Enter your username:
Do you want to login or register?
  • Forgot your password?

    Login / Register



    Page 1 of 2 1 2 LastLast
    Results 1 to 20 of 40
    1. #1
      Join Date
      Aug 2010
      Posts
      440

      Symptoms of having the wrong sized master cylinder?

      What would be the symptoms of having a master cylinder that is the wrong size? I have a manual Wilwood 7/8" (rebuilt by Wilwood) on my project with Aerolites front and rear, all new copper lines, stainless flex lines, bled...driven...bled...driven, vacuum bled, reverse bled, pedal pump bled, pads bedded, etc. It just seems like the brakes don't wake up unless I really slam on them with my foot...almost like I have to think ahead about stopping when I am driving around town. I have a '15 Z/28 and a '17GT350R and the slightest touch of the pedal gets an immediate response (granted they are power brake cars). I'm just not sure what a manual brake car is supposed to feel like. I can get the brakes to lock up if I really slam on them. Thoughts?
      Joe
      1969 Firebird Project
      1967 Frirebird 400 convertible
      2013 Boss 302

    2. #2
      Join Date
      Jan 2006
      Posts
      385
      Country Flag: United States
      generally speaking, either too hard of a pedal with too much pedal effort to stop the car (piston size top large) or a soft pedal with too much travel to stop the car (piston too small).
      1971 Camaro
      GM HT383, MiniRam EFI, AFR heads
      "8-speed" trans (700R4 + Gear Vendors OD)

    3. #3
      Join Date
      Dec 2005
      Location
      TuoCo, CA
      Posts
      992
      Country Flag: United States
      Also manual brakes you need to get into them. You're comparing manual v. power assist.
      Steve
      '68 Camaro - SBC, TKO600, 3.73 Moser 12-bolt, Speedtech, ATS-AFX, Hotchkis, Forgeline, Ron Davis and C5 brakes (Kore3), Holley Terminator TBI.
      Check it Out Here

    4. #4
      Join Date
      Jan 2006
      Posts
      385
      Country Flag: United States
      My Camaro was originally manual brakes and yeah, it took some pedal effort... came factory with 12" rotors up front too, so it wasn't terrible for a car of that era... but it's nowhere near what the car is now with power assist.
      1971 Camaro
      GM HT383, MiniRam EFI, AFR heads
      "8-speed" trans (700R4 + Gear Vendors OD)

    5. #5
      Join Date
      Apr 2001
      Location
      The City of Fountains
      Posts
      15,971
      Country Flag: United States
      Quote Originally Posted by jlwdvm View Post
      What would be the symptoms of having a master cylinder that is the wrong size? I have a manual Wilwood 7/8" (rebuilt by Wilwood) on my project with Aerolites front and rear, all new copper lines, stainless flex lines, bled...driven...bled...driven, vacuum bled, reverse bled, pedal pump bled, pads bedded, etc. It just seems like the brakes don't wake up unless I really slam on them with my foot...almost like I have to think ahead about stopping when I am driving around town. I have a '15 Z/28 and a '17GT350R and the slightest touch of the pedal gets an immediate response (granted they are power brake cars). I'm just not sure what a manual brake car is supposed to feel like. I can get the brakes to lock up if I really slam on them. Thoughts?
      You're comparing some of the best stopping cars to an old car with manual brakes...LOL

      Manual brakes are very linear. Mine don't do much until the pedal is half way down, then they start to grab. If you want to stop quicker, step harder.

      Some things to look at is the pedal ratio and pedal to rod geometry. The angle between the pedal and the rod should not exceed 90 degrees on the angle that points up, if that makes sense.

      Andrew
      1970 GTO Version 3.0
      1967 Cougar build
      GM High-Tech Performance feature
      My YouTube Channel Please Subscribe!
      Instagram @projectgattago
      Dr. EFI
      I deliver what EFI promises.
      Remote Holley EFI tuning.
      Please get in touch if I can be of service.

      "You were the gun, your voice was the trigger, your bravery was the barrel, your eyes were the bullets." ~ Her

    6. #6
      Join Date
      Sep 2010
      Location
      Beach Park IL
      Posts
      2,838
      Country Flag: United States
      If you have link to your actual brake kit part numbers then we know caliper size but I bet it is 4" front and 2.25" rear. If it came with BP 10s or 20s you won't like it....just not enough bite for typical manual brake line pressures.

      I personally prefer a 15/16" master cylinder with most off the shelf brake systems of that approximate size with a 6:1 pedal ratio, but it is not the difference between stopping and STOPPING, I just prefer the pedal height and the smaller window between starting to stop and locked up.
      Donny

      Support your local hot rod shop!

    7. #7
      Join Date
      Oct 2014
      Location
      DFW, Texas
      Posts
      422
      Country Flag: United States
      Sounds like you want power assist, my manual brakes are the same way, it comes with the territory.

      Also, I hope your lines aren't copper, like you mentioned.
      1972 Plymouth 'Cuda - Not LS-swapped, 5.7L Hemi [MS3 Gold Box], T56 Magnum 6-speed - 'Cuda Build Page
      1976 Dodge D100 - Warlock
      2016 Subaru WRX - E30 Tune

    8. #8
      Join Date
      Aug 2010
      Posts
      440
      I guess I just don't know what to expect. I just want to make sure I am getting optimal brake performance. It will be a car that spends a lot of time on the track. Brake calculations done by Ron Sutton and complete package purchased from RSRT: Front Aerolite 6 Brake Kit, Rear Superlite 4 Brake Kit,Tandem M/C w/Built In Reservoir, proportioning valve for a 3500# '69 Firebird with Toyo R888 275 and 315 tires. Last summer I had pressure gauges on the calipers and they speced out with good pressure after the rebuilt/recalled master was put back on.
      Joe
      1969 Firebird Project
      1967 Frirebird 400 convertible
      2013 Boss 302

    9. #9
      Join Date
      Nov 2014
      Posts
      233
      Country Flag: United States
      My Camaro has a very similar system. As noted above comparing late model power assisted systems is not apples to apples. My car stops well but the feel is very different. Also, pad compound was not mentioned. If you do have BP10 or 20, there are much more aggressive compounds that will give you the "bite" you are looking for.

