Rear Axle Help

[mvfd70]

Well I surprised myself today. I'm rebuilding a 72 5 lug rear end to put under my 68. The surprise was that I got it apart without breaking anything that wasn't already broke and without loosing any parts. I've never worked on a rear end before so this is all new. Glad I got a shop manual for the truck. Anywhoo...I've got two questions about it so far. First, can the pinion gear shaft be separated from the pinion gear or is it one piece? The pinion bearing evidently went bad and tore up the shaft. I've got another rear end that I can harvest parts from but the gear ration is not the same. I haven't counted the teeth on that pinion yet to see if its different. If it's the same then that wont matter. Second, does anyone sell the rear drum brake dust covers that go on the inside of the drum? The plate that holds all the drum brake hardware and that the brake cylinder is attached to. Thanks in advance for your help.

[1969k10stepside]

I don't know about the 2 being seperated.Just don't put a different ring with a different pinion.What parts do you need.What ratio? I have an extra 5 lug rear over at my house that I dont need

[Longhorn Man]

The backing plate for the brakes... I am pretty sure it is a junk yard part only. Shouldn't be TOO hard to locate a set, have them blasted and painted... I would POR-15 them personally... it is much harder than paint, and won't rub off.
I don't THINK the gear and shaft are 2 pieces. If the gear ratio is the same, you could try mixing and matching parts, however, like a cam and liffters, they should be kept together.

[mvfd70]

I would like to keep them together. The rear that I'm building has 3.08 gears and the other one i've got has (i believe) 3.73 I haven't actually taken the donor rear end apart enough to count the teeth on the pinion. If the pinion gear and shaft don't separate then I need a new pinion for a 72 1/2 ton 3.08 rear.

[1969k10stepside]

FYI,you dont have to count teeth,get some numbers off the ring gear and compare them with the list below.Makes it a hell of alot easier.You should get a ring and pinion together.They are a matched set.The 5 lug rear I have has 3:07 or 3:08 gears.I cant remember.
Ratio 2.56:1 - Tooth Combination 41,16
Ratio 2.73:1 - Tooth Combination 41,15
Ratio 3.07:1 - Tooth Combination 43,14
Ratio 3.08:1 - Tooth Combination 40,13
Ratio 3.08:1 - Tooth Combination 37,12
Ratio 3.31:1 - Tooth Combination 43,13
Ratio 3.36:1 - Tooth Combination 37,11
Ratio 3.42:1 - Tooth Combination 41,12
Ratio 3.55:1 - Tooth Combination 39,11
Ratio 3.73:1 - Tooth Combination 41,11
Ratio 4.10:1 - Tooth Combination 41,10
Ratio 4.11:1 - Tooth Combination 37,9

[mvfd70]

guess I should have used a calculator instead of my head. Mine is a 3.07 according to your chart. 43 ring teeth and and 14 pinion. I'd like to keep that ratio if I can find em cheap. If not i've got more gears in the donor axle. If they're good that'd sure beat spending a bunch of money on new gears.

[mnunn454]

Pinion gear and pinion shaft are all one piece. Not separable.

I got my ring gear from www.drivetrainspecialists.com for less than $150 delivered a couple years ago.

Pinion gears are not "swapable" between ring and pinion sets, even if they're the same numerically. They are lapped in at the factory, plus the user's wear causes ring and pinion to fit "hand-in-glove". Swapping them will result in excess noise and wear, and with enough torque applied, break something.

When you do get the pinion out and the large pinion bearing seperated from it, take note of the pinion shim. You'll want to use it as a "starting place" for fitting any new ring and pinion set.

If you've never swapped one out before, it's be best to get a buddy who has, over as a coach. Doing this incorrectly can ending costing a lit of time and money.

Good luck.

[mvfd70]

Thanks. I'll probably just end up pulling the 3.73 gears out of the other axle.

[mvfd70]

OK i'm stumped again. What is the best way to get a pinion gear out of the axle housing without damaging it? I wouldn't think pounding on it with a hammer would be good on it.

[CMars45000]

Originally Posted by mvfd70

OK i'm stumped again. What is the best way to get a pinion gear out of the axle housing without damaging it? I wouldn't think pounding on it with a hammer would be good on it.

Many times, as was the case on my rear axle, the pinion can be ruined when knocking it out...Once the carre and ring gear are out and the pinion yoke is off, you have to hit the pinion snout with a hammer to knock it into the case... I tried to save it using a block of wood but I ended up having to use a 7lb sledge and reef on it for 10 mn to knock it out...

[Jim_PA]

I'm pretty sure the backing plates from 73 and up are similar (or the same) as yours, as long as they are for 2" shoes. Some had 2 3/4" shoes, and unless you want to upgrade to bigger rear brakes, you don't want them.

[Robznob11]

well i hate to be the bearer of bad news but like said befor a set is a matched no mixing and matching. my pinion came out easy on 2 diff rears i can't imagin having to beat it out, also when you put a gear set from one rear to the other you will probably be ok with the pinion shim on it but check. but more than likley you will need a shim pack to re shim the carrier (side) berrings becuase all rears are machined diff, also you need to use the carrier that the 3.73 is on cause it is a 4 series and 3.08 is 3 series the 4 is stronger, you will also need a in lb tq wrench to check pinion bearing preload and the used set will be a diff recomendation than a new set would, finally just to help others most all gm ring/pinion sets are stamped on the ring gear what ratio it will look like this 41:14 so there is no need to bust you bottom tring to see that pinion gear just turn the yoke till you see the stamp on the side of the ring gear. i have the richmond gear install video at the house when i get home next week ill email you the clearances and preload specs. pm me next wed if you interested.

[mvfd70]

Yeah I've learned that I cannot just replace the pinion. I think i'm just gonna swap out to the 3.73 gears. So there is no set way to get a pinion out? The 3.07 one was bad so I didn't care if it got busted, which it did while beating on it. I don't want to ruin a good pinion if it is still usable. Worst case though I suppose is i'll have to buy a new ring and pinion set.

[mnunn454]

Originally Posted by mvfd70

So there is no set way to get a pinion out?

Best way I've found is a solid brass drift (or round stock) about 8" long and an inch in diameter. After you have the carrier out and pinion nut and yoke off, place the drift squarely on the small end of the pinion and whack with a hand held sledge hammer or equivalent. Have a buddy nearby to catch the pinion because it'll come out quite quickly when it finally does move.

Also, watch the fingers. You'll need them later.


Good luck.