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

[snarl95]

To get the gmt800 brakes you need to do a knuckle swap.

 

[THEFERMANATOR]

Fermanator! Thank you for the kindness of a reply! To summarize:
1. My 8 lug C2500 2WD semi floating Axel WILL NOT ACCEPT the 3.5” drums and shoes.
2. I can upgrade the FRONT BRAKES using ALL the GMT800 parts without difficulty, and improve the braking for a reasonable cost.
Did I get it right??

Grateful to you!!
Bob

1. As far as I know, no. Trucks with the 13x3.5" brake shoes were all 14 bolt full floaters with the drums that slide over the hub. The 13x2.5" shoes were on semi-float axles and 14 bolts with the drums behind the hub. The 3.5" wide drums are pretty massive.

2. It's doable as several have done it, but it requires reamers, and quite a few parts be swapped out.

 

[Big T]

1. As far as I know, no. Trucks with the 13x3.5" brake shoes were all 14 bolt full floaters with the drums that slide over the hub. The 13x2.5" shoes were on semi-float axles and 14 bolts with the drums behind the hub. The 3.5" wide drums are pretty massive.

2. It's doable as several have done it, but it requires reamers, and quite a few parts be swapped out.

Definitely doable, but if you go all new quality parts, it will run you $1,200.

 

[Pistachiobob]

Dear Fermanator: You have been exceedingly gracious with your time and expertise! Many Thanks!
I have to review the details of your original post back in, I believe, 2016, where you provided photos of the parts needed to upgrade the front braking system of C and K 2500 GM vehicles. Based on the responses of BIG T and your last reply, I apparently am confused on what the GMT800 vehicle is; I thought it was the 3500 series, which I recall as having front rotor and caliper parts that would interchange with the C2500 parts without modifying any of the front suspension. I am GREATLY appreciative of EVERYONE’s replies to assist me in driving a safer 1999 C2500 Suburban!!
Best, Bob

 

[Will L.]

GMT400 is 1988-1999.5
GMT800 is 1999.5-2006

 

[THEFERMANATOR]

Dear Fermanator: You have been exceedingly gracious with your time and expertise! Many Thanks!
I have to review the details of your original post back in, I believe, 2016, where you provided photos of the parts needed to upgrade the front braking system of C and K 2500 GM vehicles. Based on the responses of BIG T and your last reply, I apparently am confused on what the GMT800 vehicle is; I thought it was the 3500 series, which I recall as having front rotor and caliper parts that would interchange with the C2500 parts without modifying any of the front suspension. I am GREATLY appreciative of EVERYONE’s replies to assist me in driving a safer 1999 C2500 Suburban!!
Best, Bob

Most refer to the gmt800 as the nbs. They started in 99 with the newer body style truck's, and then in 01 the 2500hd and 3500 trucks. They have dual piston caliper brakes front and rear compared to the gmt400(excluding the c3500hd) with single piton in front and drums in rear.

 

[Pistachiobob]

To all members on this thread: I am overwhelmed with your knowledge and graciousness to share it with C2500 neophytes like me! I’m especially grateful to Fermanator and Will L! Will, you solved my very basic but confusing problem of explaining the difference between a GMT400 and GMT800! Until your response, I couldn’t understand why Fermanator stated the C3500 DWR FRONT BRAKES were a straight swap onto my 1999 C2500 Suburban! I thought GMT800 was synonymous with C3500! Now I understand why Snarl95 said a knuckle swap was required to use GMT800 front brake parts. I’m staying with Fermanator’s original recommendation of the straight swap using C3500 DRW FRONT brake parts. BTW (By the Way), simply removing the spring and plunger seal from the updated proportioning valve has made a BIG improvement in the braking of my otherwise unmodified system. Just FYI! I hope you laugh, rather than shake your head, when I confess it also took me awhile to figure out nbs and obs! I now realize the old and new body styles are described by GMT400 and 800! If you asked me about the photosynthetic efficiency of a pistachio tree, I could tell you all about it!!! LOL!! Thanks!! Bob

 

[Will L.]

We are all here to help and enjoy new friends. Wise choice in heeding Ferm- dude is an automotive rock star. And I love pistachios too btw. No idea how any of it works other than the trick of using a shell of one to open the others that are hard to open- that made a difference in my pistachio life. Haha

 

[Pistachiobob]

Will!! LOL on the closed shell pistachios! This is a very fascinating nut, and is mentioned by name in Genesis! It’s the only Drupe (a botanical family of fruit) that grows the pericarp (shell covered in a green hull) in the spring (April to early June) and THEN FILLS the shell with the developing embryo (nut meat) from July to harvest in September! The nut meat actually outgrows the size of the shell, and forces it to split! The “non-splits” are thought to be late set nuts that do not have sufficient time or competitive ability to split! Think how cool it is that our brains quickly figure out how to use the shell half as a “tool”! I’d better stop! This is Truck Stop, not NUT STOP!!!

 

[Big T]

Will!! LOL on the closed shell pistachios! This is a very fascinating nut, and is mentioned by name in Genesis! It’s the only Drupe (a botanical family of fruit) that grows the pericarp (shell covered in a green hull) in the spring (April to early June) and THEN FILLS the shell with the developing embryo (nut meat) from July to harvest in September! The nut meat actually outgrows the size of the shell, and forces it to split! The “non-splits” are thought to be late set nuts that do not have sufficient time or competitive ability to split! Think how cool it is that our brains quickly figure out how to use the shell half as a “tool”! I’d better stop! This is Truck Stop, not NUT STOP!!!

