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 Post Posted: Tue Aug 28, 2012 5:57 pm 
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Joined: Tue Jun 08, 2004 1:06 pm
Posts: 224
Location: Houston, TX
Before you go buying the $90 a piece front Wilwood calipers, let me see if I can get them to work with the 24mm bore master cylinder.  I wouldn’t want you to spend $200 and it still didn’t fix your hard pedal problem.
 
I also didn’t know if you needed to use an adapter to mate you stock lines with the mopar master cylinder or if you had to rerun different size lines from the master cylinder to the prop valve.  How are your lines run?  What is the part number for that mopar master cylinder?
 
The reason I ask is there are smaller mopar master cylinders that will work better with stock size front brakes, but they have the 3/16” lines instead of the ½-20 and 9/16-20 outlets on the 15/16” and larger bore mopar master cylinders.  The smaller master cylinders come in 7/8” and a smaller 21mm bore.  The 21mm would be the best choice if you can find them.  The ones I have bought that say 21mm, end up being 7/8” bore. They come in 1993 dodge shadows and derivatives.

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 Post Posted: Tue Aug 28, 2012 6:21 pm 
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Joined: Tue Jul 17, 2012 11:47 pm
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Location: meridian, ms
Yes, that's why I'm watching what you do here, to see how the big calipers work (both pedal effort & bias-wise) with the same size master I have.

I don't have the p/n on the Mopar piece, it was years and years ago and the box got lost long before I had a chance to use it on anything. But, it was the one commonly sold for the 'universal'* manual brake conversion, I don't think this same one is still sold thru Mopar, but it's the same as any of the other kits on the market now with 15/16" bore, as far as I know.

It came with new inverted flare fittings, but I didn't use them... with the stock line fittings, one was an exact match and fit fine, the other was just a slight difference in thread pitch, with a little monkeying I was able to get the flare seated and it's now tweaked the threads in the m/c so that it fits like it was built that way.

Don't get me wrong, the brakes work - I can lock the wheels, but it just takes too much pedal effort to be confidence-inspiring in normal driving (standing on the pedal, pulling like crazy on the steering wheel - in all your travels down this road, I'm sure you've tried a combo that acted the same, lol). It's not just the difference in manual vs. power, as I used to have an S10 with the factory manual brakes and it wasn't much different than a power setup, other than a less squishy pedal feel.


*'universal' = doesn't fit anything :lol:


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 Post Posted: Wed Nov 21, 2012 6:19 pm 
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I am done testing the manual brake setup with a stock, aluminum, rebuilt, 24mm bore, 1980 El Camino master cylinder. With only this change, I got back the brake fluid pressure that I lost when I upgraded to the Wilwood 2.75” metric calipers using the 7/8” bore master cylinder. I bench bleed the master cylinder installed it in place of the 7/8” bore master cylinder, bled the line at the master cylinder, and then bled the car at all four wheels.

On the test drive, using the 24mm master, I did a few hard stops from about 30 mph. I was rewarded with both rear wheels locking up, but the front braking system felt as if it still wasn’t grabbing. After the testing, I jacked the front of the car and removed the wheels and I unbolted the calipers so I can take a look at the pads. I suppose during my very first manual brake test, I did not bed the brakes in properly and I glazed the brake pads over. I do not know why I did not notice this when I put on the Wilwood calipers other than not recognizing what glazed pads look like. The glazing most likely happened because I had a large master cylinder and small calipers on my first manual brake test and, at the time, I wasn’t getting enough pressure to the pads to do accomplish correct bedding. The moral of the story is to bed your pads properly.

Good news is that I found out what the issue is with the front brakes not grabbing. Bad news is that I didn’t deglaze my pads and retest. I didn’t deglaze the pads I originally used because went ahead and upgraded to a Wilwood Polymatrix A brake pad.

I went to the Wilwood PolymatrixA pad because of its good, cold clamping properties and, before I realized about the glazing pads, I had thought this would help with front brakes. **As a warning from Wilwood to any one using these pads, Wilwood considers these race pads**. These are aggressive pads and will most likely wear the front rotors prematurely and are intended for race use only. These pads have almost twice the friction coefficient as a “stock” type pad. I am using this aggressive pad because the front rotors are small, the brake pads are small, the front calipers are a floating design, and the car is now has manual brakes. These pads are also a wallet buster at $150 a set.