    10. #10
      Join Date
      Aug 2010
      Posts
      440
      Part number on my pad box shows BP-10 pads on Wilwoods site.
      Joe
      1969 Firebird Project
      1967 Frirebird 400 convertible
      2013 Boss 302

    11. #11
      Join Date
      Oct 2014
      Location
      DFW, Texas
      Posts
      422
      Country Flag: United States
      Quote Originally Posted by btmatt View Post
      My Camaro has a very similar system. As noted above comparing late model power assisted systems is not apples to apples. My car stops well but the feel is very different. Also, pad compound was not mentioned. If you do have BP10 or 20, there are much more aggressive compounds that will give you the "bite" you are looking for.
      I need to look into different compounds, I could use a much more street friendly compound with more cold bite.
      1972 Plymouth 'Cuda - Not LS-swapped, 5.7L Hemi [MS3 Gold Box], T56 Magnum 6-speed - 'Cuda Build Page
      1976 Dodge D100 - Warlock
      2016 Subaru WRX - E30 Tune

    12. #12
      Join Date
      Mar 2008
      Location
      Chicago suburbs
      Posts
      667
      Country Flag: United States
      How much pedal travel do you have approximately?

    13. #13
      Join Date
      Nov 2006
      Location
      Mountain Springs, Texas
      Posts
      4,488
      Country Flag: United States
      This might be of interest.

      Don
      Attached Images Attached Images  
      1969 Camaro - LSA 6L90E AME sub/IRS
      1957 Buick Estate Wagon
      1959 El Camino - Ironworks frame
      1956 Cameo - full C5 suspension/drivetrain
      1959 Apache Fleetside

    14. #14
      Join Date
      Dec 2010
      Location
      Fredericksburg, VA.
      Posts
      3,155
      Country Flag: United States
      Pad compound has a great deal of influence on brakes. I have two sets of pads, a set of ceramic pads for the street and a high friction set for track days. If RS spec'ed out your brake system it is probably right.
      Steve Hayes
      "Dust Off"
      68 Camaro

      Given sufficient initial acceleration, even pigs can fly!

    15. #15
      Join Date
      Aug 2010
      Posts
      440
      Ya, but i wonder if we spec'ed the pads for track duty. Looks like compound E would be best for the street? That chart also explains why bite and feel get better if I go out and build up some heat in the system like I am doing a bedding session.
      Joe
      1969 Firebird Project
      1967 Frirebird 400 convertible
      2013 Boss 302

    16. #16
      Join Date
      Apr 2010
      Location
      Jersey Shore
      Posts
      695
      Country Flag: United States
      I also have the RS stoptech brakes... I think he spec'd all of them with the same "triple duty" pads (auto-x/road race/street) The ones that were supplied by RS are the Stoptech 309 (sport) pads. I cant seem to find a Cf/Temp graph on them though.

      -Chris
      '69 Corvette
      '55 Chevy Hardtop
      AutoWorks Middletown, NJ
      @autoworksnj for corvette and shop car pics
      https://www.pro-touring.com/showthre...e-Build-Thread


    17. #17
      Join Date
      Aug 2010
      Posts
      440
      Quote Originally Posted by dhutton View Post
      This might be of interest.

      Don
      On the graph, the pads all seem close at lower temps, but will these differences in CoF make a big diff yin the feel of the brakes in the street? Again, I am deal with a street and track car. Thanks!
      Joe
      1969 Firebird Project
      1967 Frirebird 400 convertible
      2013 Boss 302

    18. #18
      Join Date
      Sep 2010
      Location
      Beach Park IL
      Posts
      2,838
      Country Flag: United States
      The difference between 10s and Es is very noticeable on the street. On my personal car it was the difference between "Imma throw these in the garbage" and "This is the way it should be"
      Donny

      Support your local hot rod shop!

    19. #19
      Join Date
      Aug 2010
      Posts
      440
      You are using E's for the street? It looks like BP20's would be a good choice for the track.
      Joe
      1969 Firebird Project
      1967 Frirebird 400 convertible
      2013 Boss 302

    20. #20
      Join Date
      Oct 2014
      Location
      DFW, Texas
      Posts
      422
      Country Flag: United States
      Quote Originally Posted by dontlifttoshift View Post
      The difference between 10s and Es is very noticeable on the street. On my personal car it was the difference between "Imma throw these in the garbage" and "This is the way it should be"

      PolyMatrix E's being the one you prefer on the street over BP-10s?

      Looks like my Wilwoods came with 10's, I'd like a little more low temp bite. Brakes work great the second time I lay into them, the an initial cold hard braking event leaves quite a bit to be desired for a street car.
      1972 Plymouth 'Cuda - Not LS-swapped, 5.7L Hemi [MS3 Gold Box], T56 Magnum 6-speed - 'Cuda Build Page
      1976 Dodge D100 - Warlock
      2016 Subaru WRX - E30 Tune

    Page 1 of 2 1 2 LastLast




    Advertise on Pro-Touring.com