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Brake upgrades using factory parts for GMT-400(88-00 OBS), and 94-99 DODGE 2500/3500

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FRANKENBURBAN
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I know many out there are less than thrilled with the performance of there stock brakes, so I figured I would do this thread to post up what stock parts can be easily swapped in to improve the braking performance of our trucks.

First things first, make sure your brake system is up to par, meaning you have done all of the TSB's and such(rear brake linings if you have the big drum brakes, and roportioning valve if you have a SUBURBAN). Making sure you have the core braking system up to par is crucial for ANY of it to work. Next I like stainless braided brake lines as they take away all that sponginess to the pedal. And at teh age of our trucks, the rubber lines are for the most part getting past time to replace just due to age.

I'm going to start with the rear brakes. I know many want disc brakes, but if you're on a budget you do still have options for many of us if you have a 14 bolt axle. The 9.5" semi float and 10.5" full float both share wheel cylinders. The 9.5" semi float rear axle for the most part got 1" wheel cylinders(RAYBESTOS #WC37781). The 10.5" full float axle if it was single rear wheel got 1 1/16" wheel cylinders(RAYBESTOS #WC37290), and dual rear wheeled trucks got 1 3/16" wheel cylinders(RAYBESTOS #WC37337). So if you have a single rear wheeled truck, you can for very little money swap in a set of 1 3/16" wheel cylinders from out of a dual rear wheeled truck and get a noticeable increase in rear braking. As to linings, the TSB from GM calls for the switch to the DURASTOP rear shoes if you have the 13X3.5" shoes(AC #17452R, but should be the same as RAYBESTOS #452PG). Also for many with 2.5" wide shoes, check your drums as many have found they had the 3.5" wide drums with 2.5" wide shoes. Sorry guys with 6 lug trucks and the 10 bolt axle, I'm unaware of any brake upgrades for them.

Now on to the front brakes. 6 lug trucks used a 2.94" diameter piston in the front calipers, 8 lug single rear wheeled trucks used a 3.15" diamter piston, and dual rear wheeled trucks used a 3.285" diamter piston. For those with 6 lug wheels, you DO have an easy to swap in factory brake upgrade in the 8 lug single rear wheeled pads and calipers. GM offerred these from the factory on TAHOES sold for police and fire department use, and will work with your stock rotors. Also of note is that the 8600 GVWR 8 lug calipers actually provide more clamping force than the SSBC dual piston calipers at a fraction of the cost. And since it was a factory option, it all just bolts on, and is available at most any auto parts store for cheap. Next up is those of us with 8 lug trucks and single rear wheels. As many of us know the rotors go behind the hub bearing, so they are not fun to change, and the factory rotors tend to warp easily if you actually use your truck and get the brakes hot. But were in luck, the 3500 dual rear wheeled trucks use very similiar brakes, but the rotors are roughly a 1/4" thicker, the pads are nearly identical except for thicker backing plates, and again, it all just bolts on. So you can easily and cheaply upgrade the brakes as well on 8 lug single rear wheeled trucks(but you MUST use ALL the DRW brake parts to do so. The calipers are roughly a 1/4" wider where they sit down over the rotor to accomodate the thicker rotor). If you have a dually though, you already have the biggest brakes available from the factory.

And to those doing the GMT-800 front brake upgrade, the 3.285" single piston caliper actually provides MORE clamping force than the dual 2.25" diamter pistons of the newer calipers, BUT they win out because of the greatly increased friction area of the MUCH larger pads. Now on to some pics I took.


DRW on the left, and SRW on the right, you can clearly see theres ALOT more meat i nthe DRW rotors but they are the same exact height.1231151330.jpg DRW on the left, and SRW on the right
1231151330a.jpgHeres a side by side pic of the 3 different pads. On the left is the 6 lug pads, middle is 8 lug SRW, and on the right is DRW pads.
1231151904.jpg

Also, if you happen to have an older 94-99 DODGE 2500/3500, alot of this info applies to you as well. DODGE bought there brakes from GM back in the early days, so alot of our stuff directly bolts onto theres. They used a 7500 GVWR though for the 3.15" calipers, and went to the 3.285" calipers for anything over that. BUT DODGE never used bigger than a 1 1/16" rear wheel cylinder, so the GM 1 3/16" is a popular bolt in upgrade for them.

