Prior to the BoXa.net trackday at Donington in October I did all my usual checks on the car and to be on the safe side did a full flush of the brake fluid. All in all it was a great trackday but I had to put up with very bad judder throughout the day. The short video below shows the judder - the video bounces up and down when I'm hard on the brakes:
All the discs and pads had been changed a few months ago and I'd done three trackdays without any judder issues. However, all of those trackdays had been on the wet side, so it's possible they hadn't been worked too hard. The Donington day was very dry so the brakes got a proper work out and that's when the judder came on strong. Some immediately say that brake judder is caused by warping the discs by overheating them. Others, much more knowledgeable about brakes than me, insist that a warped disc is very rare and that judder is caused by uneven pad deposition on the disc surface. I tend to side with the latter idea, especially since there was no sign of judder on the way home when the brakes were back to normal temperature.
The other factor to consider is that while I have continued to run Pagid greys on the front I'd switched the rears to standard pads - partly because my rear pagid greys had started to fall apart (lots of use) and I wanted to see if the rears really needed an agressive pad (because they do less braking) and partly because I was too tight to spend another £200 on a new set of greys.
On inspecting the brakes the rear discs looked fine:
While the fronts were loaded with pad deposits:
The front pagid grey pads looked glazed and had started to crumble at the edges (top of photo below) while the standard rear pads looked like they had been coping very well.
On closer inspection of the front discs after I had removed them....there were clear signs of pad material being stuck all over the place and possibly some tiny cracks appearing on the disc face:
I have no way of cleaning up the front discs (if they're still good) and with a trackday coming up I decided that the only wise thing to do was buy a couple of new discs (£130) and bang them on. New and old discs shown below:
While all this was going on I'd received some advice and suggestions that there was a good chance that the Pagid greys are a very fierce brake pad and would have been doing a lot of the braking work on their own because of the standard pads in the rear. This could have lead to excessive temperatures at the front and the pads braking down, depositing on the disc and causing the judder. To prevent this I should use the same compound front and rear and move away from the Pagid grey as it heats up discs too quickly. It was recommended that I try Hawk blues for a change. This sounded worth a try, especially since the Hawks come in at a price for two sets, including shipping from the States and tax, which is the same as one set of Pagids! So the Hawk blues were duly ordered and fitted:
While working on the brakes I took the photo below - the car is only jacked up at the front left ready to change discs and pads...it's so stiff that it lifts the front right at the same time ^_^
With the brakes all sorted again and bedded in, it was off to Oulton Park for my last trackday of the season.
Yet again it turned out to be a very wet day!
This was actually the first time (in about 7 goes) I'd ever driven Oulton in the wet. It was of course much slower than normal but no where near as daunting as I thought it would be and I ended up having a great time.