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Brembo rears

100
44
Exp. Type
HPDE
Exp. Level
5-10 Years
So CA
Anyone converted their PP GT to the GT350 rear 4 piston Brembos? I have a '19 PP2 and know that the whole package is balanced already. But I trust more of Brembo's offerings. Will these fit plug-n-play or need master cyl and proportioning valve upgrades also? They will for sure fit behind my Apex's and PP2 stockers I'm sure. Thanks for any inputs.
 

TMSBOSS

Spending my pension on car parts and track fees.
6,652
3,820
Exp. Type
HPDE
Exp. Level
5-10 Years
Illinois
You may need to consider "Balance" before doing this mod. Improving rear braking while leaving the fronts stock could be a bad idea. If the rear has more brake than the front, the rear will tend to come around in hard braking. YMMV
 
100
44
Exp. Type
HPDE
Exp. Level
5-10 Years
So CA
You may need to consider "Balance" before doing this mod. Improving rear braking while leaving the fronts stock could be a bad idea. If the rear has more brake than the front, the rear will tend to come around in hard braking. YMMV
Totally true, just hard to trust those tiny OEM rears in the long run, on track use.
 
419
433
Exp. Type
W2W Racing
Exp. Level
20+ Years
Snowy North
Might be helpful to call FordPerf tech line, describe current and future application and goals.....then ask for their thoughts.

While they are in business to sell parts...they are also in business to build satisfied customers. And....they're good guys....no weasels at FP.

Good luck.
 

TMSBOSS

Spending my pension on car parts and track fees.
6,652
3,820
Exp. Type
HPDE
Exp. Level
5-10 Years
Illinois
Totally true, just hard to trust those tiny OEM rears in the long run, on track use.
Agree. I thought the same thing with my Boss. The stock rears hold up remarkably well. Rebuild with a solid high temp kit every year or so and send it.
 
100
44
Exp. Type
HPDE
Exp. Level
5-10 Years
So CA
Looks like the consensus is to keep it as-is, such an ugly 2 piston thing! The brake bias must be huge, the Mustang being all front end. I've always been used to a matched Brembo set on previous cars owned. At least the rear G-Loc R10s have more pad contact now.
 
1,084
1,035
In the V6L
Looks like the consensus is to keep it as-is, such an ugly 2 piston thing! The brake bias must be huge, the Mustang being all front end. I've always been used to a matched Brembo set on previous cars owned. At least the rear G-Loc R10s have more pad contact now.
Actually, the four-piston GT350 rears have a slightly smaller piston area (30/32 pistons vs a single 45) than the single piston units on GT's. Bias will shift forward about 5%. Best thing about the GT350 rear brakes? Easy pad changes - they're top loaders and you don't have to wind the parking brake back.
 
100
44
Exp. Type
HPDE
Exp. Level
5-10 Years
So CA
Actually, the four-piston GT350 rears have a slightly smaller piston area (30/32 pistons vs a single 45) than the single piston units on GT's. Bias will shift forward about 5%. Best thing about the GT350 rear brakes? Easy pad changes - they're top loaders and you don't have to wind the parking brake back.

Thx good analysis. You mean just wind the single piston in which I did. Parking brake still works fine.

Question is, do I need to swap rotors, spindles, parking brake, etc to convert?
 
1,084
1,035
In the V6L
Thx good analysis. You mean just wind the single piston in which I did. Parking brake still works fine.

Question is, do I need to swap rotors, spindles, parking brake, etc to convert?
I believe you have to swap a whole bunch of stuff - the FP kit instructions are on the FP website and they'll explain it all. There's a video on the job as well - one of the major retailers put it out - I don't remember which one - maybe LMR.
 
98
120
MD
The brake hoses, spindle, and hub should carry over from the GT but everything else in the picture below is GT350. The highlighted parts plus parking cables (parking brake assembly components for the swap), without the caliper, pads and rotor, are ~$500 per side.

1642624433814.png
 
1,084
1,035
In the V6L
The brake hoses, spindle, and hub should carry over from the GT but everything else in the picture below is GT350. The highlighted parts plus parking cables (parking brake assembly components for the swap), without the caliper, pads and rotor, are ~$500 per side.

View attachment 71937
The https://performanceparts.ford.com/part/M-2300-Y parts list shows replacement half-shafts and knuckles. Something must be different, but there's no explanation. Odd thing is, they replace the half-shaft and the knuckle, but keep the original hub. The half-shafts and knuckle may have been shifted inwards to make room for the GT350 parking brake.
 
Last edited:
The https://performanceparts.ford.com/part/M-2300-Y parts list shows replacement half-shafts and knuckles. Something must be different, but there's no explanation. Odd thing is, they replace the half-shaft and the knuckle, but keep the original hub. The half-shafts and knuckle may have been shifted inwards to make room for the GT350 parking brake.
From what I can find online:
GT350 rear knuckles are made out of cast aluminum, have different upgraded bushings, larger ID for the larger diameter half shafts, and smaller diameter mounting holes for the GT350-specific Brembo calipers.
 
98
120
MD
Both knuckles are aluminum. The caliper mounting bolts and bushings may be different - the knuckles have different part numbers but look physically identical. I don't have references but remember reading that the PP GT may have also used different/upgraded bushings front and rear.

When looking at the kit in pieces, the GT350 half shafts seem unnecessary because they are direct replacements in the GT and marketed as upgrades by Ford Performance. The diameter of the half shafts at the hub should presumably be the same since they don't require a GT350 knuckle or hub upgrade. The GT350 left shaft has a larger diameter vs the GT, otherwise the same dimensionally - https://performanceparts.ford.com/part/M-4130-M8S.
 
100
44
Exp. Type
HPDE
Exp. Level
5-10 Years
So CA
Well, back from Auto Club Speedway Roval using G-LOC R12/R10, Motul RB fluid, no issues at all w braking, Brembos and rear stockers were well balanced, cannot notice any fade at all. I'll probably shelf the rear Brembo conversion for now, spend the upgrade $$ somewhere else. Still trying to optimize camber, plates on order as well as oil catch cans, passenger side first. Apprec all the above details and parts though, huge thanks guys!
 
1,084
1,035
In the V6L
Well, back from Auto Club Speedway Roval using G-LOC R12/R10, Motul RB fluid, no issues at all w braking, Brembos and rear stockers were well balanced, cannot notice any fade at all. I'll probably shelf the rear Brembo conversion for now, spend the upgrade $$ somewhere else. Still trying to optimize camber, plates on order as well as oil catch cans, passenger side first. Apprec all the above details and parts though, huge thanks guys!
Good choice. Don't spend money solving a problem you don't actually have. Carry on!
 
138
87
Exp. Type
Time Attack
Exp. Level
Under 3 Years
Bulgaria
Well, back from Auto Club Speedway Roval using G-LOC R12/R10, Motul RB fluid, no issues at all w braking, Brembos and rear stockers were well balanced, cannot notice any fade at all. I'll probably shelf the rear Brembo conversion for now, spend the upgrade $$ somewhere else. Still trying to optimize camber, plates on order as well as oil catch cans, passenger side first. Apprec all the above details and parts though, huge thanks guys!
You will eventually tear dust booths on the OEM calipers and that is the good time to do the 4 piston GT350 rears. Someone had a kit just for rears with everything you need but it's a pricey upgrade:

 

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