The braking test with these pads where a noticeable night a day difference. I felt very comfortable and confident while driving and stopping. On hard stops, the nose of the car would “dive” down and the rear wheels still locked up. Only time will tell if these front pads are good for everyday use with this manual brake setup.

If your car is a daily driver and not a drag car, you most likely do not need to change out to larger wheel cylinders on the rear drum brakes like I did. The original stock 3/4” bore wheel cylinders versus the larger 7/8” bore wheel cylinders should reduce rear lock up on hard braking.

For a drag racer with large, wide, sticky tires on the back, the larger 7/8” bore wheel cylinder may be better to keep the rear tires from spinning when your holding the car on the line with just the brakes. An aggressive front pad may also be needed to hold the car on the line (contact one of the major brake pad manufactures for suggestions).

From my experience, to do a manual brake system on a g-body or s-10, some or all of the brake components will have to be replaced. You cannot just remove the vacuum booster and bolt the master cylinder to the firewall and expect your braking to function well. It is a system approach.

Do you need an oversized caliper? In my opinion, no you do not.

Do you need to change out the front calipers? In my opinion, yes you do. Why? Because the stock calipers may or may not be a LOW DRAG design which requires a step bore master cylinder. How do you know that you have LOW DRAG calipers? You actually cannot physically tell, so its best to buy aftermarket calipers to cut down on variables that may cause trouble with your braking system.

Do I recommend rebuilt front calipers from the auto parts store? No. See above.

Do you need to change out the master cylinder? In my opinion, most likely you will need to. Why? It depends on what you are starting with. If you have a GM g-body vehicle that was built from 1978 to 1980, you have a strait bore, 24mm bore master cylinder from the factory and you can just upgrade to Wilwood 2.75” bore calipers if you master cylinder is in good working order. If you have a vehicle built from 1981 through 2003 you most likely have a step bore master cylinder. These master cylinders are too large for almost all manual brake conversions on a g-body or s-10. Now a choice has to be made. How much money do you want to spend on aftermarket front calipers? Cheapest ones that I have found are around $45 each with a stock size bore from U.S. Brakes. You will then need a 7/8” bore master cylinder to match to these front calipers. For a g-body car you can go with a new or rebuilt, stock replacement from a 1978 to 1980 g-body manual brake master cylinder. For an S-10, the only option I have found that readily bolts to the firewall and to the brake lines is a Wilwood 7/8” bore master cylinder. If upgrading to the Wilwood 2.75” bore calipers, you will need a 24mm master cylinder. The g-body options are a new or built stock power brake unit from a 1978 to 1980 g-body car. New ones will be cast iron. Most rebuilt ones will be cast iron. For some reason, the 1980 model years came in aluminum and these can be bought rebuilt (like I have installed in the latest test). For a s-10, you can use a stock replacement manual brake master cylinder from a 1982 to 1992 s-10 truck with manual brakes. These are step bore master cylinders with a primary bore of 1-1/4” and a secondary bore of 24mm. I do not recommend these master cylinders because they are hard to bleed and have a bypass valve that can fail. The other options are a 24mm Wilwood master cylinder and a 1990s 24mm Dodge Dakota master cylinder. Only issue with the Dakota master is the rear brake port is 9/16-20 instead of 9/16-18. I have found no adapter for this conversion yet.

Do I recommend step bore master cylinders? No, because they are generally too large for a stock size front caliper, they are hard to bleed, and they have a bypass valve that may fail. These three issues can be remedied by using a correct size strait bore master cylinder. A 7/8” bore master cylinder for stock bore, aftermarket calipers and 24mm bore master cylinder for a Wilwood 2.75” bore calipers.

Do I recommend other oversized front calipers other than the Wilwood 2.75” front calipers? No, because their piston size in these oversized calipers are not much larger than stock. The Wilwood caliper, visually, looks to be engineered better.

