Anyone upgraded a full float 14 bolt to disc brakes?

[Schurkey]

If it has a bolt on yoke PINION CAGE it's a Aam 10.5, if not it's an Aam 11.5

FIFY. Yokes are held on with a bigass nut and washer. GM calls what you mean, a "pinion cage" on page 4B4-4 of the '97 C/K service manual. There may be other names for it.

 

[Jrgunn5150]

FIFY. Yokes are held on with a bigass nut and washer. GM calls what you mean, a "pinion cage" on page 4B4-4 of the '97 C/K service manual. There may be other names for it.

Eternally grateful

 

[joeblow867]

High Angle Driveline

I looked up the transfer case e brake from them. Looks like a pretty simple bolt on? Im interested. Do you use the stock ebrake cable?

 

[Supercharged111]

That's a cool looking piece, but it seems it'd be cheaper and easier to get rear brakes that already had a highly effective parking brake.

 

[Cadillacmak]

Thinking when my current rears are ready for shoes/drums/cylinders, it might just make more sense to upgrade to disc brakes. I found a site that sells kits for about $400 if you delete the e-brake (adding ebrake is 250-300 more which seems kinda crazy.) Truck is a 97 with 14 bolt full float and big block.

14-Bolt GMC and Chevy 14-Bolt Rear End Disc Brake Conversion

Lugnut4X4 creates the most reliable heavy duty disc brake conversion kits for 8 lug vehicles. For GMC and Chevy 14-bolt rear end disc brake conversion kits, shop now.

lugnut4x4.com

I have done this twice and the LugNut guys have a nice kit. That being said, all four calipers failed VERY premature. My 75 F250 that just started leaking out one day after very little use so I swapped it over to Wilwood. My 97 K2500 Suburban lasted a little longer and locked up, killing the rotors. The disks were a down grade over the drums in the 97 and I would not recommend it, I am going to build new brackets and run big Wilwood's in the future, kinda like I did with the front disks on my 75 F250 when I converted it from drum to 95 F250 brakes.

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[Schurkey]

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I just wanted to point out that THOSE brake pads are retained by that lovely iron all-encircling bracket, so the caliper mounting bolts aren't undergoing the awkward stresses that the crappy "disc conversion" kits promote. Since the pads themselves are restrained, there is no thrust on the caliper, unlike the older caliper design where the caliper itself held the pads, and the caliper bracket had to accept caliper thrust.

I don't know about the park brake system on that style of rear brakes--kinda guessing there's a separate shoe + drum-in-hat system like the rear disc brakes on my Trailblazer.

 

[joeblow867]

so the caliper mounting bolts aren't undergoing the awkward stresses that the crappy "disc conversion" kits promote.

Valid point.

 

[Big T]

Oh yeah, I forgot about the pinion support.

I have not seen the GMT-800 10.5 with disc brakes up close, but that's what I'd look into if I really wanted rear discs on a GMT-400. Mounts, need to be moved, but I'm unsure of other changes that may have been done to the axle.

I have a GMT-800 10.5 prepped for install on a GMT-400 K2500 Suburban 6.5 w/ 4.10 gears. The entire axle is 2” wider which brings the track equal to the front tires. You need to cut off and install new perches for the leaf springs at the narrower GMT-400 stance. Same with the snubber perches.

Saw a comment that you need to change the proportioning valve as the stock one delivers 80% to the rear. It’s just the opposite wirh 80% going to the front. GMB had a service bulletin recommending the install of a new proportioning valve that delivered a bit more (like 5%) to the rear.

I have never installed the prepped GMT-800 10.5 FF axle with disc brakes because I did the GMT-800 front disc brake conversion which significantly improved the braking performance. I’d sell it, but shipping costs are prohibitive. Axle is located at my Fullerton, CA home.

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[Big T]

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I just wanted to point out that THOSE brake pads are retained by that lovely iron all-encircling bracket, so the caliper mounting bolts aren't undergoing the awkward stresses that the crappy "disc conversion" kits promote. Since the pads themselves are restrained, there is no thrust on the caliper, unlike the older caliper design where the caliper itself held the pads, and the caliper bracket had to accept caliper thrust.

I don't know about the park brake system on that style of rear brakes--kinda guessing there's a separate shoe + drum-in-hat system like the rear disc brakes on my Trailblazer.

You are correct on the parking brake system.

 

[Gibson]

I did the swap years ago on the 14 bolt FF in the '80 I had.
Used the calipers with the parking brakes and used the SS lines in the rear and new lines in the front.
The brakes worked great, the parking brakes worked great, never had any trouble at all.
Used a modified combination valve.
Removed the residual from the rear wheel section of the MC and used a Wilwood adjustable valve and spent some time on a deserted road dialing it in, the valve connected right in where the stock Chevy connection was in the frame rail.
Had to make-up a couple simple brackets for the parking brake cables.
When all done the pedal was at the top, you started getting brakes in less than an inch of travel and the pedal was solid.
It wasn't a hard job, just a lot of fuss-an-fidget work.
Before I stated the job I got a set of hubs from a yard and put new bearings/races/seals in them and mounted the discs with new studs.
That way, when I jacked up the rig I already had the rebuilt hubs with discs ready to go, saved a lot of time.
Edit: If I'd had the "slip over" drums I probably wouldn't have done the conversion, but I came to hate having to do a brake job when you had to pull the axles and hubs off.
Today I'd probably just swap in an 800 axle.