Nightmare 10” drum brakes

[Cadillacmak]

I have a 97K1500 with junk 10” drum brakes. I’ve been fighting clunk and popping ever since I can remember. I’ve been fighting e-brake disfunction as well. Here recently, the right cylinder front cup blew out. Replaced cylinder, shoes, and hardware. Bled and drove, and blew it out again. Noticed when all reset and shoes adjusted to slight drag, front cup nearly to end of travel. Moderate hard braking blows cup out of cylinder. Anyway, I’m done with these 10” drums as I have been doing a lot of research on them and consensus is they are junk. I was considering a disc brake conversion for ease of maintenance but have read mixed results. I’m not concerned about gaining stopping power. I want mechanical peace of mind. MY MAIN QUESTION, some have recommended swapping the entire axle with the 11 inch dual servo axle from a larger truck or burban. What do I need to consider a must when finding the salvage yard axle. Gear ratio? Tube length? Etc. Do I also need the master as the disc conversion kits do?

Just in case you go disc brake, here is a link https://lugnut4x4.com/
Now here is the warning, mine have about 10k on them and junk, locked up solid and heat warped the rear rotors. Thanks to being in Alaska, no replacement calipers are available so I had to throw cheap ones on and forgo the E-Bakes until I can get a set of Wilwoods and a Wilwood hand brake. That and some better rotors, kinda frustrating for low mileage! Had a similar event with my Ford.

 

[Schurkey]

^^^ Flat-bracket garbage. Apparently engineered by a high-schooler who wasn't sharp enough to learn from GMs OEM caliper brackets that take braking thrust from the MIDDLE of the caliper instead of way off to the inside edge. Braking thrust therefore puts stress on the caliper mounting pins that they were never designed to accept.

 

[ShadeTreeMechanic]

Pop the cover off--you're going to have to do that anyway--and LOOK at the ring gear. (You'll want a fresh gasket, and correct gear lube. While you're in there, verify the condition of all the other gear teeth, look for rust/pitting, check the debris stuck to the magnet, and so forth. Pull the cross-shaft, then remove the C-clips and slide the axle shafts at least part-way out--If the seal surface isn't grooved or pitted, and the bearing surface isn't grooved or pitted, and there's no actual evidence of axle leaks...you probably can slide the axle shafts right back in without dicking with the axle seals or axle-shaft bearings. Be sure the cross-shaft itself isn't worn.)

You must be registered for see images attach

In this case, 41 / 11 = 3.73

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

You must be registered for see images attach

Do you have backing plates attached to the axle? Measure the backing plates, and hope they're about 12", to accommodate 11.x brakes suitable for a 6-lug truck. If you've got backing plates that are ~14", the thing has probably got 8-lug axle shafts, and you'd be better off with a different axle.


It probably came with 7200 GVWR wheel cylinders. SOME guys are installing the 8600 GVWR cylinders (slightly larger than the 7200 cylinders) as an "upgrade". I have no opinion on this. I haven't done that mod.

I will definitely be popping the cover off as I intend to give this axle a complete run through so I will check out those stampings. Thanks for that. New bearings, seals, and anything else it needs as well. I did measure the backing plates and they are around 12-13" total but not 14 or beyond. It came with six lug axles so good on that aspect. I might try the 8600 GVW cylinders just to be a guinea pig for ya and report back. @Schurkey, man I can't tell ya how much I appreciate the help!

 

[ShadeTreeMechanic]

Just in case you go disc brake, here is a link https://lugnut4x4.com/
Now here is the warning, mine have about 10k on them and junk, locked up solid and heat warped the rear rotors. Thanks to being in Alaska, no replacement calipers are available so I had to throw cheap ones on and forgo the E-Bakes until I can get a set of Wilwoods and a Wilwood hand brake. That and some better rotors, kinda frustrating for low mileage! Had a similar event with my Ford.

I appreciate that Cadillacmak. That's a nice website. I did some digging on the conversion kits for this truck. The thought of pad slapping the rears when the time comes was extremely appealing. I just can't stomach shelling out that kind of dough! The 10 to 14 bolt just seemed like a more economic approach. Maybe the tougher of the two options, but easier on the billfold!

 

[ShadeTreeMechanic]

^^^ Flat-bracket garbage. Apparently engineered by a high-schooler who wasn't sharp enough to learn from GMs OEM caliper brackets that take braking thrust from the MIDDLE of the caliper instead of way off to the inside edge. Braking thrust therefore puts stress on the caliper mounting pins that they were never designed to accept.

I feel like that flat bracket would have to be REALLY thick or else you would get flex from it when applying the brakes. Is that what you're referencing?

 

[1998_K1500_Sub]

I feel like that flat bracket would have to be REALLY thick or else you would get flex from it when applying the brakes. Is that what you're referencing?

This is how a proper, OEM disc brake backing plate design manages the braking forces. In particular, see the pictures. Go here:

Post in thread 'Need Help Advice On Rear Disc Conversion On DRW DUALLY'
https://www.gmt400.com/threads/need...c-conversion-on-drw-dually.59842/post-1279709

 

[Schurkey]

I feel like that flat bracket would have to be REALLY thick or else you would get flex from it when applying the brakes. Is that what you're referencing?

I'm less concerned with the flat-bracket itself flexing; more concerned with the caliper thrusting on the mounting pins. The pins were never intended to take the caliper thrust. Metal fatigue is a real thing. Pin breakage would make a significant difference in braking ability.

 

[Erik the Awful]

Pull the cross-shaft, then remove the C-clips and slide the axle shafts at least part-way out

If you pull the pinion shaft, replace the lock bolt. Never reuse these bolts. If the bolt breaks you have to invest in an extractor kit. Ask me how I know.

GM Genuine Lock Bolt (available in 1 pack or 10 pack)

More Information for GM GENUINE 14012702

Extractor kit.

differential pinion shaft lock bolt extractor kit - Google Search

Interestingly enough, the same bolt is used on GM, Ford, and Chrysler axles.

 

[1998_K1500_Sub]

If you pull the pinion shaft, replace the lock bolt.

I wondered about that little bolt…

I see they sell them by the 10pk. That’s telling.

The FSM says to use Loctite 242 on it and torque it to 24lbft.

I thought “Hmm… hope it don’t break”

Considering its function, I wonder why so tight. It’s got 242 on it to assure retainment, 14-17lbft (168-204lbin) seems adequate(?)

 

[Erik the Awful]

They usually come with thread locker already on them.