Should new brake discs warp?

specialman

specialman

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Pat MacInnes
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I'm guessing no, not after three weeks, but just thought I'd ask those who might have more automotive knowledge than me....

Had new pads and discs fitted recently (also had the brake fluid done at service the week before) but within about 10 days they started feeling a bit lumpy when braking above 60mph. Now the steering wheel wobbles like a motherhumper above 50mph and when coming to a halt, i can feel an unevenness right down to stationary.

Car is a Volvo S60 D5 fitted with uprated 'R' brake kit (Brembo callipers), so big brakes trying to stop a big, heavy lump.

Thoughts people?
 
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I also believe if they are not torqued up correctly they can do.
 
specialman said:
I'm guessing no, not after three weeks, but just thought I'd ask those who might have more automotive knowledge than me.... Had new pads and discs fitted recently (also had the brake fluid done at service the week before) but within about 10 days they started feeling a bit lumpy when braking above 60mph. Now the steering wheel wobbles like a motherhumper above 50mph and when coming to a halt, i can feel an unevenness right down to stationary. Car is a Volvo S60 D5 fitted with uprated 'R' brake kit (Brembo callipers), so big brakes trying to stop a big, heavy lump. Thoughts people?
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Get the front wheels balance checked too. Wheel weight might have gone adrift.

You can warp new disks quite easily. Also sticking caliper can lead to wheel wobble and a general feeling of fighting with the brakes.
 
I have been told that if you heat the discs with heavy braking, and then sit with your foot on the brake, instead of using the handbrake, the discs could warp. Apparently caused by the pad preventing the disc from cooling evenly.
 
As others have already said, if the discs are not fitted correctly on their hubs due to debris between the hub flange and the disc, or if the wheels have been over torqued the disc can be physically distorted.

Overheating of the rotor surface due to heavy braking during the first use period of the disc can also cause a distortion, which is why the discs should be allowed to "bed in" for around 500 miles.


I'd not expect a wheel weight to cause such an issue as the "judder" is felt from speed down to stationary. Wheel balance typically manifests itself within a speed range dependant on the resonant frequency of the out of balanced wheel.
 
BTW, I've done about 2,500 miles in the last three weeks... Lots of varied driving on m'ways, A-roads and back lanes.... Would have expected them to be bedded in by this point, or am I missing something? :)
 
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It's more than possible a disc could have just been made wrong, a typical limit for brake disc run out would be 0.05mm.

Take it back to the garage and tell them that you know have a judder since the brake work.
 
digitalfailure said:
It's more than possible a disc could have just been made wrong, a typical limit for brake disc run out would be 0.05mm.

Take it back to the garage and tell them that you know have a judder since the brake work.
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I have a slight runout on my front o/s disc at the moment, and it is driving me mad. Everyday running is good, with no vibration, but gentle braking causes a little vibration, and moderate to hard braking downhill causes real juddering through the steering wheel.
I jacked the car up last week and spun the wheel, and it was smooth with no rumbling from the bearings, no movement. So, I took the wheel off and turned the disc by hand, and it is binding ever so slightly on the pads in one place.
I think the discs and pads are going to get changed this weekend:(
Weather permitting.
 
Hot spot maybe, something got too hot and scorched a warp feel, it will just get worse...check runout across he whole surface with a dial gauge.
Also check your steering track rod ends as well, a lose worn bush could also cause wobble when braking, especially in conjunction with slightly out wheel alinement.
 
Forbiddenbiker said:
Hot spot maybe, something got too hot and scorched a warp feel, it will just get worse...check runout across he whole surface with a dial gauge.
Also check your steering track rod ends as well, a lose worn bush could also cause wobble when braking, especially in conjunction with slightly out wheel alinement.
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..and worn/tired shock absorbers
 
specialman said:
BTW, I've done about 2,500 miles in the last three weeks... Lots of varied driving on m'ways, A-roads and back lanes.... Would have expected them to be bedded in by this point, or am I missing something? :)
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Depends on how you drove/braked those miles, heavy braking etc particularly in the first couple hundred miles can easily cause your issue. Not just about the distance unfortunately.
 
Sorry for my English, but it is possible, if You brake from 60 mph to 20 or less and drive in the puddle of water. Otherwise it is garage mistake. Cheap or expensive but they should do the job.
 
Using a jet wash to clean your wheels whilst brakes are still hot can cause them to warp.
Or cheap discs from China have been fitted. No telling what crap was chucked in the melting pot.
 
nilagin said:
Using a jet wash to clean your wheels whilst brakes are still hot can cause them to warp.
Or cheap discs from China have been fitted. No telling what crap was chucked in the melting pot.
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My car and jet washes have a non-exist ant relationship ;)
 
B1ts said:
Depends on how you drove/braked those miles, heavy braking etc particularly in the first couple hundred miles can easily cause your issue. Not just about the distance unfortunately.
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A bit of hard braking, to be expected during the rush hour on faster roads.

