Confused about brake upgrades for 93 K1500

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nick7269

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I have been searching the net about brake upgrades. I did buy a NBS master cylinder and stainless steel brake lines (not installed yet). Then started reading that may not be a good idea to change the master cylinder. I see the forums talking about 2500 and 3500 series calipers as well. Then the topics go into hydro boost or converting the whole system of other models. Now I have just simply gotten confused and lost. I don't want to go that extreme.
Can anyone help a layman figure out what simple upgrades from rockauto will help please? At this piont of time I am just trying to improve the front end only. I will get to the rear later.
It sounds like if I change my calipers to the 2500 or 3500 series calipers with 1500 series pads & rotor that might be all I need for better stopping power? Im I correct?
What are your thoughts?
thank you
nick
 
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df2x4

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Check your RPO codes, do you have the JB6 brakes? If so then personally I wouldn't even bother changing calipers or anything like that. You can get that system to perform very well with just some basic maintenance and small upgrades IMO.

First off, if you're not sure when it was done last, I would recommend bleeding the entire brake system with fresh fluid. This includes bleeding the ABS module, which requires a GM Tech2 or equivalent scan tool. If you don't have a tool that can do this you may be better off taking the truck to a shop. While you're at it, if your soft lines are questionable at all I would replace them with a set of braided stainless lines. Both of these things will improve your pedal feel.

Next, get a set of aggressive pads and shoes on it. Long story short, all pads and shoes sold in the US have a two letter DOT friction code on them somewhere. The letters indicate the coefficient of friction both cold and hot. Basically the closer the letters are to Z, the more aggressive the friction material is. The most aggressive pads I'm aware of that will fit JB6 trucks are the Raybestos EHT369H, they're HH code. Unfortunately FF code shoes are the most aggressive I've been able to find, but the bias still feels good to me even with the Raybestos pads on the front.

Don't be deceived by expensive price tags on "track pads" from some manufacturers. The Raybestos EHT369H pads I mentioned have a more aggressive friction code than anything from EBC or Hawk, and at a fraction of the price.
 

SUBURBAN5

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X2 to what df2x4 said. My 2 cents to add is on my suburban I have the jb6 brake code mentioned. All I did was new factory calipers, wheel cylinder, drums ,pad and shoes. The only mod I changed was ss braided brake lines on the front and rear. Pedal feels awesome to me and it stops the truck pretty well. The mc is factory replacement and the abs was bled by the dealer. I would start with that before you go Frankensteining the brake system. Also keep in mind well adjusted shoes makes the brakes pedal feel firmer then never adjusted shoes......
 

nick7269

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Thank you for taking the time to reply. This is really great information that helps me out tremendously! I am rebuilding the front end right now. I will be replacing the soft lines at the same time. I will ask about the ABS brake bleed when I get the alignment done this next week. I'm already shopping for the brake pads and shoes.
thanks again for the help
 

Schurkey

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As said--if you have JB6, make sure the hoses are in good condition, bleed 'em including the ABS, good pads, assure that the calipers are in good condition--pistons move freely, not seized or sticking, caliper slides easily on the guide-pins. Make sure the rotors are reusable--not heavily scored, not warped. Easy, effective, not real expensive.

If you have JB5, doing anything more to the front brakes other than what's listed above, is a waste of time, money, effort, and enthusiasm until you've gotten-rid of the horrible rear brakes.
 

df2x4

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If you have JB5, doing anything more to the front brakes other than what's listed above, is a waste of time, money, effort, and enthusiasm until you've gotten-rid of the horrible rear brakes.

I know the JB5 systems (understandably) don't get a lot of love around here, but I have to say I got very similar good results by following the advice I posted above on my red truck that's JB5 equipped. If anything the pedal feels better than my (JB6) Suburban. Might have something to do with the fact that I put braided soft lines on the red truck, the 'burb is still running factory style rubber lines IIRC.
 

1998_K1500_Sub

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Next, get a set of aggressive pads and shoes on it. Long story short, all pads and shoes sold in the US have a two letter DOT friction code on them somewhere. The letters indicate the coefficient of friction both cold and hot. Basically the closer the letters are to Z, the more aggressive the friction material is. The most aggressive pads I'm aware of that will fit JB6 trucks are the Raybestos EHT369H, they're HH code. Unfortunately FF code shoes are the most aggressive I've been able to find, but the bias still feels good to me even with the Raybestos pads on the front.

A follow-up comment on this: The buyer can't (generally) tell beforehand what friction code they'll get when shopping for pads; it's not as though the DOT friction code is listed on RockAuto along with the part numbers. Rather, if you first buy a set of pads and then look at them, you'll find the code on the back.

@df2x4, did I get that right?

