Liz

Every rainy morning, at the same stop sign (about 8 blocks from my driveway), I mentally prepare myself for my early morning coronary. I approach the sign (at the end of a slight decline) at about 25 miles per hour, apply the brakes and feel nothing momentarily, which triggers heavy ABS "thumping". The ABS stops the car - but for a couple of seconds there, I feel like Katarina Witt preparing for a triple axel. Is this the same exact "wet braking" problem that others are experiencing? Does your ABS aggressively take over like mine? How does the ABS get triggered?

Tom

Every wet days I tried to brake my A4 with 4 seconds wet braking delay problem. Here are what will happened:
1) The first 3-4 seconds there were no braking input or braking response from the brake pedal
2) When I pressed down brake pedal deeper, the ABS kicks in aggressively. What I meant aggressively? Since the first 4 seconds don't have response, your initial response is try to press the brake as bit harder. As I tried to brake harder, I almost kicked in the ABS for a couple of times on the wet.
Now I learned to brake much much earlier during wet days or even drive my Bora instead of A4 when the weather gets really poor. Funny thing is I have no problem when brake in snow but freezing rain or any rain will have a huge problem.
Tom
97 A4 1.8TQMS
99 BORA GLS 2.0
00 (OR 01) NEW BEETLE GLS 1.9TDI (ON ORDER)
98.5 A4 1.8TQAS WETTED

ErikR

Audi has one of the best abs systems in the world, it also occasionally has a very scary initial wet braking feel. They happen in two very different conditions, niether is dangerous imho, just an issue to get used to.

If your abs is kicking in there are several things that are going on. 1. Your car is new and the pads are not "broken in." This has been talked about forever. It takes a few hundred street stops to get the grabbiness out of new brakes. 2. You have new or the wrong tires on the car. (are you using p8000's on snow or gravel? Or, non-sport in the winter?)

ABS is supposed to feel like it does. Jamb the pedal to the floor, keep it there. Ignore all noises and pedal feedback. This WILL NOT HAPPEN unless you are in an emergency, on ice or 1/2 above.

If you do not feel inital brake grab, you are driving in the wet or you have the wrong tires on the car. Many a4's have an inital lack of grab in wet conditions due to THE LACK OF REAL INNER BRAKE SHIELDS. Audi has a fix available.

pauls

Have not seen a "formal" release of any fix. Can you provide more info?

ErikR

But if you complain to your dealer they will magically find at least 1 of the two tsb's that I'm familiar with (sorry no numbers on hand). There is a replacement inner brake shield discussed on the board and a pad "fix."

Liz

Just for the record...my 1998.5 A4 Quattro now has over 18,000 miles on it - so the brake pads have been broken in. My tires are from the original Dunlop 16" sport package. The ABS kicks in when braking from relatively slow speeds (20-35mph) in mild rain. My question is, what exactly causes the ABS to kick in? Does it sense skidding? Or, that the regular braking system is not responding? (It feels as if the regular breaks have failed for a couple of seconds.) To my knowledge, I have not slammed on the brakes or pumped them. I merely press down to stop, the car continues to glide and then the "thumping" takes over. I tend to press down harder at this point, to make sure I'm going to stop. The car does stop - it's just very weird and a bit frightening.

ChrisR

Try searching the archives for "Wet Braking"..have fun...

mac

release pressure from that brake. It will build pressure again almost immediately trying to give you the same braking deceleration of the other wheels/tires. That build/decay cycle is what you feel back through the pedal. Next time you are approaching that scary stopsign on a wet day, apply your brakes once one block before you usually would. This will do two things, 1. ensure that your piston is in a proper location, 2. clear off and dry the rotor/pad interface of excess water. You may want to change your lane position on the road in case there is a slick spot causing only one side of the car to skid (and engaging the ABS to prevent a skid).

Let us know and good luck.

Mark 99.5 1.8Tqms

ErikR

I would suspect your tires are toast. The abs detects large differences in rotational speed. So, one wheel actually has to lock up before it engages. The only other logical possbility is that one of the calipers is frozen (piston not moving). This is very unlikely, less likely still is a pad failure. These are all easy to test. Look for the tread wear bar on the tires. Jamb on the brakes on sandy, gravelly surfaces and look and see if only one tire drags. Listen for a loud screeching noise when you brake.

Tony

nt