Technical Brake Information

January 9th, 2009

A) Stop! Always Bleed Master Cylinder Before Installation.

B) No or Low Pedal Condition. Testing of Combination/Proportioning Valve

  1. Using the test light, attach clip to a positive and touch the point of the tester to the electrical connection of the combination valve.
  2. If NO light goes on, the valve system is operating correctly. No further testing is required.
  3. If light goes on, this indicates the pressure differential valve in the combination valve is stuck in front or rear position.
  4. Bleed brake system to determine which system, front or rear is not getting proper flow of fluid; one system will squirt out of the bleeder, and the other will trickle out.
  5. The system with the flow must be opened for the flow to alter the pressure on opposite side of pressure differential valve to center valve.
  6. Slowly depress pedal with steady pressure until light goes out. When light goes out close the bleeder.
  7. Your system is now centered. Bleed complete system.

C ) Are you doing a Disc Brake Conversion and need to add the correct valving? Here are your choices.

  1. Metered Valves: Used in the disc portion of a disc/drum system to hold off the application of the discs slightly allowing the drums to catch up. This provides rear stability on wet surfaces and reduces front pad wear.
  2. Proportioning Valves: Used in the rear to decrease the rate of pressure rise to the drums relative to pedal force as weight is shifted to the front drums during braking. This prevents the rear from locking up. Proportioning Valves are available either in a preset or adjustable configuration.
  3. Residual Pressure Valves: Used to hold a residual pressure in your system.  You will require a 2lb to the discs if the master cylinder is lower then your calipers and a 10lb to the drums to prevent air ingestion when the brakes are released.
  4. Combination Valves: These valves provide metering to the front PLUS proportioning and residual to the rear. This is the recommended valve for all front disc brake conversions.

D ) To increase the life and performance of your new brakes, follow these steps.

  1. Make approximately 20 complete stops from 30 mph, or 20”slow down” from 50 mph to 20 mph, with light to moderate pressure.
  2. Allow at least 30 seconds between brake applications for the brake shoes or pads to cool down.
  3. You can do this as part of your normal driving time during the first 100 miles. Try to avoid hard stops during this time period also.
  4. Brake fluid should be changed once a year. D.O.T. 4 is recommended.

E ) Before Calling: Brake System Checklist

  1. Clean and flush complete hydraulic brake system before installing calipers and master cylinders.
  2. Use a good grade of brake fluid for best performance D.O.T. 4. Note: We do not warranty brake system parts that have silicone fluid introduced to the hydraulic system.
  3. Master Cylinders Test: Plug outlets with correct type and size plug (inverted flare or supplied plastic plugs). Step on pedal and hold pressure for 30 seconds.  Pedal should be firm and not drop to the floor.
  4. Calipers: Bleeder screws should be facing to top or face upward for bleeding of air out of caliper. Sometimes it is required to remove caliper from bracket and hold it up so the bleeder screw is at 12:00 o’clock to remove all the air in the system.
  5. Pedal Adjustment: Always have ¼” play at top of pedal clearance.  Without clearance brakes will apply or lock up wheels. Check adjustment of stop light switch.
  6. Valving: All types of valving should be lower than reservoir of master cylinder to function properly. All original equipment valves should be removed when combination valve is installed. Residual pressure valve should be as close to the master cylinder as possible.
  7. Follow the bleeding instructions that come with your master cylinder and calipers.
  8. Vacuum Test: Need minimum of 18” of vacuum for power booster to function correctly.
  9. Booster Test: With engine off, pump brake pedal to evacuate vacuum in booster.  Hold foot on brake pedal, start engine, if booster is working the pedal will drop about ¼”. Vacuum may be increased by adjusting ignition timing for maximum vacuum.
  10. Do not fill master cylinder to top. Leave about 1” from top for heat expansion.
  11. Keep combo valve away from exhaust headers.
  12. Check brake hose length and clearance while all four wheels are on the ground.
  13. Booster rod adjustment between booster and master cylinder should have approximately .020 clearance.


In order for your braking system to function properly the system must be properly balanced. This is accomplished through the use of the correct valves. Below is a description of what types of valving may be used on your system. If you have any questions please feel free to contact us at 1-800-638-1703.

