Rear disc brakes for 3/4 ton?

[bohmankid]

Does anybody have any info on a rear disc brake conversion for my 85 gmc 3/4 ton?
Anybody who's done it have any good info/tips or drawbacks to the swap?

[mike in mo]

i have used the disk brackets from www.diy4x.com on both my 1 tons and they are great for a single wheel 14 bolt you use all the 4x4 front stuff the only thing after market is the brackets so you can buy parts at about any parts store when needed.

[Firebirdjones]

The swaps I've seen haven't used an E-brake setup so it's not an option for myself. Maybe they are out there however, something to keep in mind if that matters to you.

[bohmankid]

Originally Posted by mike in mo

i have used the disk brackets from www.diy4x.com on both my 1 tons and they are great for a single wheel 14 bolt you use all the 4x4 front stuff the only thing after market is the brackets so you can buy parts at about any parts store when needed.

Sweet, thank you. That is exactly what I was looking for. Can you give any extra info on hooking up brake lines? and the E-brake using the Cadillac calipers?

[bohmankid]

Originally Posted by Firebirdjones

The swaps I've seen haven't used an E-brake setup so it's not an option for myself. Maybe they are out there however, something to keep in mind if that matters to you.

After some research it appears most people would use 1976-1978 Cadillac Eldorado rear calipers(emergency brake equipped.)

[Firebirdjones]

Originally Posted by bohmankid

After some research it appears most people would use 1976-1978 Cadillac Eldorado rear calipers(emergency brake equipped.)

That sounds extremely simple, it's what I've seen on classic car rear disc swaps. Wonder why so many 14 bolt rear truck swaps I've seen didn't do that?
Calipers don't cost that much and adapting a cable to work with it shouldn't be too difficult.

[86c20]

i was thinking that same thing firebird. so many 14 bolts with no ebrake. in my state it is the first thing they check for inspection. that is the only thing stoping me from doing it. NEED MORE INFO lol
]

[Firebirdjones]

Originally Posted by 86c20

i was thinking that same thing firebird. so many 14 bolts with no ebrake. in my state it is the first thing they check for inspection. that is the only thing stoping me from doing it. NEED MORE INFO lol
]

Yep, I'd think most all states are like that. I know here to make the sandrail street legal I had to have an Ebrake on it. Required by law here.

Not to mention I tow a 10,000 lbs. trailer with my 1 ton, and that ebrake is a necessity. I can't (and won't) trust that cheesy parking pawl in the trans to hold this entire rig still when I park it and/or load it Besides that, it was pounded into my brain at a very early age to always use the parking brake no matter what, especially on inclines, much easier on the trans. I cringe when that sucker gets locked in because the weight of the truck is putting pressure on it, and then it BANGS out of park.

[bohmankid]

Okay guys, so I might be trying this soon. The reason you don't see many 14 bolts with E-brakes is probably because these Cadillac calipers are EXPENSIVE. here are some links to parts I might be ordering:
The disc brake conversion brackets
The Cadillac calipers

The calipers are $100 dollars EACH SIDE and they come with everything (springs, bolts, brake pads). You can get just the caliper only on Ebay for around $60. They say they work with GM and Lokar E-brake cables.

[Firebirdjones]

Cadillac calipers aren't that bad really, I can get them loaded (as you described with pads) new pins etc...for about $75 each. When you consider your standard front disc brake caliper loaded is about $50 it's not that much more money. You can spend $100 just on a decent set of pads.....

I mean if we are going to go through the trouble to make this swap, let's do it right.

I just wasn't aware the cadillac calipers were a fit for the 14 bolt swap or I'd have already done this.

[bohmankid]

Originally Posted by Firebirdjones

Cadillac calipers aren't that bad really, I can get them loaded (as you described with pads) new pins etc...for about $75 each. When you consider your standard front disc brake caliper loaded is about $50 it's not that much more money. You can spend $100 just on a decent set of pads.....

I mean if we are going to go through the trouble to make this swap, let's do it right.

I just wasn't aware the cadillac calipers were a fit for the 14 bolt swap or I'd have already done this.

I'll have to do some more searching to see if I can't get them loaded for that cheap as well. But if you do it soon, let us all know how it turns out! I might also try to tackle it as long as it stays under my budget of $300.

[bohmankid]

Oh yeah and then you need the rotors (same as the front of your truck) and figure out how to hook up the brake lines. Shouldn't be difficult at all.

[Firebirdjones]

Originally Posted by bohmankid

I'll have to do some more searching to see if I can't get them loaded for that cheap as well. But if you do it soon, let us all know how it turns out! I might also try to tackle it as long as it stays under my budget of $300.

I just deal with the local Napa, good bunch of guys that cut me 10-20% on parts because I'm in there all the time. I think they treat me like any other good customer or die hard car nut so nothing special really.

I'll have to dig into this again and see about the rotors for a full floater and make sure they are big enough.
The cadillac caliper swaps I've seen on classic cars were for small rotors, not something I've seen (or would want) on a 1 ton before so I'm curious.

[clinebarger]

I know rear Disc brakes are all the rage, But using a D52 caliper on the rear of a 3/4 ton truck is NOT a good idea, The rotor can only be so big & the Friction area is tiny compared to a 13" X 3" drum or a 13" X 3.5" drum. With the size of these drums, Fade isnt a valid argument. If you going after looks....Fine, If you tow I would take the drums or atleast a Factory engineered rear disc set-up made for a 3/4 ton.