Do I recommend stock size calipers? U.S. Brake is the only caliper, of the aftermarket cast iron replacements I know, that is not a low drag caliper. There may be other aftermarket, “metric” calipers, but I cannot confirm if they are low drag or not. The U.S. Brake calipers are based on a stock casting. The other alternative is a stock, replacement aluminum, “metric” caliper from Wilwood. I have not used or viewed one of these calipers, but from engineering of the 2.75” bore and 2.00” bore calipers I have viewed, I suspect they should be just as well engineered and lighter.

Do I recommend larger wheel cylinders? If the car is street driven, most likely no. If drag raced, most likely yes to keep the rear tires from spinning when doing a brake stand

Do I recommend braided stainless steel flex lines? Yes, for the reduced ballooning and better pedal feel, but is not necessary.

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www.manualbrakes.com
https://www.facebook.com/manualbrakescom-576443512373024/


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 Post Posted: Sat Nov 24, 2012 10:04 am 
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Dave, Awesome write-up!

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 Post Posted: Fri Jun 21, 2013 10:04 pm 
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Here is a list of strait bore master cylinders that will bolt up to a G-body’s angled firewall when using a flat, manual brake adapter plate. This is a list from smallest to largest.

21mm (0.826”) bore 1993 Dodge Shadow master cylinder (other years and models may work)
• Requires adapters to mate master cylinder outlet to stock lines. The adapter Part number is MC-SF at http://www.classicperform.com.
• Mounting holes spaced 3.25” versus GM master cylinder’s 3.375”.
• Hard to find.
• Light in weight.
• Advertised as 21mm, but may be delivered in 7/8” or 24mm bores. Measure bore size before you buy. Rebuilt/Used ones will have a “1” cast into the front of the aluminium body under the reservoir.
• Can buy new or used. New ones are fairly cheap to purchase.
• Aluminium body – new, used, or rebuilt.
• Large reservoir can hold enough fluid for rear disc brakes.

7/8” (0.875”) bore 1978-1980 GM G-body manual brake master cylinders.
• Can buy new or used. Rebuilt are fairly cheap. New are fairly expensive.
• Reservoir too small for rear disc brakes. The reservoir from 1979 Buick Riviera with four wheel disc brakes can be retrofitted to this master cylinder.
• Advertised as manual brake units, but may be delivered as a 24mm, vacuum power boosted unit. Measure bore size before you buy.
• Bolt in.
• Cast iron body – new, used, or rebuilt. (no aluminium)

7/8” (0.875”) bore 1993 Dodge Shadow master cylinder (other years and models may work)
• Requires adapters to mate master cylinder outlet to stock lines. The adapter Part number is MC-SF at http://www.classicperform.com.
• Mounting holes spaced 3.25” versus GM master cylinder’s 3.375”.
• Easier to find.
• Light in weight.
• Advertised as 7/8”, but may be delivered in a 24mm bore. Measure bore size before you buy.
• Rebuilt/Used ones will have an “8” cast into the front of the aluminium body under the reservoir.
• Can buy new or used. New ones are fairly cheap to purchase.
• Aluminium body – new, used, or rebuilt.
• Large reservoir can hold enough fluid for rear disc brakes.

24mm (0.944”) bore 1978-1980 GM G-body power brake master cylinders.
• Can buy new or used. Used are fairly cheap. New are fairly expensive.
• Reservoir too small for rear disc brakes. The reservoir from 1979 Buick Riviera with four wheel disc brakes can be retrofitted to this master cylinder.
• Bolt in.
• Come in cast iron and aluminium. 1978-1979 are cast iron. 1980 is aluminium (some models i.e. El Camino).
• New master cylinders will most likely be cast iron regardless of year.
• Rebuilt units come in cast iron and aluminium (1980 – some models).

24mm (0.944”) bore 1993 Dodge Shadow master cylinder (other years and models may work)
• Requires adapters to mate master cylinder outlet to stock lines. The adapter Part number is MC-SF at http://www.classicperform.com.
• Mounting holes spaced 3.25” versus GM master cylinder’s 3.375”.
• Easiest to find.
• Light in weight.
• Advertised as 24mm, but may be delivered in a 7/8” bore. Measure bore size before you buy.
• Rebuilt/Used ones will have a “4” cast into the front of the aluminium body under the reservoir.
• Can buy new or used. New ones are fairly cheap to purchase.
• Aluminium body – new, used, or rebuilt.
• Large reservoir can hold enough fluid for rear disc brakes.

