Upgrade Front Brake Calipers

[Treb]

Hi I am new to the forum. I Looking to upgrade my brakes. I have a 88 GMC K2500 with 6 lug wheels..(7200lbs). I have front calipers with the 2.94 diameter piston. Has anyone upgraded to the 3.15 calipers from the 8 lug (8600lbs) calipers. Is this a direct bolt on caliper. The only difference being the size of the piston. Will the original brake hoses work. Do you use the original style pads or the ones that go with the bigger calipers. How is this different from the Little Shop front caliper upgrade kit. The pistons on the Little Shop calipers is also 3.15 diameter. I am also wanting to replace the rear set up with the Little Shop rear disc brake kit.

 

[offroadtahoe]

yes it's a direct bolt in,i used k3500 drw calipers and pads with no grinding,you can also use the k3500 drw rear brake cylinder it will bolt to any 4x4 rear axle,i also used the 1 ton master these are the same on srw or drw, i also did abs delete and ss lines but still massive improvement in braking

 

[Dravec]

The 8600 calipers are a direct bolt on, and use a 370 series pad, rather than the 369 series pads of the 7200 calipers.

 

[94K3500PROJECT]

Direct swap.
Best 6 lug brakes I’ve ever driven was the 8 lug calipers/pads and gmt800 rear disks and master cylinder

 

[454cid]

yes it's a direct bolt in,i used k3500 drw calipers and pads with no grinding,you can also use the k3500 drw rear brake cylinder it will bolt to any 4x4 rear axle,i also used the 1 ton master these are the same on srw or drw, i also did abs delete and ss lines but still massive improvement in braking

Those calipers get thicker pads and rotors. Did you do anything there, or are you running them on the 1/2 ton rotors?

 

[1998_K1500_Sub]

The 8600 calipers are a direct bolt on, and use a 370 series pad, rather than the 369 series pads of the 7200 calipers.

I've got a 1998 K1500 Suburban which was equipped with JB6 brakes.

I bought the 8600 calipers and 370-series pads and they are "bolt on", but in my case the outboard pads rubbed ever-so-slighly against the hub of the rotor (others may or may not have this problem). I had to grind the outboard pads (not the inboard) to clearance them, which wasn't a difficult undertaking. See the attached image.

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I've heard of others who used the 7200 pads (369-series, e.g., RAYBESTOS EHT369H) with the 8600 calipers instead. Assuming these fit and function propertly on the 8600 caliper, they would provide more clearance for the hub of the rotor. I haven't tried this yet, however, and can't comment.

Part numbers I used, for the 8600 calipers and 370-series pads:

Caliper w/ 3.15" diameter piston RAYBESTOS FRC4414C
Caliper w/ 3.15" diameter piston RAYBESTOS FRC4413C
Pads for above calipers RAYBESTOS EHT370H

(Edit: As posted later in this thread, the K3500 DRW calipers w/ piston diameter 3.386" can also be used, e.g., see CENTRIC 14266021 et al.).

Finally, the argument has been made that the JB5/JB6 MC, which is a "Quick Take-Up" design meant to be used with corresponding JB5/JB6 "Quick Take-Up" calipers, should not be used with the 8600 calipers as they're not "Quick Take-Up" calipers (the "Quick Take-Up" feature was OE for JB5/JB6 GMT400s at least in later years GMT400s, see the attached .pdf for its explaination; I'm not certain if it was deployed in 1988). On account of the "Quick Take-Up" MC or for other reasons, many have "upgraded" to the 8600 MC or the NBS MC. Personally, I used the NBS MC from a 2001 1500 Silverado. Some adapters may be required, e.g., to mate the NBS MC to the brake lines, but otherwise the NBS MC bolts right in. Do your homework; the NBS MC swap is discussed in many places here on GMT400.

Part number:

NBS MC ACDelco 18M1159


I have the 11" drums in the rear and I installed the 1.1875" diameter JB8 cylinders in place of the 1" OE diameter cylinders. I did not change the drums / shoes as they were serviceable. This change IMHO works particularly well on the Suburban because it's a$$-heavy compared to an (unloaded) pickup, i.e., about 3020# in front and 3160# in the rear. These cylinders bolt right in, without issue.

Part number:

Cylinder ACDELCO 18E1362


I've also installed braided SS lines front and rear. Bear in mind that some of the aftermarket SS lines are better than others as noted by @Schurkey in recent discussions. If I find a link to his post I'll pass it along. (Edit: see here https://www.gmt400.com/threads/upgrade-front-brake-calipers.58795/post-1254517)

The part numbers I've given are what *I* used. Equivalent parts are available from other mfgrs.

IIRC, during the life of the GMT400 platform the some / all of the brake line fittings were changed from SAE to metric... perhaps around 1997. The information I've given you is relevant to my 1998 Suburban. Before you commit to installing new parts, make certain the fittings are appropriate. I've "been there" and I've suffered the consequences.

Finally, peruse this thread as it has a lot of discussion that's relevant to your vehicle:

Need help with brakes plz!

Hi, I couldnt find a brake section. I have a newly aquired 1996 C1500 i think it's called. 4.3l, 8 ft bed. I bought it for a teenage stepson and really need to figure out the brakes. The owner before me put in new brake hoses, new master cylinder, new rear drums, new rotors and pads up front...

www.gmt400.com

 

[92GMCK2500]

I was always under the impression that 2500/3500 calipers on a 1500/LD 2500 required the 1500/LD 2500 pads to avoid the extra pad thickness clashing with the caliper bracket.

Can anyone confirm this?

Edit: posted same time @1998_K1500_Sub. Thanks for clearing that up

 

[offroadtahoe]

Those calipers get thicker pads and rotors. Did you do anything there, or are you running them on the 1/2 ton rotors?

yes,running on 1/2 ton rotors.A few others have ran this for years so i didn't worry about the difference in rotor thickness,
6 lug 32.7mm
8 lug drw rotor 39.1mm
3.2mm custom pad shims per side would make up the difference
i had srw the k3500 caliper/pads on it too before this drw setup,i definitely like the drw better

 

[1998_K1500_Sub]

i had srw the k3500 caliper/pads on it too before this drw setup,i definitely like the drw better

Why were DRW caliper / pads "better" than the SRW caliper / pads, given you were using the same 1/2-ton rotors?

 

[offroadtahoe]

Why were DRW caliper / pads "better" than the SRW caliper / pads, given you were using the same 1/2-ton rotors?

the srw 1 ton piston is 3.15" drw is 3.285" i don't think much gain if any came from the drw pads over srw but they are a bit thicker and designed different.