Rearend Problems (with pics)

[lukecp]

As many of you know i have been having problems with keeping a 12-bolt in my '72. The original one started howling, so i replaced it with a junkyard 12-bolt, and it lasted all of like a week before it started howling too. That was about 3,000 miles ago, and i have been driving my truck with the howling rear, fed up and waiting for it to break.

So, today is the first day of my spring reccess from college, and i had some free time so i decided to pop the cover and see what was up. I was expecting to find that the pinion would turn over roughly, but that wasn't the case. Looks like the gears are shot.

Since the rearend sat in the junkyard for proably a decade, the axleshafts were covered in rust. I did not see this when i put in the rearend. And the fluid that came out was really, really dark. I pulled out one of the axleshafts, and rust was flaking off of it. The axle tube had lots of little rust bits sitting in it.

So, if you can see from these kinda fuzzy pics, it looks like the rust got ground up in the gears. You can catch the pits with a fingernail, so it looks like my ring and pinion are shot.

[lukecp]

Here is a close up of the gears

[lukecp]

Close up of the rusty axleshaft, you can see the rough patches of rust. Most of the loose stuff flaked off and ruined the fresh fluid i put in. The fluid looks like it is about 10 years old, when it is only a few months young.

[lukecp]

And the ring gear/carrier from the original 12-bolt, also in good shape.

[lukecp]

And the last one, the original pinion from the 12-bolt i took out of the truck. Also looks to be in good shape.

I think i am going to put the old 12-bolt back together with a new pinon bearing, then swap it in the truck. Hopefully i can get this done tomorrow or the day after. If not, looks my truck will be parked for awhile

If anyone has any imput, that would be great

[lukecp]

Also, how do i remove the bearing race from the rear? The outer pinion bearing race has some pits in it, i bought a new one along with the bearing, and i don't want to put in a new bearing with an old race.

I tried an hammer+screwdriver to pound it out, it wouldn't budge. Do i need a puller to do this?

I know i should buy the shop manual, but i have to get this done ASAP if i want to drive the truck back to college on Sunday. If i don't get it done this weekend, it may sit dormant until this summer

[1969 GMC]

ttt

[Yellow Cheyenne]

First off, don't mix parts from the two rear ends. Also, keep track of what side the bushings that are at the outside edge of the bearing races came out of. By keeping track of everything and keeping it straight where they came from, you may be able to get away with not having to do a complete setup on the rearend. Even though they may look like the same size to the naked eye, they are likely different. The bearings on the carrier require a special puller to remove them. You will also need to buy a new crush sleeve kit for reinstalling the the pinion. It may be better to carry the complete rearend into a shop and have them rebuild it. By not making them lay under the vehicle to do all the work, you may save some money there. If cheap is on your mind, clean everything up, put it together, and see what happens. You may be surprised at how well it quites down with some clean, fresh oil.

Good luck,

Randy

[Erl]

Well I have good news and bad news. Yes it takes a special puller to remove the pinion bearing (if you want to reuse it). If you are replacing the bearing then you can use another more crude method. The best way in your situation is to grind the bearing race off. I have also used a torch and cut them off. Get a small angle grinder and first cut the cage. Pull the cage off and remove the rollers. Now grind along the bearing (direction, axis of the shaft). Try not to hit the shaft, but a little will not hurt. Once you get close the bearing will split on its own or take a punch and hammer and wack it. Bearing inner race will come off.

[cdowns]

my theory on rearends is to have it done ONCE by a pro with NEW pieces using used and or junkyard pieces results in repeating the task over and over

[lukecp]

Well, i was planning on putting the old rear back together. The outer pinion bearing is toast, but the inner bearing as well as the carrier bearings seem fine. I kept track of the carrier shims and races when i took it apart so i am OK there. I'm not planning to mix any parts between the two rears.

I'm thinking i might just put some fresh fluid in the one thats in the truck and keep driving it. Since there was only dirty and rusty fluid in the housing and no metal specks (like in the housing of the rearend i have dissassembled) it might be OK for awhile longer....

I know i should do this properly or have a pro set it up, however there is no one in my area that does this kind of work that i have found. There is a retailer of ring and pinions who i have talked to, but that is it. The guy didn't know of anyone doning driveline work like that in mp part of the state.

Is there any kind of an additive "snake oil" i can dump in there so it might last a little longer? Like i said, i'm not concerned with doing this the right way now, because i have neither the time nor money to do it the right way, i just want to try and make it last a little longer until i can afford a proper rebuild or buy a second vehicle. I don't really need to drive my truck, but it sure is alot easier if i have a vehicle and don't have to rely on friends, family, and my bike to cart me around, lol.

Thanks for all the help!

[71-longbed]

try lucus oil additive in your gear oil .... a guy i know swears by it

[72hotrod]

Bro,if you took it apart, you got to put it back the right way or it wont last very long. Drive the old race out with sturdy punch and small sledge,debur the edge of hole, drive in new race with old race, finish with punch to bottom it(dont miss and score it).Use a little silicone sealant on yoke splines,locktight on nut. Use new crush sleeve and long cheater to sneek up on bearing preload. To measure preload,use INCH/lb torque wrench(look up spec for used or new brngs) and spin yoke(without carrier installed).Go slow and check carefully and more often as you get close.If you blow it,start with another sleeve and do over.Be sure you already replaced seal or do over or hope for no leak(probably will). Reassemble carrier with proper torque on bolts with locktight,caps on same sides as before,original shims on same as before. You will NOT get lucky if you do it wrong. If you can't do it right, take it to someone who can. If you do not use original gearset and original shim on pinion in original housing, it is more involved and you should get a pro. you won't learn how in 1 week. Good Luck

[lukecp]

Well, i put some new fluid in the rear that is in the truck and left the internals alone. I also put in my non-rusty axelshafts to keep more of that crap from flaking off. I used a mixture of the Lucas stuff (same name as me, it has to be good ) which appears to be nothing but really thick gear oil, and some 80w90. Still howls just as bad, hopefully it will last a few more months and few thousand more miles until i have the time and money this summer to mess with it.

Once again, thanks for all the help and imput

[71-longbed]

hey lucas... if it's any consilation ... i've talked to a few guys at my work and they both say they've had chevy's go another 50k or more after the howling starts ... its annoying i know ... i think im getting use to my howl, becuase sometimes i can drive and never hear it ....

almost eveyone i talk to says its really common

[lukecp]

Thanks Mitch. Well, i might just drive it until it breaks then . Being a broke 19-year old college kid i prefer not to spend too much money on my truck.

It is actually a rather soothing noise, if the truck didn't make so much wind noise and have loud exhaust it would proably put me to sleep

[71-longbed]

thats my idea right now (drive it til it dies) .... with both my engine and my rear end .... both have 243k on them ... im curious if i'll make 300k before i need a engine or differential overhaul ....