When my VW Passat was last serviced I was told that the front disks had
corroded. This is true and there has been some corrosion at the edges. I
have been reluctant to change the disks, as neither the disks or pads are
near their wear limits, even after 45,000 miles and 5 years. The brakes
work fine.

However, the car is now due for its MOT, so my question is: Is the state of
the disks an MOT failure point?

--
Michael Chare

In article , Michael Chare says...
When my VW Passat was last serviced I was told that the front disks had
corroded. This is true and there has been some corrosion at the edges. I
have been reluctant to change the disks, as neither the disks or pads are
near their wear limits, even after 45,000 miles and 5 years. The brakes
work fine.

However, the car is now due for its MOT, so my question is: Is the state of
the disks an MOT failure point?


Yes.

I'd be inclined to whip the wheel off and tap the outside edge of the
disc with a hammer whilst rotating it to remove the lip of crud that
accumulates.

--
Conor

I'm not prejudiced. I hate everyone equally.

"Michael Chare" wrote in message
...
When my VW Passat was last serviced I was told that the front disks had
corroded. This is true and there has been some corrosion at the edges. I
have been reluctant to change the disks, as neither the disks or pads are
near their wear limits, even after 45,000 miles and 5 years. The brakes
work fine.

However, the car is now due for its MOT, so my question is: Is the state
of the disks an MOT failure point?

If the discs are 8 quid each, and the pads not far from the same, with the
wheel off you could possibly be as well just replacing them. That's the
usual crap reply for "just replace it anyway" amateur-diagnosis, however
it's been 5 years, and a new set wouldn't go amiss. Otherwise, whack a
hammer with a good edging on it around the outside if you feel sure they're
not worth replacing quite yet.

In article ,
Michael Chare wrote:
When my VW Passat was last serviced I was told that the front disks had
corroded. This is true and there has been some corrosion at the edges. I
have been reluctant to change the disks, as neither the disks or pads
are near their wear limits, even after 45,000 miles and 5 years. The
brakes work fine.

However, the car is now due for its MOT, so my question is: Is the state
of the disks an MOT failure point?

Unless the car has been unused for some time the only corrosion you get is
where the pads don't touch the disc - and this doesn't matter. A few good
applications of the brakes will remove any surface corrosion where they do
touch. If it doesn't you have a seized caliper which really will fail the
MOT.

--
*I don't know what your problem is, but I'll bet it's hard to pronounce

Dave Plowman London SW
To e-mail, change noise into sound.

"Robert" wrote in message
...
"Michael Chare" wrote in message
...
When my VW Passat was last serviced I was told that the front disks had
corroded. This is true and there has been some corrosion at the edges. I
have been reluctant to change the disks, as neither the disks or pads are
near their wear limits, even after 45,000 miles and 5 years. The brakes
work fine.

However, the car is now due for its MOT, so my question is: Is the state
of the disks an MOT failure point?

If the discs are 8 quid each, and the pads not far from the same, with the
wheel off you could possibly be as well just replacing them. That's the
usual crap reply for "just replace it anyway" amateur-diagnosis, however
it's been 5 years, and a new set wouldn't go amiss. Otherwise, whack a
hammer with a good edging on it around the outside if you feel sure
they're not worth replacing quite yet.


Trouble is, even on Euro car parts the cost of the pads and disks is £80! I
will take another look with the aid as it is now a few months since the car
was serviced. I expect to wear brakes out rather than just have them rust
away.

--
Michael Chare

Michael Chare wrote:

When my VW Passat was last serviced I was told that the front disks had
corroded. This is true and there has been some corrosion at the edges. I
have been reluctant to change the disks, as neither the disks or pads are
near their wear limits, even after 45,000 miles and 5 years. The brakes
work fine.

However, the car is now due for its MOT, so my question is: Is the state
of the disks an MOT failure point?


Reason for rejection:

"a brake disc or drum insecure, cracked or excessively scored, pitted or
worn"

See here, section h:

http://www.motuk.co.uk/manual_350.htm

Corrosion is not specifically mentioned. The friction material wear limit
(WRT the MOT) is 1.5mm. I would imagine you would not get a fail.

Chris

--
Remove prejudice to reply.

