Brake discs below minimum thickness?

jimjames

Mercedes18 said:

Belenus said:

Is it dangerous driving with the current brake disks thickness?

It may or may not be dangerous but it just isn't worth the risk for the reason that tacpot12 gives above and probably for other reasons too.

Your brakes are there to potentially save your life and the lives of others and the manufacturers specify minimum disk thicknesses for a reason.

Without wishing to appear overly dramatic, if you have an accident that seriously injures or kills someone else, the Police will be all over your car and its service record and will know that you knew about the disk thickness issue. I would not like to be in your shoes defending that in court.

Get new disks asap.

I was advised by the lady who done the handover after my service that even though my brake discs are below the minimum thickness it’s okay to wait until the pads have worn down (until brake pad light comes on) and just wait until then to change the discs and pads together.

I asked her is it still safe to drive and she said yes. Hence why I’ve come onto here for a second opinion. 

I'd certainly say it was safe to carry on using and replace when the pads need doing. Main reason for changing discs is if they are scored or lipped, I've never had to change because they were claimed to be too thin by a garage.

Ibrahim5

Well 'lipped' means that the part of the disc used for braking has become thinner than the rest of the disc. I always replace mine before they are below the minimum thickness. I suspect you would get away with going below as long as you did change them at the next pad change although I wouldn't do it. I am surprised a garage has recommended driving with them below the minimum specified thickness.

Ibrahim5

I have got a big car and Pagid discs and pads are £160 for the whole car (front and rear). I would just do the whole lot and then forget about it. I couldn't really be bothered messing about doing anything else.

EssexExile

jimjames said:

I'd certainly say it was safe to carry on using and replace when the pads need doing. Main reason for changing discs is if they are scored or lipped, I've never had to change because they were claimed to be too thin by a garage.

It's the modern way I'm afraid. Discs never used to wear out but nowadays they do and need replacing regularly.

OP My experience was that the dealer told me I'd need new discs and pads "within a couple of months". I took it to my local trusted garage and he said they'll be fine for a year or so. I took it back for an MOT after about 6 months and he said they're still fine. I eventually had them changed the next year.

Grey_Critic

When I was with Ford brake discs had Min and Max engraved in the discs. If a mechanic reported that the discs were worn then he used a micrometer or calipers to measure them. Leasing companies always asked for the measurement before authorising disc replacement.

If I recall correctly Mazda discs when scored could be skimmed up to three times before needing replacing - sorry cannot remember the thickness.

As others have said better to fit new pads at same time as it is only material cost as they have to remove them to replace discs - personally I always go on the cautious side - it is my life at risk.

We were called by the Police one day to recover a car that hit a bus shelter at morning rush hour. Fortunately nobody was injured. When SOCO came to look at the vehicle they found no front disc pads fitted. When they looked in the boot they found the pads neatly wrapped in a  rag. When questioned the driver said that as the pads were well worn he did not want to go metal to metal so removed the pads until he could get them replaced.

sevenhills

jimjames said:

I'd certainly say it was safe to carry on using and replace when the pads need doing. Main reason for changing discs is if they are scored or lipped, I've never had to change because they were claimed to be too thin by a garage.

This is both front and rear, the rear discs wear is a lot slower.

Ibrahim5

EssexExile said:

jimjames said:

I'd certainly say it was safe to carry on using and replace when the pads need doing. Main reason for changing discs is if they are scored or lipped, I've never had to change because they were claimed to be too thin by a garage.

It's the modern way I'm afraid. Discs never used to wear out but nowadays they do and need replacing regularly.

OP My experience was that the dealer told me I'd need new discs and pads "within a couple of months". I took it to my local trusted garage and he said they'll be fine for a year or so. I took it back for an MOT after about 6 months and he said they're still fine. I eventually had them changed the next year.

I think you have to be fair to the garage. They don't know how many miles are driven and the driving style. They don't know how long it will be before the car goes for another service. When you service your own cars you know those facts. Garages don't.

[Deleted User]

I have had several sets on various cars over the years. All changed when they go under the recommended level. I just don't mess around with the bits that will try to keep me and others in one bit. One car I have at the mo is basically 2 ton of pig iron and just had the third set in its life fitted (138thou miles), they work hard on big cars I suppose. Brakes wear out cos they work and driving styles differ, loads carried, roads driven and so on.

Seeing an old worn and new side by side is interesting. Especially with vented fronts.

sheslookinhot

The car would fail an MOT with undersized brake discs. They should be changed. Always wise to change pads with discs.

Ibrahim5

Can they measure them for the MOT? I have to take the wheels off before I can get my micrometer on. I measure them in thousands of an inch before converting to metric. Maybe there is a more modern way.