Big Big Problem.......help!!!!!
#16
01-12-2008, 07:35 PM
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Typical ABS systems have speed sensors at each wheel that continuously feed information, The computer uses this data to determine overall vehicle speed, and to detect when a wheel begins to lock, pressure is automatically limited or reduced to only the wheel that is locking,they work by automatically actuating the brakes on and off during emergency stops.If a wheel tries to lock up, a series of hydraulic valves limit or reduce the braking on that wheel.There are electrically operated solenoid valves are used to hold, release and reapply hydraulic pressure to the brakes.Which is where you get the pulsating effect.Most of the newer vehicles use what they call a Nonintegral ABS systems,it uses a conventional master brake cylinder and vacuum power booster with a separate hydraulic modulator unit,but some do use an electric pump for ABS also.So what I am saying here,it is ok to bleed the system either by gravity bleeding,or by pressure,by that I mean either pumping the pedal,or using an air operated devise that attaches to your master cyl,or another way is by vacuume.
#17
01-14-2008, 12:00 PM
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Originally Posted by adeese660
ABS is just sensors,so yes,the regular way,get the fluid out of master cyl,fill it up with clean fluid,and bleed the brakes till fresh fluid is comming out,make sure you check the fluid level often while you are flushing the system.
there is also the ABS module with valves and the controller that reads the sensors at the wheels.
Yes, the ABS module will trap a small amount of fluid in the valves. But its not enough to worry about when you bleed your brakes. That little bit of fluid shouldn't be enough to hurt the other fluid (providing your "contamination" is just for normal use of the fluid and you didn't accidentally add something like engine oil to the brake system).
The one time you need to take it in to a shop/dealer to be bled... if you put on a new ABS unit that is dry. You have to have a computer hooked up so you can cycle the ABS valves while bleeding to get the air out.
(or you can usually just buy a "wet" ABS module that already has fluid in the valves)
#18
01-14-2008, 05:23 PM
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#19
01-15-2008, 02:21 PM
Originally Posted by mkosu04
where does this myth come from???? 
The only possible explanation for a brake line (flexible or solid) trapping pressure is that somehow it gets kinked. And this should be pretty obvious.
The brake fluid pressure is exerting force outward on the tube. If there is pressure in the caliper it will push back through the tube and expand it if it is collapsed. :
The only possible explanation for a brake line (flexible or solid) trapping pressure is that somehow it gets kinked. And this should be pretty obvious.
The brake fluid pressure is exerting force outward on the tube. If there is pressure in the caliper it will push back through the tube and expand it if it is collapsed. :
Originally Posted by mkosu04
To my knowledge (and I've asked some of the other engineers I work with... we make automotive brakes) there is no way that a flex line can trap pressure. The problem with flex lines as they get old is the opposite... they start to swell under pressure and your brakes feel soft. That is when you need to replace them.:
You might want to ask engineers that have field experience about other issues brake hoses may have besides swelling.
Originally Posted by mkosu04
If you have a precise explanation of why/when a flex line can trap pressure, please let me know. Do not just reply with "well, one time my cousin Billy Bob Joe had a dragging caliper and he replaced the flex line and that fixed it".
Thanks
Thanks
This is a problem I see all the time (not just on Fords either). The interior lining of the hose breaks down and becomes swollen causing a blockage, the pressure of applying the brake pedal can overcome the blockage but the return of fluid is under much less pressure and therefore keeps that wheel locked(espessially after it heats up and closes the blockage even more). Kind of like a valve in a human heart, one way only. I hope that helps.
#20
01-15-2008, 02:24 PM
Originally Posted by adeese660
On the brake line ''myth'',what happens is the brake line will act like a backflow valve.It will allow fluid in one way,and not back out,you are applying ALOT more pressure to the calipers than what it takes to release.There is no pressure on releasing the pedal,the pressure is generated when you apply the brakes,thus causing fluid to enter the caliper or wheel cyl,when you release the pedal,the fluid flows backwards,not under pressure,The lines will get swollen inside ,and not allow the fluid to flow back out.Also,sometimes the line will start to deteriate inside,,thus causing the same problem.I have been ASE certified in brakes and front-ends for 13 years,and been working on brake systems since 1981,I have seen a brake line collapse inside and/or get swollen inside many times,causing the same symptoms as a frozen caliper,When I say frozen,I don't mean from cold,I mean from contanminates in the fluid/caliper.Also,there are some manufactures that make phenolic pistons,which also will get swollen from contanimates in the fluid and cause the caliper to stop working.So,actually,it is not a ''myth'',it is a fact.The biggest problem i see here is you are talking to engineers,get out in the field and see for yourself,I am NOT by any means bashing engineers,but they can do it on paper really well,but, allmost anyone on this forum can agree upon this statement,they do not have the field experience,although it works on paper,does not mean it works in the real world.I am not trying to make you or anyone else mad on here,but that is the way it is.
