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B8 S4 Brakes spongy and ABS kicking in WAY too early following HPDE track runs
I have a 2012 B8 S4. Stock rotors, PC Hawk pads (to cut down dust). AFTER 1st of 4, 25 minute high performance drivers ed (HPDE) track session the brakes were quite "spongy" with 3x normal travel. Also, the ABS would kick in WAY too early (e.g. way before the wheels were even close to locking up) resulting in poor brake force. Also, when ABS kicked in prematurely, brake pedal would drop another 1-1.5 inches. Consulting with more experienced instructors and drivers, the best guess was that the brakes got hot enough to boil the standard DOT 4 fluid (which had JUST been replaced) and a brake bleed and flush were in order. Pushed nearly 1.5 liters Motul 600 through the system using Motive pressure bleeder to push new fluid into reservoir and out to calipers. This resulted in no change; brakes were still spongy with too much travel, ABS continued to kick-in WAY too early and cause brake force to be maybe a third to half of what it should be. The car was no longer track worthy; I removed it from the event.
This also happened after my last track event after the 2nd 25 minute run - but then the brake system "healed" over the next several days/week after the event. Any ideas as to what is the cause and how to correct/fix? |
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Originally Posted by Chip58
(Post 24952883)
I have a 2012 B8 S4. Stock rotors, PC Hawk pads (to cut down dust). AFTER 1st of 4, 25 minute high performance drivers ed (HPDE) track session the brakes were quite "spongy" with 3x normal travel. Also, the ABS would kick in WAY too early (e.g. way before the wheels were even close to locking up) resulting in poor brake force. Also, when ABS kicked in prematurely, brake pedal would drop another 1-1.5 inches. Consulting with more experienced instructors and drivers, the best guess was that the brakes got hot enough to boil the standard DOT 4 fluid (which had JUST been replaced) and a brake bleed and flush were in order. Pushed nearly 1.5 liters Motul 600 through the system using Motive pressure bleeder to push new fluid into reservoir and out to calipers. This resulted in no change; brakes were still spongy with too much travel, ABS continued to kick-in WAY too early and cause brake force to be maybe a third to half of what it should be. The car was no longer track worthy; I removed it from the event.
This also happened after my last track event after the 2nd 25 minute run - but then the brake system "healed" over the next several days/week after the event. Any ideas as to what is the cause and how to correct/fix? "Discussion forum for the D2 Audi A8 and S8 produced from 1994-2002" |
Originally Posted by Chip58
(Post 24952883)
I have a 2012 B8 S4. Stock rotors, PC Hawk pads (to cut down dust). AFTER 1st of 4, 25 minute high performance drivers ed (HPDE) track session the brakes were quite "spongy" with 3x normal travel. Also, the ABS would kick in WAY too early (e.g. way before the wheels were even close to locking up) resulting in poor brake force. Also, when ABS kicked in prematurely, brake pedal would drop another 1-1.5 inches. Consulting with more experienced instructors and drivers, the best guess was that the brakes got hot enough to boil the standard DOT 4 fluid (which had JUST been replaced) and a brake bleed and flush were in order. Pushed nearly 1.5 liters Motul 600 through the system using Motive pressure bleeder to push new fluid into reservoir and out to calipers. This resulted in no change; brakes were still spongy with too much travel, ABS continued to kick-in WAY too early and cause brake force to be maybe a third to half of what it should be. The car was no longer track worthy; I removed it from the event.
This also happened after my last track event after the 2nd 25 minute run - but then the brake system "healed" over the next several days/week after the event. Any ideas as to what is the cause and how to correct/fix? |
Originally Posted by socrates42
(Post 25391922)
I have the same issue. I'm running track pads, braided lines and Castrol SRF high temp fluid. Did you ever find out what the root cause was? My dealership is thinking brake master cylinder.
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