Brake disc running-in?

[tuscan_thunder]

Do new discs (not pads) need any kind of running in?

[cuzza]

New discs (and therefore new pads) should be pretty much spot on from the off - I'd bed the pads as normal then you should be fine.

[adrianr]

Allegedly there are benefits to running them through a heat cycle or two before using in anger, for race cars anyway. It's described in one of Carroll Smiths legendary race car prep books - "Drive to Win" probably.

If I remember correctly it's drive, use brakes lightly then progressively harder for a few laps/miles, then brake really hard once or twice without locking the wheels, then roll to a stop and allow to cool fully.

Check this before trying it, my memory is fuzzy.
AdrianR

[alicrozier]

Gentle use until you have full pad coverage on the disk then bed in pads as normal.

Cheers,
Ali

[rixge]

I would imagine that you should just break gently and steadily for the first 100 miles to give them a long term future !

[tuscan_thunder]

Ok guys, I'll go gently for the first wee while then work some heat into them. The discs were changed as I warped one but the pads are pretty new so I've just stuck them back in.

Thanks

[CUZZA]

Bad idea. The pads will wear themselves into the contours of your disks very quickly and if you then transfer them to new disks, some of that pattern wiil transfer to the new disks.

New disks should always be accompanied by new pads.

[greenv8s]

Almost all pads benefit from being bedded in properly, and there's far more to it than just driving gently for a few hundred miles. Different manufacturers give different bedding in instructions. You need to follow the instructions for your pads. If you don't have any, then braking successively harder and harder (with plenty of cooling down time in between) without ever coming to a complete stop is a good bet. Interestingly, the discs need to be bedded in too, and some places will recomend that you bed the discs in using the old pads, and then fit the new pads. It depends what state the old pads were in of course, if they're worn unevenly or down to the back plate then they could easily damage the disc. Personally I don't go that far, if I'm replacing the discs I fit new pads and then bed them in as normal.

[alicrozier]

tuscan_thunder said:

Ok guys, I'll go gently for the first wee while then work some heat into them. The discs were changed as I warped one but the pads are pretty new so I've just stuck them back in. Thanks

Not ideal, should really use new pads...make sure they are smooth and you'll be ok.

Just make sure the pads are contacting over the whole disk area before you try getting proper heat into them (you will see on the disk surface).

What pads are they? Recommended bedding in will be different depending on the compound.

Cheers,
Ali

[tuscan_thunder]

alicrozier said:

tuscan_thunder said: Ok guys, I'll go gently for the first wee while then work some heat into them. The discs were changed as I warped one but the pads are pretty new so I've just stuck them back in. Thanks Not ideal, should really use new pads...make sure they are smooth and you'll be ok. Just make sure the pads are contacting over the whole disk area before you try getting proper heat into them (you will see on the disk surface). What pads are they? Recommended bedding in will be different depending on the compound. Cheers, Ali

Ali,

They're Mintex 1144s and have only done about 1,000 miles. That was all pretty light use and commuting so I'm not too worried about them - they looked like they were just bedded in when they came out. They seem to be sitting fine on the disc.

My mechanic mate was happy they'd be ok as there was so little pad wear. I'll keep an eye on them but think they'll be fine as the pads aren't far off new.

(car's getting MoT'd this week so it'll be ready for a run next time you guys are heading out.)