1991 corvette brake syatem

Clutch bleeding can be problematic and I have had to resort to removing the slave cylinder but leaving the hydraulic line connected and raising it as far as the flexible pipe will allow. above the master cylinder and bleeding it in mid-air.

Reverse bleeding can be very effective and with a long-travel large capacity cylinder the piston can be pumped out to the limit of its travel and then forced very quickly back in as far as it will go.

Anotther type of reverse bleeding I have been forced to employ a few times is connecting the clutch bleed screw to a nearby brake bleed screw with some very good fitting hose. Both bleeders are opened and the clutch is bled by pumping the brake pedal. An assistant adds fluid to the brake reservoir and removes it from the clutch reservoir.
Four or five vigorous pumps usually does the trick.

Good luck!

Here's a link to bleeding your brakes. Repair Guides Brake Operating System Bleeding The Brake System AutoZone...

Fill master remove bleeder have somebody rapidly pump brake pedal while you hold your finger over the hole. within ten pumps (usually) fluid should come out.By holding your finger over the hole you will feel air pressure let that pass Then do your manual bleed.If still nothing check the rubber line sometime they get messed up inside and fluid will not go through

you have someone helping you right? cuz you cant do it yourself, and the brakes need to be pumped only enough to get a solid midway stop of pedal travel, and with the brake still depressed by your assistant, you open the bleeder a bit until the pedal goes to the floor, you tighten bleeder, they then release brake pedal and pump it up again, rinse, repeat, until there is no spongy feel in brake pedal

PRESSURE BLEEDING

MANUAL BLEEDING

Print
For vehicles equipped with an Anti-lock Brake System (ABS), please refer to the ABS bleeding procedure at the end of this section.
The purpose of bleeding the brakes is to expel air trapped in the hydraulic system. The system must be bled whenever the pedal feels spongy, indicating that compressible air has entered the system. It must also be bled whenever the system has been opened or repaired. If you are not using a pressure bleeder, you will need a helper for this job.

WARNING Never reuse brake fluid which has been bled from the brake system.

MASTER CYLINDER

See Figure 1
If the master cylinder is off the vehicle, it can be bench bled.

1. Secure the master cylinder in a bench vise.
2. Connect 2 short pieces of brake line to the outlet fittings, bend them until the free end is below the fluid level in the master cylinder reservoirs.
3. Fill the reservoir with fresh DOT 3 type brake fluid.
4. Using a wooden dowel, or equivalent, pump the piston slowly several times until no more air bubbles appear in the reservoirs.

Fig. Fig. 1: Attach bleeding tubes to the master cylinder and position them as shown

1. Disconnect the 2 short lines, refill the master cylinder and securely install the cylinder cap.
2. If the master cylinder is on the vehicle, it can still be bled, using a flare nut wrench.
3. Open the brake lines slightly with the flare nut wrench, while pressure is applied to the brake pedal by a helper inside the vehicle.
4. Be sure to tighten the line before the brake pedal is released.
5. Repeat the process with both lines until no air bubbles come out.
6. Bleed the complete brake system, if necessary.

If the master cylinder has been thoroughly bled and filled to the proper level upon installation into the vehicle, it is not necessary to bleed the entire hydraulic system.

PRESSURE BLEEDING

When bleeding the brakes, air may be trapped in the brake lines or valves far upstream, as much as 10 feet from the bleeder screw. Therefore, it is very important to have a fast flow of a large volume of brake fluid when bleeding the brakes, to make sure all of the air is expelled from the system.
On Cirrus, Stratus, Sebring convertible and Breeze models, the following wheel sequence should be used to ensure that all the air is removed from the system:


Left rear wheel Right front wheel Right rear wheel Left front wheel
On Sebring coupe and Avenger models, the following wheel sequence should be used to ensure that all the air is removed from the system:


Right rear wheel Left front wheel Left rear wheel Right front wheel

1. You should use bleeder tank tool C-3496-B or equivalent, with the required adapter for the master cylinder reservoir to pressurize the hydraulic system for bleeding. Make sure to follow the manufacturer's directions for using a pressure bleeder.
2. Attach a clear plastic hose to the bleeder screw located at the right rear wheel, then place the hose into a clean jar that has enough fresh brake fluid to submerge the end of the hose.
3. Open the bleeder screw at least one full turn or more to get a steady stream of fluid.
4. After about 4-8 oz. of fluid has been bled through the brake system and an air-free flow is maintained in the hose and jar, close the bleeder screw.
5. Repeat the procedure at all the other remaining bleeder screws. Then, check the pedal for travel. If pedal travel is excessive or has not improved, enough fluid has not passed through the system to expel all of the trapped air. Be sure to monitor the fluid level in the pressure bleeder. It must stay at the proper level so air will not be allowed to re-enter the brake system through the master cylinder reservoir.
6. Once the bleeding procedure is complete, remove the pressure bleeding equipment from the master cylinder.