24mm (0.944”) bore 1993 Dodge Dakota master cylinder (other years and models may work)
• Rear brake line outlet is 9/16-20 versus GM rear brake line fitting of 9/16-18. The fitting for GM brake line may be used to “rethread” the master cylinder’s outlet.
• Front brake lines bolt up.
• Mounting holes spaced 3.25” versus GM master cylinder’s 3.375”.
• Can buy new or used. New ones are fairly cheap to purchase.
• Aluminium body – new, used, or rebuilt.
• Large reservoir can hold enough fluid for rear disc brakes.
• Reservoir not angled like above Dodge and GM master cylinders.

1.0” bore 1979 Buick Riviera with 4 Wheel Disc Brakes.
• Can buy new or used. Used are fairly cheap. New are fairly expensive.
• Reservoir is made for rear disc brakes.
• Bolt in.
• Come in cast iron and aluminium.
• New master cylinders will most likely be cast iron.
• Rebuilt units usually come in aluminium.

1 1/32” (1.03”) bore 1985 Dodge Diplomat master cylinder (other years and models may work)
• Rear brake line outlet is 9/16-20 versus GM rear brake line fitting of 9/16-18. Fitting for GM brake line may be used to “rethread” the master cylinder’s outlet.
• Front brake lines bolt up.
• Mounting holes spaced 3.25” versus GM master cylinder’s 3.375”.
• Can buy new or used. New ones are fairly cheap to purchase.
• Aluminium body – new, used, or rebuilt.
• Large reservoir can hold enough fluid for rear disc brakes.
• Reservoir not angled like above Dodge and GM master cylinders.

1 1/8” (1.125”) bore 1985 Dodge Ram master cylinder (other years and models may work)
• Rear brake line outlet is 9/16-20 versus GM rear brake line fitting of 9/16-18. Fitting for GM brake line may be used to “rethread” the master cylinder’s outlet.
• Front brake lines bolt up.
• Mounting holes spaced 3.25” versus GM master cylinder’s 3.375”.
• Can buy new or used. New ones are fairly cheap to purchase.
• Aluminium body – new, used, or rebuilt.
• Large reservoir can hold enough fluid for rear disc brakes.
• Reservoir not angled like above Dodge and GM master cylinders.

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MalibuDave
www.manualbrakes.com
https://www.facebook.com/manualbrakescom-576443512373024/


Last edited by malibudave1978 on Sat Jun 22, 2013 8:06 pm, edited 1 time in total.

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 Post Posted: Sat Jun 22, 2013 7:31 pm 
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I too am on the hunt for a manual brake conversion. Nice work Dave, lot of good reading here. dancin_banana.gif

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 Post Posted: Thu Jan 01, 2015 7:39 pm 
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One of the main problems that arise when converting to manual brakes using a 7/8" bore master cylinder is LOW drag calipers.

LOW drag calipers require a step bore (quick take up) master cylinder. In my opinion they are too large to operate smaller 2.50" bore calipers with sufficient pressure, they are harder to bleed, and they have a 100lb residual valve that can fail. My opinion also is to change out to new (NOT rebuilt) calipers to make sure you do not get a set of LOW drag calipers.

To learn a little bit about new stock size calipers, I just purchased a set of left and right AFCO 2.5" bore metric calipers that are a bolt in, stock, replacement caliper for g-bodies, S10s, and most 3rd gen f-bodies. I removed the stainless steel piston and square piston seal to make sure it was not a LOW drag caliper.

SPECS:
MFG. Part #: 7241-9003 RH and 7241-9004 LH
Centerline of Holes: 5.50
Caliper Pistons: Single Piston Diameter: 2.50
Inlet fitting: 10mm-1.5 Material Type:
Steel Finish: Natural
Sold in Quantity: Each

Description:
The 2 1/2" bore steel GM metric caliper is designed to be a used as a stock replacement caliper. The caliper features a stock appearing remanufactured castings, remanufactured grounded 2 1/2" stainless steel piston, and low drag seals (see below) . Each caliper is assembled and pressure tested.

