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Mike S.
Mike S., Mechanic
Category: Car
Satisfied Customers: 7567
Experience:  25+ years experience as an auto mechanic.
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pistons..front brake..braking are: vibration, judder or steering pull

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When I brake at speed, particularly once warmed up, I encounter a rather pronounced rumble from the OSF of my vehicle. That is despite my having renovated (& further freed) the pistons of each front brake caliper. What I cannot claim to have experienced upon braking are: vibration, judder or steering pull. I drive an '08-plate R/Kangoo van (in limited 'Estate-like' Venture trim) powered by a 1.5DCi engine with 63,000+ miles recorded. Also, despite having passed its MoT last Dec', the ventilated discs now appear lipped by approx 3mm and the OSF wheel-rim feels only slightly warmer than the other at the end of a motorway journey. Is it possible for my van's OSF disc to be so tolerably distorted as to create unhealthy sounds with no other obvious symptom? I'm hopeful of no more sinister an underlying cause than a minor irritant and that SL08 TLN is safe to continue driving.

I can think of one thing. If that rotor is too thin. If it's been machined too thin in the past, that could cause problems with heat and thus possibly the rumble you hear. Although, I have no manual or specs for that vehicle, most of the time the minimum thickness is stamped right on the rotor. You will need a micrometer to measure the thickness, plus measure in 3 spots around the circumference to check for uneven thickness, which also could cause a rumble before it becomes so bad the brake pedal actually pulsates when braking.

Also, check that wheel bearing for being loose or worn.

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