Warped disks

np · Post by np » 27 Aug 2005, 22:47

Hi there every body[:)].1st post for a while as i`m still working away in Devon.Anyway,i think my front disks are warped again[:(!].Ok most of the time,but braking at motorway speeds etc,i can feel them start to vibrate.These are only a year old as i replaced them Aug last year,as the last set only lasted just under 2 yrs[V].Both sets were from the same suplier,both made by Bendix.I do drive fast sometimes,though i`m not heavy on the brakes,but do a fair bit of towing as well.
Can anyone recomend a good set of disks that might last a bit longer?Or can cope better with high speed stopping.As i think its the commute up & down the M5 to Devon thats done it.70-90 mph,then hard on the brakes as everyone comes to a stop,then off again ...........
Typical summer M5 traffic![}:)]
Many thanks.

Kowalski · Post by **Kowalski** » 28 Aug 2005, 00:14

Have you lubricated the caliper slides?
Brake discs always have some degree of run-out in them and the brake calipers have slides so that they will cope with a certain amount of warp. If the slides are sticking it can make a tiny bit of runout feel like the discs are badly warped and need changing when in fact they're within tolerance.

citronut · Post by **citronut** » 28 Aug 2005, 00:24

check slides are free as kowalski said,but also check hand brake cables for cracks where they run through guides on legs,as they are flexed every time you turn your steering,cracked cables can cause hand brake to stay on slitely
regards malcolm

Dave Burns · Post by **Dave Burns** » 28 Aug 2005, 14:57

Look at the discs, can you see any marks in the shape of the brake pads on them, if so thats your problem, basically they don't warp they wear at differing rates on the friction surface.
Dave

citronut · Post by **citronut** » 28 Aug 2005, 15:11

if they have been binding they most defenatly do warp,because they over heat
regards malcolm

Dave Burns · Post by **Dave Burns** » 28 Aug 2005, 20:00

Brake discs are designed to get hot, very very hot, they are stress releaved during manufacture, if they were going to warp because of heat build up they would do so the first time they got hot, not a year down the line.
Dave

citronut · Post by **citronut** » 28 Aug 2005, 21:54

yes but they get an aufull lot hotter when brakes are on all of the time through binnding
regards malcolm

Kowalski · Post by **Kowalski** » 28 Aug 2005, 22:03

<blockquote id="quote"><font size="1" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Dave Burns</i>

Brake discs are designed to get hot, very very hot, they are stress releaved during manufacture, if they were going to warp because of heat build up they would do so the first time they got hot, not a year down the line.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
A brake disc has a maximum temperature that it will tolerate, if you get them too hot they warp. Steel is elastic to a degree, so they can take a certain amount of heat distortion before they "stretch" and stay permanantly warped. A binding brake will make the disc get hotter than it would normally get, possibly just enough hotter so they distort enough to deform permanantly.
Higher performance brake discs have a separate hub, and the disc is floated on this, so it can expand at a different rate to hub and not cause a problem.
Google found this,
http://www.buybrakes.com/brembo/faq.html#q18

AndersDK · Post by **AndersDK** » 28 Aug 2005, 22:15

In my experience it is often greasy dirt that destroys your brake discs. These days with very high traffic intensity and thereby high frequency of road repairs - it is very common to get tarmac on the discs. This creates hot spots on the discs - which feels exactly like warped discs.
The smalliest leak from a CV bellow do the same - as do a brake hose leak - a front strut leak - greasy fingers when doing service - etc. etc .

pete_wood_uk · Post by **pete_wood_uk** » 30 Aug 2005, 13:39

Rightly or wrongly I was always told / taught to come off the brakes, if possible, when halted after a heavy stop, otherwise (I was told) the disk retains heat where the pads grip it and cools faster where it's exposed to the air. This differential cooling can perhaps lead to warping. I've no idea if this is true; when done in a Citroen (with handbrake on the front wheels) it's certainly in contravention of the UK highway code which states that you should apply a brake when stopped in traffic, but on the other hand I've been doing it for many years and have never (yet!) suffered from warped disks...
I simply offer this as flame-bait to my fellow members... [:)]
Cheers
Pete

oscarloco · Post by **oscarloco** » 30 Aug 2005, 21:30

Try using Brembo rotors. They are the best. I used them in a Honda I had that had the nasty habit of warping discs. Problem solved.

madasafish · Post by **madasafish** » 30 Aug 2005, 22:33

>np . Do you brake hard on motorways and then leave your brakes on?