9.5 14 bolt swap questions, beat to death I know............

[Supercharged111]

^^^ This is some horrible brake engineering.

GM (whos engineers have actual college degrees, and who can think beyond "can we make this bolt together", and who might consider secondary forces acting on the structure) supports the caliper by having the caliper bracket take the caliper thrust centered between or inline-with the pads, so there's no net twisting of the caliper when the brakes are applied. These clowns take the thrust way off to the inside of the inboard pad. There's about a three-inch "lever" from outside pad to mounting bracket.

This creates a torque reaction that would tend to twist the caliper on the mounts. At best, it would lead to uneven pad wear. At worst, it's going to fatigue the caliper mounting ears, caliper bolts, and caliper bracket, leading to potential failure.

Pure junk. Nobody with an actual mechanical-engineering degree would build something like this.

I'm with you on the concept, but in application how much actual deflection do you think there is? I run *gasp* slip on spacers on my road race Camaro and have no issues. Everyone else does too but we do all run ARP studs.

 

[Schurkey]

Given that GM mounts the caliper on rubber, I'd expect a heap of deflection from the leverage and the braking force generating torque on the mounting system--which wasn't designed to deal with that twist. Look at the aftermarket mounting bracket--flat steel who's only resistance to twist is the thickness of the plate. Even worse--consider the two steel bolts (pins) that are intended by GM to keep the caliper from falling off, but in this design are the only things holding the caliper in position.

In the GM system, with thrust being taken in-line with the pads, the rubber compresses a little, evenly on both the inside and outside of the caliper mounting. The caliper butts up against the bracket in the direction of rotor rotation. The amount of rubber compression is limited by the clearance between caliper and caliper bracket. There's zero "twist" on the caliper, zero twist and no appreciable stress on the caliper mounting bolts, and the caliper bracket is huge and sturdy enough to accept the torque.

I hope "Little Shop" has good liability insurance. Their design is faulty, stresses parts in ways they weren't designed for, and sooner or later someone is going to get hurt. Then the liability lawyers come and feast.

 

[Supercharged111]

Given that GM mounts the caliper on rubber, I'd expect a heap of deflection from the leverage and the braking force generating torque on the mounting system--which wasn't designed to deal with that twist. Look at the aftermarket mounting bracket--flat steel who's only resistance to twist is the thickness of the plate.

In the GM system, with thrust being taken in-line with the pads, the rubber compresses a little, evenly on both the inside and outside of the caliper mounting. The caliper butts up against the bracket in the direction of rotor rotation, but there's zero "twist" on the caliper.

I'm lost on where the rubber is on the newer stuff? Should be steel pins in the iron abutment brackets.

 

[Schurkey]

On my K1500, the steel pins ride inside extended steel sleeves...that have rubber seals holding them away from the caliper housing..

The older calipers had rubber O-rings in the caliper ears, a short steel sleeve went on one side, the outside was just the pin on the O-ring.

I'm not sure what I'm looking at in the photo above, but I'd expect the O-rings-in-the-caliper.

 

[Supercharged111]

I was under the impression this was an 800 or newer caliper. Now that I'm awake again, little shop uses the older style caliper, don't they? In which case it would ride on rubber.

 

[badco]

I took a 14 bolt out of a 90 and put in my 96 and it has a big drum brake that works better than any disc ive had.

 

[Schurkey]

Hell, yes. PROPER drums in back is no shameful thing; and the park brake system tends to be easier to work with than what often shows up with discs in back.

I have no idea why GM thought the Leading/Trailing Shoe brake system was a good idea. Common as dirt to pull the drums off, and find the front shoe on each side is totally shot, while the rear shoe looks nicely broken-in. It's not like we consumers expect to ROTATE OUR BRAKE SHOES. (Yep--with Leading/Trailing shoes, this could be a valid procedure to equalize wear if the drums aren't too badly scored--but who's going to go through the effort?)

Part of the problem is that GM--Ford--Chrysler--AMC (and others) spent decades thinking that brakes could be terribly weak as long as they were reliable. This leads to a society that ****** and cries about "speeding"--even though pretty-much everyone does it. Speed limits are set DELIBERATELY too low, and motorists are blamed, fined, maybe imprisoned if they drive a reasonable, safe, but illegally-fast speed. Made worse by the near-universal practice of "Policing for Profit".




I've got the parts--but little motivation or ambition--to stuff 11" drums in back of my El Camino instead of the OEM 9 1/2" drums. Maybe next summer.

 

[Supercharged111]

The only area a drum brake is inferior is its inability to deal with heat, a disc is easier to cool. Still though, out back you're hard pressed to smoke brakes. I'm not swapping to disc on either truck, just gonna keep rocking those semi metallic bonded shoes. Blue truck is due for shoes and drums and I really should have redrummed the dually back in the spring.

 

[DamHoodlum]

I'm with you on the concept, but in application how much actual deflection do you think there is? I run *gasp* slip on spacers on my road race Camaro and have no issues. Everyone else does too but we do all run ARP studs.

^^^ This is some horrible brake engineering.

GM (whos engineers have actual college degrees, and who can think beyond "can we make this bolt together", and who might consider secondary forces acting on the structure) supports the caliper by having the caliper bracket take the caliper thrust centered between or inline-with the pads, so there's no net twisting of the caliper when the brakes are applied. These clowns take the thrust way off to the inside of the inboard pad. There's about a three-inch "lever" from outside pad to mounting bracket.

This creates a torque reaction that would tend to twist the caliper on the mounts. At best, it would lead to uneven pad wear. At worst, it's going to fatigue the caliper mounting ears, caliper bolts, and caliper bracket, leading to potential failure.

Pure junk. Nobody with an actual mechanical-engineering degree would build something like this.

Im not road racing the thing, I wanted an emergency brake for a future 5 speed swap I preferred this setup over the weight of the drum setup (94#) They perform flawless, I have an exceptionally good pedal with the adjustable proportioning valve.

IF they are "deflecting" I can't tell.
Thanks for your concern though
Lets see your 14 Bolt setup......

 

[Schurkey]

They perform flawless, I have an exceptionally good pedal with the adjustable proportioning valve.

IF they are "deflecting" I can't tell.
Thanks for your concern though

That's the danger with fatigue failures. Things can work just fine, right up to the point of catastrophic failure.

Example: The first jetliner. Killed a lot of people due to fatigue failures from square holes in the fuselage, concentrating stress at the corners.
https://simpleflying.com/de-havilland-comet-first-jet/

Those long bolts weren't designed to take the thrust of the brake caliper, the fact that it's a bending load makes it even worse.

Lets see your 14 Bolt setup......

Nothin' special on either one.
The 9.5 semi-float in the K1500 came from an extended-cab "light-duty" 3/4 ton truck a few years newer. Apparently, I poisoned the clutches in the Gov-Lock. It doesn't work any more, but there's nothing busted inside. I need to pull the drums and verify no axle seal leaks, other than that it's working great.
STOCK DRUM BRAKES.

The 10.5 Full-float on the K2500 needs the drums pulled, I haven't inspected the brakes since I bought the truck. 'Course, I probably haven't put a thousand miles on it, either. Again, it all works fine. I've got a Tru-Track to shove into it, hopefully before winter sets in; I've got about a month to move on that project. With the axle apart for the Tru-Track, the brake inspection will be easy.
STOCK DRUM BRAKES.

Nothing wrong with decent rear drums. This would not include the ****** leading-trailing shoe rear brakes included on 1500s.