Car is going in on Monday
 
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specialman said:
Now the steering wheel wobbles like a motherhumper above 50mph and when coming to a halt, i can feel an unevenness right down to stationary.
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It's not totally clear if you have one of 2 issues.

Does the steering wheel wobble above 50mph always or only under braking ?

Is the vibration only through the steering wheel or also the brake pedal and the chassis in general i.e. a wider vehicle vibration ?

Its important to explain this accurately when you take it back to the garage.

Causes: Faulty discs, cheap pads, hub run out, suspension bushes, wheels or tyres out of true, sticking or seized callipers, wheel bearings.
 
Defiance said:
It's not totally clear if you have one of 2 issues.

Does the steering wheel wobble above 50mph always or only under braking ?

Is the vibration only through the steering wheel or also the brake pedal and the chassis in general i.e. a wider vehicle vibration ?

Its important to explain this accurately when you take it back to the garage.

Causes: Faulty discs, cheap pads, hub run out, suspension bushes, wheels or tyres out of true, sticking or seized callipers, wheel bearings.
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Vibration wobble is only under braking. No feedback through the pedal, just the steering wheel. Above 50 the wobble is serious, lessening as the speed drops... Braking from below 50 it's not as bad. It's a recurrence of the problem I had which prompted the disc to be changed in the first place.

Won't be wheel bearings - replaced them 3 months ago. Suspension has been given the all-clear.

I'm pretty much now convinced that the discs have warped... Exactly the same feeling as the old discs.
 
It's entirely possible that the new discs are faulty and have warped. However, if it is a recurrence of the same concern, it would suggest that the discs are the symptom and not the root cause i.e. they have warped as the result of another underlying issues. It's very unusual in today's cars to have brake judder twice in quick succession without there being another issue.

Would recommend getting hub run out checked and also check that the wheel bearings have been seated correctly. Also have the callipers checked for sticking or partial seizure as this can cause overheating of the discs.
 
Defiance said:
It's entirely possible that the new discs are faulty and have warped. However, if it is a recurrence of the same concern, it would suggest that the discs are the symptom and not the root cause i.e. they have warped as the result of another underlying issues. It's very unusual in today's cars to have brake judder twice in quick succession without there being another issue.

Would recommend getting hub run out checked and also check that the wheel bearings have been seated correctly. Also have the callipers checked for sticking or partial seizure as this can cause overheating of the discs.
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Can I ask - what's hub run out?

RE: old discs - they were the originals that were fitted in 2008. The car had only done about 15,000 miles on them by the time I purchased it in 2011, but I've put 60,000 on them in the last two years so I kind of just assumed they'd reached the end of their life and that warping was their way of telling me that they needed replacing. It didn't occur to me that is could possibly be a sticking caliper....

...I like looking at cars but as you can tell, I know sweet FA about the mechanics of them!! :)
 
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I'd go down the sticky piston in caliper ,my friend had the same problem ,he went through 3 pairs of discs until he found the problem with the piston on the caliper wasn't returning properly .
 
specialman said:
Can I ask - what's hub run out?
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Hub run out is when the wheel hub warps or distorts very slightly causing the wheel to no longer run in a true and level circle. We are only talking about fractions of a millimetre so nothing dramatic safety wise.
 
It all sounds like warped disks until you say there is no vibration feedback through the pedal, only steering wheel. If the disks are warped I'd expect very clear feedback through both. If it's steering wheel only, I'd be more suspicious of worn bushes, be it trailing arm (wishbone) bushes or something else in the chassis that is worn and allowing movement. That would give significant wobble/vibration through the steering wheel, and potentially none through the pedal.

However, please don't take offence to this, but I've had non-car interested friends describe problems with their cas before and when I've driven their car or listened to the problem, I've interpreted very differently to them.
 
Shine On said:
It all sounds like warped disks until you say there is no vibration feedback through the pedal, only steering wheel. If the disks are warped I'd expect very clear feedback through both. If it's steering wheel only, I'd be more suspicious of worn bushes, be it trailing arm (wishbone) bushes or something else in the chassis that is worn and allowing movement. That would give significant wobble/vibration through the steering wheel, and potentially none through the pedal.
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I agree...It doesn't sound like the discs to me either, Its usual to feel a warped disc pulsating at the brake pedal....therefore logically, its something else lose or worn out that's the cause.
 
Maybe the new wheel bearings need to be adjusted? It's possible that they weren't completely seated and have come slightly loose.
 
The above illustrate why it is really important to fully define the concern when you give the car back to the garage e.g.

When is the vibration felt - road speeds, speed ranges, certain road surfaces, wet or dry roads, in a straight line or cornering, car is hot or cold etc...

Where is the vibration felt - if the most noticeable vibration is through the steering wheel, it is easy not to identify the level of vibration also present through the brake pedal.

