At a loss with the brakes.
03-18-2016, 03:48 AM
#1
At a loss with the brakes.
I've never had a a vehicle give me such headaches with simple things such as this one. So my 81' had a low, spongy pedal, with minimal stopping power and hissing from the booster.
First I replaced the MC (the old one was leaking from the rear and the pedal wouldn't keep going to the floor slowly) and rebled. No change.
Then I had the pleasure of ripping everything apart again. Diagnosed the booster to be bad, not keeping vacuum.
New booster went in, hooked everything back up and rebled. Same issue. Pedal felt slightly firmer, but with the car off the first pimp is firm, then it looses pressure it seems like.
It is now however keeping a vacuum, when I let the engine idle and push the brake then turn off the engine the pedal stays put so that's good. I sprayed a bit of soap near the reservoir seal to see if air was getting in to the system there, nothing. I have bled and rebled, manually. And I'm not getting air in the lines. The calipers do not appear seized up. I have also not driven it again because the pedal does not feel firm at all. Im comparing what the pedal should feel like to modern cars, should firm up pretty well when the vehicle is off right?
Also I'm hearing a lot of slushing in the resevior when I pump the brake as if air bubbles are making it to the top of the resevior but again, no air in the lines?!
This, on top of a **** paint job, a motor with a steady oil leak and a sunroof that will not deal correctly is making me very dis interested in keeping the car.
First I replaced the MC (the old one was leaking from the rear and the pedal wouldn't keep going to the floor slowly) and rebled. No change.
Then I had the pleasure of ripping everything apart again. Diagnosed the booster to be bad, not keeping vacuum.
New booster went in, hooked everything back up and rebled. Same issue. Pedal felt slightly firmer, but with the car off the first pimp is firm, then it looses pressure it seems like.
It is now however keeping a vacuum, when I let the engine idle and push the brake then turn off the engine the pedal stays put so that's good. I sprayed a bit of soap near the reservoir seal to see if air was getting in to the system there, nothing. I have bled and rebled, manually. And I'm not getting air in the lines. The calipers do not appear seized up. I have also not driven it again because the pedal does not feel firm at all. Im comparing what the pedal should feel like to modern cars, should firm up pretty well when the vehicle is off right?
Also I'm hearing a lot of slushing in the resevior when I pump the brake as if air bubbles are making it to the top of the resevior but again, no air in the lines?!
This, on top of a **** paint job, a motor with a steady oil leak and a sunroof that will not deal correctly is making me very dis interested in keeping the car.
03-18-2016, 07:34 AM
#2
Burning Brakes
Lots of loops and high and low spots in the plumbing for the brake tubes. Manual bleeding sometimes cannot get out all the air out. It is even worse with the ABS cars. You will need to get a power bleeder to get all the air out....
03-18-2016, 09:18 AM
#3
Burning Brakes
Did you bench bleed the new master cylinder?
Are the brake hoses going to each caliper original? Hoses get weak from age and will expand like a balloon under pressure.
Are the brake hoses going to each caliper original? Hoses get weak from age and will expand like a balloon under pressure.
03-18-2016, 09:54 AM
#5
Team Owner
Ok lets see what you did.
Please answer these questions.
Did you use a new or rebuilt MC?
Did you use a new or used Booster?
When you put the booster in,
did you make sure that the surface where the MC seats was scratch free?
Did you install new stainless flex lines?
What fluid are you using with the new to the car parts?
Describe exactly how you bled every part of the system?
Please answer these questions.
Did you use a new or rebuilt MC?
Did you use a new or used Booster?
When you put the booster in,
did you make sure that the surface where the MC seats was scratch free?
Did you install new stainless flex lines?
What fluid are you using with the new to the car parts?
Describe exactly how you bled every part of the system?
03-18-2016, 09:59 AM
#6
Team Owner
NOTE you may feel like being in a hurry here BUT take your time, slower is better.
From here this is how I would proceed.
NOTE Only use the ATE fluid.
NOTE mixing the fluids could induce seal swell and damage the new parts.
This is done via gravity. no pressure bleeder.
Fill the MC with ATE, Wait for 20 mins till the fluid works into the MC.
then one at a time, open each B nut line on the MC about a half a turn .
Wait ,.....you will see fluid and bubbles start issuing from each b nut ,
once the fluid is clear move to the next line.
NOTE start at the rear of the MC and move to the front.
Once you have the lines bled then open the tip and let the air out.
Get a helper to operate the foot pedal and then do the lines sequence again.
This will be to bleed the MC.
pump a few times slowly,
hold down,
then crack the line nut.
You should have minimum bubbles but possibly a few.
When the line is clear fluid move to the next, then do the tip bleeder.
NOTE if your car doesnt have ABS disregard bleeding the ABS unit.
Once done,
then move to the ABS unit and do the line nuts there till you get blue fluid clear of bubbles.
Once done then do the wheels .
NOTE open the inner bleeder first till you get blue fluid,
then do the outer bleeder.
