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Discussion Starter #1
I just finished up upgrading the brakes on my father’s 1980 El Camino. This is a daily driver that I am testing several different master cylinders for a manual brake conversion swap. His brakes worked good before exchanging out all the parts, but I wanted to take out most of the variables when testing master cylinders. First and foremost, I wanted to make sure this 1980 El Camino did not have quick take up front brake calipers. In my research, quick take up calipers will make it difficult do get good pressure to the caliper when using manual brakes.

Here is the rundown of the parts I used:
• Speedway Motors Big Bore Metric Calipers - PN# 91031040 $59.99 each
• Bendix Titanium metallic front brake pads (FF Rated) - PN# MKD154 $38.22
• Turned the stock rotors $30 Local Auto Parts Store $15 each
• Edelbrock/Russel Stainless Steel Braided Flex Lines PN# 692100 $54.80
• Wagner 7/8” Wheel Cylinders from an manual brake S10 PN# F110261 $13 each
• Wagner Thermo Quiet Rear Shoes (EE Rated) - PAB514R from O’Reilly’s Auto $32.99

The Speedway Motors big bore metric calipers (2.75” bore v 2.38” bore standard) came with brake pads, but the pads did not have a rating on them. I DID NOT want to use a brake pad that would need a lot of heat to be effective. The weight difference between the two calipers is less than ½ of a pound. This is a daily driver and not an autocross car, so I chose the Bendix Titanium pads because my research and reviews showed them to have good cold clamping friction. Based on the EE rating, the rear shoes should also have good cold stopping abilities. Look on the pads or shoes when you buy them to make sure they have a rating on them. The higher up the alphabet you go the hotter the pads will have to be to work effectively. Pads or shoes with no rating on them should be avoided.

It was surprising to me to find a 24mm strait bore aluminum master cylinder on this 1980 El Camino. I didn’t know they made aluminum ones with a strait bore for g-bodies. I had always been under the impression, because it was aluminum, that this was a step bore master for quick take up calipers. I do know for a fact that any NEW replacement master cylinders for g-bodies will for than likely be cast iron. So if you want aluminum master cylinder for power or manual brakes that bolt up to your brake lines, a rebuilt master cylinder may be your only option.

I changed out the 30 year old rubber brake lines with the braided stainless. The front lines were a little longer than the originals, but I routed them so they were not touching any suspension pieces. The rear was a little more difficult to replace because the clip that holds the rubber line to the frame was difficult to get at. The new braided rear line was fairly easy to install also.

The hardest part to the entire swap was installing the rear wheel cylinders. Getting the clip off was not too bad, but getting the clip back on was a pain. I did it with two c-clamp, and open ended wrench, and the lid off of an old battery terminal cleaner (don’t ask for these details because I do not recommend doing it this way. G-H-E-T-T-O).

After the system install, bleeding the fluids, and bedding in the pads and shoes I took it out for a spin to test the brakes with the same master cylinder and vacuum booster from the original test with the original brakes. Even though I was able to easily lock up all four wheels, it seems to have a little more pedal travel before you could feel the brakes start to grab. I believe this has to do with the increased piston area in the front calipers and rear wheel cylinders while using the strait bore 24mm master cylinder. The 24mm master cylinder will have more pedal travel to fill the extra volume of fluid required by the calipers and wheel cylinders.

If keeping the vacuum booster, it might be best to step up to the step bore master cylinders that are used on the 1981 and up g-bodies. The primary bore is still 24mm, but it also has a larger step bore of 36mm that will increase the volume of fluid to the larger calipers and wheel cylinders.
 

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Discussion Starter #2
The manual brake conversion went well when using the manual brake hole that is already predrilled in the factory vacuum booster power brake pedal. I kept the stock , 31 year old, 24mm master cylinder that came with the stock power boosted brake system. I kept the 24mm master, for now, because I upsized the front calipers and wheels cylinders. It stopped the car ok, but I felt I still had too much pedal travel and I couldn't get the front brakes to lock up. I am going to rebleed the calipers, unbolted from the spindle, to point the bleeder screws up at the 12 o'clock position. If this doesn't do the trick, I will bolt on a brand new manual brake master cylinder from a 1978 to 1980ish g-body. This master cylinder has a smaller bore which should give me higher pressure at the pad.
Before manual brake conversion:



After manual brake conversion:


 

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Discussion Starter #4
Weight of Cast Iron 7/8" Manual Brake Master Cylinder
3 lbs 5 1/8 ounce
Weight of Aluminum Step Bore S-10 Master (24mm / 1 1/4" step bore)
2 lbs 8 1/4 ounce - difference of 12 7/8 ounces or a little over 3/4 lbs over the cast iron unit
Weight of an Aluminum Mopar / Strange style master cylinder
2 lbs 2 3/4 ounce - difference of 1 lb 2 3/8 ounces over the cast iron unit
 

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Discussion Starter #5
Here is a link to a person that carries new Proportioning Valves for Ford, GM, and Jeep.
http://proportionvalves.com/
Here is a link to a disc/drum PV for a g-body from the http://proportionvalves.com/ site.
http://www.carolinaclassictrucks.com/78-86-malibu-PV2.html
Here is a link to a disc/disc PV for a 2nd gen f-body that looks like it will work with g-body brake lines if you convert to rear disc brakes. Please call to confirm it will bolt in.
http://www.carolinaclassictrucks.com/79-81-TransAM-PV4.html
MOPAR MASTER CYLINDER RETROFIT
I may have found a way to retrofit a 7/8” mopar (1993 Dodge Shadow) master to a g-body for manual brakes. I have not tested this yet to see if this works.
For the Front Brake port on the Proportion Valve:
Edelmann 258350 - Adapter-Standard To Dual Master Cylinder - 3/16" Tube - 3/8-24 Female Inverted Flare Seat x 1/2-20 Male Inverted Flare
For the Rear Brake Port on the Proportion Valve:
Edelmann 258340 - Adapter-Standard To Dual Master Cylinder - 3/16" Tube - 3/8-24 Female Inverted Flare Seat x 7/16-24 Male Inverted Flare
I don’t know the length of the brake lines from the proportion valve to the mopar master, but flared lines are less than $10 each from the auto parts stores. It should be about 2 to 3 foot of line. A coat hanger can be used to find the actual length needed.
If this setup works, this will be the cheapest way to get an aluminum master cylinder retrofitted to a g-body.
Let me know if you see any issues with what has been posted above.
 

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Discussion Starter #6
I have purchased 3 different metric calipers for comparison:

**CCP big bore 2.75" bore (2.565" piston diameter) metric cast iron caliper – WEIGHT 6 lbs 11.2 oz bare with slider bushings installed
**US Brake standard bore 2.5" bore (2.376" piston diamter) metric cast iron caliper- WEIGHT 6 lbs 4.7 oz bare with slider busings installed
**Wilwood small bore 2.0" bore (1.981" piston diameter) metric cast iron caliper - WEIGHT 4 lbs 1.7 oz bare with NO SLIDER BUSHINGS INSTALLED.

A while back I purchased NEW the $59.95 each, big bore calipers from speedwaymotors.com. There was some manufacturing issues or problems with these calipers and they sent me replacement calipers. The replacement calipers are NEW CCP big bore metric calipers. PN CP412526. Online, these are the same price of $59.95 each from classicperform.com. They look exactly the same except for the paint on the calipers. The originals where painted/powder coated silver. These are painted/powder coated black. The caliper housing, compared the standard bore US Brake 2.5” calipers and 2.0" Wilwood calipers, are a different casting. The piston looks to be stainless steel and comes with a dust boot installed. The piston diameter is 2.565" in diameter. These calipers came loaded with pads, slider bolts/pins, and hose fittings. You should be able to bolt these to your car, bleed the brakes, and drive. The piston cylinder side of the caliper is roughly the same size as the as the standard 2.5” bore caliper.

I recently purchased NEW, US Brake/Afco branded 2.5” standard bore metric calipers. They are $45 to $50 each online. The casting is not painted or powder coated. They come in a right PN 7241-9003 and a left caliper PN 7241-9004. They cannot be interchanged from side to side. The piston looks to be a cast steel/iron, unlike the CCP 2.75” and Wilwood 2.0” bore calipers. They are also 2.376" in diameter which matches stock advertised piston/bore sizes. The casting looks to be a stock casting and comes with a dust boot installed. It has all the markings of a stock calipers. This caliper came unloaded with no pads, slider bolts/pins, and hose fittings. It does come with the bleeder screws and bushing inserts for the slider bolts/pins. You will have to reuse your slider pins from your stock calipers and hose fittings. You will need to purchase new pads or reuse the ones you have on your car.

