14 Bolt Full Float Drum Brakes

[Hoplite]

This is a really good thread. We should get the section out where he went step by step and sticky it. I'm sure plenty may know how to do this but there's plenty more that could use the run down.

 

[Schurkey]

I absolutely hate working on drum brakes.

Forty years ago, I heard the same stuff about disc brakes. It's all a matter of what you're used to.

The whole assembly looks too complicated for what it has to do, as far as I'm concerned. Could never figure out why they just didn't go to disks at the rear and be done with it. Even if they had to put a handbrake mechanism in there somehow.

If you have to ask "why", the answer is always "money". Big drums cost less than big discs.

I hate drums brakes. I agree with Ironhead. Disc brake swap is in my future.

I'm going to look into milling out my own adapter plates to swap discs out

It's going to be REALLY EASY to swap in ******, weak, poorly-engineered discs in place of those bigass drums. Doing this RIGHT, with discs that have at least as much stopping power and fade-resistance as the big drums, with calipers that are mounted properly to accept braking thrust, will not be cheap or easy.

Make sure you don't get into a collision with me.

Drum brakes are actually just as if not better mechanically for stopping a large vehicle. Only recently did they move to large enough calipers and pads to equal the stopping power of drum brakes...

THANK YOU. Saved me a bunch of typing.

 

[Caman96]

And aside from having to adjust them, now and then, they do last quite awhile too.

 

[someotherguy]

While I don't disagree about drums being perfectly fine (when correctly engineered and sized) for stopping a heavy truck..

The GMT400 3500HD trucks are 4 wheel rear disc (13.8" front, 13.5" rear) from factory and they stop the heaviest GMT400 truck ever made, even when loaded down beyond the 15K GVWR. The parts exist, so it's not like some new thing that discs only recently got "good enough" to use on the rear of trucks.

They use the same calipers front or rear unless you have the "wrecker package" which uses a dual piston caliper in the rear position, vs. single piston. The bummer is that being made for the straight axle front end / Dana 80 rear end, and 10x7.25" lug pattern, it's not like you're gonna easily adapt this stuff to a non-3500HD GMT400. Plus, no provision for parking brake, so the parking brake on those trucks is incorporated into a special extended tailhousing on the transmission.

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Richard

 

[95C1500]

Make sure you don't get into a collision with me.

You know it won't stop with disc brakes so stay out of the way

 

[Schurkey]

You know it won't stop with disc brakes so stay out of the way

The problem is not with properly-sized, appropriately-engineered disc brakes. The problem is with cheap-junk aftermarket "kits" or home-brew thrown-together crap that have less stopping power than the OEM drums, and/or improperly-mounted calipers where the caliper thrust is taken by the mounting pins on one side of the caliper, instead of the iron or steel bracket.

 

[95C1500]

The problem is not with properly-sized, appropriately-engineered disc brakes. The problem is with cheap-junk aftermarket "kits" or home-brew thrown-together crap that have less stopping power than the OEM drums, and/or improperly-mounted calipers where the caliper thrust is taken by the mounting pins on one side of the caliper, instead of the iron or steel bracket.

What's a "cheap-junk aftermarket kit" in your mind? Simply curiosity, no argument.

Also, I'm curious. Automotive engineer? Avid enthusiast?

 

[Schurkey]

What's a "cheap-junk aftermarket kit" in your mind?

Top of the list would be the typical flat-bracket fodder from Little Shop of Horrors, or any similar kits from their competitors (Lugnutz4X4, and others) that also use a flat-bracket and Delco or Delco-style calipers mounted via the long pins, caliper "floating" on O-rings or other rubber bushings. This forces the caliper pins and rubber to resist caliper thrust, stresses they were never engineered to accept--since GM doesn't use flat-bracket caliper mounts. The GM mounting system for this style caliper takes the caliper thrust between the pads, in-line with the rotor instead of an inch-and-a-half off-center, leading to both thrust and twisting stress on the guide pins. When it comes to metal fatigue, things work great...until they don't.

There was a big-long thread a year or so ago, where even the guy from Little Shop of Horrors posted that their kits were bottom-feeders designed to be cheap and available, not effective; they "aren't aware" of any failures. Post 54, but the thread is good right from the beginning. Read the whole thing. Other folks posting photos of their disc conversions DEFENDING THEM in fact display exactly what the problem is.
www.gmt400.com/threads/disc-brake-upgrade.57241/

Disc brake upgrade

Anyone have a review on these disc brakes…..or any other kit to put disc on the rear of a 97 2 wheel drive 1500?……………https://littleshopmfg.com/

www.gmt400.com

These companies selling cheap-junk kits are taking folks who don't know better "for a ride". I'd prefer they had ethics and sense.

