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(Diesel?) Brake creep...

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1 month 1 week ago #18354 by zefal
zefal created the topic: (Diesel?) Brake creep...
Thought I would just post this to raise awareness. Got a 2013, 2.3 turbo diesel auto (flappy paddle) ASX. It could just be our car but it suffers from brake creep.
i.e. (with the engine running) when pumping brake pedal to get it firm and then holding it down will show the pedal slowing creeping down further/sinking slightly. It shouldn't really do this. It's not a faulty/leaking master cyclinder issue as when the engine is turned OFF, the pedal will pump, get firm and remain firm.

It's not an issue in itself as such... however, we just changed the front pads. The old discs were well within spec so we kept them. What entailed was a terrible brake feel! You needed to depress the brake pedal to halfway to even get any braking and then when you felt the braking work, the pedal would start to sink further. If you kept at it, pushing harder and harder, it would finally brake well but felt awful.

Made it very unnerving to drive. Anyway, we put the old pads back in to test and braking was back to what it was (braking occurred just by touching the pedal and was progressive, just like it was before...felt the same)....however the brake creep was still present and must have been present before but we didn't notice it as the pads were bedded in fully and effectively braking.

So it looks like the combination of brake creep and new pads on old discs really exacerbated the poor braking feel! In general putting new pads on used discs will cause much more spongy feel due to new pads needing to bed into the uneven surface on used discs, but add in brake creep into the mix and it's horrible!

Did some more reading and now believe it's normal for the car. I think it's just what they call "diesel brake creep". It's because newer diesels use a pump to create the vacuum for the servo.

What this means is that when putting new pads on half warn discs (i.e. perfectly acceptable half warn discs), can lead to unnerving pedal feel.

I actually put in new discs too to test further and it improved things immensely as uneven disc surface isn't so present for the new pads and you don't need to depress pedal over half way to get any braking.

TL;DR - brake creep on 2.3TD ASX can make braking feel very unnerving when you put new pads in, on used discs.
Downside to this "normal" brake creep is that you'll probably want to replace perfectly good, half worn discs when you need new pads....just to not have this pedal feel... luckily the discs are not too expensive on an ASX.

Side note - no idea if all ASX (petrol or diesel) have this brake creep but it's possible if Mitsi used a pump to create the servo vacuum...traditionally petrol cars took the vacuum from the inlet. Diesels don't have a vacuum and use a pump to create it, hence why they call it "diesel brake creep".

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