Brake discs skimmed below minimum thickness!!
Discussion
BritishRacinGrin said:
MOT will be an effectiveness inspection and a visual inspection, both of which the OP's brakes are likely to pass.
And how does that work then, it's a pretty stupid comment to make. That degree of under sizing will make no difference on the mot test, and when was the last time you saw a disk check with a Mic or vernier.It probably won't happen in your case, but I once ordered replacement discs for my van and they sent solid units instead of vented. The old ones were shot, so I fitted the solid ones with the intention of replacing them with vented when I had the chance.
I never did get round to it and as the pads wore down, they became thin enough to slip out of the carriers and jam themselves between the calliper and the disc!
I've also had a disc on a works van shatter because it was so thin!
Don't risk it!
I never did get round to it and as the pads wore down, they became thin enough to slip out of the carriers and jam themselves between the calliper and the disc!
I've also had a disc on a works van shatter because it was so thin!
Don't risk it!
Warmfuzzies said:
BritishRacinGrin said:
MOT will be an effectiveness inspection and a visual inspection, both of which the OP's brakes are likely to pass.
And how does that work then, it's a pretty stupid comment to make. That degree of under sizing will make no difference on the mot test, and when was the last time you saw a disk check with a Mic or vernier.I presume you meant to quote WelshBeef?
Even if you did, unnecessarily rude.
BritishRacinGrin said:
hidetheelephants said:
disc brakes need some run out to work properly.
I know the theory is going to be pad knock-backb but does anybody care to confirm or deny that a degree of run-out is desirable? I've certainly never heard of it. BritishRacinGrin said:
I know the theory is going to be pad knock-backb but does anybody care to confirm or deny that a degree of run-out is desirable? I've certainly never heard of it.
I must have been writing that on autopilot; I don't know about making them work better but the amount of runout on the average disc is going to make bugger all difference, even when added to the amount of endfloat the wheelbearings will have. Leptons said:
It's perfectly safe to re-face discs. The problem here is they've skimmed too much off, probably on discs with not enough material left anyway. I don't really see how they can suggest it's going to make them last longer though, that's b
ks.
Exactly. As long as the discs are over 1mm minimum thickness it's fine. There is no need to do it on cars where the brake discs are cheap, but on bigger brakes such as those fitted to sports and prestige cars it can save many hundreds of pounds, and is perfectly safe. Here's our set-up being used on a Ferrari 360;ks.
Mazda will always reskim discs on a car under warranty if there is judder. It is a perfectly normal operation and can extend the life of discs that are grooved.
What the OP needs to do is to speak with the garage and find out what information they have to confirm they have machined to a reasonable disc thickness.
Many disc manufacturers will quote differing minimum thickness figures, some being ,more generous that others. You may find they have machined them to the level the disc machine manufacturer recommends. As I said this could vary between manufactures and the machine supplier.
As for performance, if done correctly they will perform as well as before and wear as well. They will pass the MOT if they are working well.
Having said all that, I would always fit new unless there was a huge price difference.
What the OP needs to do is to speak with the garage and find out what information they have to confirm they have machined to a reasonable disc thickness.
Many disc manufacturers will quote differing minimum thickness figures, some being ,more generous that others. You may find they have machined them to the level the disc machine manufacturer recommends. As I said this could vary between manufactures and the machine supplier.
As for performance, if done correctly they will perform as well as before and wear as well. They will pass the MOT if they are working well.
Having said all that, I would always fit new unless there was a huge price difference.
BritishRacinGrin said:
Warmfuzzies said:
BritishRacinGrin said:
MOT will be an effectiveness inspection and a visual inspection, both of which the OP's brakes are likely to pass.
And how does that work then, it's a pretty stupid comment to make. That degree of under sizing will make no difference on the mot test, and when was the last time you saw a disk check with a Mic or vernier.I presume you meant to quote WelshBeef?
Even if you did, unnecessarily rude.
The best "I am stupid" post ever, which is really stupid because, Warmfuzzies, your comment is correct as is BritishRacingGrin.
The only reason to skim is if you're suffering from judder and it's the economical solution. It's a repair, not a life extension for discs.
It's true that it can actually be better than a new set as all discs will come with a small amount of runout (or a large amount if they're poor quality) and you're compensating for hub runout, however all discs develop an element of runout and disc thickness variation (DTV) over time and up to a point it makes no difference.
I can't say I've ever heard of any amount runout or DTV being desirable though, if it were to push the pads away then your caliper setup has got inadequate piston fallback and it'll probably generate its own runout or DTV quickly enough anyway!
Also, minimum thickness is there for a reason, it's probably safe enough 1mm underneath the minimum for normal driving but obviously it will wear and there will come a point where it stops being safe. It's weakened and there is less thermal capacity so getting it hot will cause judder far more quickly and might even cause the disc to crack or fail completely... Generally that's best avoided.
Shove a new set of discs on it yourself OP, lesson learnt.
It's true that it can actually be better than a new set as all discs will come with a small amount of runout (or a large amount if they're poor quality) and you're compensating for hub runout, however all discs develop an element of runout and disc thickness variation (DTV) over time and up to a point it makes no difference.
I can't say I've ever heard of any amount runout or DTV being desirable though, if it were to push the pads away then your caliper setup has got inadequate piston fallback and it'll probably generate its own runout or DTV quickly enough anyway!
Also, minimum thickness is there for a reason, it's probably safe enough 1mm underneath the minimum for normal driving but obviously it will wear and there will come a point where it stops being safe. It's weakened and there is less thermal capacity so getting it hot will cause judder far more quickly and might even cause the disc to crack or fail completely... Generally that's best avoided.
Shove a new set of discs on it yourself OP, lesson learnt.
so called said:
BritishRacinGrin said:
Warmfuzzies said:
BritishRacinGrin said:
MOT will be an effectiveness inspection and a visual inspection, both of which the OP's brakes are likely to pass.
And how does that work then, it's a pretty stupid comment to make. That degree of under sizing will make no difference on the mot test, and when was the last time you saw a disk check with a Mic or vernier.I presume you meant to quote WelshBeef?
Even if you did, unnecessarily rude.
The best "I am stupid" post ever, which is really stupid because, Warmfuzzies, your comment is correct as is BritishRacingGrin.
Seriously pistonheads has really gone down hill.
Edited by AngryPartsBloke on Thursday 5th February 10:14
Randomcat said:
Just to update on this, i took the car back to the garage and they agreed to fit new discs free of charge, which they have now done. :-) Thanks for the comments
That's the right result - and really its good to see a business putting right a wrong. Given the way they have resolved this you'd have no issue in using them again. Gassing Station | General Gassing | Top of Page | What's New | My Stuff