pologreen1

At this point now just gathering info and keeping it here to come back to.

Mildly modified car, has new rotors,pads "stock size" and stainless lines etc...

If I have to replace it I would rather order an upgrade in performance or technology for the car. The car has a cam and is auto so I'm thinking a later MC would be good to help increase the pedal pressure too and help the vacuum canister.

I'm not ready for wilwood or anything like that on this car.

I remember a few years back people putting a larger bore MC on their older cars.

This information below I found in regard to how the brakes were rigged on these cars.

"That said, the late C4 Corvettes used .87" (88-91) and .93" (92-96) bore sizes. The pedal ratio was 3.5:1 for 88-91, and 4:1 for 92-96. The line pressure at 100 lb pedal load was 1250 PSI front and 750 PSI rear for 88-91 and 1160 PSI front and 680 PSI rear for 92-96."

Does anyone have this same info on c5+ cars for F/R distribution?

Anybody remember if it is camaro 93-02? or newer c4 vette that had the larger bore and just needed an fitting adapter

If I put in a big bore GM MC is it still a worth upgrade to put in the bias kit?

Any thoughts or input is welcome.

Found this below from Kubs old post on another forum.

Stock - 64.7% front, 35.3%
C5 Brake Upgrade - 66.3% front, 33.7% rear
Viper setup (Viper calipers and C6 Z06 rotors front, C6 Z51 rear rotors and C5 rear calipers) - 63.3% front, 36.7% rear

More info from this thread
https://www.corvetteforum.com/forums...hangeable.html

"The '88-'91 master cylinder
- has a 7/8" bore
- has discrete fr/rr reservoirs
- has a warning switch that points up
- has 12M x 1 rear (14mm flare wrench) and 10M x 1 front fittings 12mm flare wrench
- does not have low fluid sensor

The '92-'94 master cylinder
- has a 15/16" bore
- has a common fr/rr reservoirs
- has a warning switch that points down
- has 12M x 1 rear (14mm flare wrench) and 10M x 1 front fittings 12mm flare wrench
- has a low fluid sensor on the pass side

The '95-'96 master cylinder
- has a 15/16" bore
- has a common fr/rr reservoirs
- has a warning switch that points down
- has 12M x 1 rear (14mm flare wrench) and 10M x 1 front fittings 12mm flare wrench
- does not has a low fluid sensor (?)

The 15/16" bore means there would be a slight increase
in pedal pressure and a slight reduction in pedal travel
for a given amount of braking.

I do not KNOW but I suspect that the fitting locations on
the '92-'94 m/c are reversed, compared to the '88-'91.
The rear is still 12Mx1, but it may be at the front end
of the m/c instead of at the booster end. If this is correct,
my vote is that slight tweaking to reposition the brake
tubing will permit the fittings to line up with their respective
bosses in the m/c."

Thread of Camaro 1" install

https://www.corvetteforum.com/forums...r-upgrade.html

ddahlgren

Why would you want to reduce the line pressure to get better brakes? the 92-96 setup has a lower line pressure with a greater multiplication at the pedal. Seems like switching the pedal to a 92-96 with the 91 MC would have the highest line pressure using C4 parts. 14% more with the same 100 lbs foot pressure on the pedal.

Kubs

I switched to the larger 1" bore Camaro MC almost 10 years ago now. I did it because the pedal travel on my '90 was too long for my preference and made it harder for me to heel toe downshift on a road course. Yes, mathematically the larger bore provides less pressure for the same input force, so push harder... The difference in effort is hardly noticeable, but it really shortened the travel and worked out better for me.

If you take the larger pedal ratio, and match it with the smaller bore you are right the pressure would be greatest for the same 100lb input force, but the travel would be crazy long.



Both fittings on the Camaro MC are M11 I believe (been a while) but were available at any local part store. You can cut the stock lines, install the new fittings, and flare the end of the line. Simple.

0Todd TCE

^ This.

I get calls all the time about "mc upgrades"...a term that doesn't really make much sense. What's an 'upgrade'??

The mc is simply the tool by which pressure is derived. The smaller the bore; the higher the pressure, the larger the bore; the lower the pressure. All for the same given amount of Leg input.

None work better than the other. They just alter the amount of effort (and stroke) you use to slow the car. Most street cars look for a softer feel for gramda to drive whereas most track drivers prefer a shorter and harder to push pedal for "feel" and modulation.

pologreen1

Did you need a spacer ?

Perfect summation I think the 1" sounds like is does more what I am looking for in my application.

Kubs

No. You can use a small spacer or shim if you want, but I fixed the issue at the source. The booster rod has a small screw it the end of it to adjust its length. The head of this screw was too large to fit inside the dimple of the MC piston so it was applying a small amount of pressure even when adjusted all the way in. I replaced the screw with a set screw and internal hex on the end. I adjusted it to have a small gap when the pedal was not applied (like 0.010" or something). When you go to install the MC you can feel it hit the booster rod and if there is still a gap between the MC body and the booster you need to adjust the rod shorter.

I looked and dont have any pictures of that screw. Ill dig and see if I can look up the thread size or something.

aklim

Did you take out the brake fluid low sensor light or how did you put it in?

Kubs

I took it out. That pigtail was broken when I bought the car so I never had it anyway.

aklim

So it was available but you did not want it, right? But you could have if you wanted, am. I right?

Kubs

Are you talking about the sensor right above the outlet ports? There is no fitting for that sensor on the Camaro MC. IF you wanted to retain that feature it would require some creative plumbing.

C4 MC (sensor on top of 2 outlet fittings)




Camaro MC (no extra fittings)

aklim

So why did you use the Camaro one instead of the 92 to 94 C4 one? Also, what year is the Camaro one?

Kubs

The Camaro MC is the same for any '93-'02. I used it becuase I wanted the larger bore and I wanted to control my own bias. The stock setup even with a DRM spring puts too much bias in the front. Since the Camaro uses an external bias block, the MC has equal fluid output front and rear. I plumbed in a bias adjustment valve in the rear line, but I never touched it. The bias valve has always been full open. Even with the stock brakes it felt way better. When I upgraded my brakes I calculated my bias based on the mechanical components and the valve still remains full open, and the car is very stable under threshold braking.

aklim

What do you think would be the good and bad things about changing to the 92 to 96 C4 master cylinder? How different is it from the 91?

Kubs

I haven't messed with the other years so I couldn't give an accurate answer.