OOps! I didn't read ahead before posting my reply. Nicely said though.
#21
01-15-2008, 05:34 PM
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#22
01-16-2008, 06:18 AM
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I used to run a streetable race car around town and a pure race car at the track. I fully flushed each system and used silicone brake fluid in each. All flexable brake lines were made of teflon lined braided line. I just made copies of what was there. Braking was never a problem and the pedal feel was improved with no more flexing due to rubber lines.
If you ever want to have a maintenance free system that is reliable that really works. I even made braided flex lines for my old work truck. It didn't look like it could stop but I had no problems fully loaded.
If you ever want to have a maintenance free system that is reliable that really works. I even made braided flex lines for my old work truck. It didn't look like it could stop but I had no problems fully loaded.
#23
01-16-2008, 02:08 PM
Originally Posted by adeese660
Doc,you said it very well too.And yes you are right,I have seen it many,many times over the years,on any vehicle made that has a flexible brake hose.
Actually, it's quite funny, I just had a 98 F-150 come in with the L/F rotor smoking! It had all new front brake parts ,except,.......you guessed it, old hoses. At 120,000 miles they should have been done also.
It's funny how we were just discussiung this issue.
#24
01-16-2008, 02:25 PM
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No, what's funny is I know of lots of vehicles that are over 20 years old, and 120K+ miles isn't even half of what they have, and have NEVER had their brake lines changed out. NO BRAKE PROBLEMS OR ISSUES.
So, either it's a Ford problem, because we read it all the time here(myths perpetuated by paranoid and/or limited experienced individuals), or the folks doing the brake work aren't installing the pads, rotors, and shoes correctly. Most likely the later.
And some of you guys are techs, engineers, and designers of vehicles and parts?
So, either it's a Ford problem, because we read it all the time here(myths perpetuated by paranoid and/or limited experienced individuals), or the folks doing the brake work aren't installing the pads, rotors, and shoes correctly. Most likely the later.
And some of you guys are techs, engineers, and designers of vehicles and parts?
#25
01-16-2008, 04:59 PM
Originally Posted by jward
No, what's funny is I know of lots of vehicles that are over 20 years old, and 120K+ miles isn't even half of what they have, and have NEVER had their brake lines changed out. NO BRAKE PROBLEMS OR ISSUES.
So, either it's a Ford problem, because we read it all the time here(myths perpetuated by paranoid and/or limited experienced individuals), or the folks doing the brake work aren't installing the pads, rotors, and shoes correctly. Most likely the later.
And some of you guys are techs, engineers, and designers of vehicles and parts?
So, either it's a Ford problem, because we read it all the time here(myths perpetuated by paranoid and/or limited experienced individuals), or the folks doing the brake work aren't installing the pads, rotors, and shoes correctly. Most likely the later.
And some of you guys are techs, engineers, and designers of vehicles and parts?
#26
01-16-2008, 05:24 PM
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#27
01-16-2008, 05:34 PM
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I have seen vehicles come in with over 300k on them,and still have the original hoses,and I have seen them come it with 50k on them and the hose is bad,any make,model,color,it does not matter,its like buying a light bulb for your lamp on your table,it may last a few years and it may not,just depends.The miles on a vehicle or the make has no differance,just like any other part on a vehicle,it may last for a long time,and it may not.
#28
01-17-2008, 09:43 AM
Originally Posted by adeese660
I have seen vehicles come in with over 300k on them,and still have the original hoses,and I have seen them come it with 50k on them and the hose is bad,any make,model,color,it does not matter,its like buying a light bulb for your lamp on your table,it may last a few years and it may not,just depends.The miles on a vehicle or the make has no differance,just like any other part on a vehicle,it may last for a long time,and it may not.
jward, no problem
I hope I didn't come across to harsh in my response. I just wanted to explain my reasoning behind this issue.
(unless they haven't fixed them yet). It would be nice to know.