Follow this sequence ,
NOTE its opposite what has been done,
but its also pointed out in the WSM
LF, RF , LR, RR.
It seems like a lot of bleeding and you will use most of the litre of fluid ,
but the brakes should be high and hard when your done.
Caution .... NOTE ...before bleeding I would also suggest to replace the rear brake proportioning valve screwed into the ABS unit as these always are filled with corrosion.
Also replace the original rubber flex lines with stainless flex lines before you bleed the system
From here this is how I would proceed.
NOTE Only use the ATE fluid.
NOTE mixing the fluids could induce seal swell and damage the new parts.
This is done via gravity. no pressure bleeder.
Fill the MC with ATE, Wait for 20 mins till the fluid works into the MC.
then one at a time, open each B nut line on the MC about a half a turn .
Wait ,.....you will see fluid and bubbles start issuing from each b nut ,
once the fluid is clear move to the next line.
NOTE start at the rear of the MC and move to the front.
Once you have the lines bled then open the tip and let the air out.
Get a helper to operate the foot pedal and then do the lines sequence again.
This will be to bleed the MC.
pump a few times slowly,
hold down,
then crack the line nut.
You should have minimum bubbles but possibly a few.
When the line is clear fluid move to the next, then do the tip bleeder.
NOTE if your car doesnt have ABS disregard bleeding the ABS unit.
Once done,
then move to the ABS unit and do the line nuts there till you get blue fluid clear of bubbles.
Once done then do the wheels .
NOTE open the inner bleeder first till you get blue fluid,
then do the outer bleeder.
Follow this sequence ,
NOTE its opposite what has been done,
but its also pointed out in the WSM
LF, RF , LR, RR.
It seems like a lot of bleeding and you will use most of the litre of fluid ,
but the brakes should be high and hard when your done.
Caution .... NOTE ...before bleeding I would also suggest to replace the rear brake proportioning valve screwed into the ABS unit as these always are filled with corrosion.
Also replace the original rubber flex lines with stainless flex lines before you bleed the system
03-18-2016, 11:33 AM
#7
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guys it is an 81 so no ABS , has two proportioning valves on the firewall, right front left rear calipers on one half of master cylinder left front right rear calipers on the other half.
At this point possibly it has a vacuum problem ??
Try pushing down on the brake pedal then starting the car....does the pedal move down after it starts ??
At this point possibly it has a vacuum problem ??
Try pushing down on the brake pedal then starting the car....does the pedal move down after it starts ??
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03-18-2016, 06:29 PM
#9
Chronic Tool Dropper
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Bleeding can be a chore on these cars.
19PSI is on a good track with the question on bench-bleeding first. Stuffed in the ATE box there's a bit of guidance on this. In a nutshell, you connect hoses to all thedischarge ports and route them back into the reservoir. Fluid in the reservoir, and GENTLY push the piston to end-of-stroke with a screwdriver. The MC must be clamped LEVEL while you do this. The procedure gets ALL the air out of the front upper chamber of the master cylinder. Can Not Be Done with the MC mounted in the car unless you can get the master cylinder level.
I spent a good part of a day bleeding the brake system on my later car with ABS. the ABS usint sits higher than the master ylinder, so air in the system gathers there. There are a couple other higher pockets in the piping that took extra effort to purge too. Ultimately, a combination of vacuum, pressure bleeder, and persistence got things right again.
19PSI is on a good track with the question on bench-bleeding first. Stuffed in the ATE box there's a bit of guidance on this. In a nutshell, you connect hoses to all thedischarge ports and route them back into the reservoir. Fluid in the reservoir, and GENTLY push the piston to end-of-stroke with a screwdriver. The MC must be clamped LEVEL while you do this. The procedure gets ALL the air out of the front upper chamber of the master cylinder. Can Not Be Done with the MC mounted in the car unless you can get the master cylinder level.
I spent a good part of a day bleeding the brake system on my later car with ABS. the ABS usint sits higher than the master ylinder, so air in the system gathers there. There are a couple other higher pockets in the piping that took extra effort to purge too. Ultimately, a combination of vacuum, pressure bleeder, and persistence got things right again.
03-18-2016, 07:37 PM
#10
Rennlist Member
'Can hear fluid slushing in the reservoir' - doubt that very much! Maybe in a booster case with lots of fluid leaked into it, and an elephant rocking the car from side to side, but otherwise....
'wouldnt keep going to the floor slowly' - I think you mean 'would keep going' ?
If you have vacuum in the system, engine off, you should hear a hiss from the booster (in the cabin) with each application of brakes until the vacuum is exhausted - there is a filter around the pedal pushrod where the air goes in. Once the vacuum is finished, you should have a pretty hard pedal when all is well.
I had no difficulty flushing new fluid through mine with a power bleeder, but thats a different situation.
jp 83 Euro S AT 56k
'wouldnt keep going to the floor slowly' - I think you mean 'would keep going' ?
