Really bad brake judder
10-15-2010, 12:16 PM
#47
Nordschleife Master
10-15-2010, 12:26 PM
#48
Rennlist Member
If you have them off then just have the rotors surfaced. Then bed them in as new. That's the low buck option but you will use up some rotor life. Just have enough taken off to clean them up. It's only one more screw to pull the rotors after the calipers are out of the way...
10-15-2010, 12:28 PM
#49
Addict
Rennlist Member
Rennlist Member
Jeez, everybody beat me to it! 
Yes, Steve, time to change it up. Replacing old parts with exactly the same thing will probably produce the same outcome. And you'll be out a tidy sum.
Yes, Steve, time to change it up. Replacing old parts with exactly the same thing will probably produce the same outcome. And you'll be out a tidy sum.
10-15-2010, 01:46 PM
#50
Nordschleife Master
Thread Starter
Thanks for all the comments, suggestion and interest fellas 
In reply to all of them:
Craig - yep I'll be taking pics of rotors and pads tomorrow as I know you're all interested to see the state of them.
Indy - thanks for the Japspeed link. They're not showing any stock for Porsche but I might contact them to see if they can supply. It's a labour of love so that bit is no cost.
J - yep I'm good with removing rotors having done it many times. These won't be getting thrown, I'll find somewhere to get them skimmed and will try them again at some point.
Joey - I've been changing up all the time. Started tracking with standard brakes and pads (textar), then upgraded 2 pot rears to 4 pots, then went to Pagid sport (dark blue), then went to Pagid grey RS15 all round. The latter provided phenomenal braking with no fade or judder.
The only mistake it looks like I made here, according to our collective opinion, is that I tried a road pad on the rear while keeping the RS15 on the front. This seemed good initially but in retrospect, the first couple of trackdays were wet so the set up never really got tested to the full. Last week on a warm dry track it looks like the front RS15s were vastly outperforming the standard rears. I've taken the lesson on board that I need to run the same pads all round and that the RS15s are probably a bit too harsh and I would be better with RS29 yellows all round. Also, adding some more cooling is likely to be a winter project.
In reply to all of them:
Craig - yep I'll be taking pics of rotors and pads tomorrow as I know you're all interested to see the state of them.
Indy - thanks for the Japspeed link. They're not showing any stock for Porsche but I might contact them to see if they can supply. It's a labour of love so that bit is no cost.
J - yep I'm good with removing rotors having done it many times. These won't be getting thrown, I'll find somewhere to get them skimmed and will try them again at some point.
Joey - I've been changing up all the time. Started tracking with standard brakes and pads (textar), then upgraded 2 pot rears to 4 pots, then went to Pagid sport (dark blue), then went to Pagid grey RS15 all round. The latter provided phenomenal braking with no fade or judder.
The only mistake it looks like I made here, according to our collective opinion, is that I tried a road pad on the rear while keeping the RS15 on the front. This seemed good initially but in retrospect, the first couple of trackdays were wet so the set up never really got tested to the full. Last week on a warm dry track it looks like the front RS15s were vastly outperforming the standard rears. I've taken the lesson on board that I need to run the same pads all round and that the RS15s are probably a bit too harsh and I would be better with RS29 yellows all round. Also, adding some more cooling is likely to be a winter project.
10-15-2010, 02:03 PM
#51
Addict
Rennlist Member
Rennlist Member
Joey - I've been changing up all the time. Started tracking with standard brakes and pads (textar), then upgraded 2 pot rears to 4 pots, then went to Pagid sport (dark blue), then went to Pagid grey RS15 all round. The latter provided phenomenal braking with no fade or judder.
I guess I don't agree with the conclusion--using different compounds causes judder. Racers/trackday regulars mix compounds often--Yellow fronts/Black rears, Black/Orange, Pagid/PFC--and I don't recall anyone citing such "mixes" as the cause of judder. What I have heard with consistency is that specific compounds are more likely to produce judder, e.g Pagid Orange.
Given that the RS15's produced judder on your car, I'd say it's quite likely that it will happen, again. I'd consider a change in compound, as well.
10-15-2010, 04:56 PM
#52
Nordschleife Master
Thread Starter
10-16-2010, 01:30 PM
#54
Nordschleife Master
Thread Starter
Here are the photos I took of the brakes today.
A front rotor while on the car:
Close up view:
Rear rotor (no worse than I would expect after a trackday):
Front pad (Pagid RS15) on the left and rear pad (Pagid road) on the right. There was plenty of meat left on all of the pads (more than 50%):
Front rotor after I had taken if off next to a new front rotor:
Close up view of front rotor - looks like there are tiny cracks?
This view of the front rotor shows how paint has come off the hat around the lugs:
....and transferred onto the wheel shim:
I fitted the new front rotors and put these Pagid road pads in to match the ones in the rear:
I also decided to leave the shims off and went out to bed the pads on. After a few miles they were performing brilliantly. So now I need to decide what pads to get in time for the next track outing in just under 2 weeks time.
An interesting pic....when jacking up one side the opposite side comes off the ground...a testament to how stiff these cars are
A front rotor while on the car:
Close up view:
Rear rotor (no worse than I would expect after a trackday):
Front pad (Pagid RS15) on the left and rear pad (Pagid road) on the right. There was plenty of meat left on all of the pads (more than 50%):
Front rotor after I had taken if off next to a new front rotor:
Close up view of front rotor - looks like there are tiny cracks?
This view of the front rotor shows how paint has come off the hat around the lugs:
....and transferred onto the wheel shim:
I fitted the new front rotors and put these Pagid road pads in to match the ones in the rear:
I also decided to leave the shims off and went out to bed the pads on. After a few miles they were performing brilliantly. So now I need to decide what pads to get in time for the next track outing in just under 2 weeks time.
An interesting pic....when jacking up one side the opposite side comes off the ground...a testament to how stiff these cars are
10-16-2010, 04:34 PM
#56
Instructor
Hi, I had exactly the same issue with both my 964C4 and 944S2. I used EBC Yellows (rubbish) and Pagid Blacks (great breaking but the judder issue). A change to Hawk Blues fixed the issue, there was no need to skim rotors etc. You can get these easily from the States and they way their $ is at the moment, you are on to a winner.
10-17-2010, 03:45 PM
#58
Addict
Rennlist Member
Rennlist Member
Hawk part numbers are a bit odd: size and thickness (HB170x650) compound (E = Blue 9012) and partial SKU # (D345)
See line 7288 of Hawk Brake Pad Application Guide
Here's a good source from whom I buy quite a bit, Pegasus Auto Racing:
https://www.pegasusautoracing.com/pr...?Product=HB170
Although I DO buy my Pagid Blacks from Craig at RennStore!! www.rennstore.com
See line 7288 of Hawk Brake Pad Application Guide
Here's a good source from whom I buy quite a bit, Pegasus Auto Racing:
https://www.pegasusautoracing.com/pr...?Product=HB170
Although I DO buy my Pagid Blacks from Craig at RennStore!! www.rennstore.com
10-17-2010, 05:27 PM
#59
Nordschleife Master
Thread Starter
Much appreciated
With that info I managed to track down a source in the UK:
http://www.cambridgemotorsport.com/H...11---Blue-9012
With tax they work out at £159.91 + delivery. However if I get two sets shipped from Pegasus they work out at £105.60 including delivery. Plenty of food for my thoughts
With that info I managed to track down a source in the UK:
http://www.cambridgemotorsport.com/H...11---Blue-9012
With tax they work out at £159.91 + delivery. However if I get two sets shipped from Pegasus they work out at £105.60 including delivery. Plenty of food for my thoughts