Brake bleeding help
01-12-2014, 11:39 AM
#1
Rennlist Member
Thread Starter
Brake bleeding help
I finally replaced my master cylinder yesterday and now I have an issue with the brakes needing a pump for them to feel firm.
Symptoms
1-2 pumps pedal feels really firm and does not sink. even after a min or 2 of holding it there it stays strong.
Drive away and instantly pedal has long travel. 1 pump Im back to firm.
I also have a whooshing sound when depressing the brake inside the cabin until its firm the whooshing sound goes away till the next time i stop.
Even with the long travel the brakes feel good and stop the car with out a pump.
Im going to rebleed the brakes today to see if it changes anything.
Symptoms
1-2 pumps pedal feels really firm and does not sink. even after a min or 2 of holding it there it stays strong.
Drive away and instantly pedal has long travel. 1 pump Im back to firm.
I also have a whooshing sound when depressing the brake inside the cabin until its firm the whooshing sound goes away till the next time i stop.
Even with the long travel the brakes feel good and stop the car with out a pump.
Im going to rebleed the brakes today to see if it changes anything.
01-12-2014, 02:15 PM
#3
Chronic Tool Dropper
Lifetime Rennlist
Member
Lifetime Rennlist
Member
The ATE-recommended bleeding procedure starts with a "bench bleed" of the master cylinder. This involves using short sections of brake line to return the pumped fluid to the reservoir. Put the MC in a vise, level, with these return lines fitted. Using a screwdriver, gently stroke the pistons until only clear fluid is coming out of the lines. Put a section of plastic hose on the bleeder at the end of the MC and give it a few more strokes until only clear fluid and no more bubbles. This step gets the air out of the end of the front chamber.
If the MC went into the car without the bench bleeding, you'll want to bleed at that front of MC bleeder before doing anything else. Just put the outer end of a piece of plastic tubing back into the reservoir, open the bleeder with the tubing attached, and pump the pedal very gently a few times, until all fluid passes through with no bubbles. When the MC is mounted in the car, the front end is high enough that air will pocket in the end. The port for the steel brake lines is low, so the only way to get the air out completely is to bleed through that front bleeder port.
Then go on to bleed from the calipers with a pressure bleeder if you can. Your 86.5 has the 4-piston Brembo calipers, so you'll want to bleed the inner chamber before the outer chamber on each caliper.
If you are 2-person bleeding manually, do the front right, then front left, then the rears in no particular order needed. The fronts are fed from the rear chamber of the MC, and the internal design of the pistons in the MC suggest that you want to get all the air out of the rear chamber/front calipers first.
There are a couple high places where air will 'hide' in the system. One is the ABS pump, and that takes a bit of effort to recover. Theoretically, you should be able to cycle the pump while pressure bleeding, but I've never tried that. Instead, I pulled a vacuum (serious vacuum, not MityVac vacuum) on each line to the pump remove the air, then reverse-pressure-bleed from the caliper end.
The second high spot is where the rear steel lines join together with the main rear line, and the transverse sections of line between that Tee fitting and where the caliper hoses connect. Easiest way to get trapped air from that section is to umbolt the rear calipers and raise them as high as you can, and adjust the hose routing so it slopes up continuously from the steel line connection to the caliper. Tie the caliper up with a tie-wrap or mechanics wire, the caliper such that the bleeders are at the top while it's hanging. Then pressure-bleed from the master cylinder end.
----
For those playing along at home, perhaps the most important things to remember include to NEVER let the reservoir run dry while bleeding.
When replacing the master cylinder, use vacuum-line rubber caps (auto parts store item) to immediately seal each steel line end as you disconnect it. Suck as much fluid as you can from the reservoir before removing any lines, and you'll manage the mess some. The caps keep fluid from falling out of the steel lines.
On the new master cylinder, be sure to do the bench-bleeding before you install the MC. You can buy steel brake line pretty cheap at any good auto parts place, and each double-ended one will cover two ports when cut in half. Buy them long enough and bend them back around in an arc so they discharge into the reservoir. There are likely more than a few YouTube videos that illustrate the procedure if my explanation above wasn't clear enough. Between the bench bleed that removes all the air from the MC, and using the rubber caps on the lines, you significantly reduce the chances of accidentally pushing a slug of air into the system from the new MC.
