At my wicks end with this rearend...

[TrucknAndy]

I did my front brakes on Monday no problrem. I saw little improvement in braking so I thought I would dig into the rear. My first time doing drums so I was hoping for things to go smoothly. Far from it to say the least. Cant get the right parts for this thing to save my life as apparently my rear end is not native to the truck. I have a 1972 GMC fleetside with a 350(not orig. to truck), a thm 350 which may or may not be original. And, I am in desparate need of helping identifying the rear end or I may never get this rear end done...

The numbers I found were on the front pass. side of the axle tube. THSW253.
These were the only stamped numbers I found.

Other numbers found on the pumpkin 12345, 67890, 130, con2, and gm52

Lastly it has a 5 lug pattern which may have something to do with why Im having so much trouble getting parts. Maybe th pumpin is orig., and the axles were swapped for a 5 lug? Dont know much about that conversion, but at this point Im guessing. And, it is a 12 bolt rear end.

Thank you in advance,
Andy

[GASoline71]

5 lugs were standard in 1971 and 1972 in C10's.

Gary

[john]

THS = 1971 3.07:1 ratio 12 bolt.

[68gmsee]

Take a metal brush or steel wool and clean above the rear passenger axle shaft to see if there's a number stamped on top. You can see it better if you remove the wheel. I've heard that in some cases it's on the opposite side.

Also, if you can take a picture of the back of it and post it. Might be able to identify that way.

[68gmsee]

Originally Posted by 68gmsee

Take a metal brush or steel wool and clean above the rear passenger axle shaft to see if there's a number stamped on top. You can see it better if you remove the wheel. I've heard that in some cases it's on the opposite side.

Also, if you can take a picture of the back of it and post it. Might be able to identify that way.

Okay. Looks like john got it. Disregard this one..

[TrucknAndy]

John,

Is that what the THS tells you, or is that the whole thing decoded?

Andy

[cdowns]

the parts for your rear brakes are readily available from any autoparts store in the USA

[TrucknAndy]

Thats what you would think. However, the brakes that were said to fit my 72 were absent of the ebrake slot in the upper portion of the shoe. The ones that were found to fit with the proper ebrake slot were from a full size gm car. And, we are still searching for drums that will fit as in the case of the shoes the drums that are supposed to be for my truck are not correct. Very frustrating.

On a side note the parts store managers only explaination as we continue on this parts hunting journey is that my rear end might have been destined for a different type of vehicle, and that gm changed their mind. He says he has seen it before. Not sure Im buying it yet, but as long as I get the right parts, and can get back on the road I will be happy. Just with is was as simple as stating that I have a 72 gmc p/u 2wd 350 I would be happier and this would be far less painful.

Andy

[GASoline71]

I just replaced the rear drums, shoes and brake hardware on my 1972 GMC 1500 Super Custom longbed.

350 ci, TH350, 12 bolt rearend. Local parts store had the parts on the shelf.

There isn't anything special about what you have that would indicate any special parts that I can figure... just a run of the mill 12 bolt in a '72 truck.

Gary

[TrucknAndy]

Gary,

Did the shoes you got from the parts store have a triangular slotnotch for the ebrake to hook into?

Ill take some pics later so we can compare notes and hopefully get to the bottom of this...finally.

Andy
Posted via Mobile Device

[COBALT]

One word: NAPA

If you're going anywhere else and they throw themselves into a panic when you start talking about a car older than 1990 turn around and leave the store.

[geezer#99]

Here's a good reference link for drum brake rebuilding.

http://www.pbase.com/nufsed/drumbrake

[TrucknAndy]

So with the help of some really helpful guys at my local PS, and this forum my truck is almost back on the road. Awaiting parts at this point. I discovered that one of the previous owners put the rear brakes back together with parts that likely came from the junkyard. I ended up replacing everything from the axles out and it works. Just waiting for my hardware kit to arrive tomorrow and my parking brake lever from my local gm dealer. And hopefully we will be back on the road.

Andy
Posted via Mobile Device

[blackedoutharley]

With drum brakes its good to just replace everything anyways...

[TrucknAndy]

Still working on these brakes...

Ive got her all back together, but the pedal isnt buiding pressure, and having difficulties bleeding the rear drums.

A bit of background on what has been done thus far. Got all the correct hardware installed in the rearend(springs, adjusters, wheel cylinders, shoes, drums, and front pads.(PO threw parts off of god knows what to make it "work"). Replaced prop. valve w/ CPP replacement, and installed remanf. master cylinder.

Thoughts are that since the pedal isnt building pressure that a traditional bleed method wont work. Pump, pump, pump, hold, open bleeder. Rinse and repeat. Bought a hand pump style brake bleeder to elminate the pump hold method.

Problem is Im am getting just a small trickle of fluid out each time. Not a strong bubble free stream. Had to refill the rear master cyl. res. twice so I know fluid is moving, but it doesnt seem like Im making any progress to an air free brake system.

Any thoughts?

[TrucknAndy]

Bump...curious as to something else to try.

[TrucknAndy]

A flex hose!!!

Hooked by vac bleeder ahead of the flex hose in the rear. Filled the cup, and emptied the rear. MC res. in seconds. Been killing myself trying to figure this out replacing parts, and trying different bleeding methods, and its a flex hose. Ughh...lol

[Clyde65]

glad you found it Andy!