20 hours ago, Gmac983 said:

 

 

Just to be crystal clear for all the "experts" out there, as lowly tradesman of 20 years I was not talking about battering the brake disc to death with a four hammer. I was suggesting tapping round the edge with a small ballpein hammer to knock off the rust. Lightly dressing off the edge if it is more substantial with an angle grinder is another option or filling... Even a fairly new set of discs with loads of life left in them can have a good sized lip on them needing dressed off.

 

12 hours ago, benterrier said:

Yes Gmac83, the majority of us on here understood the use of a hammer to tap off the crud. Pity the experts didn't. 

 

1 hour ago, gregoir said:

I think us "experts" understood that.  My bearing damage occurred after I  indeed had used a small ball pein hammer. The Renault was red.

 

I must apologise.  If you thought I was having a go as an 'expert', I wasn't.  I've never come across this in 20yrs of motoring.  It does however make sense now I understand what you mean although I've never needed to remove the corrosion from the disc and the lips have always been far to big to warrant filing/grinding away and required replacing at anything from 50k-100k miles.  I guess I'm light on the brakes.

 

Edit:  What benefit do you get from removing the corrosion apart from cosmetics?

Edited 25 September, 20196 yr by MarkyG82

The lip can cause squealing/grumbling (as the OP describes or equally the OP could just have a corroded surfaces on his discs) . If you are unfortunate a chunk of rust from the lip could brake away and cause damage to the surface of the disc or pad. Also it's good practice to remove the lip when fitting new pads only, as the surface area of other branded pads can differ, leading to the new pads sitting on top of the lip. Meaning you would have very ineffective brakes until the new pads bed into the old discs.

What else? Oh aye, removing the lip back to flush allows you to more accurately gauge the remain material/life left in the disc. There is a cosmetic element to removing the lip as well. 

As above, I'd noisy brakes . It looked like the large rusty lip was contributing to the problem. I was living in Buxton, at the time ,where the roads seemed to be permanently covered with rock salt. The winters in the 1970s and 1980s were dire.