Mostly, these are at best "Half-Ton" brakes, they'd be a disaster on something with a heavier GVW, which is why it's so easy to "convert" a heavier truck to discs, and LOSE stopping power or fade resistance, and some of these dumbass kits delete the park brake, making them illegal not merely stupid.

But discs are magic, and drums are evil.

Automotive engineer? Avid enthusiast?

Avid enthusiast, former "Technician" with a real-live diploma or two from a High School With Ashtrays (i.e., "Two-Year Trade School") IF you go back to when Fido's Great-Great-Granddoggy was a pup. Still, I've kept up my ASE certifications although I don't really know why.

For about thirteen years, my job with The City Bus Company included fixing the engineering problems caused by folks with college Mechanical Engineering degrees but no damned intuition, sense, imagination, or time to think things through. I think they had 35 engineers scrambling to do the work of 70. That company never released a "Revision A" drawing and Bill of Materials (parts list) for my departments (Powertrain including rear axle and A/C) that could be built as-designed. So far as I know, things were no better in Seats, or Lights, or Wheelchair Lifts, or Bike Racks, or whatever other part of the bus a person could be assigned to. Part of my job was to make what they designed, actually work in the real world, AND keep records of what I changed so that we didn't have to invent another "fix" the next time we were building that assembly.

If you guys had any idea how City Buses were built, you'd not only never ride one, you'd truly, madly, deeply resent how your tax money is wasted on "Transit".

 

[someotherguy]

A smart fella I know on a Mopar forum would refer to those kits as "bar napkin engineered"

Richard

 

[Dravec]

Top of the list would be the typical flat-bracket fodder from Little Shop of Horrors, or any similar kits from their competitors (Lugnutz4X4, and others) that also use a flat-bracket and Delco or Delco-style calipers mounted via the long pins, caliper "floating" on O-rings or other rubber bushings. This forces the caliper pins and rubber to resist caliper thrust, stresses they were never engineered to accept--since GM doesn't use flat-bracket caliper mounts. The GM mounting system for this style caliper takes the caliper thrust between the pads, in-line with the rotor instead of an inch-and-a-half off-center, leading to both thrust and twisting stress on the guide pins. When it comes to metal fatigue, things work great...until they don't.

There was a big-long thread a year or so ago, where even the guy from Little Shop of Horrors posted that their kits were bottom-feeders designed to be cheap and available, not effective; they "aren't aware" of any failures. Post 54, but the thread is good right from the beginning. Read the whole thing. Other folks posting photos of their disc conversions DEFENDING THEM in fact display exactly what the problem is.
www.gmt400.com/threads/disc-brake-upgrade.57241/

Disc brake upgrade

Anyone have a review on these disc brakes…..or any other kit to put disc on the rear of a 97 2 wheel drive 1500?……………https://littleshopmfg.com/

www.gmt400.com

These companies selling cheap-junk kits are taking folks who don't know better "for a ride". I'd prefer they had ethics and sense.

Mostly, these are at best "Half-Ton" brakes, they'd be a disaster on something with a heavier GVW, which is why it's so easy to "convert" a heavier truck to discs, and LOSE stopping power or fade resistance, and some of these dumbass kits delete the park brake, making them illegal not merely stupid.

But discs are magic, and drums are evil.


Avid enthusiast, former "Technician" with a real-live diploma or two from a High School With Ashtrays (i.e., "Two-Year Trade School") IF you go back to when Fido's Great-Great-Granddoggy was a pup. Still, I've kept up my ASE certifications although I don't really know why.

For about thirteen years, my job with The City Bus Company included fixing the engineering problems caused by folks with college Mechanical Engineering degrees but no damned intuition, sense, imagination, or time to think things through. I think they had 35 engineers scrambling to do the work of 70. That company never released a "Revision A" drawing and Bill of Materials (parts list) for my departments (Powertrain including rear axle and A/C) that could be built as-designed. So far as I know, things were no better in Seats, or Lights, or Wheelchair Lifts, or Bike Racks, or whatever other part of the bus a person could be assigned to. Part of my job was to make what they designed, actually work in the real world, AND keep records of what I changed so that we didn't have to invent another "fix" the next time we were building that assembly.

If you guys had any idea how City Buses were built, you'd not only never ride one, you'd truly, madly, deeply resent how your tax money is wasted on "Transit".

My cousin bought 5(?) retired busses at auction to scrap out. I've helped him a bit. Holy carp, these things really are a nightmare. Their build quality is sketchy at best. And the way things are routed makes less than no sense. I plan to try to never ride on one again.