[Firebirdjones]

Originally Posted by clinebarger

I know rear Disc brakes are all the rage, But using a D52 caliper on the rear of a 3/4 ton truck is NOT a good idea, The rotor can only be so big & the Friction area is tiny compared to a 13" X 3" drum or a 13" X 3.5" drum. With the size of these drums, Fade isnt a valid argument. If you going after looks....Fine, If you tow I would take the drums or atleast a Factory engineered rear disc set-up made for a 3/4 ton.

That's exactly my concern and why I was hinting at the size of the cadillac caliper. My 1 ton full floater has massive rear drum brakes (can't remember the size off hand) but the last set of shoes I put on cost $120 many years back Some auto chain stores don't even have a lathe big enough to turn the drums I ended up at a local big rig service store.

The cadillac rear disc swaps I've seen were for smaller 11" or less rotors that are meant for a 3400 lbs. car,,,that's just too small for the back of a 1 ton truck in my opinion, or even a 3/4 like you mention.

Honestly I've never had an issue with the rear drums, and never experienced any brake fade to speak of. If I do disc on the back of this thing, it needs to be a very large disc, a caliper to match, with an e-brake.

After I hit Napa tomorrow for some dimensions, I'll dig around for a dedicated swap kit that is worth of 1 ton braking power and see if there is anything out there. All the new trucks now have them so there should be a way.

[russgt]

http://offroaddesign.com/catalog/14FFdisckit.htm
Off Road Design, I've been very happy with their products. Very few people talk about what to use for a proportioning valve kind of like its some kind of secret. I installed a Disc/Disc valve from inline tube, but havent driven the truck yet to tell you how well it works.

[Firebirdjones]

Interesting, nice to see a kit out there. It says they are using front calipers from a 3/4 ton. What are they doing for an e-brake, I don't see it mentioned.

[bohmankid]

The kit that Russgt has posted doesn't use an e-brake unfortunately..

Aren't the calipers on Cadillac Eldorado 'big' enough? lol I mean, they fit over the stock chevy 3/4 ton rotors.
Here is a pic of a dana 60 with the cadillac calipers:

[bohmankid]

Here is a link to another forum with some guys talking about putting the Cadillac calipers on the 14 bolt full floaters as well. Those Cadillac calipers look pretty heavy duty if you ask me

[MofoG23]

Guys - keep in mind, the most important part is the size of the rotor when it comes to braking capacity. To me, that rotor looks a bit on the small side - especially if you are towing heavy loads.

My rear drums have worked great with no issue when I'm maxed out hauling firewood.

[clinebarger]

Firebirdjones, I was directing my post to the original poster, I applaud you for NOT being one sided on the subject like most people that automatically assume Disc are better than Drum in EVERY application.

The Late 70's Trans AM WS6 F-bodies have the same rear calipers as the Cadillac, The rear brakes on these cars are more of a token item....Similar Disc-Drum cars stopped better.

[bohmankid]

good arguments here, keep em coming. I might have to stick with ugly ol drums. The front discs work so well that rear discs might be overkill on these heavy trucks.

[Firebirdjones]

Originally Posted by clinebarger

Firebirdjones, I was directing my post to the original poster, I applaud you for NOT being one sided on the subject like most people that automatically assume Disc are better than Drum in EVERY application.

The Late 70's Trans AM WS6 F-bodies have the same rear calipers as the Cadillac, The rear brakes on these cars are more of a token item....Similar Disc-Drum cars stopped better.

Thanks, I'm on the same page.
I'm not what you would call a disc brake finatic, although they are nice in some ways. I still have 2 cars here with 4 wheel manual drums and really don't mind it. With a few tricks like larger wheel cylinders, better liners and using the large shoes on front and back on each wheel (not using the small shoes) they perform decently for what they are.
Also less drag = better mpg and more power to the ground, no brake dust issues either

But they aren't for everyone I guess.

The only real attraction for rear disc on the 1 ton for me is the easy (and cheaper) rear brake pad changes/turning rotors vs. removing those drums, dealing with the bearings and torque settings, expensive shoes and finding someone to turn the drums.
Otherwise there is no other real advantage from my perspective. So it would take a long time for it to pay for itself since this isn't something you are doing all the time.

[GM-power]

I agree with the other guys. Keep the drums. In a towing application those brakes would probably be worked hard and heat up fast causing increased wear. The fact of lacking a e-brake also is a turn off.
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[mike in mo]

i have had disc on my 1 ton for 3 years now and it stops better now than it ever did with drum brakes. i have not tested the brakes on my 3/4 4x4 yet so i cant say what the smaller rotors will stop like as for the e-brake i cant say what works best there my is on the aux tranny and will be on the t-case in my 4x4 but the lines i used front hoses to match the calipers and made some tabs to weld on the axle tube to hold them. the line needs to float some.
im not going to say disc is best for everything but the self cleaning of disc is what i was after for my 4x4 drums full of mud and water don't stop anything. my road test of the rear disc brakes in on my 1 ton crew cab and that set up uses a lot bigger rotor than the 3/4 ton .