Amc,

Tonight coming back home from work I heard my brakes grinding when slowing down

Neglectful yes but now I require need pads and a maching

How much can I expect this to cost me for new front pads and maching of them also? I won't be doing either myself but rather pay someone else to

Thanks

Do the remove and replace part yourself, and the machining will cost $50 or so, pad price depends on what you get. $25 - $85.
The grinding may just be the wear indicators on the pads (start to scrape when the pads are down to about 2 mm) rather than the rotors being damaged. Have a look at the surface of the rotors - you may just need new pads.

Do the remove and replace part yourself, and the machining will cost $50 or so, pad price depends on what you get. $25 - $85.
The grinding may just be the wear indicators on the pads (start to scrape when the pads are down to about 2 mm) rather than the rotors being damaged. Have a look at the surface of the rotors - you may just need new pads.

There is something cut onto the rotor
I'm not massively mechanically minded but it's all along the rim of the rotor

There is something cut onto the rotor
I'm not massively mechanically minded but it's all along the rim of the rotor

Will need machining then. Try a brake shop like ABS and ask for a drive in/drive out quote.

I do machining at my workshop

If your rotors can be machined within spec 22.4mm min thickness then machining will cost you $40.00 for the pair. If not a freshly machined pair is $55.00

QFM HPX pads are $79

Above is you fitting, if you need them fitted adds $60.00

Speaking of brakes. mine seem crap and always have even after new pads. Machining or bleeding being the likely fix?

Or are stock brakes a bit average? (TFsedan 242k)

Unfortunately i didnt get onto this as soon I should have and had to replace the rotors so make sure you get it looked at asap, usually a pad change change can be $25-$85 like MadMax said. Better safe than sorry and costing you a lot more. I cant remember how much machining is as i usually get it done when i get a service

Speaking of brakes. mine seem crap and always have even after new pads. Machining or bleeding being the likely fix?

Or are stock brakes a bit average? (TFsedan 242k)

Nothing special but you shouldn't really feel as if they are absolutely terrible. As far as i know anyway.

Std magna brakes properly maintained are actually quite good even for some spirited driving.

Pads installed without machining is simply silly

Std magna brakes properly maintained are actually quite good even for some spirited driving.

Pads installed without machining is simply silly

Is your disc lathe set up to machine slotted rotors? If not, how much for a set of DBA slotteds to suit a TF?

Don't get crap pads whatever you do. The ones Madmagna suggested are excellent. Spend at least $50. And machine your rotors while you're at it. Do it once and do it right.

I don't machine my rotors everytime I get pads, I get it done every 2-3 times depending on if my mechanic thinks the rotors require it.

Machining the rotors too often cuts the long tern viability of them and ends up costing you more in the long run for no real benefit.

Rubbish, rotors get glazed, grooved etc etc, a light skim will if anything lenghen the life of a rotor by keeping them straight and clean.

Most brake pad manufacturers will void the warranty on a pad if the surface is not nice and clean and you can evedence that they have been skimmed.

Remember that a light skim may only take off 1/4mm off each side so 1/2mm all up, if grooved then will take a little more

Due to poor casting techniques (I assume), rotors can wear more in one spot or another. I've seen rotors with shiny patches and extremely rough patches, as though the surface has lost small nodules of steel. Needless to say, this affects braking, setting up a low speed shimmy as though the rotor is warped. A skim will fix this, but replacing the rotor is the only long term solution. Something to look for when you examine used rotors.

Got the car booked in this morning and done today for $220 from Kmart tyre and auto since its close and able to do it today

Cost was a bit above what I was expecting to pay but atleast it's done today rather than next week when I was free again

Hi. I am going to replace my front rotors so I am wondering whats the largest sized socket I will need to do the job? It looks like I will need 1 in the 30+mm range, is this correct?

Nope. Wheel nut wrench, 14,15,17 mm sockets.

Don't touch the axle nut in the centre.

10, 14, 17 and a wheel brace or 21.

Don't touch the 32mm.

Will need machining then. Try a brake shop like ABS and ask for a drive in/drive out quote.

In preparation for the roadworthy I had ABS handle ours (I knew the front pads were really low and the rotors had a lip). They charged me $224 for new pads, machining and a clean and lube of the slides on the rear calipers (were squeaking at times). I was pretty happy with both price and service.

Steve

Madmagna, I'm happy that you talk about a light skim of 1/4mm. I own a number of vehicles including a Magna and in the last five or more years I've given up having rotors machined and just buy new ones because of the poor work I've received from brake machinists. Even though I give them rotors that have never been machined before and are in good condition they mill off huge amounts of metal and give them back cut to the minimum thickness or below the minimum thickness. I couldn't find anyone who would just take off a 1/4mm. I watched once and they just wound up the cutters and walked away to do something else. There was no effort to look at the rotor to take off the minimum necessary.

Madmagna, I'm happy that you talk about a light skim of 1/4mm. I own a number of vehicles including a Magna and in the last five or more years I've given up having rotors machined and just buy new ones because of the poor work I've received from brake machinists. Even though I give them rotors that have never been machined before and are in good condition they mill off huge amounts of metal and give them back cut to the minimum thickness or below the minimum thickness. I couldn't find anyone who would just take off a 1/4mm. I watched once and they just wound up the cutters and walked away to do something else. There was no effort to look at the rotor to take off the minimum necessary.