I’m doing a Disc Brake Conversion and need to add the correct valving. What do I use?
The valving associated with braking falls into five basic categories:

Valve Type  Description

  1. Metering The metering or hold off valve is used in the disc portion of a disc/drum brake system to better balance the front to rear brakes. The valve does not allow the pressure to rise at the front disc brakes until the pressure at the rear drums has risen sufficiently to overcome the brake shoe springs, allowing the drums to catch up.  At this point the valve opens to allow full pressure to build at the front brakes. This provides rear stability on wet surfaces and reduces front pad wear.
  2. Proportioning The proportioning valve modulates the pressure in the rear, to decrease the rate of pressure rise to the drums to the rear brakes. The modulation is necessary to minimize rear wheel lock up found in heavy braking and to compensate for the differences in braking conditions in front disc/rear drum systems. As pressure is applied to the system full pressure is allowed to the rear drums up to a certain point. Beyond that point the pressure to the rear is reduced preventing rear brake lock up. Relative to pedal force as weight is shifted to the front during braking. Proportioning Valves are available either in a preset or adjustable configuration.
  3. Residual There are two different residual valves. A ten pound residual valve will maintain a line pressure to the rear to keep the drum brake shoes out close to the drums giving a higher firmer pedal. Without a ten pound residual pressure to the rear you will experience a spongy pedal. Prevents air ingestion when the brakes are released. A two pound residual valve is required whenever the master cylinder is lower than the calipers to prevent backflow of fluid from the calipers to the master.
  4. Combination A combination valve incorporates metering, proportioning and 10 pound residual into one valve. These are available for disc/drum or drum/drum systems. These valves provide metering to the front PLUS proportioning and residual to the rear. This is the recommended valve for all front disc brake conversions. Available for: GM, Fords, Chryslers and Jeep.
  5. Adjustable Prop The adjustable proportioning valve is used when you have a special rear condition that requires higher or lower pressure than a normal condition. You should always use a metering valve to the front when using the adjustable.

Tools Required

  • Pressure Tester
  • Booster Gauge
  • Vacuum Gauge
  • Pedal Pressure Gauge

55 Responses

  1. RUSS DYER says:


    • admin says:

      Sorry for long delay. Still working out the kinks on the blog so if this is old news please disregard this reply. We can definitely help you with the power booster and master cylinder. Call us at 800-638-1703. Thanks

  2. reece says:

    will this master cylinder MC36445 fit onto my stock 7″ booster and between the shock tower

    • admin says:

      Sorry for the long delay. This master will not work on the stock power brake unit with the stock type front end on your Ford Mustang. You must purchase a different booster kit. We can supply you the new booster with the shorter mounting brackets. Hope this helps.

  3. Mr Byron E Fulbright says:

    I’m considering one of your rear disc bracke conversions. My concern is which one
    to purchase. I have a 1973 Chevelle Malibu with a 9″ Moser housing with the GM
    bearing ends. Which kit do you recommend? And I want to use my e-brake

    • admin says:

      Hello, Thanks for your interest in our product. We would need to see a picture of the axle housing to determine whether or not one of our rear disc brake kit will work.

  4. Pete Bonefield says:

    I have a 70 chevelle, front disc brakes, and I have installed rear discs. At present it has a metering valve at the master clyinder, and a proporting valve down on the frame. Do I need to remove the metering valve and the proporting valve, and install a 4 wheel disc brake proportioning valve only?

  5. Tim Griffith says:

    I would like to buy a aluminum master cylinder kit # 19594, It will go on a 1964 gmc pick up, I have installed dics in the front , What is the bolt hole size center to center?? Its two wheel dwr. What is the outside bore size on the rear of master cylinder, will it fit thur the fire wall???

    • admin says:

      Lets make this easy! Our aluminum master cylinder kit will work on your 1964 GMC truck. You must specify the type of brakes front and rear. The piston bore size is 1.00″. The mounting holes are approximately 3.375″ center to center.

  6. Tim Griffith says:

    Thank you for the info, you are right . It will fit my 64 gmc truck. I will be buying this product. Can i send some pics of this ride when it is installed??? You will not be diapointed???

  7. Scott Soto says:

    I have a 1968 chevy C10 6 Lug pickup can i use the 5 Lug conversion kit # 16681
    on my pickup. i already bought new 1968 to 1972 tie rod ends for my pickup


    • admin says:

      Hello Scott,
      Yes! This kit will work great for your new original ball joints and tie rod ends!

  8. norm krenzer says:

    We added disc brakes from a chevelle on to a 69 firebird….changed out spindles, rotors, calp, now we have neg.camber we can’t adjust out….We read that the chevelle spindles are taller than a firebird/camaro….How can we salvage this project? I would like to use the rotors/calp. from the chevelle…what spindles do I need to fix this.


    • admin says:

      You didn’t mention what year Chevelle spindles you installed on your 1969 Firebird. Assuming they are the 1969-72 Type,
      they are the same. Did you change anything else when converting the brakes?

  9. Gerardo Rojas says:

    Hi; I have a 1966 Pontiac LeMans with a LS2 engine on it. I want to upgrade the suspension and brakes of it; I would like to know what lineup must I buy to have those big 13″ rotors, with 4 piston calipers on it, by using those tubular A-Arms. Which Spindles should I use?

    Do you have a Hardcore Break Kit for GM-A body? The ones I have seen are only 11″ rotors with 1 piston calipers on them.