LOW DRAG SEALS
Though the description says "low drag seals", the seals are square with no noticable taper.
Image

Image

The seal-groove in the bore of the caliper are also square with no noticable taper.
Image

When the seal is installed, it barely clears the top of the bore, and because of this, the piston to bore clearance, it seams, to have fairly tight tolerances.

The small end of the piston is what contacts the back of the brake pad. It measures 2.38".
The large end of the piston is what is inside the bore of the caliper. It measures 2.50"
Image

Inside of piston cup, facing the brake pad.
Image

Backside of piston that is installed inside the caliper bore.
Image

I have bought these same exact part numbers a few years back and these new ones are a different casting with, what looks to be, a stainless steel piston. These calipers DO NOT come with pads, but they come with slider pins and slider pin bushings. At this time, they are around $40, and seem to be an improvement over the previous design.

Bottom line is that these should be a good stock replacement, NON low drag, brake caliper that will work with both strait bore master cylinders and step bore (quick take up) master cylinders.

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 Post Posted: Thu Aug 27, 2015 2:41 pm 
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Location: Houston, TX
Caliper Update:

I have found a good NON low drag (normal) bolt in replacement brake calipers for stock front brake systems. These brake calipers can be used with strait bore (normal) master cylinders and step bore master cylinders.

It is under the Centric Brand. They are about $33 plus shipping at rockauto.com.

Part number are:
14162066
14162065

AFCO has a brand new replacement brake calipers. They are about $49.99 plus shipping. $100 order are free shipping at Summit Racing, Jegs, and Speedway Motors. These should be NON low drag.

The part numbers are:
6635003
6635004

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 Post Posted: Mon Dec 07, 2015 12:26 pm 
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A Kit install with adapter plate painted satin black to match firewall better.

Image

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 Post Posted: Thu Feb 18, 2016 11:54 am 
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Below is an analysis using the Brake Torque Calculator found on Pro-Touring.com. This calculator will give you an idea of what brake torque is for a certain front and rear setups. I am just going to show the changes from the stock front g-body brake system and compare them to a Blazer dual piston brake swap, a stock LS1 Camaro brake swap, a LS1 Camaro brake swap with Corvette calipers

Page 7, Post #140

http://www.pro-touring.com/threads/1045 ... ORE3/page7
This entire post is a really good read if you are interested about brakes.


Here are the inputs that are the same for ALL different types of brake systems shown below.
• 6 to 1 pedal ratio
• 26” tall tire
• 100 ft/lb pedal pressure
• Manual Brakes – NO POWER ASSIST
• Pad Coefficient of Friction - .45
• Use of stock type (tandem) master cylinder

____________________________________________________
Stock G-body/S10/3rd Generation F-body Front Brake System
• Rotor Diameter – 10.5”
• 7/8” Bore Master Cylinder Area - .601 sq-in
• Line Pressure – 998 psi
• Front Caliper Piston Area – 4.909 sq-in
• Front Clamping Pressure – 4899 pounds
Front Rotor Torque – 964 ft/lb
• Tire Forces – 890 lb
____________________________________________________
Stock LS1 Camaro/Firebird Front Brake System
• Rotor Diameter – 12”
• 7/8” Bore Master Cylinder Area - .601 sq-in
• Line Pressure – 998 psi
• Front Caliper Piston Area – 4.931 sq-in
• Front Clamping Pressure – 4921 pounds
Front Rotor Torque – 1107 ft/lb
• Tire Forces – 1022 lb
____________________________________________________
Stock LS1 Camaro/Firebird Front Brake System with Corvette Calipers with 7/8” bore master cylinder
• Rotor Diameter – 12”
• 7/8” Bore Master Cylinder Area - .601 sq-in
• Line Pressure – 998 psi
• Front Caliper Piston Area – 3.994 sq-in
• Front Clamping Pressure – 3986 pounds
Front Rotor Torque – 897 ft/lb
• Tire Forces – 828 lb

Stock LS1 Camaro/Firebird Front Brake System with Corvette Calipers with 21mm bore master cylinder
• Rotor Diameter – 12”
• 21mm Bore Master Cylinder Area - .537 sq-in
• Line Pressure – 1117 psi
• Front Caliper Piston Area – 3.994 sq-in
• Front Clamping Pressure – 4461 pounds
Front Rotor Torque – 1004 ft/lb
• Tire Forces – 927 lb

