Smoothing brake discs?

Agile · 16 Jun 2020

When I replace brake pads I like to clean up the old discs with an angle grinder used with the disc spinning ( as if it was a lathe! )

Now on the driven wheels ( usually front now ) that is easy using the engine power.

However, what are the best suggestions for the back wheels, rather than rotating them in jerks by hand!!!

I think that I know the answer but I am asking in case anyone has an idea that I have missed!

Thanks

Tony

Mottie · 16 Jun 2020

If you’re replacing the discs, why are you bothering to clean them?

Agile · 16 Jun 2020

Oops, sorry! In my rush to post it I mixed up the words!

Corrected now!

Agile · 16 Jun 2020

Oops!

Burnerman · 16 Jun 2020

If you want to clean up the disc edges, use a flap wheel in an angle grinder - but keep it away from the braking faces or you'll get a bumpy pedal.
John

Mottie · 16 Jun 2020

Whenever I replace pads and there’s a slight lip on the discs, I just nib off the inner and outer edges of the new pad with a flat file so that it misses the lip.

johnny2007 · 16 Jun 2020

I know it could be impractical, but if you buy exactly the same pads they sit perfectly in the disc area worn by the previous.
Done dozens of times.

DIYspanner · 18 Jun 2020

If the rear wheels are stud mounted like the VWs, take the rear discs off and bolt them to the front hubs if you want to spin them off the engine to spin grind the outer edges.
Apply extreme caution!! Get those SAFETY glasses on!!

You can't really access the inner ridge on the hub side of disc.

Mottie · 18 Jun 2020

johnny2007 said:
I know it could be impractical, but if you buy exactly the same pads they sit perfectly in the disc area worn by the previous.
Done dozens of times.

Sorry, but they just don’t. The pads from any manufacturer will be made to the same dimensions as the OE pad. Seen it thousands of times.

DIYspanner · 18 Jun 2020

What depth of lip have the pads created?

johnny2007 · 18 Jun 2020

Mottie said:
Sorry, but they just don’t. The pads from any manufacturer will be made to the same dimensions as the OE pad. Seen it thousands of times.

Not really.
All brands that fit a particular model are just a tiny bit different.
By buying the same brand you don't need to touch the discs and the new pads will bed in within a day.
Done dozens of times.

Burnerman · 18 Jun 2020

If there's a significant lip worn on the discs, fit new ones (with pads) and save clarting about!
For me, cleaning up the disc edge is done with a hammer to dislodge the rust that's there - and that's it.
John

DIYspanner · 18 Jun 2020

The likes of Mintex market boxed pad/disc sets.

Burnerman · 18 Jun 2020

Motor factors are reporting significant shortages of many items at the moment, notably filters and discs/pads......things will recover in due course but I do prefer to use them rather than Ebay or whatever. So helpful they are - if there's a choice of say three filters for a vehicle, they send all three along and I return the unwanted items in a day or so.
John

DIYspanner · 18 Jun 2020

I do use ebay and there are two sellers I've knocked on the head for sending me rubbish.

However, two I recommend are

For Mintex
For Blue Print

Smoothing brake discs?

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