Replacing brake master cylinder without replacing vacuum booster?

[BBLDarkStar]

I have searched a lot on this subject but not been able to find any reliable answers....

What is the difference between the 2013+ master cylinder and the 2010-2012? Is the newer master cylinder proportioned more to the rear because of the change in caliper piston bore size?

I replaced the brakes on my 2011 with all 2013+ rotors, calipers, lines and pads about 3 weeks ago. I went with the drilled and slotted rotors from Detroit Axle as well as their pads and brand new calipers. After installing everything, it seemed like it took forever for the cross hatching on the rear rotors to get worn off whereas the fronts were broken in within a couple days.

I drive up and down a mountain every day for work, from under 1000' elevation to over 8,000' at the summit I have to drive over. You can imagine how much abuse my brakes get. About two weeks after putting the new brakes on, the fronts started to make a harsh grinding sound under heavy braking and if I'm really aggressive with them they will vibrate like the rotors are starting to warp already. I had read that the rear calipers on the newer brakes have a different piston bore, but haven't' been able to determine if the bore is larger or smaller. I have also read that the MC and booster for the later models are different but can't find any exact information on what the actual differences are.

My question is if you can replace just the MC and not the booster. My pedal feels great right now, it's just the grinding noise and feel in the fronts that concerns me. It feels to me like the brake bias is too much hydraulic pressure to the front brakes so that they are taking the majority of the braking load. There's nothing wrong with my brake booster and I'm already into these brakes for enough money that I need to stop the bleeding. Will the new style master cylinder mate up to the old style booster?

I don't need to hear that I should have gone with Brembos or Wilwoods or anybody's opinion on what kind of brakes they prefer, lol. I just want to know if my MC may be the reason my fronts are taking more of the abuse than the rears and whether or not I can replace the MC without changing the booster.

Thank you in advance as the information I found in SHO Forum about upgrading to the newer brakes was awesome.

 

[kryptto]

Great question, can't assist you there might be a person here or two that might know.

 

[BBLDarkStar]

I've been doing more research on this topic. In case anybody else is in the same pickle.

Apparently the ABS pump and controller handles a lot of the brake bias and may be responsible for the excessive front bias I'm experiencing. From what I understand, it can be replaced with a later model part, but then it needs to be updated with as-built info for a later model VIN but with compatible options for the current vehicle.

 

[6500rpm]

Research brake booster push rod adjustment. Considering the mix and match, it could be a bit off with the 13 master cylinder and older booster. Just throwing it out there.

 

[BBLDarkStar]

Research brake booster push rod adjustment. Considering the mix and match, it could be a bit off with the 13 master cylinder and older booster. Just throwing it out there.

I'm pretty sure that would only affect the initial onset of braking, but good looking out.

 

[BBLDarkStar]

For anybody that cares. I did the research and found that the front caliper piston diameter increases from 48 mm to 51 mm when upgrading to the new style larger brakes. That's a change from a front rear bias ratio of 2.49:1 to 2.81:1 or about a 13% increase on front brake bias. I can't believe nobody else has noticed this when doing the upgrade.

I'm going to experiment with a more aggressive pad compound in the rear to try to compensate. The other route is to replace the ABS pump/controller with the newer style and try to trick it into working with the older build and not throwing an ABS code.

Wish me luck.

 

[LilCop2002]

Part of the reason it might not have been an issue is that most people who do the upgrade are doing the whole job at the same time. After 5.5 years I redid my rotors and pads this weekend with no noticeable difference in pads front/rear.