    • admin says:

      We do carry the 13″ big brake for the GM A Body. We also offer the 12″ rear kits too. Our kits utilize Corvette rotors and matched PBR calipers. All of these items are available on the website and or through our catalog. If you need any further assistance please do not hesitate to contact us.
      Thank you,

  10. gary moore says:

    I have a 1969 chev c-30 one ton. and purchased a 1984 surburan for the engine and and transmission, It is a 3/4 ton. What parts can I use off the Surburan ? Would like to Use the disc. brake set up.. will this work on the 69????

    • admin says:

      Many of the parts from the 3/4 ton 1984 Suburban can be utilized on the 1969 Chevy C-30. You can use the front disc and the power booster setup up but you will have to do some alterations especially on the wheel portion of the disc setup. You may want to contact our Tech dept at 800-638-1703 and they can fill you in much easier on what it takes to finish the conversion.

  11. gary moore says:

    Would I also be able to utilize the power steering and tilt wheel from the surburban ?

    • admin says:

      You should be able to use the steering column out of the 1984 Suburban. You will have to make modifications to the intermediate shaft going to the gear box. If you need help once you start, please contact us and we can set you up with the proper parts!

  12. russ kearby says:

    I have a custom 55 chevy 4×4 with a 7″ corvette style master/booster that does not stop this truck.It is a firewall/flush mount assy. The rear axle is a 1976 corporate 14 bolt drum,the front axle is a 1985 3/4 ton disc.There is only a wilwood proportioning valve to the rears. The pedal is super hard to push. I would like to know what master/booster assy and any valving you have or can recommend.The pedal assy is out of a 71 chev truck and was lengthend about 3″ to get the pedal the right distance off the floor.Did that hurt the pedal ratio? The tires are 38′ super swampers,it weighs quite alot. got to get the ol’ girl back out to the truck shows.Any info will be great. Thanks,Russ

    • admin says:

      Hello Russ,
      The main issue that we see right now is that 7″ booster. We would highly recommend running our 8″ dual diaphragm setup. This will produce about 150-200 psi more line pressure than what you have currently. The other thing that was not mentioned was the master cylinder piston bore diameter. We recommend it to be a 1″ bore as this will also provide more line pressure. Please check what you have!

      By lengthening the pedal arm, this should have increased the pedal ratio making it easier on your leg. You can check to see what your ratio is by measuring from the pivot point to the center of the pedal pad and then measure from the pivot point to where the booster rod hooks to the pedal. Divide the second measurement into the first measurement and this is your pedal ration. Typical power brake systems have a ratio of 4 to 4.5:1.
      Lastly, we would definitely recommend removing the adjustable valve and run our GM type combination valve. All the adjustable valve does is restrict fluid flow to the rear brakes. Hope this helps!

  13. russ kearby says:

    Thanks for the info,I am intrested in starting from square one and purchasing both master cyl.and booster and GM type combination valve do you have these in possibly chrome? If not that is ok also. Part #’s and prices would also be helpful.Another thing,does brake line diameter need to be a certain size? Thanks,Russ

  14. i have a 72 duster with power disc small bolt pattern, want to change to large bolt pattern, will upper cintrol arms and spindels from 73 b body work

  15. Chris Shanahan says:

    What is your part number for this combination valve? It is mentioned in item 4 above: “Combination valve incorporates metering, proportioning and 10 pound residual into one valve. These are available for disc/drum”

    • admin says:

      Yes, the proportioning valve incorporates all of the functions you have mentioned. The valve is available in a 2 wheel disc (pv2) and a 4 wheel disc (pv4) configuration.

  16. Eddie Spence says:

    I have a 1957 chevrolet 4door hardtop and I would like to know if your MC36006C #19533 master cylinder will bolt up to my firewall with no problem and work with standard drum brakes. Or do you recomend a different style for my car. Any help would be most helpful. Thank’s!!!!!!!!

    • admin says:

      The MC36006C will work on your 1957 chevy fullsize. It bolts up a little different than the original by only using two of the firewall studs as opposed to the four that the car has. The spot in which the brake line hooks up is also slightly differenty.

  17. Eric Johansen says:

    I have a 4 wheel drum 68′ Camaro, I want to convert to front disc and keep the rear drum. I would like to know the criteria is for using 14″ rims, the ones I would like to use are GM rally wheels 14×7, they have a 4 1/2″ backspace, and +1/2″ offset.
    And do all of yer kits push the offset outward 3/8″, because I want this, due to the fact that my tires rub the tie rod end, and the frame, even though I am only using 215/70(BFG T/A’s) tires, they need replacing, and if so, I will be going to a 205/70(BFG T/A’s) and cross my fingers. Also, do you sell the vacuum piece that fits on the intake manifold, I will need the 3 pronged 1 (AT,AC, PB). and are the yokes, that connect the booster to the pedal available from you folks as well.I would also like to get, control arm bumpers, upper lower ball joints(just the cover for the lower 1’s if u sell them separate), and the steering coupler. Does the vacuum valve come on the booster? ty

    • admin says:

      Wow you have quite a few questions. Lets start with the brake kit. Our kit will move the wheels out 3/8″. This is how GM did it from the factory. Your rim size and type should work as the Camaros did use 14″ rally type wheel on the factory disc setup. The back space is a bit for a 7″ wheel but it should clear barely. As for all the other sales questions, please contact our sales department at 800-638-1703. Thank you!

