GM Brakes – Theory: The Fluid Reservoir

The fluid reservoir does exactly that.  It stores and supplies fluid to the master cylinders of your brakes.

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GM brake fluid reservoir in a third gen camaro

Fluid is incompressible.  So it acts like a liquid linkage between the master cylinder and each of the wheel brakes.  When you press the brake pedal, the force is instantly transferred to the brakes.  The master cylinder has a push rod and a pair of pistons that exert force against the fluid in the cylinder bore.  When you push the brakes, the pistons in the master cylinder push against the fluid, which flows through the brake lines and pushes the caliper pistons outward to apply the disc brakes.  When you release the brake pedal, the spring loaded piston in the master cylinder returns to its rest position.  The fluid that was displaced by the pistons is pushed back to the master cylinder as the brake pads retract.

My Camaro has a plastic reservoir that is attached to a composite master cylinder.  It is held in place by a pair of O-rings.  The translucent plastic allows me to see the fluid level inside without having to open the filler cap-which helps keeps the system free of moisture and dirt.

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You can see the min. line through the GM brake fluid reservoir. There is no need to lift the cap.

There were no fluid sensors for the brakes system in my particular model year.



1.  Keep the reservoir full-but don’t over fill it!  Keep your fluid at the full mark, because it drops as your brake pads wear.  It if gets too low, air can be drawn in.  Unlike brake fluid, (yes, I know air a a gaseous fluid) air is compressible and will reduce hydraulic pressure, creating a soft and/or low brake pedal.  If you over fill the fluid reservoir, you’ll prevent the fluid to return after the brakes you let off the brakes.  Also, a little space is needed for the changes in fluid volume that results from temperature changes.


2.  Keep out anything that doesn’t belong in the reservoir.  No oil, no power steering, transmission, coolant, or water!  Anything with oil distillates in it can attack and ruin the rubber components in the brake system (O-rings etc.)  If you do accidentally get anything but brake fluid in the system, you’re going to have to disassemble, rebuild or replace the master cylinder, calipers and wheel cylinder and flush the system with new brake fluid.     Also, make sure you avoid getting dirt into the system as it acts as an abrasive and can plug up the master cylinder.


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You can see the brake lines going to the front and rear of the vehicle

On the third gen, you have a dual master cylinder.  This is good because a leak in a single piston master system will cause you to have no brakes!

One half of the master cylinder works the front brakes and the other the rear.  (Front wheel drive cars split the system diagonally.)  The GM cars past 1980 had a special kind of master cylinder called a “quick take-up” master cylinder.  This design reduces the brake drag by using a stepped bore that delivers a large volume of fluid when the brake pedal is initially depressed.  This allows the caliper piston seals to retract the pistons when the brakes are released so the pads don’t drag against the rotors. The old method required the rotors to kick out the pads so they didn’t rub.  The drawback with this design is that the caliper pistons have to travel further when you apply the brakes and the reservoir has to hold more fluid.

If you compare a master cylinder from an 80’s GM car with some other car manufactures (think Honda) the GM brake fluid reservoir is huge!

Upgrading my stock non-performance GM Brakes on the third gen f-body

This is my blog for upgrading my non-performance Camaro.  Unfortunately, my 1988 Camaro did not come with the 1LE brakes, so I’m stuck with the stock 10.5″ disk brakes on all four corners.  Since I live in Canada where car parts are expensive and shipping charges are a rip-off with the duty and taxes, the most cost effective option for me was to upgrade what I have.

Most people will say upgrade to the LS brakes or something better.  (That’s the 1998-2002 Chevrolet Camaro brakes, which are very good or the C5 Covette brakes.)  However, it was more than double the cost of upgrading my stock brakes here in Canada.  In fact, most car parts here are more expensive when bought retail and when you buy through mail order, you end up paying UPS or FEDEX high brokerage fees as well as duty and taxes.  So I’ll document a way to somewhat get around that (sort of.)

I relied a lot on the book Brake Systems by Mike Mavrigian & Larry Carley to guide my decisions as well as a few articles from various magazines and some great discussions over at for this project.   Also, although most people just slap on new rotors, calipers and pads, there are some checking of run-out that you’ll need to do with some precision tools.

Some important links:…g_system_heat/


There are only so many ways you can upgrade a stock system without replacing the whole thing.  Since I’m trying to keep the costs down while getting more performance, I’ll be addressing some inherent flaws as well as the strengths of the stock system.

To give you an idea of performance (which was considered good back in the mid 1980’s!)

1988 Road and Track Special : (Back to V-8 Basics by Ron Sessions )

Stock Brakes:  Braking 60MPH-0 = 154 ft.  Braking 80MPH-0=266 ft.

When the 1LE brake package came out, the 60MPH-0 Braking performance was 135-140ft according to June 1990 Motor Trend Secret Chevy’s.     (Keep in mind, that was without ABS)


With today’s supercars braking performance from 60MPH-0 there is a lot of room to improve.


Everyone touts the LS1 brakes.   They were better.  Not super-car better but according to Road and Track:

January 2001 Road and Track (Sibling Rivalry)

An LS1 Equipped Camaro SS stoped from 60MHP-0 in 129 Ft.   This was 25ft. better than the stock 10.5″ GM Brake system.  (Also, this was probably with ABS.)


As time progressed though, even the LS1 brakes were not good enough (but still a cheap upgrade if you lived in the USA as salvage yards had them for cheap!)


Using this study here:

A sample of vehicles in the 2006-2007 model year, the average 60-0 stopping distance of those vehcles was 111.8ft  with a maximum distance of 126 ft.  The best distance that year was 104ft by a 2006 Buggatti Veyron 16.4.    The slowest to stop was a 2006 Ford Escape XLT FWD at 145 ft.   The single stop from 60-0 makes a good metric for day to day driving because it mimics a real life panic stop on the highway.  (Although it is over the legal speed limit in many places.  For you metric people this is 96.56KPH)

So the goal for this project is to see how well I can get the stock 1980’s GM four disc setup to stop with some minor upgrades and some precision measurements.  It would be nice to say that the upgrades would get me to the 2007 average 60-0 stopping distance at preferably at 112ft but this would be a rather unreasonable goal considering the 20 years in technology gap.  Even setting 126ft is a maybe.  It’s currently 2012 and the new 1LE Camaro stops from 60-0 in 108ft.  


So let’s see how well, in a single stop I can get the stock non-performance 10.5″ Delco Morraine GM brakes to stop.

Some people will argue that this isn’t a true racing system.  Well, fair enough.  When you’re on the brakes all the time in the corners, you’re putting a lot more demand on the brake system, and brake fade can happen with any brake system.  We will discuss the main disadvantages of the stock system in another post, but mostly it’s heat rejection.  But my car is mostly a street car with some autocross and limited track days.  I’ll have to report on that way later, after I test my stock brakes.   But for now, let’s see what happens with a single stop.  It’s November 2012 as I write this.   It’s been 24 years since my car rolled off the factory with the stock 10.5″ delco morraine GM brakes.  Performance from 60MPH-0 has gone from 154 ft. down to 135ft with the 1LE.  Then down to 129ft. with the LS1 brakes.  With the new 2012 1LE camaro’s they are down to 108 ft.  That’s 46 ft of stopping distance improvement in 24 years for stock GM brakes!