fast speed drop from 70

[sean443]

bit off a newbie question i was out driving tonite and was on the motor way i went up to 70 car was in 6th gear i took my feet off the pedals and i was back at 50 in 4 seconds my brakes dont feel to be rubbing any info on this problem

 

[LEE69]

Engine braking?

 

[Willie]

Try touching your alloys after a drive and see if there very hot, obviously expect them to be hot so as not to scald your hand if they are.
This would point towards binding brakes.

 

[Slimy]

I've had this a few times for apparently no reason. Most times I could take my foot off and it would drop to 65 after a few seconds, other times I could feel a distinct nosedive and see cars behind me having trouble to slow down as quick. Both could be felt in the same journey, with no application of brakes at all.

I can only think that the ECU sometimes takes different approaches to a released gas pedal, sometimes reducing the fuel gently and other times cutting it to idle levels.

 

[sean443]

i will go for another drive tonight and check my wheels after a good drive but my brake pads do seem to have uneven wear on them

 

[LEE69]

Just jack each wheel up and spin it (handbrake off obviously for the rears)

 

[Willie]

Pads will always wear inside first as this is where the hydraulic oil come in.

 

[Slimy]

Pads will always wear inside first as this is where the hydraulic oil come in.

I don't think that's right, in fact I might go as far to say that you're way off the mark . The whole caliper moves on the sliders, the pressure is split 50:50 between the piston side pad and the opposite side pad. If it doesn't, then the caliper or it's carrier needs cleaning or overhauling.

 

[Ronin225]

Yes, when using a single pistoned caliper but me and willie have the brembo four pots
So two pistons either side

 

[Graham89]

Sounds like a binding brake. As mentioned above i would try raising the vehicle (Dont climb underneath a jacked car without axle stands or similar) and spin the wheels?

 

[Slimy]

Yes, when using a single pistoned caliper but me and willie have the brembo four pots
So two pistons either side

And you reckon there is a pressure imbalance on either side? I'm still not convinced that's right, or healthy!

My bike brakes are a similar four pot design, with a fixed caliper, and they wear both sides evenly.

At least, that's what is meant to happen, the OP suggesting uneven pad wear does suggest a binding brake.