Guinness
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| posted on 22/3/06 at 04:44 PM |
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O/T Warped my discs
As title really, I have warped the discs on my tin top. They were cheap pattern parts put on by the dealer when I bought the car. Now 2 months later
and 2,000 miles they've gone.
Any suggestions for an upgrade to performance discs? They need to stop a 155mph German V8 with a two tonne weight problem, towing an Indy!
Should I change the pads as well? They don't have any wear on them, but thinking they might be contributing to the heat / warp.
Any advice gratefully recieved.
Mike
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chockymonster
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| posted on 22/3/06 at 04:50 PM |
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You may find it's pad build up and not warping. A couple of hard 60-0 stops usually sort it, get it so the brakes are smoking 
I've found this happens with cheap pads, EBCs were famous for it on the FTO, especially as they were autos and owners would hold them on the
brakes at the traffic lights.
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DaveFJ
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| posted on 22/3/06 at 05:02 PM |
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you should always replace the pads when you replace the disks.......
Dave
"In Support of Help the Heroes" - Always
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UncleFista
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| posted on 22/3/06 at 05:25 PM |
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Whatever disks you get, try holding the car on the handbrake when the brakes are hot and (dunno whether its specific to my mondeo or applies to all
cars) tighten your wheels up to the specified torque and no more.
I've found I've stopped going through disks every pad change, after sticking to them 2 rules 
Sorry if you find this condescending, it's not meant to be
Tony Bond / UncleFista
Love is like a snowmobile, speeding across the frozen tundra.
Which suddenly flips, pinning you underneath.
At night the ice-weasels come...
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DaveFJ
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| posted on 22/3/06 at 09:03 PM |
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quote:
Originally posted by UncleFista
Whatever disks you get, try holding the car on the handbrake when the brakes are hot and (dunno whether its specific to my mondeo or applies to all
cars) tighten your wheels up to the specified torque and no more.
I've found I've stopped going through disks every pad change, after sticking to them 2 rules
Sorry if you find this condescending, it's not meant to be
errr - surely you mean NOT holding the car on the handbrake when the brakes are hot ???
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Lawnmower
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| posted on 23/3/06 at 09:01 PM |
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a lot of people dont use the handbrake at traffic lights, they just use the footbrake.
If a car is driven hard, say in rush hourm traffic lght to traffic light sprints, then the wheel brakes will get used often and get very hot. Holdibng
the car still on the foot brake instead of te transmission brake, stops the heat esaping, and the brakes discs can buckle slightly. dont do this.
as asutomatics only have limited engine breaking capacity, then the foot brakes gets used even more, and is even hotter!
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britishtrident
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| posted on 24/3/06 at 08:19 AM |
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I think it was I who originated this tip some years back in a usenet news group -- the reason is the brake pad is considerably hotter than the brake
disk and is made of an insulating material, Even when stationary brake discs cool pretty quickly but if you hold the car on the foot brake the brake
pad is clamped hard to the disc and heat transfer occurs between the the pad and disc the area of disc under the pad dosen't cool down in fact
initially it may get a good bit hotter. The result is a hot spot forms on the disc resulting in a warped disc.
How to avoid warping --- don't hold the car on the foot brake and don't park up the car when the brakes are stonking hot --give them a
couple of miles to cool down.
At track and speed events don't let the car sit with stonking hot brakes -- when first parked up in the paddock after a minute or so roll it
forward a couple of feet -- repeat a couple of times to try and even out the disc cooling rate.
[Edited on 24/3/06 by britishtrident]
[Edited on 24/3/06 by britishtrident]
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UncleFista
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| posted on 24/3/06 at 11:49 AM |
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quote:
Originally posted by DaveFJ
errr - surely you mean NOT holding the car on the handbrake when the brakes are hot ???
No
If you hold the car on the footbrake when the disks are hot, there will be a hotspot under the pads (due to the pads insulating a part of the disk) if
you hold it on the handbrake it just holds using the rears, which don't get anywhere near as hot. Which allows the fronts to cool evenly.
Tony Bond / UncleFista
Love is like a snowmobile, speeding across the frozen tundra.
Which suddenly flips, pinning you underneath.
At night the ice-weasels come...
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DaveFJ
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| posted on 24/3/06 at 12:15 PM |
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fair point - but I have had rears warp in this way. My old Galant was a nightmare for disks warping 
I make of point of never holding the car on the any type of brakes if i can help it (my drive is level!) If I have been 'working the brakes
hard...'
Dave
"In Support of Help the Heroes" - Always
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tks
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| posted on 11/8/06 at 08:39 AM |
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Ok
its logic that the best solution is to simply drive them cold... but i can imagine that it isn´t always possible...
how do truck brakes cope with this?? and the one with water injection??
TKs
[Edited on 11/8/06 by tks]
The above comments are always meant to be from the above persons perspective.
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owelly
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| posted on 11/8/06 at 01:49 PM |
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My T5 Volvo used to eat discs. A set would last a week or so before becoming 'warped' and made the car shake so bad, the front used to pop
off the stereo.
I swapped a set and set a warped disc in the lathe to skim but it was as true as an incredibly true thing. So was the other one.
When the new ones 'warped', I just fitted new genuine Volvo pads and the problem was solved!
http://www.ppcmag.co.uk
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