Angle grinder, just say no

[Andy Dingley]

'Merkins, I assume. 8-(

[Bob Minchin]

I use a similar method to get the hooked edge off worn discs provided that there the overall swept area and thickness are within specified limits.

Done carefully with wheels chocked it is perfectly safe.

Bob

[Andy Burns]

And a brick on the accelerator to spin the axle?

[Tabby]

I dont see a problem, as long you leave the surface flat enough for the brakes to work correctly.

NT

[Jules Richardson]

"Brake disc being polished after damage by worn brake shoes" - except they'd call them pads in connection with a disc over here, and shoes for drums. Same with the UK, I'd expect. Oh, hang on, there's a camera location link - looks like it's in Germany, if that's accurate.

I'm not sure how you can polish a disc with what looks to be a grinding wheel. I can imagine that you can (safely) remove the lip that forms on old discs (so long as the disc isn't otherwise too thin) - but I think of that as disc wear, not damage that occurs due to worn pads (or shoes ;) Something lost in translation, perhaps.

cheers

Jules

[fred]

In article , Andy Dingley writes

Feck, has anyone _not_ done that :-?

[MuddyMike]

Te he, I like that idea. I have taken many a lip off brake disks with an angle grinder. Sanding the whole surface with a flapper wheel can be good as well.

Mike

[Ron Lowe]

AARG.

I just tried that on the Land Rover, with one front wheel jacked up, and both rear wheels on the ground.

I just drove it off the jack.

( only joking ).

-- R

[Onetap]

Wow, are brake discs so expensive? Besides which, I can't see how you'd get a flat surface. Is there a pic of the cam belt change with a stanley knife ?

[Andy Dingley]

HTF do you do that? If you do this wth an on-car disk lathe, the clamping needed to ensure that the end result is flat enough is a significant problem. If you get the slightest run-out, then you have severe judder when you apply the brakes.

There is no need to "polish" brake disks. Pads do this well enough (too well in fact) already. The only time you need to machine them is if they're grooved, and that means removing a significant volume of metal, across the full width of the disk. I don't believe anyone can do this with a hand-held angle grinder that won't leave the disks either dished or with run-out. This also assumes that they're not worn out for thickness already.

[Andy Dingley]

It's an Americanism. They think that disks need to be machined every pad change.

You don't change cam belts in America. You wait until they break, then complain about these funny furriners and their "interference engines". A real V8, like Cusn Bubba's, can of course keep on running with half the lobes missing off its cam.

[newshound]

To be fair, although the photo description says different, the highlight on the "lip" region is consistent with the guy *just* removing the lip. I'm with Bob Minchin, taking the lip off is perfectly acceptable as long as the disks are in spec. And you don't need a brick on the accelerator; idling speed is fine. I tend to do it with both wheels "off".

[abba doodoo]

If the pads are being changed then there will be a lip on the disk's outer edge, particularly now pads are almost as hard as disks. Removing the lip allows the new pads to bed in properly as there's no chance of them catching on the lip. Never bothered doing it myself mind you.

[Bob Minchin]

Tick over and top gear give a suitable speed for the job and does not unduly stress the diff as you only need a few minutes per side.

Bob

[Dave Liquorice]

Only with 4WD and the center diff lock engaged. Assuming that there is a center diff to be locked of course. B-)

[The Other Mike]

If you align the angle grinder flapper disc correctly the disc will rotate automatically with the friction from the cutting action so there is no need for the car to be in gear.

I often do something similar to one of my vehicles that would otherwise wreck a pair of brand new manufacturer supplied rear discs in a typical British winter. This enables the discs to last two years before I have to remove and skim them, at 250 quid a pair I call that a result.

[Ron Lowe]

Yes, but the modern discos do all the traction control electronically and automagically. There's no Diff Lock button. I don't know how it's implimented internally, if the centre diff can be locked by the magic or not. I believe that it applies braking to the spinning wheel to apply power to t'others ( like split-pedal brakes ), but I'm really not sure.

I *do* know I'd not put one in 'Drive' with one corner up on a jack just to find out...