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After completing my hydroboost conversion (and solving the "Service Brakes Soon" message), I still want better brakes. The hydroboost conversion was a SIGNIFICANT upgrade, but my original factory brakes are wore out after 135k miles. There is not enough rear brake bias and the fronts pulsate.
Today, I tested to see if I could fit GMT800 2 piston rear calipers... and the answer is mostly yes! The larger 2 piston calipers and brackets will bolt right up to the backing plate on the axle. However, I will need to trim the backing plate and use the GMT800 rotors. Although the GMT800 rotors are 15mm smaller in diameter, that equates to just over a 1/4 inch in radius... I can live with that considering the brake pad surface area is about 1.6 times as much with about 1.7 times as much piston power:
Now that I've confirmed that the caliper and bracket bolt up, I've ordered rotors and pads. Once I upgrade the rear brakes and drive around for a while, I'll upgrade the fronts to the 2020 Silverado 4 piston calipers. I'll keep everyone posted on progress.
Just in case; when I did the hydroboost, I had to change HOW I braked. Its not that the hydroboost stops better once you hit the pedal, its that it allows you to keep stopping harder. If vacuum brakes stop in a linear: 50, 40, 30, 20, 10. I think hydroboost stops you progressively, 70, 60, 45, 15, 0. I had to go out and find room, so I could learn a new way to brake. If you just hit your brakes hard, your tires won't have the grip from the sudden change in acceleration. With hydroboost, you can keep pushing the pedal harder once you start slowing. You can slow good from 60 to 40, but you can face plant into the windshield from 40 to 0.
If they pulsate I'm pretty sure you got some warped rotors
If you really wanna get big brakes buy the K2XX or T1XX Brembo kit for the front and rear. I believe it is 6 pistons fronts 4 piston rears
Yeah I saw those and the similar 6 and 4 piston Bear kits. I just can't justify spending $6k on brakes! This upgrade should be less than $850 for the front and rear.
Just in case; when I did the hydroboost, I had to change HOW I braked. Its not that the hydroboost stops better once you hit the pedal, its that it allows you to keep stopping harder. If vacuum brakes stop in a linear: 50, 40, 30, 20, 10. I think hydroboost stops you progressively, 70, 60, 45, 15, 0. I had to go out and find room, so I could learn a new way to brake. If you just hit your brakes hard, your tires won't have the grip from the sudden change in acceleration. With hydroboost, you can keep pushing the pedal harder once you start slowing. You can slow good from 60 to 40, but you can face plant into the windshield from 40 to 0.
I was very tempted by that conversion! Looks great, but still too pricey for me. I hear you on the difference in linear power on the hydroboost. I've been using my left foot to brake for over 27 years, so I'm very good at modulating brakes by pressure and modulating throttle by distance. My formula-style race car has no booster and performs similar to the hydroboost... very little dead-zone and firm peddle once pads engage the rotors. I'm very happy with the hydroboost conversion!
Hopefully, I won't be face planting after the caliper upgrades. Thanks!
So, I wish I had better news, but I was not able to swap to the dual piston calipers today. I discovered two things:
1) the backing plate needs more than just the trimming the ears off. You can still use your backing plate, but you will need to spend about an hour per side brutally, but meticulously beating the lip down about a 1/4".
2) one of my axle seals is leaking... so, I've ordered new seals and GMT800 backing plates. Since I'll have the axles out for the seals, I'll replace the backing plates then too.
before:
and after a bit of shaping and sanding:
Axle seals and backing plates should be here next week... maybe I'll be able to do this on Saturday the 14th.
It wasn't completely clear, but the best brake upgrade in that budget is the 2020+ 4 piston caliper brakes. I know you used to be able to get the parts for about $300 when it first came out, and now it's about sold out everywhere and expect to pay about $500.
04-23-2022, 05:43 PM
Factory Brake Upgrade: From 6 Pistons to 12