What is the repair history of the vehicle - previous brake, wheel bearing, suspension repairs etc. - and when were these done.

Is the concern recurrent and if so, how soon did it reappear.

If you give the garage all of this information they stand the best chance of diagnosing the concern - while many posts provide suggested causes, diagnosis by internet is not very reliable.
 
Forbiddenbiker said:
I agree...It doesn't sound like the discs to me either, Its usual to feel a warped disc pulsating at the brake pedal....therefore logically, its something else lose or worn out that's the cause.
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To be totally honest, I'm too busy getting annoyed at the steering wheel and turning the air blue to have really noticed whether there's anything noticeable happening through the pedals. :)

EDIT: Yes, there is feedback through the brake pedal. Didn't really notice it before because of the steering wheel wobble pulsating through my skeleton.

Defiance - agreed about problem solving via Internet forum, but its the same scant info the garage will be getting... I'll be expecting them to be the automotive version of Sherlock Holmes and deduce the ailment from a single sniff of the stain on the drivers seat :lol:
 
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Feedback through the pedal indicates the discs are warped.
The issue is to determine what is causing them to warp. Have the garage check the run out of the discs first. This will confirm the warp. Then get them to check the run out of the disc mounting face on the wheel hubs. It is possible for the hubs to distort especially when bearings have been changed.
If the hubs are warped it is possible to get the discs ground true whilst fitted to the car - check out your local Porsche dealer - they tend to specialise in this type of work.
If the hubs are OK then the most likely problem is a sticking calliper.
One other thing to try before going back to the garage is a few emergency type stops - on a quiet road obviously. Some time gentle braking can cause a build up of deposits on the discs and a few emergency stops will clear them. After the emergency stops, be sure to drive around for a little while to ensure the discs have cooled to normal temperatures.
HTH
 
Took it in yesterday. Needed the rear disks and pads changing, as they were knackered. The symptoms are still the same so at least I know it's something at the front of the car (plus braking doesn't see the pedal being pushed through the floor).

Uprated discs are on order from Volvo and because it's under warranty, pads and discs are being changed for free. The technician said that the current discs don't seem warped but he feels changing the discs at least removes that from the equation and then hub run-out can be explored as the main issue. Suspension is all good.
 
specialman said:
The technician said that the current discs don't seem warped but he feels changing the discs at least removes that from the equation and then hub run-out can be explored as the main issue. Suspension is all good.
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Although that's a good result for you (new discs etc) doesn't that sum up the trial and error approach adopted by lots of garages these days? What's wrong with actual measuring and testing things to see if they are out of tolerance rather than just swapping them out :shrug:
 
Sometimes with new high performance brake pads and discs, you can get material transfer (resins etc) from the pads to the discs if you get them hot and then sit with your foot on the pedal when you come to a stop (e.g. traffic lights on a downhill slope). This can cause hot spots and a juddering effect similar to the discs being warped when you brake from higher speeds, and tends to get worse over time. I've had this in the past with a set of uprated AP Racing brakes.

It can be cured with a light skim of the discs, or in my case I gave the brakes hell over about 15 laps at Cadwell park, they came good, and then let them cool down gently by driving around the paddock for about 15 to 20 minutes. Never had the issue again.
 
Spuff said:
Although that's a good result for you (new discs etc) doesn't that sum up the trial and error approach adopted by lots of garages these days? What's wrong with actual measuring and testing things to see if they are out of tolerance rather than just swapping them out :shrug:
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Quite possibly. He did admit that the discs they fitted the other week were standard, non-OEM discs from a reputable 3rd party manufacturer. By fitting the ones from Volvo at least they're identical to the ones they took off. Like you say though, there could be a manufacturing error (or suchlike) that will never be identified.
 
specialman said:
Quite possibly. He did admit that the discs they fitted the other week were standard, non-OEM discs from a reputable 3rd party manufacturer. By fitting the ones from Volvo at least they're identical to the ones they took off. Like you say though, there could be a manufacturing error (or suchlike) that will never be identified.
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at least they sorted out for you sounds like a good garage:)
 
specialman said:
Quite possibly. He did admit that the discs they fitted the other week were standard, non-OEM discs from a reputable 3rd party manufacturer. By fitting the ones from Volvo at least they're identical to the ones they took off. Like you say though, there could be a manufacturing error (or suchlike) that will never be identified.
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Just out of interest, did they charge you for Volvo discs?



Heather
 
LCPete said:
at least they sorted out for you sounds like a good garage:)
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No they don't, they sound like absolute amateurs!

They are guessing not testing and measuring, they are re-placing out of ignorance of the actual fault and charging for it all....Volvo are paying for nowt I mean.

What part of that is good?

Pat, find a better mechanic I say. ;)
 
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Probably cheaper for them to replace the disks (even with genuine parts) than diagnose the fault (which could be the disks).
 
The discs need skimming and all will be sorted
 
Only if the disks are the true cause of the problem...
 
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