck]

X3. It would be less expensive to keep and fix the 12-bolt. The 12-bolts are good, reliable units. Everything will wear out, given enough time. Chances are good that yours may never have been touched. I'd fix what you have, if it were me. My humble opinion.

[MikeB]

Originally Posted by nxtruck

X3. The 12-bolts are good, reliable units. Everything will wear out, given enough time. Chances are good that yours may never have been touched.

I've worked on 40+ year old truck 12-bolts that had never been touched. Ring gears looked like new on both of them, and backlash was in spec.

I added a limited slip to one of them and went from 6-lug to 5-lug axles on the other. Changed the big pinion bearing and race on the one that got the limited slip, just for the heck of it.

[climberman]

Thanks for all the advice its appreciated. I found an axle for $95 off of a C20 long bed. If that is the same as mine it will be cheaper to just buy it and replace the seals and bearings.

[AcampoDave]

You're gonna put a c20 axle on your c10? Don't do it. I've been there and done that as a young punk back in the 80's. C20 axles are 8 lug with numerically high gear ratios. 55mph was about as fast as I could go without winding the heck outta the motor. Just recenly when I needed a different ring and pinion set in my c10, I googled up related business that dealt specifically with rear differentials. I found one locally with very high ratings. I took it to them and was very pleased with the entire experience. I'm sure there are many all around mechanics who can do the work, but I felt better with a specialist. I know they are not likely located anywhere near you, but here is the website all the same just in case you can glean any important info from it.
https://www.ringandpinionservice.com/

[jayoldschool]

He's right, 100%. You don't want a C20 axle.

[climberman]

I wasn't going to necessarily I posted that to see if it was a fit but now I won't do it. That is why I am here posting to find out before do the wrong thing. Before I have it rebuilt I am still going to find one that is good shape if I can I am not in a hurry.

[Captainfab]

What year C20 rear end? Is it 8 lug or 6 lug? Any rear end newer than '70 will be wider than the 12 bolt you have. That can cause tire clearance issues. The '71-'87 differentials are 1.5" wider. The '88-'98 differentials are about 2.5" wider. I agree with keeping your 12 bolt and just fixing it. It can be done for less than $1k.

[MikeB]

IMO, wheels & tires actually fit the wheel wells a little better with the wider 70-72 rear ends. And you see a ton of 70-72 trucks with 8" rally wheels and 255 tires. In fact, I wouldn't be surprised if GM widened the axle to accommodate larger tires.

Found this on our forum:

The 70 1/2 and earlier width is 62-3/8" from wheel mount to wheel mount.
The 70 1/2 and later (up to about 78 or so) width is 63-3/4" from wheel mount to wheel mount.

That means with the longer axles, each wheel will stick out 11/16" more on each side.

[Heater63]

Keep your diff, rebuild and your good for another 40 years. Nothing wrong with drums on the back, but do put discs up front. If you have the budget, it might be an opportunity to go change lug pattern all around? I did, 5 lug, but Im purely street cruising.

[MikeB]

Originally Posted by Heater63

If you have the budget, it might be an opportunity to go change lug pattern all around? I did, 5 lug, but I'm purely street cruising.

I did the same. Had a machinist re-drill the axle flanges for 5x5". That was back around 1995, and probably 50K miles ago. They've stood up to a tire-burning 383 and an over aggressive limited slip diff (chirps around corners).

To the OP: Beware of cheap front disc kits that use the 5x4-3/4" passenger car bolt pattern.

[climberman]

I'm not sure what year it is but it won't work anyway so I will stick with what I have

Thanks for the help