  18. eric johansen says:

    on the prop valve, the button under the rubber dust cover, does that have to be pushed in when bleeding rear brakes, or what is it for?

  19. Matt Bedard says:


    Do you have a disc brake conversion kit that will work on a 1954 Pontiac Starchief? I was wondering if the 54 Chevy kit would work. If so, are there any issues with tire clearance? Thanks

  20. Phil says:

    I’m thinking of converting to front discs brakes on my 1962 C10. There is a note on your kit description that I can’t use my stock steel wheels. Is this true of all conversions? Why do the wheels matter?

    • admin says:

      Our drop spindle disc kits use 12″ rotors which require a 15″ disc brake type wheel. Later model truck rallys work great if that is the look you are wanting.

  21. Larry Andrews says:

    I m building a 63 chevy pickup,put a 67 ford 9in in the rear.I want to do a 2in spindle drop,with disc brakes,with 5 on 5 1/2 in lug pattern.I need spindles,rotors,and calipers.Thanks la.

    • admin says:

      Check out our webiste for all the different kits we offer. Remember the two bolt patterns we offer for the drop spindle setups are 5 x 5″ and 6 x 5.5″

  22. Kevin says:

    I will be installing the hydraboost brake system on my 68 Camaro. I am now looking to buy a steering pump and was interested in your #18904 kit. Is it compatible with a hydraboost brake system?

  23. Josh says:

    I have a 1959 GMC Fleetside that has the stock brake system on it. I bought the front disc brake conversion kit. My question is with it being all stock, do I need to change anything else out? I bought a proportioning valve but I don’t know where to install it? My brake component is underneath the truck. Can I only just install the disc kit?

    Thanks, Josh

    • admin says:

      We highly recommend that you run the appropriate dual disc master cylinder or our power brake unit. Please call us at 800-638-1703 to discuss your options.

  24. I have a 55 210 sedan with disc conversion on the frt. & org.type drum brakes or the rear. Use a 7 1/2 booster (called booster and a half) w/a vacuum pump. Have tried two different proportioning valves so far with no succuss to get the front brakes to lockup. Both of the valves are suppose to be “for disc brake conv.” Will a adjustable valve work/be of any benefit or do you another suggestions.

  25. Great Post! I love reading it.

  26. Larry Caudill says:

    I have a 1968 Camaro prostreet now weighing in at 2300#. I have installed Wilwood dIscs all around including duel master cylinder (mounted on the floor), adjustable proporting valve and disc equalizers to prevent back flow. When the brakes are first applied, the pedle goes to the floor, let off it is at least an 80%
    pedel. I tried to bleed the brakes from the right rear first but now i have no pedel.
    No leaks, all connections are tight and do not leak or allow air into the system. The master cyclinder is purged of all air. The discs have (4). 2 top and 2 bottom bleeders. What is the proper method to bleed the system?
    Appreciate your input. Thank you

  27. Bobby says:

    I’ve started installing a booster/dual mc to my 55 Belair .On the prop. valve the front 2 fittings are 3/16 the lines in my 55 call for a 5/16 fitting .Do you know if there is an adapter for this or will I have to do something else. ( 55 is disc/drum )

    • admin says:

      Well we assume the front lines are 1/4″ in diameter making the fitting 7/16″-20 thread. Yes this adapter is available at most good “NON commercial ” auto parts stores. We can help if you do not find one locally.

  28. victor says:

    I have a 1981 chevy stepside c10 pickup and changing over from no brake booster to booster. Issue is that I ordered a 7 inch 1″ bore chrome booster, now what chrome master cylinder do you have that i can add without changing my brake lines or maybe you have chrome brake line adapters

  29. have a 69 firebird backhalf about 3200 lbs with driver would the d52 caliper kit with new vented rotors work as good as the 140-10996 disc kit and maybe save a little wght

  30. Hydraulic Pressure Testing, The Ultimate Hydraulic pump is what I’ve been reading.

  31. I have tow chevy trucks one is a c15 the outer is a c30 I want to change the cabs put the c15 on the c30 fram the c30 has a biger breke boster do I need to use it on the c15 cab or is the smaller one on the c15 cab ok

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