Its a shame - and there's absolutely no reason why they couldn't do a light skim just to create a fresh, flat surface. I know I used to do it for our customers (Holden dealership) when I was in the trade

Madmagna, I'm happy that you talk about a light skim of 1/4mm. I own a number of vehicles including a Magna and in the last five or more years I've given up having rotors machined and just buy new ones because of the poor work I've received from brake machinists. Even though I give them rotors that have never been machined before and are in good condition they mill off huge amounts of metal and give them back cut to the minimum thickness or below the minimum thickness. I couldn't find anyone who would just take off a 1/4mm. I watched once and they just wound up the cutters and walked away to do something else. There was no effort to look at the rotor to take off the minimum necessary.

I always love being quoted for something I stated 9 months ago :)

Some of these idiots do now know how to use the equipment they have or the equipment is rubbish to start with. When I do rotors I take off as little as I can, an example is the set I did yesterday still had 23.8mm on them after the machine, far from min thickness

What happens to a rotor once it goes past minimum thickness?

You chuck it out and get a new one because it's illegal for a mechanic to put it back on.

You chuck it out and get a new one because it's illegal for a mechanic to put it back on.

I think he wants to know what happens if you put an undersized thickness rotor back on the car.

No idea myself there. lol Probably increases the likelihood of the rotor failing disasterously in use perhaps?

The rotor can crack. The minimum thickness is a safeguard though. The likelihood of a rotor cracking at just under minimum thickness is remote. It is however highly illegal for a mechanic to machine under minimum thickness.

The rotor can crack. The minimum thickness is a safeguard though. The likelihood of a rotor cracking at just under minimum thickness is remote. It is however highly illegal for a mechanic to machine under minimum thickness.

So there will be a policeman watching the whole process and will use a micrometer to check if the disc is legal or illegal before it is put back on?
Rules that aren't enforced are pretty useless.
I'd be more interested in real life experiences, ie seeing if anyone with a Magna has had a rotor fail, and it turned out to be below minimum thickness. Or for that matter people who have Magna discs fail without any thickness problems.

Something like this: lol

http://t2.gstatic.com/images?q=tbn:ANd9GcSQtuVrv1MqzSy5exa5AjYhVpcsewISv _S-gkgTtTdKGgv4uetF

http://www.olct.co/images/News/Fails/Mechanical/brake-rotor-failure.jpg

So there will be a policeman watching the whole process and will use a micrometer to check if the disc is legal or illegal before it is put back on?
Rules that aren't enforced are pretty useless.
I'd be more interested in real life experiences, ie seeing if anyone with a Magna has had a rotor fail, and it turned out to be below minimum thickness. Or for that matter people who have Magna discs fail without any thickness problems.

Something like this: lol

Really Max, did you seriously post that dribble up

Of course there will be a Policeman in every workshop with a micrometer to measure :nuts:

What happens is that if the rotor does fail and there is an accident and there is an investigation the person who put that rotor on had better get ready for lots of real bad trouble and ready to hope he/she has no assetts as I would think that insurance would struggle to cover pure negligence like that

Call me "Mr Dribble" from now on. lol

Didn't answer the serious part of my post though, and I quote myself here:

"I'd be more interested in real life experiences, ie seeing if anyone with a Magna has had a rotor fail, and it turned out to be below minimum thickness. Or for that matter people who have Magna discs fail without any thickness problems."

A couple of good papers on the internet, lots of stresses in a solid hat/disc setup due to differential heating, even manufacture can leave behind a lot of stresses.
Now I know why racing cars use separate hats and discs!

I think he wants to know what happens if you put an undersized thickness rotor back on the car.

No idea myself there. lol Probably increases the likelihood of the rotor failing disasterously in use perhaps?

Two things could happen. First as there is less mass to absorb the heat of braking you could get overheated brakes. The other is less area carrying the same load which leads to an increase in stress in the material, pushing it past its safe limit and leading to plastic deformation then failure.

I'd been previously before getting my rotors done driving on rotors that were below minimum thickness and I was driving with them for probably a good 12 months, nothing happened they just became very annoying to stop with as they needed machining but were illegal to do so

Two things could happen. First as there is less mass to absorb the heat of braking you could get overheated brakes. The other is less area carrying the same load which leads to an increase in stress in the material, pushing it past its safe limit and leading to plastic deformation then failure.
This seems to be the best perfect answer to me. I remember a set of rotors that were very close to minimum and brake fade became an issue when traveling down mountain roads and with a little bit of brake pedal riding. First braking event would be ok, but if I needed a second application shortly after then they would just fade to nothing.

I wouldnt think it would affect fade to much. that is usually caused by pads and fluid overheating, id say its very dangerous if you slam on the brakes, your rotor could potentially snap into pieces, especially if the thinner metal heated enough and cooled enough to cause stress fractures

If you look at the design of racing brakes, the disc is a separate piece from the disc hat, joined together with rivets, or on splines for easy disc change during a race. Differential expansion between the hot disc and the cooler hat on a solid disc and hat, during high performance use, can cause sudden radial cracks in the disc or separate the disc from the hat altogether.

If you look at the design of racing brakes, the disc is a separate piece from the disc hat, joined together with rivets, or on splines for easy disc change during a race. Differential expansion between the hot disc and the cooler hat on a solid disc and hat, during high performance use, can cause sudden radial cracks in the disc or separate the disc from the hat altogether.

which is generally why they're only used for racing - short runs with high amounts of stress placed on them.

What happens is that if the rotor does fail and there is an accident and there is an investigation the person who put that rotor on had better get ready for lots of real bad trouble and ready to hope he/she has no assetts as I would think that insurance would struggle to cover pure negligence like that

What happens if you do DIY servicing and get into an accident because the rotor fails? Is your insurance void?

Could be as you have increased the risk to your insurance company plus if you kill someone other than having to live with that yourself I could imagine the law suit

How many kilometers do brake rotors generally last before going below minimum thickness?
Assuming they were never badly damaged and skimming was always light and the car was driven normally