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Disc brakes on a 12 bolt

J

Jester1

1/2 ton status
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May 8, 2011
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Belgrade, MT
Since my son is on the national shooting team and we shoot 4 nights a week and fund raise another 2 days a week the only work on the blazer getting done is the planning. And since I have time to think about the suspension setup parts I need, I came to the need for longer brake lines, then started thinking of rear disc.

Now I have done some searching and found a ton on 14 ffb conversions and a couple on 10 bolt conversions, but I can't seem to find any on 12 bolt. Also looked into aftermarket a bit and saw no real suport there for brackets or parts. (Was amazed to fing diff cover)

I am thinking the 14 swap has become so common the poor 12 has been left behind. So has anybody done one? Is there something out there I am not seeing? Even a stockish setup (like getting the disc from an 82 Monte Carlo or caddy, brackets from a 91 half ton sort of deal?

Keep in mind still just a toy and not wanting some $1200 wilwood or brembo setup. The rig is a 73-350-350-203-12 with possible a gov bomb (for now) any thoughts are appreciated.
 
I'm running the TSM e-brake kit in my S-10 (has the 12 bolt from my '72 blazer). I have the Caddy calipers on it now, but I was running the non-ebrake calipers before.

http://www.tsmmfg.com/2531.html

They are bolt on, but the bolts kept coming loose so I ended up welding it to my axle.

I liked their kit because the rotor slides on over the lugs rather than being pressed on from behind like some kits. This makes it easier if you ever need to replace a shaft.

Unfortunately I don't really have very good pictures posted for the kit installed on my rig. This is a shot with the old calipers:
P1040867.jpg


And this is a bad angle shot of the caddy calipers installed.
P1050728.jpg
 
GM didn't use rear disks back in the day on anything that we could feasibly use except the big Cadillac's and Camaro's up until the 90's, and neither of those designs are very good, particularly compared to the later "drum in hat" e-brake design.

The problems I've seen with car/truck 10 bolts is that the brake mounting flange changed, so that might be part of the issue on the 12 bolts as well in terms of having a bolt on solution. Not to mention the 12 bolt was long gone by the time rear disks started to modernize.

As said, for these trucks, rear disks are pretty iffy in terms of necessity. GM has rear disk designs that work, but they seem to have really gone back and forth in terms of using them on the light duty trucks, and if they really had huge benefits over drum, they probably would have been 100% rear disks once they got the design figured out. It might solely be a cost issue for all I know, but that probably is not the only consideration they had.
 
I'm not so sure a set up for a ten bolt wouldn't work. The 12 bolt in mine now has the backing plates and drums off my stock ten bolt.
 
I want to keep the 12 cause my wheeling needs don't require a 14. It was just a thought of a simple upgrade if it was cheap or simple. Like I said it is a toy and I am being very realistic about the capability. If I want to get nuts I have three other rigs in the drive with 14's in them now. I am a fan of some stock and some mod stuff. Read rodsteration as my hot rod buddy's would say.

I have seen the brothers kit was looking more at stockish setup as in caddy calipers and stock bolt on brackets from something newer. I have set forth some cost/budget numbers that I want to stick to. I don't have a problem with the drums, but it's like tbi or efi disc are just nicer.

With that said I am sticking with my carb so may as well stick to my drums.
 
I have the kit from TSM on my '70. I have not had any problems with it, but I did have some testing to find the right master/booster combo for my truck. Some of that is due to my swapping of parts. (Bigblock and Sanden A/C compressor) As stated, the E-brake doesn't work very well. The service brakes work great. I didn't notice any huge difference in braking power initially, but I think that is due to not having the right stuff up top at the same time. I really like how disc brakes will modulate better when close to lock-up. I don't know if you would be able to justify that much money and work for that upgrade alone.
 
Not sure if they are the same but my '72 12bolt axle in my C10 has a CPP kit on it, and they can supply what is suppose to be a matching master cylinder and prop valve for it. (haven't driven the truck yet)

Having said that, I'm still trying to get my Blazer's 4wdb set up to stop as well as it did when I had drums.
 
Well with troubles some have had and cost of aftermarket kits I think stock it is. It this was a camaro or impala frame off then money well spent, but for a weekend woods runner, boat towing, gopher killer money well saved. It doesnt seem to have issues with stopping considering it 40+ years old.

On to other bright ideas, and silly daydreams.
 
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