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Factory brake options/setups for heavy 1/2 light 3/4

dyeager535

dyeager535

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I keep forgetting to post this, finally remembered when I have a chance.

Ignoring the disk brake craziness, when swapping a 14SF into a 1/2 ton (as I have) rear braking is too much. I admit, I know little about any variations in brake calipers that were used. I suspect at least one tons were all different, but beyond that, no idea if all 1/2 and 3/4 were the same, different, etc.

Since I have the parts catalog (although apparently they are finally in PDF online now) I'd like to look at all the various components, and see if GM took the time to match masters/combo valves/calipers/wheel cylinders depending on the various brake setups, or if perhaps in some cases the master was the only difference.

I know the RPO's like JB7 and so on, but I guess the starting point would have to be, were "small calipers" used on the front, with larger-than-10-bolt drums in the rear? If so, what applications and maybe what RPO?

Obviously I'm looking for a setup with 1/2 ton calipers in front, with the 14SF in the rear....of course I don't know the diameter on my 14SF drums, but they are 5.25" deep vs. 4" on the 10 bolts. Edit: Looks like 6 lug 14SF's were all 11" drums, which I then have.

I also know I *could* use the smaller 10 bolt wheel cylinder with these brakes, but I'd rather swap the master than mix and match cylinders.
 
Yes, that's WAY more work than I want to tackle lol. Awesome, just more than what I want to do.

Really all I'm looking to do is reduce the rear braking. I drive this thing so little, and with so little weight when I do, that stopping isn't really an issue, just control in slick conditions with the rears locking up too soon.

I'm sure I can compare part numbers for the calipers 1/2 and 3/4, but the rear axle, not sure if I can determine which rear axle a particular model got, to cross reference that with the masters/combo valves used.
 
I have the exact same problem. Upgraded to a 6lug 14bsf rear and now the rear locks up pretty easy.
 
Could you put in an adjustable prop valve? Dial in exactly how much rear brake you want.
 
x eleventy... summit, wildwood, etc.. like $25, 2 flares, done...
 
I could, but I don't like additional junk and connections. Probably be fine, just not for me.

My suspicion is there already is something with the right proportions dialed in, just don't know what setups may have come with the matching front calipers, rear cylinders, combo valve, and/or master cylinder.

If there was no factory setup that used the correct combination of parts, it's either an adjustable valve, or try the 10 bolt wheel cylinders on the 14SF. I know they will fit and work, just no idea if they would work properly.
 
He could always splice in the "load compensator valve" GM put in the rear hard line too,and "adjust" it to the right setting where the rears wont skid,and secure the sensor arm there...too bad I threw away about 3 of those things,I'd send him one!..
 
I have not noticed the same thing. Mine is a hydro boost setup though. I did notice an slight increase in stopping power it felt like at least but my rears are not locking up prematurely

10 bolt front 6 lug 14 sf out back
 
Yeah, I've got to be real careful on anything other than dry pavement.

Is your hydroboost from a 1/2 ton, or 3/4+?
 
1/2 ton it's a diesel jimmy so other than the rear brakes and some extended brake lines the brake system is stock
 
blazinzuk said:
I have not noticed the same thing. Mine is a hydro boost setup though. I did notice an slight increase in stopping power it felt like at least but my rears are not locking up prematurely

10 bolt front 6 lug 14 sf out back
Click to expand...

same here, no issues w/ the 6 lug 14bsf :dunno:
 
Happen to know if you've got the big or small brakes on those? Donor vehicles?

I'd like to try and cross reference the wheel cylinders, donor vehicle/year would help with that. This is partially just to satisfy my curiosity, but it would be helpful as well to see why some have problems and some don't.

Mine is stock half ton stuff other than the rear axle/brakes back there.
 
I have 11" drums I thought all 6 lugs 14 sf had 11" drums

Donor vehicle was a K 2500 1994 6 lug rig
 
I would think pedal travel would need addressed if the fronts were swapped out. The problem is that the rears come in too fast, and too hard. They need delayed and/or lightened.

Not saying better fronts wouldn't help, but as quickly as the rears lock up, fronts that were more aggressive I would think would give little room for modulation of braking pressure.
 
blazinzuk said:
I have 11" drums I thought all 6 lugs 14 sf had 11" drums

Donor vehicle was a K 2500 1994 6 lug rig
Click to expand...

Ok, I think you just learned me something I didn't know. According to the generic parts catalogs (rockauto.com in this case) all 11" brakes on that truck were SF 6 lug. If they were 13" brakes, they were 8 lug/FF.

I was not aware of that...I thought you could get big and small drums with the SF, but at least for the 6 lug vintage, it would appear not.

Edit: So 1987 V20 (14SF) vs. V10 Suburban..Masters are the same, but the part numbers for the calipers are different. Saw reference on one board saying that they are dimensionally the same, but different pistons or something. Can't confirm, don't have the parts to check.

Combination (proportioning) valve I found one place selling them, claiming all the same for 1/2 to 1 tons. Might be correct, doesn't seem quite right, but if they are all the same, then that means no differences in brake bias, and the only way I can see that could be true, is if the increase in rotor and drum diameters were proportional to the smaller 10 bolt stuff.

Thanks
 
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There are three (I believe) different front calipers for 1/2 and 3/4 ton. They are interchangeable. I would swap to the bigger ones.

Martin
 
I suppose if the pistons had more surface area, it would actually work out by requiring more movement of the pedal to mvoe the pistons?

I'm going to check the part numbers when I get home.
 
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