How To: Camaro Rear Disc Brake Swap to G-body Axle

Monte Cristo

Apprentice
Aug 10, 2015
82
8
I don't see any discussion of changing the master cylinder for this mod. I would think that the rear disk pistons displace more fluid to move them and activate the brakes. Even if the stock m/c will work normally under optimal condition, I would think it's a safety issue because they probably don't if there is some leak in the system somewhere. Did I miss something here?
 
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TURNA

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Jul 24, 2009
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Socialist NY
Master is OK, proportioning valve should be changed.
 

Monte Cristo

Apprentice
Aug 10, 2015
82
8
Master is OK, proportioning valve should be changed.

Right, but the master is only "OK", it isn't really "good" because it was engineered for a different hydraulic system. Changing the proportioning valve only does so much. Because the rear brakes now have larger cylinders, unless the m/c is upgraded too, it will now require more pedal travel to move them. Pedal movement is designed to include many things, like brake clearance, clearance and wear in the linkage, swelling of hydraulic hoses and other parts in the system, compression or bubbles in the fluid, bending of metal parts, etc. By not upgrading the m/c too, it requires a lot of faith that everything else is in top condition. The same brake system that stops at the corner just fine, may not work under emergency braking conditions. Also note, that on a big car, the disc brakes will require the power assist to stop the car, unlike the servo action of drum brakes. If the engine stalls, and the driver needs to stop the car, he would be wise to practice using the emergency brake somewhere, and that needs to be kept well balanced and in working condition, because a car with this mod may not have braking in any wheels in that case. With the stock drums, at least the two rear wheels are braking

I'm all for keeping a stock look, but if I am driving a car on the road with this mod, I would want to at least use the m/c from the rest of the donor hydraulic system. If I'm not driving the car on the highway, and it just sits in the garage or moves only on a trailer, why bother to make the change?
 
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TURNA

Rocket Powered Basset Hound
Jul 24, 2009
10,955
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Socialist NY
So then use a 4 disc master from an 81 Trans Am
 

Monte Cristo

Apprentice
Aug 10, 2015
82
8
So then use a 4 disc master from an 81 Trans Am

Well that might work, but the point that I am making is that by changing the hydraulic system, there is a little re-engineering required. That means more thought than just swapping out parts. Fred Puhn's Brake Handbook has a lot of information on how to calculate the pedal movement, and the changes in the hydraulics for brake system mods. (There is applied math involved in this.) I would want to know how the size of the m/c and the all wheel cylinders compare to the donor system. If the wheels cylinders are still bigger than what was stock on the donor m/c, then there still can be a problem.

Making a car faster and look nice are great things to do, but it is critically important that the car stop properly in emergency situations. Safety always should come first.
 

Monte Cristo

Apprentice
Aug 10, 2015
82
8
So then use a 4 disc master from an 81 Trans Am

Well that might work, but the point that I am making is that by changing the hydraulic system, there is a little re-engineering required. That means more thought than just swapping out parts. Fred Puhn's Brake Handbook has a lot of information on how to calculate the pedal movement, and the changes in the hydraulics for brake system mods. (There is applied math involved in this.) I would want to know how the size of the m/c and the all wheel cylinders compare to the donor system. If the wheels cylinders are still bigger than what was stock on the donor m/c, then there still can be a problem.

Making a car faster and look nice are great things to do, but it is critically important that the car stop properly in emergency situations. Safety always should come first, which is what this mod should be all about.
 
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TURNA

Rocket Powered Basset Hound
Jul 24, 2009
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The safest thing would be not modifying anything on your car since the engineers that designed it figured it out already.

Yet even though they make mistakes sometimes.

That book is over 30 years old. While the basics stay the same.

The parts from a year 2000 car are newer and more efficient.

Even brake fluid has changed since that book was written.


While safety is extremely important, part of the fun of hot roding is piecing things together to make them work.

No one can prepare 100% for an emergency situation. That is why it is called an emergency.
 
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Monte Cristo

Apprentice
Aug 10, 2015
82
8
The parts from a year 2000 car are newer and more efficient.

That goes without saying, but if the hydraulic system is half original stock and half from newer model systems, it all needs to work properly together. If I upgrade, I would take the entire newer hydraulic system, or be damn sure everything was going to work together properly.

The safest thing would be not modifying anything on your car since the engineers that designed it figured it out already.

Not at all. They designed a system that was practical thirty years ago. It's safer to upgrade the brakes to something better when the car is driven on the road with lots of smaller, lighter cars that can stop quicker than an old heavy car, if its done right. It's not rocket science, but there is some engineering involved.

No one can prepare 100% for an emergency situation. That is why it is called an emergency.

Everyone should do his best to prepare for emergencies. That's what a good brake system is designed to do. Operating without any margin for error is tempting fate, and quite irresponsible.
 

TURNA

Rocket Powered Basset Hound
Jul 24, 2009
10,955
113
Socialist NY
It seems to me you have all the answers you are looking for already.
 

Monte Cristo

Apprentice
Aug 10, 2015
82
8
It seems to me you have all the answers you are looking for already.

No, I don't have all of the answers yet, but I am sure that I am asking the proper questions. Do all of the components work together properly with sufficient margin for error? It may be fun to mix and match old and new hydraulic systems, but if it isn't engineered properly its irresponsible. So you and I have a fundamental difference in philosophy.
 
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