V50 Brakes : Do brake discs really warp?...I'm not so sure they do...

[Volvo6]

warped disks are not a myth.

Fair enough, those discs in the video do look pretty bent out of shape. Nonetheless though I'd be very surprised if a genuine Volvo disc on my V50 had actually warped...it just seems like such a huge lump of iron to change shape under the sorts of temperatures you'd get on a road car's brakes.

Never said it was, mate. It just doesn't happen as often as garages would like you to believe.

Yes I very much agree, whether the cause of the vibration is indeed the disc changing shape or pad deposits (as I suspect it is most of the time) garages (at least the ones I've been to) don't seem to understand what usually causes it. Having done some reading about it the main causes seem to be incorrect bedding in of the pads and as mentioned previously holding the discs in one place on the footbrake when the disc is hot. Neither of which the garage explained to me.

[david philips]

i only had one set of discs warp on me and i know when and where it happened

a few years ago i was driving about 70 or so, on a duel carageway in my peugeot when some idiot pulled out i hit the brakes really hard and managed to miss the twit.

every time after this when i braked i had a shutter , went back to normal after i fitted new discs and to look at them they looked ok.

[jasonb]

Could this also happen if you have after-market wheels and the bore on the wheel is slightly larger than the diameter of the contact surface on the disc?
I'm referring to vibration under braking, not discs being warped.

[ian7675]

I doubt very much the discs fitted by Volvo are actually manufactured by Volvo. The discs are more likely to be the same as you can get from any car parts suppliers just a lot more expensive and just as likely to warp as any other.

One example is when I had a BMW Coupe, the discs and pads fitted by the dealer cost around £5-600 and were made by a company called Pagid. The same pads and discs from ECP cost around £150 and were exactly the same so don't expect the quality to be any better because they're fitted by Volvo.

[Supraweld]

I managed to warp a pair of front discs in one of my old modified 940turbos. Took my junction off the M1 at 130ish after racing a berk in a subaru. (He lost). Lifted myself out of the seat trying to stop for the roundabout. Massive brake fade, entered roundabout at 50ish. Great fun!!! Next time I pressed brake pedal juddering through the car. Brakes still smoking when I got home. (only a mile from junction). When cooled I took front discs off and put them on my lathe. A noticable sway on the discs when spun slowly. I only use grooved discs now to help with cooling at speed.

Juddering on new unused discs is usually poor fitting. The hub face has to be spotless. A tiny amount of dirt between the disc and mounting face can cause disc run out/judder. Unless you buy discs from eur*car*arts, they are just S**T.

[ian7675]

Originally Posted by Supraweld

Unless you buy discs from eur*car*arts, they are just S**T.

As in my post above, ECP supplied me parts that are the same as what the dealer fits so I doubt you could call them anything bad really.

[Volvo6]

I doubt very much the discs fitted by Volvo are actually manufactured by Volvo. The discs are more likely to be the same as you can get from any car parts suppliers just a lot more expensive and just as likely to warp as any other.

Possibly, I'm fairly sure that Volvo brakes are made in Sweden though so presumably Volvo have oversight of the quality.

[Supraweld]

Originally Posted by ian7675

As in my post above, ECP supplied me parts that are the same as what the dealer fits so I doubt you could call them anything bad really.

Im commenting on personal experience only mate. There are different discs available from them, with different prices. You get what you pay for and all that. A disc sold for 95 quid is superior to a disc sold for 17.50. You can tell a cheap disc instantly by the machining. A quality machined part does not have machine 'cross hatch' marks all over it.

[thealchemyst]

Firstly brake discs do warp very common on older cars and cars with solid discs also happens to vented discs but modern cars are usually fitted with large brakes by comparison
Brake discs are cast iron and reach very high temperatures during braking 3-400f in normal use more if braking from very high speeds and heavily some brakes are even designed to work upto 900f so the temperatures involved are much higher than you seem to think.
Brakes quite often glow red orange or yellow hot under use and as anyone who's ever done any metal work or seen a blacksmith or farrier work will know it's quite easy to bend metal at those temps.
Plus it only needs a very slight distortion of the disc to create quite a large judder.
In my personal experience and I've owned over 20 cars and worked on all of them myself I have never seen or indeed heard of any pad material sticking to the discs, not even halfords own brand cardboard pads.
I have litteraly set pads on fire before so am pretty harsh on my brakes never had material stick to discs and if it did the very action of the discs operation would scrape it of very quickly

Your habit of holding hot brakes on will of been the major factor in disc warpage
It's also bad because it prevents the pad caliper and fluid from cooling down quickly so will be hotter come the next application of the brakes exacerbating the problem

[Volvo6]

Brakes quite often glow red orange or yellow hot under use and as anyone who's ever done any metal work or seen a blacksmith or farrier work will know it's quite easy to bend metal at those temps.

I think it highly unlikely though that the brakes on a normal road car like the V50 with normal or even spirited driving would ever change colour with temperature. I find it difficult to believe that the system is powerful enough to generate that much friction.

I've seen it on sports cars on a track but only after a real pounding so I'd have thought for the V50 it actually get the brakes to the temperature that one might use as a farrier for example to bend a horse shoe would be so far outside of normal driving that it's just not likely. I've taken the car around Knockhill for example which was pretty hard on the brakes and as far as I remember there was no change in colour even after about 20 laps or so.

The imprint of the pad material on the discs was clear to see the last time it happens, I wish I'd taken a picture now before throwing them away...

One of the articles I read was this which seemed to confirm this belief. It seems pretty clear from the posts on here that warping is not a complete myth but having thought about it I just think that pad material is a much more likely explanation for a car like the V50.

Either way the cure, ie not using the footbrake when stationary, is the same.