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 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.

[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?

[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.

[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.

[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.

[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.

[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.

[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 .

[Billy81]

The main reason a lot of these guy's do the rear disc swap is because the drums can get full of mud and water when you go off-roading. That is also why most of them don't bother with the E-brake since they don't usually drive their trucks around town or do any towing.

[Firebirdjones]

Originally Posted by Billy81

The main reason a lot of these guy's do the rear disc swap is because the drums can get full of mud and water when you go off-roading. That is also why most of them don't bother with the E-brake since they don't usually drive their trucks around town or do any towing.

That makes sense. Not an issue with mine however, a 2wd 1 ton wasn't meant for off roading so it doesn't see that type of abuse.

[Mr. 250r]

If you can get a newer rear end cheap enough might as well do it as its not hurting anything except maybe taking up your time lol o and if you don't like the look of wider rear ends but i can't notice it but then again maybe im not looking

[wyattglock]

I have rear disc brakes on my 1 ton dually. Towing my 8000lb camper with a full load of firewood in the bed and my wife and kids in the truck, it stops shorter and better than it ever did with the drums. The drums I had were only reliable for blowing wheel cylinders. I tried everything from AC Delco to a no name brand and even after rebuilding the entire system front to back, a wheel cylinder would only last about 2 months. After 6 rebuilds I spent the money on the disc setup. Total spent was $365 and that included the Right Stuff prop valve for disc/disc. I guess it is all in what you are looking for.

[Firebirdjones]

Originally Posted by wyattglock

I have rear disc brakes on my 1 ton dually. Towing my 8000lb camper with a full load of firewood in the bed and my wife and kids in the truck, it stops shorter and better than it ever did with the drums. The drums I had were only reliable for blowing wheel cylinders. I tried everything from AC Delco to a no name brand and even after rebuilding the entire system front to back, a wheel cylinder would only last about 2 months. After 6 rebuilds I spent the money on the disc setup. Total spent was $365 and that included the Right Stuff prop valve for disc/disc. I guess it is all in what you are looking for.

Wow, blowing wheel cylinders definately sounds odd. I have the hydroboost on mine, still has the original 1979 issue rear wheel cylinders, no problems towing or anything.