Pedal To The Floor On Low Revs

[TaffyTim 6]

My brake pedal is going close to the floor on low revs.

 

On normal driving the pedal fine and has good pressure.

 

But when coming to a stop and depressing the clutch so the revs are on tickover i sometimes have to pump the brake to feel comfortable that i'll stop in time.

 

I noticed my fluid was a little low tonight so I'll top this up tomorrow but could this be the cause or is the MC shot?

Edited October 16, 2014 by TaffyTim

[Anthony 1,002]

At low revs and on overrun the engine will be generating more vacuum which would potentially lead to more servo assistance, but I'm not sure from your description that's what you're seeing if the pedal will "pump up" and subsequently be OK.

 

If you maintain hard constant pressure on the brake pedal, does it creep to the floor?

 

If so, you've likely got a leak somewhere - drum wheel cylinders are common but check everything.

 

If not, personally I'd replace the MC as a matter of course if there's any doubt as to its condition.

[Tom Fenton 1,536]

 

If not, personally I'd replace the MC as a matter of course if there's any doubt as to its condition.

This, they are not expensive and easy enough to replace. I have never had it happen to me, but I've heard many a tale of failed master cylinders on 205's causing unintended front end restyling.

[TaffyTim 6]

At low revs and on overrun the engine will be generating more vacuum which would potentially lead to more servo assistance, but I'm not sure from your description that's what you're seeing if the pedal will "pump up" and subsequently be OK.

 

If you maintain hard constant pressure on the brake pedal, does it creep to the floor?

 

If so, you've likely got a leak somewhere - drum wheel cylinders are common but check everything.

 

If not, personally I'd replace the MC as a matter of course if there's any doubt as to its condition.

When pressure is applied initially it seems to keep a constant bite but if i back off slightly then reapply pressure it seems to loose its bite and i have to travel down the pedal to find that bite again. If I haven't pumped it and then and ease off and back on a third time it slips down the pedal further but I feel as if I'm too close to the floor and then it really needs a pump.

 

I think I'll get it booked in for a new MC as its almost caught me out a couple of times.

Edited October 21, 2014 by TaffyTim

[dobboy 231 2 Cars]

Are your brakes bled ok?

 

When was last fluid change?