"Non-splits are thought to be late set nuts." Does that make is easier and safer to just hop on a bike?

 

[Will L.]

Big T: our highest educated, most money earning guy who still sees everything as a 13 year old jokester. Haha
Reminds me of A guy at work who says “If it was funny at 7, it’s funny at 97!”

 

[Big T]

Big T: our highest educated, most money earning guy who still sees everything as a 13 year old jokester. Haha
Reminds me of A guy at work who says “If it was funny at 7, it’s funny at 97!”

If you’re laughing in life, you are not having fun.

Now can we talk about guns? I just ordered a Benelli Super Black Eagle III. Sportsman’s Warehouse had a loyalty rewards program of $600 off ($1,099) which is a damn good price for that gun. One per customer at that price. My first ever gun purchase. Haven’t told my wife yet.

 

[Will L.]

I taught my wife how to shoot when we were dating. Don’t start her out on anything big or loud. Build confidence with simple shots. Next thing ya know she will be buying you a gun every 5 years and ammo at every birthday. Your wife is kinda small frame- I would start her on a .22 to .38 If she has fun at it, ya both will.

Oh, There is a problem however. I don’t back talk her now- she hits what she aims at...

 

[Big T]

I taught my wife how to shoot when we were dating. Don’t start her out on anything big or loud. Build confidence with simple shots. Next thing ya know she will be buying you a gun every 5 years and ammo at every birthday. Your wife is kinda small frame- I would start her on a .22 to .38 If she has fun at it, ya both will.

Oh, There is a problem however. I don’t back talk her now- she hits what she aims at...

She grew up shooting guns. We’ve got her Winchester 101 over/under 20 gauge, which is a beautiful gun. She’s shot Paveltolz’s Glock 21, though she was breathing like a beached carp before pulling the trigger. Last but not least, she’s a lawyer.

 

[Husker6.5]

I taught my ex-wife the basics of boxing: How to properly throw punches, the types of punches and a couple of basic punch combinations (like a double left jab followed by an overhand right) back when we were first married since I had boxed Golden Gloves a couple of years in college and was a sparing partner for a couple of local pros then, too and she was working a job where she often got off of work later at night (waitressing) to an empty, near dark parking lot.

 

[Big T]

I taught my ex-wife the basics of boxing: How to properly throw punches, the types of punches and a couple of basic punch combinations (like a double left jab followed by an overhand right) back when we were first married since I had boxed Golden Gloves a couple of years in college and was a sparing partner for a couple of local pros then, too and she was working a job where she often got off of work later at night (waitressing) to an empty, near dark parking lot.

Hope you didn’t bruise her up and have the social workers show up.

 

[Husker6.5]

Nah, stood next to her and showed her how to stand, pronate when you throw the punch, how to rotate through with hips and shoulders for power and speed throwing and recoiling. Shadow boxed a little and had her hit my open hands while she wore my bag gloves.

She did wind up successfully using the skills I taught her one night after work a couple of months later, but that's another story for another time and place.

 

[mwyson]

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.View attachment 46807 DRW on the left, and SRW on the right
View attachment 46808Heres 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.
View attachment 46809

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.

I have a 90 K2500 7600lb 6 lug. I bought some 2000 ish front calipers. Now braking is crazy strong in the front but can't even get the rear to skid, even in gravel. I ordered the 1-3/16 rear cylinders. I'm guessing the pistons in the front new calipers are much larger than stock 90ish.

 

[FellowTraveler]

I taught my wife how to shoot when we were dating. Don’t start her out on anything big or loud. Build confidence with simple shots. Next thing ya know she will be buying you a gun every 5 years and ammo at every birthday. Your wife is kinda small frame- I would start her on a .22 to .38 If she has fun at it, ya both will.

Oh, There is a problem however. I don’t back talk her now- she hits what she aims at...

Learning gun craft is a must IMO, my 1st was at the ripe old age of seven, it was a single shot .22 LR.
Doing business as an Class 3 FFL, I taught my children how to "instinct shoot" pistols, then riots guns, then SMG's and long range precision rifles...all tools they hopefully may never need but can and will use when needed.

 

[C30454]

Thanks to the OP for this valuable information posted within this thread. I have been a professional auto tech for 40 years, and this kind of information is unavailable through the normal SI channels. Thank you for your efforts and sharing.

I have a '99 C3500 SRW truck that I bought brand new. It is all stock except for towing mirrors and Kodiak door handles. I have done the 1 3/16 rear wheel cylinder upgrade, and that improved rear braking. The original rear shoes had 22 years and 290,000 on them and could have gone for another 22 years based on the wear, so they were not being utilized as much as they could have been. I think the 1 3/16 wheel cylinders will help.

The front brakes are not upgraded yet. I read about the upgrade in rotor, pads, and larger piston caliper for the K trucks, but the thicker rotor for the fronts only appears to come with the DRW front rotor.

I have considered putting on the upgraded pads and larger piston calipers anyway. Obviously, the piston would need to start out a 1/4" out of the bore to compensate for the thinner C3500 SRW rotor. But I am also worried about increased pedal travel with the larger pistons.

It seems like the upgrade options are limited for the 3500 C trucks.

Any other info for these?


Thank you,

Tom