I also recently purchased NEW, Wilwood 2.0” small bore metric calipers. PN 120-9333. The price is round $80 each online. It is also a different casting from the other two. Visually the casting looks better and it looks to come with a stainless steel piston that is 1.981" in diameter. The casting comes bare with no paint or powder coating and they can be interchanged from the right and left hand side of the car. The piston cylinder portion of the caliper is physically smaller than the other two because of the reduced size of the piston. The piston bore and stainless steel piston look to have a better, tighter fit. The clearance is so tight there is no dust boot installed around the piston like the 2.75” and 2.5” bore caliper above. These calipers only come with a bleeder screw. It does not come with any other hardware. You will have to supply the slider bolts/pins, slider bolt/pin bushing inserts (I need to make sure this is possible), brake pads, and hydraulic hose fittings. All hardware should be able to transfer over from your original caliper. Please refer to this web page for more details. http://www.wilwood.com/PDF/Flyers/fl176.pdf

Out of the three calipers above, I was most impressed with the Wilwood calipers. These calipers have a very clean casting that weigh at least 2 lbs less than the other two calipers. The Wilwood website list a 2.75” bore version also that weighs just 5 more ounces than the Wilwood 2.0” bore versions (4lb 6.4oz v 4lb 1.6oz). These Wilwood iron calipers weigh roughly 1lb more than the Willwood comparable aluminum metric caliper with the 2.38” bore (4lb 6.4oz v 4lb 1.6oz v 3lb 6.4oz). I also suspect that the piston to bore clearances are just as tight as their 2.0" verson which will give the 2.75" version of the Wilwood caliper a larger piston that that of the CCP version. It theory this gives more clamping force.
 

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Discussion Starter #10
I purchased my second new master cylinder from rockauto.com, because the other new one I had would not blled. The master cylinder is a Centric brand PN# 130.62005. It is a manual brake master cylinder for a g-body with a 7/8" bore. I installed it and bleed the brakes from back to front and got a good, firm pedal. I left the speedway motors recalled calipers installed, for now, to see how the system all worked together. I noticed, while I was under the car bleeding the brakes, I saw a lot of caliper defection as my dad pumped the brake pedal when the bleeder screws where closed.

How did it do? For the setup I have, it did very well. I could not lock up the front brakes, but the braking felt more confident than when I had the stock, 24mm bore power master cylinder . I felt, if I was driving this on the street a lot, I wouldn't have to anticipate my braking. I felt I could stop where I wanted to when I wanted to under normal street driving. As expected, the pedal stroke is longer than a power brake pedal.

What would I do different? I would find a better front caliper. I think I will try the Wilwood single piston, 2.75" bore, metric caliper. From my experience with the inspection of 2" bore, Wilwood, single piston, metric calipers, I think the 2.75" big bore Wilwood will have a larger piston that the CCP/Speedway Motors 2.75" big bore caliper. I just worry that any 7/8" bore master cylinder may not have the volume of brake fluid needed to make these work.
 

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Discussion Starter #11
Things I learned from this process.

*New master cylinders are hit or miss in functionality. My first new one I bought did not work, but it was a clearance item from rockauto.com. I ended up spending another $80 plus shipping for the Centric brand one that actually worked.
*The larger the caliper piston is the better the clamping force.
*Caliper deflection affects brake performance more that I thought.
*The smaller the bore of the master cylinder is the better the pressure to the caliper.
*But if the bore of the master cylinder is to small, it may not have enough fluid to fully compress the caliper piston.
*The diameter of the brake rotor also affects the performace of the brakes not only because of rotor area and heat dissipaton, but also a larger diameter rotor gives the brakes greater leverage. Just think of using a 6" long breaker bar instead of a 5.25" braker bar to get a bolt loose. A longer bar will have a easier time getting the bolt loose. A 10.5" rotor has a 5.25" (half the rotor diameter) of "leverage". A 12" rotor has 6" of "leverage". Larger is better.
*They make brake pad designed for drag racers. They work better when cold and are for vehicles that do not use their brakes on a daily basis.
*Wilwood makes nice metric calipers.
 

