Switch to Power from Manual brakes????

[protour73]

I finished the build on my '73 Camaro earlier this year. At that time I decided to go with a manual brake setup using Wilwood Dynalite 12" rotors with 4 piston calipers at all four corners and a Wilwood tandem master cylinder with a 7/8" bore.

The stopping power is just not there. I tried a few simulated panic stops from 50 mph and could not even achieve lockup. So maybe the next step is to add the power assist of a 7" or 8" dual diaphragm booster to the system for some more pressure.

My engine is a ZZ4 350 with the H.O.T. cam, so vacuum is not a problem. I also have a Wilwood proportioning valve that can be added as well. I'm just not feeling the love with a Hydroboost system, I have a couple friends that have them and love them but it just seems like the majority of folks pass up this choice. The majority of my driving is just cruising, but I plan on attending the Motor State Challenge next June, so occasional track time too.

Any recommendations??

THANKS,
Scott

[Cris@JCG]

The bore on the M/C is to small.. Need to go with a 1.00 bore M/C.. If the bores on calipers are 1.75 & 1.375 in rear, this the m/c bore size I would recommend.. another thing you want to look @ is the clevis mounting hole on the pedal.. OE levers have to points to mount clevis on pedal.. The highest hole on pedal is for manual brakes to attain more leverage out of the pedal.. the lowest clevis hole is for power brakes, the booster will aid in leverage from the pedal

Originally Posted by protour73

I finished the build on my '73 Camaro earlier this year. At that time I decided to go with a manual brake setup using Wilwood Dynalite 12" rotors with 4 piston calipers at all four corners and a Wilwood tandem master cylinder with a 7/8" bore.

The stopping power is just not there. I tried a few simulated panic stops from 50 mph and could not even achieve lockup. So maybe the next step is to add the power assist of a 7" or 8" dual diaphragm booster to the system for some more pressure.

My engine is a ZZ4 350 with the H.O.T. cam, so vacuum is not a problem. I also have a Wilwood proportioning valve that can be added as well. I'm just not feeling the love with a Hydroboost system, I have a couple friends that have them and love them but it just seems like the majority of folks pass up this choice. The majority of my driving is just cruising, but I plan on attending the Motor State Challenge next June, so occasional track time too.

Any recommendations??

THANKS,
Scott

[protour73]

Originally Posted by Gonzo

The bore on the M/C is to small.. Need to go with a 1.00 bore M/C.. If the bores on calipers are 1.75 & 1.375 in rear, this the m/c bore size I would recommend.. another thing you want to look @ is the clevis mounting hole on the pedal.. OE levers have to points to mount clevis on pedal.. The highest hole on pedal is for manual brakes to attain more leverage out of the pedal.. the lowest clevis hole is for power brakes, the booster will aid in leverage from the pedal

You are right on....The Wilwoods are 1.75" pistons in front and in the back are 1.38". The M/C rod is in the upper hole in the pedal, so that is not an issue.

I got the system through Frank @ Prodigy, and I believe he will swap the master out for me. I got ahold of him on Friday, but he was on his way out of town.

[Apogee]

Originally Posted by Gonzo

The bore on the M/C is to small.. Need to go with a 1.00 bore M/C...

Why do you recommend that he run a larger MC, one that will generate aproximately 30% less caliper pressure for a given pedal input force?

As for a power booster setup, a dual 8" or single 11" both have about the same effective area and would match up pretty well with a 1" bore MC given the 4.8/3.0 square inch front/rear caliper piston areas that you're running. A dual 9" booster would give you another ~30% boost...something that could come in handy if you want to run a low-dust, low coefficient of friction (CoF) pad (ie ceramic). What brake pads are you running? Low CoF pads combined with relatively small diameter rotors and performance tires can make achieving lockup much more difficult.

Tobin
KORE3

[protour73]

Originally Posted by Apogee

Why do you recommend that he run a larger MC, one that will generate aproximately 30% less caliper pressure for a given pedal input force?

As for a power booster setup, a dual 8" or single 11" both have about the same effective area and would match up pretty well with a 1" bore MC given the 4.8/3.0 square inch front/rear caliper piston areas that you're running. A dual 9" booster would give you another ~30% boost...something that could come in handy if you want to run a low-dust, low coefficient of friction (CoF) pad (ie ceramic). What brake pads are you running? Low CoF pads combined with relatively small diameter rotors and performance tires can make achieving lockup much more difficult.

Tobin
KORE3

Hey Tobin thanks.....I was waiting for you to chime in. I still have the stock Wilwood pads that came with the setup. Are they a sub-standard pad?

[Cris@JCG]

Why do you recommend that he run a larger MC, one that will generate aproximately 30% less caliper pressure for a given pedal input force?

Cause this has always been the caliper to M/C combination that I have always used for manual setup on a Camaro!!! Without getting techincal into it & will stand behind it 100%..

[chr2002ca]

This is an interesting topic because I'm struggling a bit with the same problem, except I already have a 9" dual diaphragm booster. I just don't get enough pressure to my brakes to lock them up either. I'm running the Baer Track 2-piston 13" kit up front and the Baer Track single piston 13" kit in back and I pull plenty of vacuum(18) at idle and on up to 23 when cruising. I believe I'm close to getting the brakes right, but I'm still not getting enough pressure, so I feel your pain! I went from an 8" dual diaphragm to a 9" dual and that helped a little. I then went from a 1 1/8" bore MC down to a 1" bore MC and that helped also(going smaller increases brake pressure but also increases brake pedal travel). However I'm still not getting the brake pressure I should be, and it's been frustrating. I have bench bled my MC twice now, and bled my lines with 3 different methods(foot, vacuum, and power bleeder).

I would think you should be able to lock up your brakes with your current setup because it's a common one, as I should with mine, so either one of us buying more or different equipment may not be the answer. My next step is to measure the brake pressure at each caliper and also coming out of the MC and call up Baer to get their advice. I just purchased a brake pressure guage kit and hopefully it'll help me to debug the issue over the holidays.

I would recommend that you do some double and triple-checking on your current setup before you decide to purchase additional equipment. I don't recommend going to a larger bore size MC. I can't see how that would help. Some people who run manual setups like to run a 13/16" bore size on their MC. That might be a consideration for you after you've done all you can to prove your current setup just ain't capable of doing what you like.

If you do finally determine the answer, feel free to PM me, and I'll do the same from my end.

[Vegas69]

You may want to check your brake pads to make sure they are correct. Wilwood has a bunch of compounds. I'm a firm believer that two sets of pads are needed. Street/autoross and road racing. I've never been thrilled with my street performance. I think you must get accustomed to them as well. Most of us drive around in highly boosted modern cars, then we jump into a car with manual racing brakes. I've just recently got mine to where I like them on the street. That took some tapered axle bearings. Going to a smaller master will add pad travel as mentioned by Chris. I woldn't want a smaller cylinder on mine. In fact, I would love to run a larger but already suffer from brake pad knock back on the race track and it would only get worse. At the end of the day Wilwood brakes are for racing not street driving.