Pulsing brakes

[nip]

Yup, front and rear.

Got built with new ones

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i was told the seals are sided if they go in the wrong way the brakes would feel weak

[willg54]

Will when it was off the road did u strip the pistons and seals out of the calipers ?

Where were you going with this comment? I thought as it doesn't pull in any direction when braking that it wasn't a caliper issue but more an hydraulic assist one

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[MarkT]

If its pulsating at low speed then I would think its one of the sensors on the hubs.
I had this on my S2, ur and A4.

[Error404]

Will in my experience if its a bad servo you can feel it pulsing with your foot on the brake sitting at idle as well as when you are braking on the move

[willg54]

If its pulsating at low speed then I would think its one of the sensors on the hubs.
I had this on my S2, ur and A4.

I think all the sensors are working ok now.

you can feel it at high speeds too, but just more obvious at lower speeds.

It feels like im coming on and off the brake pedal a bit, the front of the car is going up and down with the braking power

[willg54]

Will in my experience if its a bad servo you can feel it pulsing with your foot on the brake sitting at idle as well as when you are braking on the move

there's nothing at idle.

im starting to think that one of the pads is contaminated or the front discs arent within the correct tolerance of run out...might go pick a dti up tomorrow and measure them

interestingly..the rear right disc still has a band around the centre of the contact face that looks like it hasn't bedded in. i think they brakes are still coming in a bit

[Error404]

go pick a dti up tomorrow and measure them

check the hub face too

[MarkT]

Will,

The sensor position is critical, on the ur there are white plastic caps that position the sensor at the correct distance away from the reluctor ring on the cv joint. Have you you checked each reluctor ring for debris or even a crack that can offset the distance?

Mark

[nip]

Where were you going with this comment? I thought as it doesn't pull in any direction when braking that it wasn't a caliper issue but more an hydraulic assist one

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Thats what I was told when I rebuilt my calipers , when I first drove mine after ages I had the same problem with the pedal feeling like it was pulsing all I done was re-bled the brakes then they felt much better

[willg54]

Thats what I was told when I rebuilt my calipers , when I first drove mine after ages I had the same problem with the pedal feeling like it was pulsing all I done was re-bled the brakes then they felt much better

ive rebled them 3 times now! was your whole car jerking as you braked?

[willg54]

thought i'd clear this up a bit!

Symptoms

• under braking, the car brakes in a straight line but jerks with hard and soft braking
• has had a few abs errors with sensors but all currently working

Whats been done:

• all brakes rebuilt - new seals etc
• 993 front brakes
• re-bled several times - no air present
• all pads are new
• rear discs are new
• front discs are skimmed (with in tolerance as far as i know, will check)

I've tried driving the car with ABS disabled and there was no change in the symptoms.

If a disc was warped or contaminated, would the car pull in the opposite direction to the stronger side?

I might do another 130mile round trip to measure everything up tomorrow. It's playing on my mind

[nip]

ive rebled them 3 times now! was your whole car jerking as you braked?

yes was jerky

[willg54]

yes was jerky

out of interest, which way round were you told the seals should sit?

[nip]

out of interest, which way round were you told the seals should sit?

Domed bit facing outwards remind me tomorrow and il find u a pic of mine out

[Tony Stark]

If you're parked up and it doesnt pulse in neutral at idle, then 60mph in neutral at idle and they DO pulse its got to be discs or something.*Or is the speed of the pulsing consistent regardless of road speed?

Like Error said Id go for the dti gauge on each brake disc at a time, if the wheel's off at the time of checking then put the bolts back in tight with spacers of some sort, if and when you find the corner with runout take the disc off and check the hub right across the face of it and inside the hat of the disc.