Pagid RS4-2s pad build up / vibration

[xjay1337]

Can I get a bit of input from those knowledgable or have tried a variety of pads.
Both Rich and I seem to have this problem, me more so than him.

I did a trackday last Wednesday and the brakes did not fade at all. However by midway through my second session I was getting HUGE wheel shake (to the point where I thought the subframe was going to fall off) and ultimately why I stopped after one session after lunch

I have 340mm EBC USR Slotted rotors and Pagid rs4-2s. All were new fitted in December last year with new TTRS calipers and new fluid
The car has seen (fast) road use

Breaking from around 100 to 40 would give an AWFUL amount of vibration. sometimes it would be OK but you'd go to use them again and it'd be awful.
Once you hit 40 it stopped and didn't vibrate at all.

Alex seems to think this is pad build up but I'm not sure...

I'll probably be trying some mtec j-hook discs and new pads (either pagid rs29 or some project mu's that alex has) but want to understand what is going on....
shouldn't be getting pad build up with grooved discs.

Ironically now everything has gone back to normal with only a very faint high-speed vibration on light application - heavier stops eliminates the wobble.

[rich83]

Basically.. the pads just are not great. I think thats what it boils down to.

[pudding]

shouldn't be getting pad build up with grooved discs.

Are the grooves filled with compacted brake debris?  My old AP Racing grooved rotors did that.  Had to scrape them out with a pick periodically.  I was using Pagid RS15 at the time, which is a very soft pad.

[xjay1337]

shouldn't be getting pad build up with grooved discs.

Are the grooves filled with compacted brake debris?  My old AP Racing grooved rotors did that.  Had to scrape them out with a pick periodically.  I was using Pagid RS15 at the time, which is a very soft pad.

Does look like theres some build up in there.
But surely this shouldn't happen.
I am not sure if its pad build up or the remnants of the black coating that was on the disk when new.

Ironically some of the grooves have flattened off... these pads may have ruined the discs.

Overall I am not really impressed. Its a shame really.  They never faded.

[pudding]

I used DS2000, YellowStuff (rubbish), DS3000, RS15 and some Performance Friction Carbon Metallic...... they all clogged up the grooves with pad material.  And yep, the grooves will wear down also.  I wanted plain discs as it was predominantly a road car, but AP only offered drilled or grooved.  Not a fan of either tbh.

To be fair, I did get about 40,000 miles out of a set of AP grooved rotors before the grooves disappeared, though.   I used to clear them out every 500 miles or so.  Only took a few mins a side.  I did used to get a very harsh rumble through the pedal with soft pads like the RS15 too.

[rich83]

I hope I get 40k out of mine. That should mean mine last another 2-3 years

[Tfsi_Mike]

I have had this too. @DaveB@Vagbremtechnic able to offer any input?

[dan930]

I've also,had this too..sometimes I get vibration between 80-85

[Tfsi_Mike]

My vibration happens under braking

[dan930]

I used to get it between 55-60,but it's gone now,sometimes I get it between 80-85
& if I brake between 70-80 HARD

[Wash]

Is this just not warped discs?

[Tfsi_Mike]

I should hope not with fully floating 370mm brembo motorsport rotors 

[pudding]

Just to clarify, my vibration wasn't warped rotors (pulsing pedal), it was more like a grinding feel, like the ABS kicked in.  Pretty sure that was just soft pads being chewed up by the grooves in my case.

[rich83]

Is this just not warped discs?

Its very hard to warp a disc... and even harder if its 2 piece. But its very easy to get the pad outside their correct working temperatures and make them sh*t themselves.

[xjay1337]

Is this just not warped discs?

I wouldn't expect EBC rotors to warp in about 30k of mostly motorway mileage. I don't slam my brakes on and then sit on them. never had a warped set of brakes in my life less so with a new brake set up costing north of £1200 (I did source the discs on mine own cos Alex's ones were unfortunately not in stock).

Already going to try looking at new discs and pads in the coming months.