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Dave, welcome! I have two questions.

One, why manual brakes over power? Especially with disk brakes.

Two, are your valve covers painted in "Buick Nailhead Blue"? Ive always loved that color, I'm a big Buick fan haha

Good luck with te conversion!
 

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Discussion Starter #15
One, why manual brakes over power? Especially with disk brakes.QUOTE]
Some engines don't create enough vacuum to power the brakes, so some drag racers covert to manual brakes. The conversion also looses some weight when removing the brake booster. Some autocross racers like the feel of manual brakes and allows them to control the brakes better.

For the '78 to '88 A/G body cars, the conversion is a little more difficult because of the small size of the brakes rotors, the low drag metric calipers, and the step bore master cylinders. Brake rotors are harder to overcome unless you go with an aftermarket or B-body brake swap. The low drag calipers can be easily converted to aftermarket NON low drag calipers, but I have found deflection issues which will reduce the effectiveness of the manual brake system. The step bore master cylinders are usually too large, are troublesome when bleeding, and have internal bypass valves that could malfunction.

I am in search what is the most effective manual brake system for the a/g body cars for the least amount of money. For these cars, it not as easy as bolting on a manual brake master cylinder and expecting your car to stop well. I believe I have gotten it down to finding a good caliper choice that doesn't deflect. I hope the Wilwood calipers give me less deflection and, with ethe larger diameter piston in the caliper, greater clamping force on the stock, small, 10.5" rotor.

Two, are your valve covers painted in "Buick Nailhead Blue"? Ive always loved that color, I'm a big Buick fan haha.
That "blue" is the original, 32 year old, faded, oil stained, and rusty Chevy blue for that model year. The engine is a 267 cubic inch small block chevy. It has over 200K miles and is still running after it was locked up from oil starvation (the sunpro mechanical oil pressure gage line came undone at the back of the engine and pumped all the oil down the back of the engine and locked up before my dad noticed what had happened). It does have a "slight" knock when it gets hot, but still runs.
 

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Discussion Starter #16
Just recieved my Wilwood 2.75" big bore calipers in today. These are very nice calipers, just like the Wilwood 2 inch metric calipers. The piston diameter measures 2.704 inches. On the underside of the caliper, there are ridges that bridge the piston side (inside) of the caliper to the wheel side (outside) of the caliper. These ridges are not present on any of the other calipers. These ridges should cut down of caliper deflection. The weight of each of the 2.75" calipers is 4 lbs 8.6 ounces with out the bleeder screw. I hope the 7/8" bore g-body manual brake master cylinder can handle the increase in volume these calipers may require.





 

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Discussion Starter #17
Caliper Specs

Caliper............................Part Number........Advertised Bore Size.......Actual Piston Size.....Weight
Wilwood 2" Bore Caliper........PN 120-9333...................2.00"..........................1.981"................4lb 1.6oz
US Brake / AFCO Caliper.......PN 7241-9004..................2.50"..........................2.376"................6lb 4.7oz
CCP Big Bore Caliper............PN CP412526...................2.75"...........................2.565"................6lb 11.2oz
Wilwood 2.75" Bore Caliper....PN 120-8926...................2.75"...........................2.704"................4lb 8.6oz
 

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Discussion Starter #18
This week I put on the Wilwood big bore calipers. I got them bled and immediately had less pedal pressure when using the 7/8” G-Body manual brake master cylinder. The pedal almost went to the floor. I assume it is from the increased piston diameter over the Speedwaymotors.com “Big Bore” calipers (2.704” Wilwood v 2.565” Speedwaymotors/CCP) that I replaced. When driving with the Wilwood big bore calipers, I could pump the pedal 3 or 4 times and get the pressure I needed and would lock up the right rear tire and stop the car just like the other calipers. I suspect now I will need a 24mm bore G-body master cylinder (from a power, vacuum boosted G-body) and EE rated front pads to replace the FF rated front pads I have on the front now. The EE rated front pads have better “bite” when the rotor is colder. FF rated front pads have better “bite” when the rotor heats up. Since this is a street driven car, the EE rated pads should be a better choice and will match the rear EE rated shoes that are already on the car.
 

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Discussion Starter #19
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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Discussion Starter #20
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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