Leaving this one open for now, but please lets keep it to technical info and responses since it is a sticky. And if anybody sees a mistake, please point it out so we can keep this info as correct as possible.
 

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I'm running plain rotors on mine. I started to go with drilled or slotted, but to many horror stories of them cracking in the holes in drilled rotors, or warping along the slots under extreme high heat braking conditions. So I stick with high quality plain rotors.
 

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Heres a link to the GMT-800(01-07) brake upgrade for those looking to go that route http://www.thetruckstop.us/forum/threads/brake-upgrade-for-my-98-k3500.34931/ . And here is a link to a discussion regarding doing away with the adapter for the outer tie rod end. http://www.thetruckstop.us/forum/threads/gmt-400-to-gmt-800-brake-conversion.45012/ The rotor is the same thickness and roughly a 3/8" larger diameter rotor, but the main difference is the size of the pads. Because the pads are so much larger, they last a LONG time and provide a bit better braking. They also have 4 wheel disc brakes, and a larger bore master cylinder with a different hydro boost that puts out more braking assist so they could reduce pedal travel to give an improved brake feel. I know I read that the GMT-800 master cylinder upgrade if you have vacuum assist is pretty common, but with a hydro-boost it would require hydroboost and master cylinder change to accomplish it. And the GMT-900(mid year 07-10) has even more hydroboost assistance to it for more braking).
 
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so we could use as new as 10 on hydroboost?
Not sure. I know they do the swap with vacuum boosters, but haven't found anybody whose tried a hydro boost yet. You might be able to, but I know 1 of the mountung bolts is in a different location on the newer hydroboosters.

OK, you got my curiosity peeked, so I did some digging. It is possible to use a new style hydroboost on the older trucks. You can either redrill the lower mounting holes, OR you can swap the mounting plate(theres a snap ring, then a nut, and then the plate slides right off). Next hurdle will be the pedal rod as newer trucks use a rod about 2/3rds the length of ours. So you have to either find a pedal rod puller, or make a tool to swap pedal rods. Next hurdle is the master cylinder. Ours uses a 9/16"x18 in the front and a 1/2"x20 in the back. The 01-early 07(mid 07-10 is metric with the same piston size) master uses 1/2"x20 for both, so you will need an adapter fitting for the front, and also a residual valve installed for the rear(newer trucks use 4 wheel disc brakes, drum brakes need 10 PSI of residual pressure in the system to keep the wheel cylinder cups sealed. Our master cylinder has it built in, but since the newer trucks are 4 wheel disc, it doesn't have it). Then you might have problems with the reservoir as it uses one TALL reservoir for the 4 wheel disc brakes. So yes, its doable, but alot of work.
 
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JayTheCPA

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. . . I like stainless braided brake lines as they take away all that sponginess to the pedal.
Any sources / part numbers?

Tried to do braided flex hoses the last couple of times I had brake work done, but came up short on a supplier. In fairness, I did try a set from Summit which claimed that they were for a K2500, but they did not fit (too short).


Any thoughts about using a master cylinder from the P30?
 

JayTheCPA

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What rotors do you suggest? Slotted, drilled/slotted, plain?
X2 on using plain. Not sure if this applies to a truck, but . . . My experience with slotted is that I lost braking power when I did it on my gasser.

Toward heat dissipation, am considering ceramic (heat dissipating type) on the caliper.
 

Burning oil

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As far as Hydro Boost rod go's. I did one in my old Chevelle obviously is was different so I just cut the rod then ran a die over the rod. That allowed me to install the Chevelle's linkage to it.
Might be able to do the same type of thing on our trucks?
 