MANUAL BLEEDING

See Figure 2
Proper manual bleeding of the hydraulic brake system will require the use of an assistant.
On Cirrus, Stratus, Sebring convertible and Breeze models, the following wheel sequence should be used to ensure that all the air is removed from the system:


Left rear wheel Right front wheel Right rear wheel Left front wheel
On Sebring coupe and Avenger models, the following wheel sequence should be used to ensure that all the air is removed from the system:


Right rear wheel Left front wheel Left rear wheel Right front wheel

Fig. Fig. 2: With a clear plastic hose in a container of clean brake fluid, open the bleeder screw at least one full turn

1. Attach a clear plastic hose to the bleeder screw located at the right rear wheel, then place the hose into a clean jar that has enough fresh brake fluid to submerge the end of the hose.
2. Have an assistant pump the brake pedal 3-4 times, and hold it down before the bleeder screw is opened.
3. Open the bleeder screw at least one full turn. When the bleeder screw opens, the brake pedal will drop.
4. Close the bleeder screw. Release the brake pedal only AFTER the bleeder screw is closed.
5. Repeat the procedure 4 or 5 times at each bleeder screw, then check the pedal for travel. If the pedal travel is not excessive, or has not been improved, enough fluid has not passed through the system to expel all of the trapped air. Make sure to watch the fluid level in the master cylinder reservoir. It must stay at the proper level so air will not re-enter the brake system.
6. Test drive the vehicle to be sure the brakes are operating correctly and that the pedal is solid.

Hello....sounds to me like you have air in your brake system...need to bleed it yourself or have it done to remove all the air from the brake lines.http://stoptech.com/technical-support/technical-white-papers/bleeding-brakes...this is a good site for the instructions....I hope this was helpful....PEACE....

Hi Chris, The brake system is basically very simple. If you have duel braking on your vehicle, the usual method is having two brakes operate on the front with for example the left rear and the other system will also operate two front and the right rear. This type of system will have two calipers on each of the front wheels. The tandem system works in a slightly different way, having the forward part of the cylinder pressurizing the rear brakes and the rear part of the cylinder pressurizing the front. I think under the circumstances you are describing, I would have a friend sit inside and pump the brakes repeatedly until the system becomes pressurized (maybe twenty thirty times of pumping the brake pedal) and then ask him or her to keep it pushed firmly down until you find out where its leaking. The amount of brake fluid you report having been sed would indecate a severe leakage. Check the lower parts of the rear wheels for signs of leaking wheel cylinders and then dito for the front wheels. Any signs of wetness at these areas and along the brake system (the plumbing or pipe work) will indicate where the leakage is. If you cannot identify a wheel which is leaking, carefully inspect around and blow the master cylinder and if this no sign go along the fluid lines, taking special note of where the damaged pipe was repaired. If there is a blockage in the line, air may be trapped at that point causing difficulty in pressurizing. Once the place of leakage has been identified it must be attended to before bleeding the system. When bleeding, begin with the wheel furthest from the master cylinder, and work your way back to the master cylinder one wheel at a time, until you reach the closest.Keep in mind that you may find it required to pump the pedal many many times before opening the bleed nipple.Regards John

If you are losing brake fluid you still have a leak in the system, if not then take it into a garage and have it pressure bled.

ANTI-LOCK BRAKE SYSTEM (and HCU-Hydraulic Control Unit)
General Information The 4-Wheel Anti-lock Brake System (ABS) is an electronically operated, all wheel brake control system. Major components include the power brake booster, master cylinder, the wheel speed sensors, and the Hydraulic Control Unit (HCU) which contains the control module, a relay, and the pressure control valves. The system is designed to ****** wheel lockup during periods of high wheel slip when braking. Retarding wheel lockup is accomplished by modulating fluid pressure to the wheel brake units. When the control module detects a variation in voltage across the wheel speed sensors, the ABS is activated. The control module opens and closes various valves located inside the HCU. These valves, called dump and isolation valves, modulate the hydraulic pressure to the wheels by applying and venting the pressure to the brake fluid circuits. Some models are equipped with a Traction Assist (TA) system. The TA system senses wheel spin upon acceleration, turns on the Hydraulic Control Unit (HCU) pump and applies fluid pressure to the appropriate rear wheel. Two additional isolation valves in the HCU will also close to permit fluid to flow only to the rear wheels. The TA system monitors TA usage to avoid overheating the rear brakes. If the system does sense brake overheating, the ABS module will inhibit TA operation until the rear brakes are permitted to cool down.
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SYSTEM COMPONENTS The anti-lock brake system consists of the following components:

• Vacuum booster and master cylinder assembly
• Hydraulic Control Unit (HCU)
• ABS module
• Wheel sensors
• Pedal travel switch

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On 1992-1994 and 1995-00 a scanner is used to perform the brake bleed. But on yours, I think it's different according to the manual.
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What do you mean change the cal. on the rear also? Do you mean Caliper?

You have to check your master cylinder, pump your brake several times and hold it, see if is going down to the bottom, if does, the master cylinder is wrong, check the brake pressure hose, maybe you have some air in your brake lines, be sure you have enough brake fluid