Now, @nick7269, regarding the NBS MC you said you've already bought. It's designed to be used with calipers that are not the "low-drag" type. AFAIK the GMT400 calipers having the larger bores (3.15 aka 80mm and 3.38 aka 86mm, typically deployed on 2500/3500s with JB7/JB8 brakes), are not the "low-drag" type... so the NBS MC will work well with them (as will an MC designated for JB7/JB8, as it is not a “quick-take-up” MC).

The 3" aka 76mm bore calipers are AFAIK "low-drag" type and were used on JB5/JB6 equipped vehicles. These "low-drag" calipers require a corresponding "quick take-up" MC designated for JB5/JB6.

(edit: See @Schurkey ’s remarks in the subsequent post.)

See the attached .pdf regarding “low-drag” calipers and “quick take-up” MCs, and be enlightened.

Somebody correct any mis-statements I've made above; there's probably at least one.

This thread (link below) is reasonably coherent IIRC on the topic of front wheel brakes, but it does disclose a lot of different combinations of front equipment, possibly to the point of confusion (including front brake combinations which came on single or double rear wheel 3500s). It touches on the rear brakes a bit too.


I modified my K1500's JB6 brakes years ago using the NBS (for a 2001 Silverado w/ vacuum boost) and 3.15" bore calipers in front, with K2500 pads in the calipers and SS lines. I've made minor changes to the rears too (SS lines and bigger cylinders).

I'm very pleased with the performance of my brakes, which BTW use OE vacuum boost. Others here will tell you hydroboost is notably better. While I believe they're correct, I'm so darn pleased with how mine work now, esp. compared to how they once worked, that I'm staying-put. I DO have the hydroboost valve body NIB on a shelf, and the requisite PS cooler I have already installed; all I need AFAIK are the brake pedals, hoses and motivation.

Knowing what I know now, I probably would have used a JB7/JB8 vacuum boost MC instead of the vacuum boost NBS MC, as AFAIK NBS has a larger piston diameter 1.34" aka 34mm vs. the JB7/JB8 1.125" (vacuum boost) or 1.25" (hydroboost) bore MC. The larger bore of the NBS MC offers less hydraulic advantage ("leverage") over the slave cylinders, by a factor of the ratio of the bore area, e.g., for a 1.125" bore (vacuum) to a 1.34" bore it's 70%, and for 1.25" bore (hydroboost) it's 87%. All that said, I don't feel like my NBS MC brakes are underboosted.

For the record, I believe the hydroboost NBS bore is 1.46" aka 37mm, at least for some 2001 GMT800s.

The NBS MC is suitable for rear disc brakes by virtue of its larger reservoir, which may be useful for others but that doesn’t apply to me (tho maybe someday I’ll graft on a GMT800 disc brake rear).
 

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  • Low drag calipers - Quick Take-up.pdf
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df2x4

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A follow-up comment on this: The buyer can't (generally) tell beforehand what friction code they'll get when shopping for pads; it's not as though the DOT friction code is listed on RockAuto, along with the part numbers, for pads they sell. Rather, if you first buy a set of pads and then look at them, you'll find the code on the back.

@df2x4, did I get that right?

Yes, unfortunately. It seems like manufacturers don't advertise this information at all.

If you're lucky sometimes you can find pictures of the pads/shoes in question that are clear enough to make out the friction code. I've found that eBay auctions are a good place to check for this. You just have to make sure you're looking at a listing with pictures of the actual product, not stock photos.
 

Schurkey

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The JN/JB3 brakes had low-drag calipers, the smallest pistons in the calipers, the smallest pistons in the master cylinder, the narrowest rotors, and the crappiest (vacuum-powered) booster. The "3" brakes were discontinued after...'91 (?) or '92 (?).

JN1 brakes were the same as JN3, but without the booster. Plain ol' manual brakes of the smallest kind used on GMT400s. Not popular. I've never seen a GMT400 with manual brakes.

So the "1", "3", "5", and "6" all had low-drag calipers (no "NBS" master cylinder for those) and the "1", "3", and "5" had the terrible rear 254mm (10") leading-trailing drums.
 
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kylenautique

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I have the JB6 brakes with the 14bolt rear end. If you really want to make it stop great, get a hydroboost and matching master cylinder from a 2500/3500 truck (use a 1994 k3500 diesel or 454) 3500 front calipers (uses your stock pads..just spread out the metal retainer), delete the rear ABS and install an adjustable proportioning valve. You will have to modify the brake pedal or find one for a hydroboost at a wrecking yard. I would just find a complete system from the wrecking yard. Worst case you use it as a core to replace it at the auto parts store. Not a hard project and you will have AMAZING brakes. Take it one step further and install the spacers and NBS rear disc brakes from a 02 silverado/suburban/tahoe. Feel free to PM me about anything on this or the rear disc brake setup.
 
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