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So that would be the only upgrade for my dually then?
I THINK I found another master cylinder that would provide some better pedal feel, but would require more pedal effort to push. The master cylinder that was used on the square bodies at this time used a 1 5/16" bore master VS the 1 1/4" the GMT-400 came with. As to upgrading your dually, you can go to better pads and shoes, stainless braided brake lines, and if you want to spend the time and money, you can go to the later model hydroboost and master cylinder, but there just isn't much you can do to them short of upgrading to newer gen brakes.
 

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That description matches what I heard about the P30's master cylinder. Is this the square body part you are thinking about?
 

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That description matches what I heard about the P30's master cylinder. Is this the square body part you are thinking about?
Just looked, and yep, thats the one.

I also just added some info to the post about the master cylinder upgrade as it would also require a residual valve to be installed.
 
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SmithvilleD

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Heres a link to the GMT-800(99-early 07 NBS) brake upgrade for those looking to go that route http://www.thetruckstop.us/forum/threads/brake-upgrade-for-my-98-k3500.34931/ . The rotor is the same thickness and roughly a 3/8" larger diameter rotor, but the main difference is the size of the pads. Because the pads are so much larger, they last a LONG time and provide a bit better braking. They also have 4 wheel disc brakes, and a larger bore master cylinder with a different hydro boost that puts out more braking assist so they could reduce pedal travel to give an improved brake feel. I know I read that the GMT-800 master cylinder upgrade if you have vacuum assist is pretty common, but with a hydro-boost it would require hydroboost and master cylinder change to accomplish it. And the GMT-900(mid year 07-10) has even more hydroboost assistance to it for more braking).
I'm near finishing the swap to GMT800 K2500HD brakes (GMT800 calipers/rotors frnt & rear, adapted hydroboost from '04, new '04 mastercylinder & the adaptor to fit our GMT400 brake lines, etc., etc. Thought I'd add a link to my thread for easy cross reference. Last post in thread shows a DIY tool I made to pull DMax hydroboost's pedal rod so could swap in GMT400 pedal rod.

In trying to find a pedal rod tool (before making my own), I got the sense the tool use to be more common, but someone did a rebuild & didn't get the pedal rod staked in well & evidently it failed there & led to a wreck, lawsuit, etc. So it's worth noting that pulling & replacing the pedal rod is a "do this at your own risk" project.

http://www.thetruckstop.us/forum/threads/bolt-in-disc-brake-and-3-73-conversion.21563/page-3#post-501596
 
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WarWagon

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Make sure you buy the expensive shoes (cost over $100.00 a set) vs. the cheapest pads and shoes you can get. This cheap/expensive material used makes a big difference in stopping power. Aka not standing on the brakes and stopping in a shorter total distance where wheel traction will allow you to do so. Again expensive rear shoes will improve your stopping ability over cheap or OEM factory stuff.

Adjust the rear shoes every other oil change.

Abuse of your brakes: Doing a panic or hard stop and then sitting with the brakes on. This keeps part of a red hot rotor under the red hot pads. The rest of the rotor cools while the part under the pads undergoes a hardening heat treatment aka Pad Etching or forming Cementite. You have to creep on your brakes after a hard stop: make sure you leave room to do so after a hard stop. Total brake overheating can form Cementite. Cast iron will transform into a super-hard material called Cementite at temperatures of around 1200 – 1290°F. You can not have Cementite turned out of the rotors as the tool just bounces off the hard spots. Note Cementite will form on Cryo treated rotors and will end their useful life just as fast as normal rotors.

I personally hate AutoZone's brake parts as they (top of the line) don't stop well and had a pad come clean off the backing plate trashing a new rotor. I suggest avoiding the store brands unless you are doing an in-law's car and you want to get rid of them without going to prison.