If the MC went into the car without the bench bleeding, you'll want to bleed at that front of MC bleeder before doing anything else. Just put the outer end of a piece of plastic tubing back into the reservoir, open the bleeder with the tubing attached, and pump the pedal very gently a few times, until all fluid passes through with no bubbles. When the MC is mounted in the car, the front end is high enough that air will pocket in the end. The port for the steel brake lines is low, so the only way to get the air out completely is to bleed through that front bleeder port.
Then go on to bleed from the calipers with a pressure bleeder if you can. Your 86.5 has the 4-piston Brembo calipers, so you'll want to bleed the inner chamber before the outer chamber on each caliper.
If you are 2-person bleeding manually, do the front right, then front left, then the rears in no particular order needed. The fronts are fed from the rear chamber of the MC, and the internal design of the pistons in the MC suggest that you want to get all the air out of the rear chamber/front calipers first.
There are a couple high places where air will 'hide' in the system. One is the ABS pump, and that takes a bit of effort to recover. Theoretically, you should be able to cycle the pump while pressure bleeding, but I've never tried that. Instead, I pulled a vacuum (serious vacuum, not MityVac vacuum) on each line to the pump remove the air, then reverse-pressure-bleed from the caliper end.
The second high spot is where the rear steel lines join together with the main rear line, and the transverse sections of line between that Tee fitting and where the caliper hoses connect. Easiest way to get trapped air from that section is to umbolt the rear calipers and raise them as high as you can, and adjust the hose routing so it slopes up continuously from the steel line connection to the caliper. Tie the caliper up with a tie-wrap or mechanics wire, the caliper such that the bleeders are at the top while it's hanging. Then pressure-bleed from the master cylinder end.
----
For those playing along at home, perhaps the most important things to remember include to NEVER let the reservoir run dry while bleeding.
When replacing the master cylinder, use vacuum-line rubber caps (auto parts store item) to immediately seal each steel line end as you disconnect it. Suck as much fluid as you can from the reservoir before removing any lines, and you'll manage the mess some. The caps keep fluid from falling out of the steel lines.
On the new master cylinder, be sure to do the bench-bleeding before you install the MC. You can buy steel brake line pretty cheap at any good auto parts place, and each double-ended one will cover two ports when cut in half. Buy them long enough and bend them back around in an arc so they discharge into the reservoir. There are likely more than a few YouTube videos that illustrate the procedure if my explanation above wasn't clear enough. Between the bench bleed that removes all the air from the MC, and using the rubber caps on the lines, you significantly reduce the chances of accidentally pushing a slug of air into the system from the new MC.
01-12-2014, 07:21 PM
#4
Rennlist Member
Thread Starter
The ATE-recommended bleeding procedure starts with a "bench bleed" of the master cylinder. This involves using short sections of brake line to return the pumped fluid to the reservoir. Put the MC in a vise, level, with these return lines fitted. Using a screwdriver, gently stroke the pistons until only clear fluid is coming out of the lines. Put a section of plastic hose on the bleeder at the end of the MC and give it a few more strokes until only clear fluid and no more bubbles. This step gets the air out of the end of the front chamber.
If the MC went into the car without the bench bleeding, you'll want to bleed at that front of MC bleeder before doing anything else. Just put the outer end of a piece of plastic tubing back into the reservoir, open the bleeder with the tubing attached, and pump the pedal very gently a few times, until all fluid passes through with no bubbles. When the MC is mounted in the car, the front end is high enough that air will pocket in the end. The port for the steel brake lines is low, so the only way to get the air out completely is to bleed through that front bleeder port.
Then go on to bleed from the calipers with a pressure bleeder if you can. Your 86.5 has the 4-piston Brembo calipers, so you'll want to bleed the inner chamber before the outer chamber on each caliper.
If you are 2-person bleeding manually, do the front right, then front left, then the rears in no particular order needed. The fronts are fed from the rear chamber of the MC, and the internal design of the pistons in the MC suggest that you want to get all the air out of the rear chamber/front calipers first.