If you have vacuum in the system, engine off, you should hear a hiss from the booster (in the cabin) with each application of brakes until the vacuum is exhausted - there is a filter around the pedal pushrod where the air goes in. Once the vacuum is finished, you should have a pretty hard pedal when all is well.
I had no difficulty flushing new fluid through mine with a power bleeder, but thats a different situation.
jp 83 Euro S AT 56k
03-18-2016, 08:21 PM
#11
sounds like you got a defective replacement cylinder. my condolences. Two years ago my pedal flopped too. I installed a new MC from Pelican, did a half-assed relacement, and it works just fine.
guess I'm lucky. proper bleeding procedure is paramount.
guess I'm lucky. proper bleeding procedure is paramount.
03-20-2016, 02:33 AM
#12
Update and clarification.
The master cylinder was a refurb and the booster was used (I know I know). The lines appear to be the original hoses.
I picked up a motive black label bleeder and cycles a liter of fluid through the system. There was a minimal amount of air that was forced out.
Now the pedal is firm-ish when off. Start the car and it becomes less firm. The vacuum is good from what I can tell. Most of the stopping power is in the last half of pedal travel of that makes sense. Before it was not drivable, now I would say it is but the pedal is definitely not completely firm and let's just say if a dear jumps out I could possibly have a new hood armament. Tried locking up the wheels at a lower speed, no luck.
This is probably also due to the condition of the brake components themselves the rotors sat for a long time and are semi glazed over.
I'm happy that it is semi drive able but obviously this isn't an end all. Any other thoughts? Would hoses affect pedal firmness and stopping power so drastically?
The master cylinder was a refurb and the booster was used (I know I know). The lines appear to be the original hoses.
I picked up a motive black label bleeder and cycles a liter of fluid through the system. There was a minimal amount of air that was forced out.
Now the pedal is firm-ish when off. Start the car and it becomes less firm. The vacuum is good from what I can tell. Most of the stopping power is in the last half of pedal travel of that makes sense. Before it was not drivable, now I would say it is but the pedal is definitely not completely firm and let's just say if a dear jumps out I could possibly have a new hood armament. Tried locking up the wheels at a lower speed, no luck.
This is probably also due to the condition of the brake components themselves the rotors sat for a long time and are semi glazed over.
I'm happy that it is semi drive able but obviously this isn't an end all. Any other thoughts? Would hoses affect pedal firmness and stopping power so drastically?
03-20-2016, 03:18 AM
#13
Former Vendor
Update and clarification.
The master cylinder was a refurb and the booster was used (I know I know). The lines appear to be the original hoses.
I picked up a motive black label bleeder and cycles a liter of fluid through the system. There was a minimal amount of air that was forced out.
Now the pedal is firm-ish when off. Start the car and it becomes less firm. The vacuum is good from what I can tell. Most of the stopping power is in the last half of pedal travel of that makes sense. Before it was not drivable, now I would say it is but the pedal is definitely not completely firm and let's just say if a dear jumps out I could possibly have a new hood armament. Tried locking up the wheels at a lower speed, no luck.
This is probably also due to the condition of the brake components themselves the rotors sat for a long time and are semi glazed over.
I'm happy that it is semi drive able but obviously this isn't an end all. Any other thoughts? Would hoses affect pedal firmness and stopping power so drastically?
The master cylinder was a refurb and the booster was used (I know I know). The lines appear to be the original hoses.
I picked up a motive black label bleeder and cycles a liter of fluid through the system. There was a minimal amount of air that was forced out.
Now the pedal is firm-ish when off. Start the car and it becomes less firm. The vacuum is good from what I can tell. Most of the stopping power is in the last half of pedal travel of that makes sense. Before it was not drivable, now I would say it is but the pedal is definitely not completely firm and let's just say if a dear jumps out I could possibly have a new hood armament. Tried locking up the wheels at a lower speed, no luck.
This is probably also due to the condition of the brake components themselves the rotors sat for a long time and are semi glazed over.
I'm happy that it is semi drive able but obviously this isn't an end all. Any other thoughts? Would hoses affect pedal firmness and stopping power so drastically?
Common to miss that seal, or for it to fall out, when installing.
03-20-2016, 06:44 AM
#14
03-20-2016, 09:53 AM
#15
Team Owner
As for the brakes always use the best parts .
I would suggest you invest in new parts here,
a new master and booster then you can forget about these issues.
I suggest to use ATE gold fluid in the system and stainless flex lines at the calipers.
NOTE in the long run most rebuilt hydraulic cylinders will not last as long as a new part.
NOTE use the fluid that was made for the system most of our vendors sell it.
I would suggest you invest in new parts here,
a new master and booster then you can forget about these issues.
I suggest to use ATE gold fluid in the system and stainless flex lines at the calipers.
NOTE in the long run most rebuilt hydraulic cylinders will not last as long as a new part.
NOTE use the fluid that was made for the system most of our vendors sell it.