Master Cylinder Choice

[Smoker03]

I have Wilwood front and rear 12.1" brakes with four piston calipers on a 67 camaro. RIght now the car has power brakes and the pedal is sensative sometimes and very stiff other times. The motor doesnt make much vacuum at idle, and that seems to be the issue. I would go hydroboost, but its not in the budget. I have heard many people say that a manual setup can be just as good with the right master cylinder. Would anyone be able to recommend a master cylinder to convert to manual brakes that would work well with my brake setup? Any info would be great, and I am always willing to purchase from a supporting vendor.

[ehummelman]

I've the same setup on my 69but with the 6 pistons in front, 4 in rear. I'm running manual brakes with a Wilwood 7/8 MC. At first it was hard to get used to coming from a power brake car, but now I really like it. You just have to put a lot of leg into it, but I find it's easier to modulate. Make sure you change the pedal or push rod mounting point to get the right ratio, otherwise you could have issues.

[Apogee]

I have Wilwood front and rear 12.1" brakes with four piston calipers on a 67 camaro. RIght now the car has power brakes and the pedal is sensative sometimes and very stiff other times. The motor doesnt make much vacuum at idle, and that seems to be the issue. I would go hydroboost, but its not in the budget. I have heard many people say that a manual setup can be just as good with the right master cylinder. Would anyone be able to recommend a master cylinder to convert to manual brakes that would work well with my brake setup? Any info would be great, and I am always willing to purchase from a supporting vendor.

Manual brakes can be made to work quite well, however the pedal feel and travel would rarely ever be mistaken for a power brake setup, which in many ways is a good thing and in others not so much. Since you're starting with a poorly functioning power system, you don't have a very good baseline for comparison. You've ruled out hydroboost due to cost, so your only other power brake option would be to somehow improve what you have. You could add an accumulator and/or an auxiliary vacuum pump, the former is pretty inexpensive while the latter is not. I'm not a huge fan of aux. pumps as they tend to be somewhat costly ($200-$300) and obnoxious in terms of noise and vibration, but in a low vacuum situation, there aren't a lot of options. The accumulator can help with the pedal consistency, although if volume isn't the issue, then it won't change anything.

Then you have the manual option with an appropriately sized master cylinder, probably 7/8" in your application. The pros to manual would be simplicity, modulation/control, driver feedback, consistency regardless of engine/cam, cost and weight...the cons are longer pedal travel, higher pedal effort and less margin for error with respect to pad selection, pad knockback, etc. When we set up C5/C6 systems for manual brakes, we typically run a more aggressive pad to help reduce pedal effort required to achieve lockup. The down side to more aggressive pads is usually more brake dust, noise and rotor wear, but still well worth it IMHO.

Tobin
KORE3

[Smoker03]

Manual brakes can be made to work quite well, however the pedal feel and travel would rarely ever be mistaken for a power brake setup, which in many ways is a good thing and in others not so much. Since you're starting with a poorly functioning power system, you don't have a very good baseline for comparison. You've ruled out hydroboost due to cost, so your only other power brake option would be to somehow improve what you have. You could add an accumulator and/or an auxiliary vacuum pump, the former is pretty inexpensive while the latter is not. I'm not a huge fan of aux. pumps as they tend to be somewhat costly ($200-$300) and obnoxious in terms of noise and vibration, but in a low vacuum situation, there aren't a lot of options. The accumulator can help with the pedal consistency, although if volume isn't the issue, then it won't change anything.

Then you have the manual option with an appropriately sized master cylinder, probably 7/8" in your application. The pros to manual would be simplicity, modulation/control, driver feedback, consistency regardless of engine/cam, cost and weight...the cons are longer pedal travel, higher pedal effort and less margin for error with respect to pad selection, pad knockback, etc. When we set up C5/C6 systems for manual brakes, we typically run a more aggressive pad to help reduce pedal effort required to achieve lockup. The down side to more aggressive pads is usually more brake dust, noise and rotor wear, but still well worth it IMHO.

Tobin
KORE3

Thanks for all the info. Is there a certain master cylinder that would work best? Also, would I be able to purchase it from you? I would need the piston rod as well, and I would guess I could get that from NPD or Classic. I would really much rather upgrade to one of your full C6 brake systems. Hopefully one day.

[Apogee]

For 7/8" master cylinders, you can go with an aftermarket unit like those offered by Wilwood, #260-9439(-BK or -P), which is typically what we would supply. Otherwise, there are guys running OE based 7/8" bore MC's like those off the mid-70's Monza and several Mopar applications. The brakes don't care if the MC is cast iron or aluminum...they all work on the same principles.

Tobin
KORE3

[TheJDMan]

I'm also running a manual 7/8" Wilwood master cylinder with 6 piston front and 4 pistion rear calipers. The pedal is solid and moves only a couple of inches. Once I became acustomed to the pedal feel I have been very pleased with the performance. I purchased my MC from Summit. It was pretty much a bolt on deal. The only real difference is that the rod is permanently attached to the MC unlike the factory MC.

http://www.summitracing.com/parts/WIL-260-9439/

[MCB Matt]

7/8" wilwood is the best on manual setup.

You can TRY a vacuum tank and or pump but with the new lower cost hydraboost units we have i would do that before the pump and tank.

Manual brakes have a longer pedal travel which some don't like....for what we sell 95% of guys are running power.

But by far the Wilwood is the best looking and performing master out....we sell a ton, espically the black.

Matt

[Smoker03]

Amazingly my wife let me splurge on the hydratech unit now. I have a corvette 1-1/8" master that was on my booster and am going to use it on the hydroboost unit. Hopefully this solves my issues.