There are a couple high places where air will 'hide' in the system. One is the ABS pump, and that takes a bit of effort to recover. Theoretically, you should be able to cycle the pump while pressure bleeding, but I've never tried that. Instead, I pulled a vacuum (serious vacuum, not MityVac vacuum) on each line to the pump remove the air, then reverse-pressure-bleed from the caliper end.
The second high spot is where the rear steel lines join together with the main rear line, and the transverse sections of line between that Tee fitting and where the caliper hoses connect. Easiest way to get trapped air from that section is to umbolt the rear calipers and raise them as high as you can, and adjust the hose routing so it slopes up continuously from the steel line connection to the caliper. Tie the caliper up with a tie-wrap or mechanics wire, the caliper such that the bleeders are at the top while it's hanging. Then pressure-bleed from the master cylinder end.
----
For those playing along at home, perhaps the most important things to remember include to NEVER let the reservoir run dry while bleeding.
When replacing the master cylinder, use vacuum-line rubber caps (auto parts store item) to immediately seal each steel line end as you disconnect it. Suck as much fluid as you can from the reservoir before removing any lines, and you'll manage the mess some. The caps keep fluid from falling out of the steel lines.
On the new master cylinder, be sure to do the bench-bleeding before you install the MC. You can buy steel brake line pretty cheap at any good auto parts place, and each double-ended one will cover two ports when cut in half. Buy them long enough and bend them back around in an arc so they discharge into the reservoir. There are likely more than a few YouTube videos that illustrate the procedure if my explanation above wasn't clear enough. Between the bench bleed that removes all the air from the MC, and using the rubber caps on the lines, you significantly reduce the chances of accidentally pushing a slug of air into the system from the new MC.
If the MC went into the car without the bench bleeding, you'll want to bleed at that front of MC bleeder before doing anything else. Just put the outer end of a piece of plastic tubing back into the reservoir, open the bleeder with the tubing attached, and pump the pedal very gently a few times, until all fluid passes through with no bubbles. When the MC is mounted in the car, the front end is high enough that air will pocket in the end. The port for the steel brake lines is low, so the only way to get the air out completely is to bleed through that front bleeder port.
Then go on to bleed from the calipers with a pressure bleeder if you can. Your 86.5 has the 4-piston Brembo calipers, so you'll want to bleed the inner chamber before the outer chamber on each caliper.
If you are 2-person bleeding manually, do the front right, then front left, then the rears in no particular order needed. The fronts are fed from the rear chamber of the MC, and the internal design of the pistons in the MC suggest that you want to get all the air out of the rear chamber/front calipers first.
There are a couple high places where air will 'hide' in the system. One is the ABS pump, and that takes a bit of effort to recover. Theoretically, you should be able to cycle the pump while pressure bleeding, but I've never tried that. Instead, I pulled a vacuum (serious vacuum, not MityVac vacuum) on each line to the pump remove the air, then reverse-pressure-bleed from the caliper end.
The second high spot is where the rear steel lines join together with the main rear line, and the transverse sections of line between that Tee fitting and where the caliper hoses connect. Easiest way to get trapped air from that section is to umbolt the rear calipers and raise them as high as you can, and adjust the hose routing so it slopes up continuously from the steel line connection to the caliper. Tie the caliper up with a tie-wrap or mechanics wire, the caliper such that the bleeders are at the top while it's hanging. Then pressure-bleed from the master cylinder end.
----
For those playing along at home, perhaps the most important things to remember include to NEVER let the reservoir run dry while bleeding.
When replacing the master cylinder, use vacuum-line rubber caps (auto parts store item) to immediately seal each steel line end as you disconnect it. Suck as much fluid as you can from the reservoir before removing any lines, and you'll manage the mess some. The caps keep fluid from falling out of the steel lines.
On the new master cylinder, be sure to do the bench-bleeding before you install the MC. You can buy steel brake line pretty cheap at any good auto parts place, and each double-ended one will cover two ports when cut in half. Buy them long enough and bend them back around in an arc so they discharge into the reservoir. There are likely more than a few YouTube videos that illustrate the procedure if my explanation above wasn't clear enough. Between the bench bleed that removes all the air from the MC, and using the rubber caps on the lines, you significantly reduce the chances of accidentally pushing a slug of air into the system from the new MC.
