Brake advice.. potentially warped discs?
11 April 2011, 12:53 PM
#1
Brake advice.. potentially warped discs?
Hey all,
Car is 2003 STi with Brembos. With the weather being so nice over the weekend I decided to go out and really drive the car. And now, it would seem, braking hard at about 80mph I get bad steering judder which I can only presume is discs warped?
I'm not entirely sure if it's one, or both of the front discs, haven't had chance to fully investigate and won't until Wednesday evening. None of the discs look cracked or damaged at all, infact they look quite healthy.
So what are my options? I drive the car only occasionally, and like to push it when I do drive it. Plus the occasional track day too.
I have considered 2 piece discs, but can't seem to find the price of replacement discs for afterwards? Just price with bell and disc.
Pads are less than 1000 miles old so I presume they would be ok on new discs? Also is disc skimming advised?
Thanks
Car is 2003 STi with Brembos. With the weather being so nice over the weekend I decided to go out and really drive the car. And now, it would seem, braking hard at about 80mph I get bad steering judder which I can only presume is discs warped?
I'm not entirely sure if it's one, or both of the front discs, haven't had chance to fully investigate and won't until Wednesday evening. None of the discs look cracked or damaged at all, infact they look quite healthy.
So what are my options? I drive the car only occasionally, and like to push it when I do drive it. Plus the occasional track day too.
I have considered 2 piece discs, but can't seem to find the price of replacement discs for afterwards? Just price with bell and disc.
Pads are less than 1000 miles old so I presume they would be ok on new discs? Also is disc skimming advised?
Thanks
Last edited by ScoobyDoo69; 11 April 2011 at 12:54 PM.
11 April 2011, 04:40 PM
#2
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What pads are you using? Most "warped" discs just have a build up of pad material on them. Use them hard repeatedly over a long time to really heat them and clean them. Should clear things...
11 April 2011, 10:12 PM
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get some discs from ian godney on here, he is doing a group but thing for his disks and i think his fronts work out to £120 or something similar. i wouldn't buy pads if yours are quite new. best thing about ian's disks are that they are guaranteed against warping even if you do trackdays, so if the same happens to his disk's then send them back and he will send you a replacement. my mate did it.
i'll find you a link
i'll find you a link
Last edited by Billet; 11 April 2011 at 10:15 PM.
12 April 2011, 11:05 AM
#7
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13 April 2011, 11:45 AM
#8
If in the past you have driven the car hard and then came to a complete halt (junction/traffic lights etc), or pitting after a track day run, then you can warp the disks or create uneven pad deposits.
As holding the pad on one half of the disk with the other half open to the air will causes uneven surface hardeening of the metal of the disk. This will affect pretty much any disk unless its been throughly heat cycled so it gains surface hardening evenly. The other issues of uneven pad deposits which is also caused by doing the above can sometimes build up and will not always clear away with use, requiring further action.
Same with washing the car and leaving it parked up allowing half the disk to rust for a week. Use easily cleans them up , but if the car is left standing too long then use does not always clean up the surfaces properly - even if they look clean, it can affect the way pad material is deposited on the disk. Weekender cars suffer this - my old impreza included, as my mate just lays it up for weeks on end outside.
This may have happened in the past from previous runs and track days etc, but only came about now as things have deteriorated to the point that its vibration frequency harmonises and resonates with the car's chassis and supension. Stick a dial gauge on it the disk and you'll see straight away - its usually combined with a slight dulling/discoluration of the surface due to the change in the carbon content of the metal or uneven pad deposits, or imprint marks of the brake pad.
You can try to skim the disks (as long as they are thick enough), which will cure it...for now at least. The problem is how deep any uneven surface hardening is, if minor and its just a pad deposit issues then it maybe OK. But in in roughly half of cases where I've skimmed disks it comes back as soon as the disk starts to wears again (partly due to the driver not bedding in what is essentually new disks again and allowing it too cool properly before stopping...i.e not keep the car creeping when waiting at traffic lights after a hard run ).
Pads can be re-used as long as they are in good condition: that meaning the pad material being completely flat and sqaure and not comming away from the back plate, if scored or unevenly worn then they can be sanded flat again...this will also help deglaze them which can happen with some pad materials that are used often at slow speeds and rarely get up to temperature.
As holding the pad on one half of the disk with the other half open to the air will causes uneven surface hardeening of the metal of the disk. This will affect pretty much any disk unless its been throughly heat cycled so it gains surface hardening evenly. The other issues of uneven pad deposits which is also caused by doing the above can sometimes build up and will not always clear away with use, requiring further action.
Same with washing the car and leaving it parked up allowing half the disk to rust for a week. Use easily cleans them up , but if the car is left standing too long then use does not always clean up the surfaces properly - even if they look clean, it can affect the way pad material is deposited on the disk. Weekender cars suffer this - my old impreza included, as my mate just lays it up for weeks on end outside.
This may have happened in the past from previous runs and track days etc, but only came about now as things have deteriorated to the point that its vibration frequency harmonises and resonates with the car's chassis and supension. Stick a dial gauge on it the disk and you'll see straight away - its usually combined with a slight dulling/discoluration of the surface due to the change in the carbon content of the metal or uneven pad deposits, or imprint marks of the brake pad.
You can try to skim the disks (as long as they are thick enough), which will cure it...for now at least. The problem is how deep any uneven surface hardening is, if minor and its just a pad deposit issues then it maybe OK. But in in roughly half of cases where I've skimmed disks it comes back as soon as the disk starts to wears again (partly due to the driver not bedding in what is essentually new disks again and allowing it too cool properly before stopping...i.e not keep the car creeping when waiting at traffic lights after a hard run ).
Pads can be re-used as long as they are in good condition: that meaning the pad material being completely flat and sqaure and not comming away from the back plate, if scored or unevenly worn then they can be sanded flat again...this will also help deglaze them which can happen with some pad materials that are used often at slow speeds and rarely get up to temperature.
Last edited by ALi-B; 13 April 2011 at 11:47 AM.
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