RAYBESTOS as mentioned above or what I use: Wagner Quiet Stop. Use Semi Metallic only. <-- That's a period. One more time WITH FEELING as Ceramic and organic is compared to noisy and dusty semi metallic that does the job of stopping your 3/4 or 1 ton: http://www.hendonpub.com/resources/article_archive/results/details?id=1569

I find (from the s#ittier undersized pre-1999 1/2 ton GM brake systems) that drilled and/or slotted rotors do improve braking. They let the outgassing from the pad dissipate, dry the pads and rotor off quicker, and run cooler than the solid rotors. They are nosier under hard braking. Drilled rotors do crack so I recommend the slotted style only. The drilled/slotted rotors can catch you with your paints down as they cool faster than the normal rotors. So you hit the freeway for a quick 1-2 mile run and expect the stopping performance of hot brakes, well, the slotted/drilled units may have cooled down and increase your stopping distance over your expected shorter 'hot brakes' stopping distance. Hot brakes stop quicker than cold brakes to the point of fade. Fact 1995 GMC Yukon pad life 12,000 miles stock parts. With drilled and/or slotted rotors pad life went up to 17,000 miles. Still ruined rotors and about no shop wants to turn the slotted or drilled rotors.
 

FellowTraveler

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Make sure you buy the expensive shoes (cost over $100.00 a set) vs. the cheapest pads and shoes you can get. This cheap/expensive material used makes a big difference in stopping power. Aka not standing on the brakes and stopping in a shorter total distance where wheel traction will allow you to do so. Again expensive rear shoes will improve your stopping ability over cheap or OEM factory stuff.

Adjust the rear shoes every other oil change.

Abuse of your brakes: Doing a panic or hard stop and then sitting with the brakes on. This keeps part of a red hot rotor under the red hot pads. The rest of the rotor cools while the part under the pads undergoes a hardening heat treatment aka Pad Etching or forming Cementite. You have to creep on your brakes after a hard stop: make sure you leave room to do so after a hard stop. Total brake overheating can form Cementite. Cast iron will transform into a super-hard material called Cementite at temperatures of around 1200 – 1290°F. You can not have Cementite turned out of the rotors as the tool just bounces off the hard spots. Note Cementite will form on Cryo treated rotors and will end their useful life just as fast as normal rotors.

I personally hate AutoZone's brake parts as they (top of the line) don't stop well and had a pad come clean off the backing plate trashing a new rotor. I suggest avoiding the store brands unless you are doing an in-law's car and you want to get rid of them without going to prison.

RAYBESTOS as mentioned above or what I use: Wagner Quiet Stop. Use Semi Metallic only. <-- That's a period. One more time WITH FEELING as Ceramic and organic is compared to noisy and dusty semi metallic that does the job of stopping your 3/4 or 1 ton: http://www.hendonpub.com/resources/article_archive/results/details?id=1569

I find (from the s#ittier undersized pre-1999 1/2 ton GM brake systems) that drilled and/or slotted rotors do improve braking. They let the outgassing from the pad dissipate, dry the pads and rotor off quicker, and run cooler than the solid rotors. They are nosier under hard braking. Drilled rotors do crack so I recommend the slotted style only. The drilled/slotted rotors can catch you with your paints down as they cool faster than the normal rotors. So you hit the freeway for a quick 1-2 mile run and expect the stopping performance of hot brakes, well, the slotted/drilled units may have cooled down and increase your stopping distance over your expected shorter 'hot brakes' stopping distance. Hot brakes stop quicker than cold brakes to the point of fade. Fact 1995 GMC Yukon pad life 12,000 miles stock parts. With drilled and/or slotted rotors pad life went up to 17,000 miles. Still ruined rotors and about no shop wants to turn the slotted or drilled rotors.
Excellent!
 

turbopower6

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Hi Folks,
If you install the front rotors and calipers for a 3500 4wd on a k2500 suburban to follow the upgrade will the original suburban 8 lug steel wheels fit without the rotors rubbing? As well I run Alcoa aluminum rims in the summer....will there be a clearance issue with these as well?
 

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Hi Folks,
If you install the front rotors and calipers for a 3500 4wd on a k2500 suburban to follow the upgrade will the original suburban 8 lug steel wheels fit without the rotors rubbing? As well I run Alcoa aluminum rims in the summer....will there be a clearance issue with these as well?
A 3500 could be single or dual rear wheels. The 3500 dual rear wheel brakes will clear anything the si,gle rear wheel brakes will. The only difference is a 1/4" thicker rotor, and a slightly larger piston in the caliper, but it takes up no more room.
 
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