Thinking of drilled rotors to improve wet braking delay - Thoughts? Durability? (bit long)
10-16-2003, 10:07 AM
#1
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Thinking of drilled rotors to improve wet braking delay - Thoughts? Durability? (bit long)
After 75K miles on my '98.5 Avant, I am thinking of putting drilled rotors on it. Reason is to cut down (eliminate?) a wet braking delay that has been in the car since day one. This "delay" is basically when driving in a heavy rain, if I apply the brakes I get NO braking action for as much as a second (which sometimes feels like a minute!). The dealer has looked at this umpteen times and can't find anything unusual. Friends wiht A4's have diffferent experiences - some have ikt, others don't. The "wet braking" kit was installed by the dealer (additional brake backing plate splash shields and water dams under the front of the wheel well) and I installed the ATE slotted rotors myself. Still feel it.
The ATE rotors are now worn down so that the slots are gone (even so, before they wore down the very thin slots filled solid with baked-in brake pad "dust") so am thinking about another set of rotors (30K on this set). Debating about drilled, because I feel if anything will eliminate this delay, drilled rotors will. Want OE rotor size; no big fat A8 or "Big Reds", etc. since they won't clear my 15" snow tires.
Was curious about forum-ers experience with drilled rotors. Get better wet braking? What about durability? I expect them to not be as durable as slotted rotors, from going thru 5 sets of front OE drilled rotors on a Porsche 993 in 70+K miles (sees maybe 5 track events/year). Good suppliers? Don't want to have happen to me what happened on the Porsche when I bought one set of drilled rotors from a supplier that warped badly in the first 10 minutes of track use and were completely cracked to the outside edge in less than 5000 miles of driving. Been thinking about ECS but your thoughts would be appreciated.
Oh yeah - did search on "drilled rotors" and didn't find much in the A4 forum.
The ATE rotors are now worn down so that the slots are gone (even so, before they wore down the very thin slots filled solid with baked-in brake pad "dust") so am thinking about another set of rotors (30K on this set). Debating about drilled, because I feel if anything will eliminate this delay, drilled rotors will. Want OE rotor size; no big fat A8 or "Big Reds", etc. since they won't clear my 15" snow tires.
Was curious about forum-ers experience with drilled rotors. Get better wet braking? What about durability? I expect them to not be as durable as slotted rotors, from going thru 5 sets of front OE drilled rotors on a Porsche 993 in 70+K miles (sees maybe 5 track events/year). Good suppliers? Don't want to have happen to me what happened on the Porsche when I bought one set of drilled rotors from a supplier that warped badly in the first 10 minutes of track use and were completely cracked to the outside edge in less than 5000 miles of driving. Been thinking about ECS but your thoughts would be appreciated.
Oh yeah - did search on "drilled rotors" and didn't find much in the A4 forum.
10-16-2003, 10:12 AM
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BTDT...
I tried both drilled rotors & slotted rotors on my A4 and found that pad material made more of a difference in reducing the wet braking issue, than the type of rotor. Mintex pads with slotted rotors seemed to be about the best in my situation. That's also what I currently have on the GTI.
What pads are you running now?
What pads are you running now?
10-16-2003, 10:21 AM
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IMO, they do not improve wet braking at all...
i have zimmerman cross drilled with mintex reds and it's my opinion that the wet braking situation has become worse than stock. i do not have the "wet braking" kit so i can't comment on them but would be interested in feedback from others as well.
10-16-2003, 10:21 AM
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Don't bother...
drilled and slotted stock sized rotors don't yield any improvements in performance (wet or dry)...people have reported on this issue many times before. Furthermore, the xdrilled rotors will just eat through your pads like a cheesegrater.
Based on the reading I've done, installing larger airdams under the bumper, directly in front of the wheel will make an appreciable difference. Audi created a a kit, but perhaps they aren't large enough. It shouldn't be too difficult to fashion your own little spoilers. You'll notice that a number of cars now use these little spoilers.
I think Craig is also right about the pad composition playing an important role. Although, I can't recommend specific pads that do work well in the rain, since this is mostly a theory. Proper pad bedding procedures, as some stoptech customers have learned, also plays an important role.
Based on the reading I've done, installing larger airdams under the bumper, directly in front of the wheel will make an appreciable difference. Audi created a a kit, but perhaps they aren't large enough. It shouldn't be too difficult to fashion your own little spoilers. You'll notice that a number of cars now use these little spoilers.
I think Craig is also right about the pad composition playing an important role. Although, I can't recommend specific pads that do work well in the rain, since this is mostly a theory. Proper pad bedding procedures, as some stoptech customers have learned, also plays an important role.
10-16-2003, 10:29 AM
#7
During heavy rain, I left foot brake to warm 'em up before really using them. end of issue.
which has been rare that I've had the issue - maybe 2 or 3 times.
When I'm on the highway in the rain for an extended period of time without braking, I just lightly hold the brakes with my left foot a few times (before the throttle kicks out). So, hold a constant speed, then hold the brake maybe 2 seconds on, off, 2 seconds on, off.... take the exit ramp, full brake, turn.... and go on about my trip without the wet braking issue.
sure, it's not a true fix, but it solves the issue.
When I'm on the highway in the rain for an extended period of time without braking, I just lightly hold the brakes with my left foot a few times (before the throttle kicks out). So, hold a constant speed, then hold the brake maybe 2 seconds on, off, 2 seconds on, off.... take the exit ramp, full brake, turn.... and go on about my trip without the wet braking issue.
sure, it's not a true fix, but it solves the issue.
slotted either