"Michael Chare" wrote in message
...
"Robert" wrote in message
...
"Michael Chare" wrote in message
...
When my VW Passat was last serviced I was told that the front disks had
corroded. This is true and there has been some corrosion at the edges. I
have been reluctant to change the disks, as neither the disks or pads
are near their wear limits, even after 45,000 miles and 5 years. The
brakes work fine.

However, the car is now due for its MOT, so my question is: Is the state
of the disks an MOT failure point?

If the discs are 8 quid each, and the pads not far from the same, with
the wheel off you could possibly be as well just replacing them. That's
the usual crap reply for "just replace it anyway" amateur-diagnosis,
however it's been 5 years, and a new set wouldn't go amiss. Otherwise,
whack a hammer with a good edging on it around the outside if you feel
sure they're not worth replacing quite yet.


Trouble is, even on Euro car parts the cost of the pads and disks is £80!
I will take another look with the aid as it is now a few months since the
car was serviced. I expect to wear brakes out rather than just have them
rust away.

--
Michael Chare

gsf are very cheap for bits like this, depending on the model the discs are
15 quid or a bit more.

To fail an mot the discs would have to be very corroded. Put it in for a
test and see what happens

"Chris Whelan" wrote in message
...
Michael Chare wrote:

When my VW Passat was last serviced I was told that the front disks had
corroded. This is true and there has been some corrosion at the edges. I
have been reluctant to change the disks, as neither the disks or pads are
near their wear limits, even after 45,000 miles and 5 years. The brakes
work fine.

However, the car is now due for its MOT, so my question is: Is the state
of the disks an MOT failure point?


Reason for rejection:

"a brake disc or drum insecure, cracked or excessively scored, pitted or
worn"

See here, section h:

http://www.motuk.co.uk/manual_350.htm

Corrosion is not specifically mentioned. The friction material wear limit
(WRT the MOT) is 1.5mm. I would imagine you would not get a fail.

Chris

--
Remove prejudice to reply.

Corrosion on a brake disc tends to remove friction material from the pad, in
much the same way that sandpaper/ emery paper removes material. Once the
material is removed from the pad this relieves the pressure on this part of
the contact area, thus allowing the build up of further rust, removing
further brake pad material and further reducing contact surface, thus
enhancing brake pad wear. In short, it's a descending spiral, a matter of
judgement as to how far you are along the way and hence the need for
replacement.

Last one I replaced had a greatly differing amount of wear across the pads,
with the most worn pad bearing on only about half the designed width of the
disc, due to rust build up = MOT failure = urgent disc and pad replacement.

Pads will not remove corrosion from discs in the course of use, it's a
fallacy.

If you can see the reduction in contact area of the pad (bright part on the
disc) so can the MOT man and he may say, "Do that and bring it back when you
have".

"Conor" wrote in message
...
In article , Michael Chare says...
When my VW Passat was last serviced I was told that the front disks had
corroded. This is true and there has been some corrosion at the edges. I
have been reluctant to change the disks, as neither the disks or pads are
near their wear limits, even after 45,000 miles and 5 years. The brakes
work fine.

However, the car is now due for its MOT, so my question is: Is the state
of
the disks an MOT failure point?


Yes.


I'm surprised to hear this. All brake discs that are more than a few days
old will have some corrosion round the edge. How much constitutes an MOT
failure? I've never had an MOT tester mention discs to me during the test
and most of them must have been corroded at the edges (the discs, I mean!).

Rob Graham

Rob graham wrote:


"Conor" wrote in message
...
In article , Michael Chare says...
When my VW Passat was last serviced I was told that the front disks had
corroded. This is true and there has been some corrosion at the edges. I
have been reluctant to change the disks, as neither the disks or pads
are
near their wear limits, even after 45,000 miles and 5 years. The brakes
work fine.

However, the car is now due for its MOT, so my question is: Is the state
of
the disks an MOT failure point?


Yes.


I'm surprised to hear this. All brake discs that are more than a few days
old will have some corrosion round the edge. How much constitutes an MOT
failure? I've never had an MOT tester mention discs to me during the test
and most of them must have been corroded at the edges (the discs, I
mean!).

Rob Graham

Have you read the rest of this thread? Specifically, the parts where a
number of respondents have reassured the OP that edge corrosion will not be
a MOT failure? The ones that were p[posted three days ago...

Chris

--
Remove prejudice to reply.