Pad Knockback
11-11-2018, 08:17 PM
#1
Pro
Thread Starter
Pad Knockback
Hey guys, anyone else having issues with pad knockback?
I'm getting a long pedal after successive high g lefts and rights, or going over ripple strips. Pedal returns to normal if I give it a short dab before hand, so definitely is pad knock back.
It's been a persistent issues that I have had ever since tracking the car. It's an '86 turbo and it used to knockback quite badly with the stock brakes and hubs. I upgraded to late model hubs and spindles with brand new wheel bearings, running 993 turbo big red calipers on cayenne 330mm rotors, stock rear brakes. Knockback was significantly reduced with this setup, but I still get it occasionally under very high load successive left and right corners.
The front wheel bearings are timken brand, and I preloaded them until it was very difficult to move the washer (so on the tight side of factory).
Anyone dealt with similar issues?
I think my next step will be taking my front calipers off and installing anti knockback springs behind the pistons.
11-12-2018, 02:32 AM
#2
Three Wheelin'
I have not experienced much of this over the years, but it sounds like you have covered most of your bases . . . any more info on the "anti knockback" springs that you speak of?
11-12-2018, 01:19 PM
#3
Race Director
I have had this issue on a 944n/a while racing - only when running over rumble strips, a quick tap brings the pads back so no big deal there.
However Im having a similar issue with an E36 M3 and have replaced the brake booster, M/C, rebuilt calipers (Stoptech ST40 F+R), brake lines, replaced all 4 wheel bearings and am still having to tap the brake pedal prior to every braking zone, Im going to replace the ABS pump next and if that doesnt do it will add the springs you speak of...so I haven't tried them yet but they are "on the list", very frustrating.
However Im having a similar issue with an E36 M3 and have replaced the brake booster, M/C, rebuilt calipers (Stoptech ST40 F+R), brake lines, replaced all 4 wheel bearings and am still having to tap the brake pedal prior to every braking zone, Im going to replace the ABS pump next and if that doesnt do it will add the springs you speak of...so I haven't tried them yet but they are "on the list", very frustrating.
11-12-2018, 01:30 PM
#4
Drifting
I have this issue but only in certain high-G corners when hitting gators or a dip before track-out that really loads the outside wheel.
I have Racer's Edge rotors and was advised by Karl to run the bearings on the loose side rather than tight. I know where the issue occurs so just do a quick left foot tap to 1) reset the pads and 2) confirm the brakes are still there. #2 isn't a bad habit to get into before any hard braking zone, anyway...
Many other racers I've spoke with have the same issue, so it's not uncommon.
I have Racer's Edge rotors and was advised by Karl to run the bearings on the loose side rather than tight. I know where the issue occurs so just do a quick left foot tap to 1) reset the pads and 2) confirm the brakes are still there. #2 isn't a bad habit to get into before any hard braking zone, anyway...
Many other racers I've spoke with have the same issue, so it's not uncommon.
