Master Clinder Bore Size
Thread Starter
Disabled by request 8 JUN 2025
Joined: May 2019
Posts: 329
Likes: 94
From: St. Augustine, FL
Master Clinder Bore Size
1981 with PB. I have reason to believe the PO relaced the master cylinder with one with a 1 inch bore. I understand that PB require a 1 1/8 bore. Pedal pressure seems a bit high compared to modern day power brakes. Would it be adviseable to replace the master cylinder with the correct one??
Le Mans Master
Joined: Aug 2006
Posts: 7,417
Likes: 1,553
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Race Director
Joined: Mar 2016
Posts: 14,299
Likes: 8,103
From: Napa Valley California
Are there any performance engine mods or was the camshaft swapped out?
The only reason I ask is that I am installing a highly modified 496 stroker engine in my 73.
When I was purchasing my new Wilwood brake system, Wilwood would not recommend which master cylinder bore size until after the engine was dyno tuned or I started the engine and determined the amount of vacuum the engine would be pulling.
Wilwood said the engine vacuum would determine whether I should use a 1" or a 1 1/8" bore master cylinder.
This seemed weird so I called back the next day and talked with another tech who told me the same thing.
The only reason I ask is that I am installing a highly modified 496 stroker engine in my 73.
When I was purchasing my new Wilwood brake system, Wilwood would not recommend which master cylinder bore size until after the engine was dyno tuned or I started the engine and determined the amount of vacuum the engine would be pulling.
Wilwood said the engine vacuum would determine whether I should use a 1" or a 1 1/8" bore master cylinder.
This seemed weird so I called back the next day and talked with another tech who told me the same thing.
Le Mans Master
Joined: Aug 2006
Posts: 7,417
Likes: 1,553
From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
Race Director
Joined: Mar 2016
Posts: 14,299
Likes: 8,103
From: Napa Valley California
The two Wilwood tech’s I spoke with both told me that vacuum pulled by the engine would actually effect the bore size of the master cylinder I would need to order.
I don’t understand the technical reasoning, but its their product and design, so I will follow their advise.
I’m sure on a manual brake system, it would make no difference, but with a vacuum assisted brake booster, maybe engine vacuum does effect the master cylinder bore size.
I sorry I can’t answer your questions about why, but maybe if you contact Wilwood’s technician services representatives they can answer any questions you may have.
I don’t understand the technical reasoning, but its their product and design, so I will follow their advise.
I’m sure on a manual brake system, it would make no difference, but with a vacuum assisted brake booster, maybe engine vacuum does effect the master cylinder bore size.
I sorry I can’t answer your questions about why, but maybe if you contact Wilwood’s technician services representatives they can answer any questions you may have.
Race Director
Joined: Jan 2000
Posts: 13,013
Likes: 2,253
From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
2020 Corvette of the Year (performance mods)
C2 of Year Winner (performance mods) 2019
2017 C2 of Year Finalist
The smaller bore size will build pressure quicker, but require more pedal travel. Larger will move more fluid with less pedal movement....but build less pressure with same pedal effort. Add in the effects of a booster and it can make the harder pedal easier to push and give you increased pressure. It can also allow you to push harder on the larger one to get the pressure you need to stop the car the way you want.
JIM
JIM
Is my vette stock?? HAHA
Joined: Oct 2015
Posts: 20,108
Likes: 9,236
From: Im not allowed to tell you
2020 C3 of the Year Finalist - Modified
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
I would buy a complete master and booster system from someone else......IF you have low vacuum add a vacuum pump. It would only be low at idle speeds anyway. Your reservoir would hold a large volume of vacuum for braking once you get up to a higher rpm. To me Wilwood is just living of name recognition from all the TV shows.
I would look at Tuff Stuff. https://www.tuffstuffperformance.com...8-5-7-350.html
Their products are American made , work great and are reasonably priced. Just look for a disc/disc setup. After doing a day of laps on a closed road course the only thing I would upgrade from stock is ceramic brake pads and drilled discs to cool them down faster. Tuff Stuff lists 1 1/8th for disc/disc setups and 1 inch for disc/drum setups....that should tell you how well the service dept at Wilwood is.
heres the one for your setup
https://www.tuffstuffperformance.com...nc-2129nb.html
in chrome of your into that look
https://www.tuffstuffperformance.com...me-2129na.html
I would look at Tuff Stuff. https://www.tuffstuffperformance.com...8-5-7-350.html
Their products are American made , work great and are reasonably priced. Just look for a disc/disc setup. After doing a day of laps on a closed road course the only thing I would upgrade from stock is ceramic brake pads and drilled discs to cool them down faster. Tuff Stuff lists 1 1/8th for disc/disc setups and 1 inch for disc/drum setups....that should tell you how well the service dept at Wilwood is.
heres the one for your setup
https://www.tuffstuffperformance.com...nc-2129nb.html
in chrome of your into that look
https://www.tuffstuffperformance.com...me-2129na.html
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
Race Director
Joined: Mar 2016
Posts: 14,299
Likes: 8,103
From: Napa Valley California
I agree that TuffStuff makes excellent products and I’m planning to purchase their power brake booster.
I have used Wilwood brakes and master cylinders systems on other projects.
I trust the quality of their products and their advice.
I have used Wilwood brakes and master cylinders systems on other projects.
I trust the quality of their products and their advice.