____________________________________________________
Stock Blazer Twin Piston Front Brake System
NOTE: The Blazer twin piston front calipers have a piston area too large to run a .875” bore master cylinder. These calculations are using a 24mm bore master cylinder.
• Rotor Diameter – 10.75”
• 24mm Bore Master Cylinder Area - .701 sq-in
• Line Pressure – 856 psi
• Front Caliper Piston Area – 5.152 sq-in
• Front Clamping Pressure – 4410 pounds
Front Rotor Torque – 889 ft/lb
• Tire Forces – 821 lb

Stock Blazer Twin Piston Front Brake System
NOTE: The Blazer twin piston front calipers have a piston area too large to run a .875” bore master cylinder. But to show the differences between the systems, these calculations are using a .875” bore master cylinder.
• Rotor Diameter – 10.75”
• 7/8” Bore Master Cylinder Area - .601 sq-in
• Line Pressure – 998 psi
• Front Caliper Piston Area – 5.152 sq-in
• Front Clamping Pressure – 5142 pounds
Front Rotor Torque – 1036 ft/lb
• Tire Forces – 956 lb


Rating from best to worst:
1. LS1 Camaro / Firebird stock front brakes with 7/8" bore master cylinder.
2. Blazer Twin piston stock front brakes with 7/8” bore master cylinder. NOTE: This setup will not work with a 7/8” bore master cylinder.
3. LS1 Camaro / Firebird front brakes with Corvette brake calipers and a 21mm bore master cylinder. NOTE: A 21mm master cylinders are fairly rare and hard to find.
4. Stock g-body/S10/3rd Generation F-body stock front brake system with 7/8" bore master cylinder.
5. LS1 Camaro / Firebird front brakes with Corvette brake calipers and a 7/8” bore master cylinder.
6. Blazer Twin piston stock front brakes with 24mm bore master cylinder.

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 Post Posted: Tue Jan 24, 2017 4:36 pm 
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Since being around brakes a lot since I started manualbrakes.com, sometimes I get a reoccurring question when people are doing the conversion.

What ports do my lines bolt up to?

The ports on all G-body master cylinders have a ½-20 inverted flare port (port closest to the firewall) for the front brakes and a 9/16-18 inverted flare port (port located toward the front of the master cylinder) for the rear brakes. The manualbrakes.com KIT comes with adapters to mate the stock GM line fittings to the MOPAR style master cylinder’s 3/8-24 inverted flare outlets.

For most GM applicatiosn, remember:
Rear port of master cylinder goes to the front brakes.
Front port of master cylinder goes to the rear brakes.

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Last edited by malibudave1978 on Tue Jan 24, 2017 5:16 pm, edited 2 times in total.

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 Post Posted: Tue Jan 24, 2017 4:37 pm 
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Master Cylinder Bleeding Proceedures.

NOTE: DO NOT bench bleed a master cylinder on the car. On a g-body the master cylinder sits at an angle and it WILL NOT get all the air out of the master cylinder. Use a vise to hold the master cylinder level to the ground to bleed the master cylinder of all its air.

I like to use plugs to bleed the master cylinder of air instead of the procedure that uses hoses to recirculate the fluid from the master cylinder ports back up to the reservoir. Why?

When using plugs to close off the ports of the master cylinder, this procedure will let you know if all the air is out of the master cylinder AND if the master cylinder is bad. You don't want to find out your master cylinder is bad after you have it installed and are trying to bleed the rest of the system. You most likely will not get all the air out of the system when your master cylinder is bad. New or rebuilt, it is always good to make sure your master cylinder is in good working order before bolting it onto the car. It will be one less thing you have to trouble shoot if you run into other issues when you are trying to trouble shoot braking issues.

