RootsBooster Posted June 29, 2011 Share Posted June 29, 2011 As for the Op, ignore myself and Obelix, we're debating about brakes, but, whoever is right, replacing the discs/pads would cure all the problems we are bickering about! Link to comment Share on other sites More sharing options...
Obelix Posted June 29, 2011 Share Posted June 29, 2011 Jeez he's at it again! It won't necessarily solve the problems. The hub could be bent. The bearings could be worn. It could be a problem with the way it's driven. The pads may not have bedded right. There's many things that will recur and you will have just swapped out £100 for nothing. Link to comment Share on other sites More sharing options...
RootsBooster Posted June 29, 2011 Share Posted June 29, 2011 The trouble is you are advising someone on braking systems when you clearly have flawed knowledge of how they work So are you I've worked on these systems. I build systems like this - it's what engineers do. Please, don;t assume that some folklore knowledge that gets handed down about warped discs is going to be true just because everyone says it is. Please don't assume that I assume folklore is true, if you are familiar with my (serious) posts you will know I don't Please don't assume you are the only engineer who works with braking systems. To the OP - take it to a reputable garage and let them have a look at it. I agree Link to comment Share on other sites More sharing options...
RootsBooster Posted June 29, 2011 Share Posted June 29, 2011 Jeez he's at it again! It won't necessarily solve the problems. The hub could be bent. The bearings could be worn. It could be a problem with the way it's driven. The pads may not have bedded right. There's many things that will recur and you will have just swapped out £100 for nothing. My bad this time, I meant the issues/problems we were bickering about with the braking system. Link to comment Share on other sites More sharing options...
toyota Posted June 30, 2011 Author Share Posted June 30, 2011 guys guys please calm down. I'm sorry, i didn't know i'd get a raging debate going. @ Rootsbooster - The nearside front tyre is worn mainly from the outer edge and offside tyre is very slightly worn all over (sorry hard to describe), although it doesn't pull to any side. I'm going to swap the wheels front to rear and vice versa to see if there is a difference. Thanks again Link to comment Share on other sites More sharing options...
RootsBooster Posted June 30, 2011 Share Posted June 30, 2011 guys guys please calm down. I'm sorry, i didn't know i'd get a raging debate going. @ Rootsbooster - The nearside front tyre is worn mainly from the outer edge and offside tyre is very slightly worn all over (sorry hard to describe), although it doesn't pull to any side. I'm going to swap the wheels front to rear and vice versa to see if there is a difference. Thanks again Okay from the wear you are describing it sounds as though the tracking is or has been out. I'd get that checked first. I doubt this is the cause of your brake pulsating though, tracking shouldn't affect that except in extreme cases. It certainly won't help matters though. Jeez he's at it again! It won't necessarily solve the problems. The hub could be bent. The bearings could be worn. It could be a problem with the way it's driven. The pads may not have bedded right. There's many things that will recur and you will have just swapped out £100 for nothing. I don't want to kick off the debate again, but now it's daytime and I'm wide awake I just re-read this. If the hub was bent or the bearing was causing the wobble, you'd most likely feel it through the steering WITHOUT pressing the brakes as described in the OP. Also I don't know any way of driving that would cause brake pulsation. When I pointed out that your link was a marketing site for a motorsports brand I meant that the info on it might be more applicable in motorsports than everyday vehicles, ie, material deposit on sports discs with grooved/vented surfaces may be a more common cause, as the grooves shave off the surface the pads as they rotate. However, the site does state that disc warping is a myth, which I believe to be totally false. Link to comment Share on other sites More sharing options...
destroyer Posted June 30, 2011 Share Posted June 30, 2011 guys guys please calm down. I'm sorry, i didn't know i'd get a raging debate going. @ Rootsbooster - The nearside front tyre is worn mainly from the outer edge and offside tyre is very slightly worn all over (sorry hard to describe), although it doesn't pull to any side. I'm going to swap the wheels front to rear and vice versa to see if there is a difference. Thanks again You need to stop taking advise on some of these idiots.Only one person on this thread i would take advise from.If the brake pedal is pulsing then its 99% the disk.As you press the pedal because the disk is not true it pushers back and it is fault through the pedal. If you want a good machanic that knows what he,s talking about send me a PM ill pass you his user name on. Link to comment Share on other sites More sharing options...
convert Posted June 30, 2011 Share Posted June 30, 2011 You need to stop taking advise on some of these idiots.Only one person on this thread i would take advise from.If the brake pedal is pulsing then its 99% the disk.As you press the pedal because the disk is not true it pushers back and it is fault through the pedal. If you want a good machanic that knows what he,s talking about send me a PM ill pass you his user name on. Agreed, since the disc is not true, it pushes the pads back on one side, and then the other; this is called pad 'knock off' and causes the brake fluid to be forced back out of the piston (s) through the hydraulic system and back to the brake pedal. You feel this as the pedal pushing back slightly. However as the OP has said switching tyres has lessened the problem I think there might also be an issue with the tracking, which has caused uneven tyre wear. My course of action would be to have discs and pads replaced (never put old pads on new discs), making sure that whoever repalces them cleans the new discs with brake cleaner to remove the protective film used whilst they are in storage. Then I'd have new tyres fitted (always fit as pairs, never just change one of an axle set), making sure the wheels are balanced once the tyres have been fitted. Finally get the tracking checked / adjusted, to avoid wearing out the new tyres on one edge. Check the tyres on a weekly basis for any excess wear, pressure and sidewall damage. Then I Link to comment Share on other sites More sharing options...
Obelix Posted June 30, 2011 Share Posted June 30, 2011 Agreed, since the disc is not true, it pushes the pads back on one side, and then the other; this is called pad 'knock off' and causes the brake fluid to be forced back out of the piston (s) through the hydraulic system and back to the brake pedal. You feel this as the pedal pushing back slightly. However as the OP has said switching tyres has lessened the problem I think there might also be an issue with the tracking, which has caused uneven tyre wear. My course of action would be to have discs and pads replaced (never put old pads on new discs), making sure that whoever repalces them cleans the new discs with brake cleaner to remove the protective film used whilst they are in storage. Then I'd have new tyres fitted (always fit as pairs, never just change one of an axle set), making sure the wheels are balanced once the tyres have been fitted. Finally get the tracking checked / adjusted, to avoid wearing out the new tyres on one edge. Check the tyres on a weekly basis for any excess wear, pressure and sidewall damage. Then I I guess people have never heard of floating calipers then. Or dual or multi piston ones which have a much larger internal gallery than a delivery line. If you had a warped disc, as one side pushes into the caliper the other side pulls away. End result there is no net change in fluid pressure. If you have thickness variations you do have a variation in pad distance and hence a fluid change each rev. That causes pulsation in the pedal. Link to comment Share on other sites More sharing options...
toyota Posted June 30, 2011 Author Share Posted June 30, 2011 ok guys, thank you for all your advice. After a long day, i think we've solved the problem. It wasn't straight forward though. I decided to swap front to rear and vice versa. Although i did the driver's side, i could not swap the passenger rear alloy wheel as the lock-nut is damaged. I instead took it to a local tyre place and got the two worn out tyres changed and balanced. The lock-nut on the 3rd wheel would not come off and we had to leave it on. It doesn't look like the tracking needs to be done as the car is as straight as possible with no pulling, but to be sure, i'm gonna drive it on the motorway to see if there is any pull or juddering. The only issue is how to get the lock nut off. Once again thanks so much. Link to comment Share on other sites More sharing options...
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