Gthayes
New Member
- Joined
- Feb 23, 2013
- Messages
- 27
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- Age
- 46
- Location
- Perth
- Members Ride
- Vr ute, Vz storm, Vz v6 ute
ABS not covered here. But I really wish I had found these key points from the off. Oh well my loss your gain, I hope. Thanks to the authors of these best bits!
Bleeding is a given so if still no good then....
Important for Ute owners!!!!! Unlike me, save 3 weeks of yr life!
Also make sure the master cylinder on the vehicle is the proper one for use on utilities, as the wagon and sedan master cylinders are different from the ute master cylinders and have no proportioning valve fitted, so instead of having the proportioning valve built into the master cylinder, utes run the seperate adjustable, or "load sensing" proportioning valve on the rear brake line at the rear of the vehicle..END
When the pedal goes too far it activates a brake warning light. There is a pin in the switch that goes into a groove in the piston and locks it about half way in the master cylinder. Undoing it until you hear the click will let the piston come back to it's proper position. Sometimes that is what causes a low pedal.
If you still have a low pedal after you have bled the brakes, clamp each of the brake hoses and see if the pedal firms up.
If it doesn't then the master is faulty.
Check the rubber brake hoses at the front wheels, get someone to push the brake pedal in and out whilst you feel along the hoses, and if you feel it bulge out anywhere as the brakes are pressed, then this could be the cause of the soft pedal.
The check valve on the vacuum hose was a bit dodgy and the vacuum hose had perished internally at the manifold end and had nearly blocked the hose. I was still getting some vacuum so I thought I had enough vacuum to run the brakes and it appeared that the booster was partially working. When I replaced the hose and cleaned out the valve (new one on order) the difference in the braking was profound
(this one is for utes only) Are you getting plenty of fluid when you bleed it?
Theres a load sensing proportioning valve on the rear brakes on utes,(utes also use a different master cylinder to sedans etc) and if this proportioning valve is closed or near closed when the rear brakes are bled, it can hold or trap air in the rear brake lines. Before bleeding the rear brakes, make sure the proportioning valve is held fully open by removing the chain and/or clamp that connects the proportioning valve to the panhard rod, and holding it in the full open position whilst the brakes are bled... This proportioning valve works by cutting brake line pressure to the rear wheels when the vehicle is unladen and it also lets more line pressure through to the rear brakes when the rear end is weighed down with a heavy load. It also stops the rear brakes locking up by controlling the brake line pressure to the rear wheels as the rear end lifts up under heavy braking.
Air Tightness Check
Start the engine and let it run for one or two minutes, then shut it off. Now step on the brake pedal several times, applying normal pressure. Be sure to wait about five seconds between each depression of the pedal. If the brake pedal reserve distance increases every time the pedal is depressed, the booster has good air tightness.
To check the Check Valve and vacuum hose piping use the following procedure:
• Remove the vacuum hose and valve from the booster.
• Block the valve with a finger and start the engine.
• A strong vacuum should be felt if the piping and valve are operating.
• The vacuum must remain unchanged for approximately one minute after the engine is stopped.
Lack of vacuum indicates a malfunction in the check valve or the vacuum hose piping. If the vacuum appears normal, there may be a problem in the booster itself.
Air Tightness Test Under Load
Depress the brake pedal when the engine is running, then stop the engine and wait for about 30 seconds. If the brake pedal position does not change, the brake booster is functioning normally. It is defective if the brake pedal moves up.
The brake pedal reserve distance remains unchanged because vacuum is maintained in the Constant Pressure Chamber.
If you bench bleed and have the reservoir full with the cap clipped on plus the brake lines ready to screw to the new MC and spanners to hand etc you should not get any air into the system. The brake lines that you disconnect from the old MC are angled so they stay full of brake fluid - you can visually inspect to make sure. A trick here is to lever back the pad on one of the brake calipers just before you attach the brake lines to the new MC
Before you refit your new/reco master cylinder, "bench bleed it".
Put the M/cyl in the vice and put fluid in the reservoir.
Place a screw driver in where the clutch rod goes
Put a finger over the hole where the pipe screws in.#
Push the screw driver in and fluid will be pushed out of the hole that your finger is trying to block, keep your finger firmly over the hole while you let the screw driver return to its outward position.#
Do it a few times, not letting air get sucked back into the hole that your finger is blocking. (This bleeds the air out of the master cylinder before you fit it).#
Keep your finger over the hole while you bolt the cylinder back on to the car, screw the pipe back into its hole. Then get a mate to sit in the car, loosen the pipe that you just tightened and tell your mate in the car to steadily push his foot to the floor and you will see brake fluid and air bubbles some out of the base of the nut where the pipe goes through it, as soon as your mate says "pedal to the floor" nip up the pipe nut, tell him to steadily let his foot off the pedal, do it a few times and it should get the air out of the system without having to get under the car. I have done it several times and it works well.
