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Posted
On 8/24/2021 at 7:09 AM, Transient said:

A Trail Boss with 20s is an oxymoron, imo.  In fact, if you really want to do some offroading in this truck you need to go to 17s.

I 100% agree,17or18 is good with a tall sidewall. It just kills me and I have to laugh at some of the trucks I see on the road with lifts and nice rims and there running low profile tires some look like rubberbands around the rim that the sidewall is so low.

  • 2 weeks later...
Posted

Just bought a 2020 AT4 that had the brake kit installed from the factory, and man can I tell a difference! Coming from a stock 2018 Silverado LTZ, the upgrade in performance and looks is quite impressive.

  • 5 weeks later...
  • 1 year later...
Posted (edited)
On 10/10/2022 at 4:30 PM, Bill Godshall said:

Anybody know what kind of mileage you get on the brembo Pads on the 2021 GMC AT4

 

For future reference, I received my truck pre-owned with 7k miles (May 2021), with of course no knowledge of driving style and currently have 41400 miles on the odo with eighth inch (3mm) pad left to wear indicator bar with normal highway/city driving. 

Edited by DenaliSS
Posted (edited)
On 7/25/2021 at 6:08 PM, DenaliSS said:

I decided to start a new thread on this dealer-installed GM performance upgrade, in the hopes of receiving some answers to questions I have and in turn, providing information I've gathered since owning this truck for a short time.

 

A little background on the truck. I bought and received my 2019 LTZ used through a dealer with 7K miles, with the 6.2L L87 / 10 speed transmission in May 2021. The previous owner had the Brembo upgrade installed and soon afterwards, installed the Kooks LT headers / Y-pipe with green cats.  

The latter I'm thinking of either doing another thread or maybe a build thread to make simple?

 

Build code: 5JL Performance Brake Kit option

Zane's thread on the kit - 

 

P/N 84766666 Formally P/N 23505023 (MSRP $2895)

Front 6-Piston Brembo Brake Upgrade System in Red with Chevrolet Performance Logo

  • Replaces the brake rotors, calipers and pads
  • Compatible with 20- to 22-inch OE and Accessory Wheels
  • Duralife 14 inch rotors offer +84% increase in brake area and a +42% increase in rotor area to increase thermal capacity
  • Testing resulted in the performance package providing -31% reduction in pedal force at max deceleration and -12% reduction in pedal travel

 

I can say in regards to the last three points, the performance brake package fits within my aftermarket 20 inch Centerline Tomahawk Stingray III just fine, with roughly ~1/2 inch from caliper to wheel sidewall. No complaints of the braking performance and the pedal force and travel would be close to description.  The couple times I had to use the brakes hard, those six pistons really clamp on and do what's intended and work exceptionally well.

 

Also offered (essentially GM OE rear matching painted single piston caliper, not Brembo)

P/N 84690453

Rear Brake Upgrade System (MSRP $575)

 

Brembo site has a Brembo upgrade (06/01/2021) pdf, larger than what I can attach, but provides part/kit numbers, notes and breakdown descriptions. This is a GT Kit. 

 

 

Questions I have at the start, I've noticed the brake lines don't need to be replaced when upgrading to this package, but do if I want to level or lift.

Anyone have that OE brake line part number or better yet, aftermarket braided stainless line brand numbers for leveling the truck from a factory LTZ? If using Eibach pro kit?

 

 

 

Brembo3.jpg

Brembo2.jpg

Brembo1.jpg

 

Since posting, Replacement Pads - 84263246, Replacement Rotors - 84070075

From Brembo site, the cross refence numbers ~ P10103N NAO (ceramic) brake pad or

P 10 103 Prime

Something I did forget to add as an fyi is that the OE 17 inch spare tire will not work and will need to be at least a 20 inch wheel.

 

I've also noticed some threads saying that they have sensors with this brake system, which this Brembo system was not equipped for.  As stated on the description and in the install sheet, this system is not ePWI compatible;

The brake pad life system (ePWI) must be turned off. This is necessary because the Performance Brake Package is equipped with brake pads without electronic wear sensors. When the system is turned off, the front and rear brake pad life percentages will not display. However, the built-in wear indicators that make a high-pitched warning sound when the brake pads are worn can still determine when the pads should be replaced.

Edited by DenaliSS
  • Like 1
Posted

If anyone has changed out their OE brake lines to SS lines, please post up what you have found.  Thanks!

Posted

Fyi i left the pad wear system enabled with mine. Theres no actual reason you must disable it. There is no data for the front brakes of course but i still have pad wear info for the rear. 

  • Like 2
  • 1 month later...
Posted (edited)
On 3/3/2024 at 5:26 PM, DenaliSS said:

 

Since posting, Replacement Pads - 84263246, Replacement Rotors - 84070075

From Brembo site, the cross refence numbers ~ P10103N NAO (ceramic) brake pad or

P 10 103 Prime

Something I did forget to add as an fyi is that the OE 17 inch spare tire will not work and will need to be at least a 20 inch wheel.

 

I've also noticed some threads saying that they have sensors with this brake system, which this Brembo system was not equipped for.  As stated on the description and in the install sheet, this system is not ePWI compatible;

The brake pad life system (ePWI) must be turned off. This is necessary because the Performance Brake Package is equipped with brake pads without electronic wear sensors. When the system is turned off, the front and rear brake pad life percentages will not display. However, the built-in wear indicators that make a high-pitched warning sound when the brake pads are worn can still determine when the pads should be replaced.

In cross-referencing between models within the GM family (GMC, Chevy, Cadillac) that share this brake package, an update to the pad replacement for P/N #84263246 (#85138044) you can refer to AC Delco 171 - 1202.  AC Delco uses original Brembo pads (P/N C5041200) in their packaging.

These are the ceramic pads.

 

Edited by DenaliSS
  • Like 1
  • 9 months later...
Posted
On 1/7/2025 at 8:05 AM, cemem said:

Never changed pads on a Brembo four piston setup before. Someone asked me how to you push the pistons back in the caliper if there are two on each side? Figured I would ask. Do you have to do that when changing pads or are these piston setups not designed that way like a traditional brake setup where you would use a c-clamp to push the pistons back in?

I use a soft face hammer to remove the guide pins and pull the retaining clip. I then use the existing pad itself or if needed to get some space between disc and pad, I have a small thin pry bar (used for wood trim work) and finish seating the piston with a spreader.  Spray down the caliper to clean, prior to installing new pads.

Others may differ on the tools or procedure, but is what works for me and with the tools I already have.  These calipers are costly and would really not use tools such as a C-clamp, with a chance to mar the finish.

 

 

  • 3 months later...
Posted
On 7/30/2021 at 11:28 PM, kodiakdenali said:

I have them on mine, I really like them! I do wish the rear were brembo also, but its a minor point.

they operate just like a factory-stock brake, no unusual noise, no unusual characteristics, just a lot more braking power than the stock brakes.

Having all the extra material in the brake is nice for towing over the mountains, much more metal for heat to dissipate into. although the stock brakes are perfectly good also, I got the brembos as much for looks as performance. They don't disappoint in either area.

 

I had some trouble with the front end shaking while going to breckenridge earlier this year. Maybe this would solve that problem. 

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