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MG MGB Technical - Brake pedal faint judder

Hi all,

This might be a daft question but I always like to have an opinion in my head before going to a garage and I don't know much about brakes!

Running my son to Cubs last night in the B, under braking I noticed that I could feel a light 'pulsing' through the brake pedal. It was very faint, not enough to call a judder, just a rhythmic pulsing through the pedal - it was quite fast, like a faint version of the feeling you get driving over cats' eyes. When I wound the window down I thought that I could hear a faint, soft tapping noise in time with it, but it was windy and so faint that I might just have been imagining it. The braking performance was normal, or at least so close to it that I could spot no difference and I'm a pretty aware driver.

It didn't improve or worsen during the six mile (each way) drive.

I'll get my mechanic to take a look, but I just wondered whether anyone on here had any thoughts, first?

Many thanks and sorry that at this stage of ownership (sub-two months!) I am a net asker rather than much of a responder to questions. I hope to do better through my ownership!

Piers Colver

I have had similar symptoms on cars which have been parked for a while and a pad shadow left on the disc. IIRC there was some discussion quite some time back about whether this shadow is corrosion or a deposit from the pad. Either way it is visible and caused that symptom, and it seemed worse with kevlar pads. There could be other causes of course.
Paul Walbran

Thanks for the response, Paul - the car has been sitting for three weeks, as we were snowed in for a week (I couldn't open the garage, ten foot drift!), then we were away for two weeks over Easter. Other than that it is used several times a week. If it were that, then should the disc clean up over time, do you think? I'll have a look for the old thread in the archive, thank you for that.

Good to see Kiwis on here, I love that about the internet - my mother's from Christchurch, I have a lot of family over there in regular contact. My mother has been over here for 30 years but is still on an NZ passport!
Piers Colver

I haven't encountered it happening in as little as 3 weeks. When it happens, there is usually some improvement over time but often the only cure is to give the discs a lick to true them up.

The other thread may have been on the midget Technical I think.
Paul Walbran

Try braking hard a few times from a decent speed, in a safe location.
PaulH Solihull

Paul, you know what, I tried that last night (fortunately our road is so quiet it counts as a safe location!) and it seems a little better. I guess (hope?!) that the fact that the three weeks the car was stationary for were among the coldest, dampest we have had and my garage is a little breezy makes this a candidate. Thanks, both of you.
Piers Colver

If it doesn't resolve itself it might be a bit of disc "run out". i.e., they have warped slightly. My "new" discs have gone that way. You might also get a slightly "longer" pedal, but as long has it doesn't become too savage and/or affect braking you can live with it.
Allan Reeling

It will go with use - you will speed up the process by installing new pads. Most new pads have an abrasive surface intended to help bed them in. Having had the desired effect, the new pads could be replaced with the originals
Roger W

Thank you very much for the responses, guys. Having only had the car for a few weeks, then having had a baby (well, my wife did) and been snowed in I have not got to know the car that well, yet - so I confess I don't know much about the history of my discs/pads. Those are reassuring thoughts, I'll keep an eye on it. Having owned my previous classic for just over ten years, I had forgotten what it is like not knowing every inch of a car well!
Piers Colver

This thread was discussed between 18/04/2013 and 22/04/2013

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