swap/upgrades to front calipers

[monstar_est87]

Hummm... Ok sounds good... Im staring a list of parts and all that good stuff...

 

[DGA1]

I just went through an upgrade on my '96 K1500 GMC with an F44 option, not to hydro boost, but the little more conventional route. When I got the truck it would stop reasonably well, but the pedal would almost travel to the floor. First thing I did was bleed the brakes which exposed that I had a leaking rear axle seal and a leaky rear brake cylinder that was coating one drum in grease and brake fluid. So after some serious cleaning, new axle seal, new brake shoes, brake cylinders, hardware, stainless steel lines all around, 1-ton calipers, I still had a pedal that traveled too far. I thought it was the booster, but after the truck was turned off I could pump up the pedal and it would hold firm and high, so it could not be that. In the end it was the master cylinder. It was leaking internally and letting the pedal fall as you applied pressure to it. Last night I replaced the MC and its much, much better. Even after a good session of bench bleeding the MC and bleeding the lines I still have a bit of mushy pedal for the first couple of inches or so, but after that the pedal feels normal and the truck stops with serious authority and I can drive it like I drive my little Subaru, tailgating if I please to work all the way again.

My truck came with brake RPO JB6, which are rated to 7200 lbs., on a truck with a F44 RPO which is rated to 6600 lbs. Now I've swapped everything but the big 14-bolt, full floating axle drums to my truck. The 14-bolt, semi floating axle, does come with bigger drums than the 10-bolt anyway. Besides that I've upgraded the truck to a full JB7 RPO brake system, meaning it's meant for 8400 lbs rated truck. One thing I've kept as it was, were the front pads and rotor. Everything bolted up and works like it should on the front end. Only thing I had to do was spread the inner pad retaining clips so they can fit snuggly into the bigger caliper cylinder. I just used my hands and it worked like they were meant to fit there...which they are.

Here is what I did to get to where I'm at and it's a huge difference from what was on the truck:
JB7 Master Cylinder - $30 after core charge
1-ton front calipers - $44 for two, after core charge
Braided stainless steel lines front and rear - $68 shipped from Summit Racing
1" bore rear brake cylinders - $20 for two; on larger drums 11-5/32" these are stock sized. On 10" drums these have a bore of 1-3/16".
Big jug of brake fluid is about $6-$7.

A total of about $170 and everything, but the lines, I got from AutoZone. Even cheaper if you leave the MC off the list and reuse your old one, but I'm not sure how much that would take away from the performance. And it’s even cheaper if you don't mess with the drums.

This is not as good as the Hydro Boost system, as it’s rated to 10,000 lbs, RPO JB8, but everything is an easy bolt on and an afternoon of work tops, with bleeding, if you want to do the drums.

 

[Arcane]

Nice write up!I'm planing to do the same.

 

[1BAD89]

wow you guys are full of advice. The 3/4-1 ton upgrade will be coming my way. I needed new calipers anyways.

 

[Darkrider]

Ok, I have an F44 spec Diesel K1500 it does have the hydraboost set up on it from the factory. Now my question is are the 1 ton calipers still a good upgrade on top of the factory HB setup? Also on a side note not all of the 1 tons came with HB my '89 K3500 only has vaccum boosted brakes. And a final note HB boost more then 10 times over the vac set up, more like 100 times...stock vac is about 14 psi and HB is closer to 1500 psi

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[outalne94z71]

Ok, I have an F44 spec Diesel K1500 it does have the hydraboost set up on it from the factory. Now my question is are the 1 ton calipers still a good upgrade on top of the factory HB setup? Also on a side note not all of the 1 tons came with HB my '89 K3500 only has vaccum boosted brakes. And a final note HB boost more then 10 times over the vac set up, more like 100 times...stock vac is about 14 psi and HB is closer to 1500 psi

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all diesel had hb no matter the weight, i don't see the calipers doing much as you are still retaining the small rotors so your brake surface area is still the same size

 

[Darkrider]

So no real reason to go with 1 ton calipers even though they are larger bore?

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[outalne94z71]

So no real reason to go with 1 ton calipers even though they are larger bore?

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larger bore just requires more fluid, have better brakes by swapping to a bigger bore master than you would just changing calipers, you still only have the 1/2 ton rotor size that have less surface area for stopping vs the bigger 9.25 ifs front rotors

 

[dagen_1]

i have a sticking caliper all of a sudden... so i guess i'll be doing the 3/4 ton caliper swap.

i have a few questions for the 2wd guys..

do i need to use 1/2 ton pads or 3/4 pads? if either work.. would 3/4 be better?

what year model truck would i ask for parts for?

my 89 has the light duty rotors by the way (smaller spindle shaft) can i still do this upgrade? (without changing spindles/rotors)

 

[ccreddell]

This is just personal opinion, but I think you should upgrade to HD spindles first. There was a reason GM did this-first on the EC, and then on the rest of the line.