Steps to bleeding a master cylinder:
1. Mount the master cylinder in a vise with the bore of the master cylinder level with the ground. Do not use the top of the reservoir as a guide because is may not be level with the bore of the master cylinder. It may be at an angle versus the bore of the master cylinder.
2. Use the appropriate size solid plugs to plug the outlets of the master cylinder so no fluid can escape the ports.
3. Fill the master cylinder with the appropriate amount of brake fluid.
4. Use a rod to SLOWLY cycle the master cylinder piston in its bore. DO NOT use a flat head or phillips heat screwdriver because they have sharp edges and could harm the bore of the master cylinder. I usually use a nut driver that is used for ¼” drive sockets as a rod because the end does not have any sharp edges and there is a handle to hold onto.
5. After cycling the master cylinder piston SLOWLY a few times, the piston should become rock solid and only move about 1/16 of an inch or less down the bore.
6. After the piston becomes rock solid, push in on the master cylinder piston and hold for 45 seconds. If the piston slowly moves down the bore of the master cylinder, you have a bad master cylinder. If the piston says rock solid and does not move, you master cylinder is good.
7. Mount to your car and bleed the rest of your system starting with the brakes furthest away (passenger rear) from the master cylinder and working your way to the closest (drivers front) brake.

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David Schultz
MalibuDave
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 Post Posted: Sat Mar 11, 2017 11:36 am 
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Amateur Racer

Joined: Tue Jun 08, 2004 1:06 pm
Posts: 224
Location: Houston, TX
This is from The Brake Man at tbmbrakes.com from his Facebook page. It may make you think a little differently about aluminum calipers and multiple piston calipers.

12 RULES YOUR BRAKES LIVE BY:

1. Pad area (volume) has no effect on braking torque. Pad area (volume) effects life and heat management.
2. Caliper clamping force is a function of piston area (on one side of the rotor) times line pressure.
3. The hotter the brake pad gets, the faster it will wear.
4. Deflection anywhere in the brake system will result in a proportional reduction in clamping force.
5. Piston count has nothing to do with clamping force, piston area does.
6. Caliper deflection that exceeds piston O-ring retraction (around .020”) will result in brake drag.
7. Given the same design, aluminum calipers will always deflect more than steel, cast iron, or steel reinforced calipers.
8. If your pads are tapered, your calipers are deflecting.
9. All brake pads perform best in a temperature range. Too cold is just as bad as too hot.
10. The smallest, lightest rotor that will dissipate the necessary heat is the best rotor for the application.
11. A smaller bore master cylinder increases line pressure.
12. Larger diameter caliper piston(s) increase clamping force.

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David Schultz
MalibuDave
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 Post Posted: Wed Jun 28, 2017 12:32 pm 
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Amateur Racer

Joined: Tue Jun 08, 2004 1:06 pm
Posts: 224
Location: Houston, TX
I pulled this information from the CPP website. I include this information on this thread because, during a manual brake conversion, the differential valve in the proportioning/combination valve may be triggered and cause only one side of the system to work resulting in poor braking performance.

The differential valve is built into most GM prop valves. It is for safety. If one side, front or rear, of the brake system looses pressure, the differential valve is triggered blocking off the low pressure side of the brake system so that the master cylinder can still provide pressure to the other side of the brake system. This ensures that there is some for of braking as a way to stop the vehicle. If a differential valve was not part of the braking system, and there is a loss of pressure in one side of the system, the master cylinder would not be able to build pressure. This would result in NO brakes.

Combination/Proportioning Valve Test

Use a test light by attaching a clip to a positive contact on the vehicle and touch the point of the tester to the electrical connection of the combination valve. If the the light does NOT come on, the valve system is operating correctly and no further testing is required.

If the light does come on, this indicates that the pressure differential valve is stuck in the front or rear position.

Bleed the brake system to determine if the front or rear lines are blocked off. Set up one front wheel and one rear wheel for bleeding at the same time. Crack both bleeder screws and gently pump the pedal a few times.

The blocked side will trickle fluid out when the bleeder screw is cracked and the pedal pressed. An unblocked line will squirt fluid out the bleeder.
The lines that are clear must be left open and the blocked lines should have the bleeder screws tight to cause pressure to build up on that side. Be sure to use the standard bleeding procedures to prevent air from entering the system.

Slowly press the pedal with steady pressure a number of times until the light goes out; this will center the differential valve. You may also hear a pop come from the proportioning valve. This is the metering valve returning to its equalized position. When the light goes out, close the bleeder screw. (See fig. below)


Image

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https://www.facebook.com/manualbrakescom-576443512373024/


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