Bleeding is a given so if still no good then....
Important for Ute owners!!!!! Unlike me, save 3 weeks of yr life!
Also make sure the master cylinder on the vehicle is the proper one for use on utilities, as the wagon and sedan master cylinders are different from the ute master cylinders and have no proportioning valve fitted, so instead of having the proportioning valve built into the master cylinder, utes run the seperate adjustable, or "load sensing" proportioning valve on the rear brake line at the rear of the vehicle..END
When the pedal goes too far it activates a brake warning light. There is a pin in the switch that goes into a groove in the piston and locks it about half way in the master cylinder. Undoing it until you hear the click will let the piston come back to it's proper position. Sometimes that is what causes a low pedal.
If you still have a low pedal after you have bled the brakes, clamp each of the brake hoses and see if the pedal firms up.
If it doesn't then the master is faulty.
Check the rubber brake hoses at the front wheels, get someone to push the brake pedal in and out whilst you feel along the hoses, and if you feel it bulge out anywhere as the brakes are pressed, then this could be the cause of the soft pedal.
The check valve on the vacuum hose was a bit dodgy and the vacuum hose had perished internally at the manifold end and had nearly blocked the hose. I was still getting some vacuum so I thought I had enough vacuum to run the brakes and it appeared that the booster was partially working. When I replaced the hose and cleaned out the valve (new one on order) the difference in the braking was profound
(this one is for utes only) Are you getting plenty of fluid when you bleed it?
Theres a load sensing proportioning valve on the rear brakes on utes,(utes also use a different master cylinder to sedans etc) and if this proportioning valve is closed or near closed when the rear brakes are bled, it can hold or trap air in the rear brake lines. Before bleeding the rear brakes, make sure the proportioning valve is held fully open by removing the chain and/or clamp that connects the proportioning valve to the panhard rod, and holding it in the full open position whilst the brakes are bled... This proportioning valve works by cutting brake line pressure to the rear wheels when the vehicle is unladen and it also lets more line pressure through to the rear brakes when the rear end is weighed down with a heavy load. It also stops the rear brakes locking up by controlling the brake line pressure to the rear wheels as the rear end lifts up under heavy braking.
Air Tightness Check
Start the engine and let it run for one or two minutes, then shut it off. Now step on the brake pedal several times, applying normal pressure. Be sure to wait about five seconds between each depression of the pedal. If the brake pedal reserve distance increases every time the pedal is depressed, the booster has good air tightness.
To check the Check Valve and vacuum hose piping use the following procedure:
• Remove the vacuum hose and valve from the booster.
• Block the valve with a finger and start the engine.
• A strong vacuum should be felt if the piping and valve are operating.
• The vacuum must remain unchanged for approximately one minute after the engine is stopped.
Lack of vacuum indicates a malfunction in the check valve or the vacuum hose piping. If the vacuum appears normal, there may be a problem in the booster itself.
Air Tightness Test Under Load
Depress the brake pedal when the engine is running, then stop the engine and wait for about 30 seconds. If the brake pedal position does not change, the brake booster is functioning normally. It is defective if the brake pedal moves up.
The brake pedal reserve distance remains unchanged because vacuum is maintained in the Constant Pressure Chamber.
If you bench bleed and have the reservoir full with the cap clipped on plus the brake lines ready to screw to the new MC and spanners to hand etc you should not get any air into the system. The brake lines that you disconnect from the old MC are angled so they stay full of brake fluid - you can visually inspect to make sure. A trick here is to lever back the pad on one of the brake calipers just before you attach the brake lines to the new MC
Before you refit your new/reco master cylinder, "bench bleed it".
Put the M/cyl in the vice and put fluid in the reservoir.
Place a screw driver in where the clutch rod goes
Put a finger over the hole where the pipe screws in.#
Push the screw driver in and fluid will be pushed out of the hole that your finger is trying to block, keep your finger firmly over the hole while you let the screw driver return to its outward position.#
Do it a few times, not letting air get sucked back into the hole that your finger is blocking. (This bleeds the air out of the master cylinder before you fit it).#
Keep your finger over the hole while you bolt the cylinder back on to the car, screw the pipe back into its hole. Then get a mate to sit in the car, loosen the pipe that you just tightened and tell your mate in the car to steadily push his foot to the floor and you will see brake fluid and air bubbles some out of the base of the nut where the pipe goes through it, as soon as your mate says "pedal to the floor" nip up the pipe nut, tell him to steadily let his foot off the pedal, do it a few times and it should get the air out of the system without having to get under the car. I have done it several times and it works well.
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