QuestionYeh the truck makes a weird clunking type noise when you press on the brakes, you feel something in the pedal then the brakes fail when pressing them down....it might be the calipers or master cylinder as you have stated, i will be taking the truck to the shop, but wanted to get some idea, that way I can at least give them a direction so they won't rake me over coals to badly.....Sound familiar at all, the clunking noise that seems to sound as if they have failed.....If it were na caliper, wouldn't the truck still stop if it had one bad caliper and one good caliper.....
Rob C
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Followup To
Question -
I am having a probelm with the brakes on my 1996 Discovery, my brake pedal just collapses, and the abs light has come on, my mechanic said that it was the anti lock brake sensor on the right front, he replaced the sensor which was very expensive, and a day or so later the brake peddle started collapsing again, but seemed to get worse, i returned the car to him again, and he has no explaination as to the source of the problem, he said possibly a bad wheel hub, which is said to be a very costly repair...what do you think, have you ever had this issue before....
Answer -
Hi Robert,
if this guy did not get the problem right away...don't waste more money on him. He replaced a part that did not need fixing!
Sounds more like your master cylinder than ABS. If it was just your ABS modulator, the system would normally just trigger a fault and your brakes would function normally. If your brake pedal has no pressure...its the master C or a leak in the line somewhere. A leak you would see both on the garage floor and in the reservoir.
See if you can get some of your money back from this guy and have the Master C problem addressed.
If it was a wheel hub...I doubt it would cause the brake pedal to fail. Very rare to have wheel hub failure...I've yet to see this. Do you do extreme off-roading?
When my master C failed, my brake pedal when to nothing! No matter how many times I pumped the pedal...no pressure would buildup. Changed the master C and brakes came back solid.
Could also be a faulty caliper. If you have some pressure and then it drops off...could be air in the line or in a caliper. Just in case, have your calipers inspected.
Best of luck,
JohnMc
AnswerHi Robert,
if you have a clunking sound each time you press the brake pedal, it could be that the caliper is moving on the wheel due to a loose bolt (very dangerous). Its also possible that whatever pressure is buildup within the braking system moves a piston suddenly (clunk) then all pressure is lost and thats when your brake pedal moves to the floor.
Its possible to rebuild a caliper even repair it. Someone would have to remove the calipers from the Disco, clean up all the rust, liberally spray brake cleaner around the moving parts, make sure the pistons move in and out freely then bleed the entire system.
Here is a website that outlines exactly what is needed to replace and repair the brake pads, rotors and even the calipers:
http://groups.msn.com/LRDiscovery
go to the PICTURES section and there will be seven (7) pages of brake repair.
Usually, a complete brake system repair can cost about $500 to $700 including labour (here in Canada) and about $300 to $400 US. Depends on the state of your rotors, if you need a master cylinder...this would then need to be added.
I don't fool around too much with salvaged parts and the braking system. I bought used calipers but I make sure they are good by rebuilding them myself. The master C is something I would buy either aftermarket OR OEM. I've yet to rebuild a master C and doubt I could do it...at least with the knowledge I currently have. I have a good friend who has the skills to do this and maybe together we'd tackle this. Its something a do-it-yourselfer usually does not touch.
So, with that additional detail of a clunking sound, I'm more confident is saying its a caliper piston that probably seized and your going to have to isolate which caliper it is and repair it. Once repaired, you might as well replace all of the brake fluid and bleed the entire system. This should be done every two years anyway.
What bothers me about this particular problem is that the mechanic you went to rooked you for an ABS sensor. Even if the sensor failed completely, you should still have functioning brakes. Any mechanic worth his certification would know this.
What I dislike is when these %@&^#%&@# guys play dumb when solving a problem: "gee...I just don't know what the problem is...maybe its the skidooddle fob in the thinga ma jig"...meanwhile their sizing up how much they can bill you in labour charges. I digress...sorry. After so many years of seeing this happen, it still 'ticks' me off.
Robert, I hope you can recover some or all of the money from that ABS sensor that was replaced.
Regards,
JohnMc
