Nasty Scrap in 64 A4 TDi. Brake failure??

[Hugie11]

I have aA4 TDie 136 in Volcano red. Already done 8900 miles since 4th of September. Company car through ALD.This week, i've been noticing the brakes have been going soft and at times ihave to really press the brake to get them working.

Today, I was parked at a friends house drive, which was on a decline, so my carwas facing downhill to the garage. It was about 5ft from the garage building.When I left, got in the car, seat belt on, started the car. As i needed toreserve, I assumed the electronic brake would would release once I got enoughpower to the wheels to reverse. It wasnt interested and instead the computertold me to manually release the electronic handbrake by putting my foot on thepedal brake. At this point I was concious at this point I would have to reversewithout the clutch and gas pedal at the same time. Anyway, I proceeded asinstructed and pressed the brake then unlocked the electric handbrake switched.However, as I did this, the pedal brakes completely failed and I rolled forwardinto the corner of the brick garage causing a lovely dent/scrap on the wheelarch and a scrap on the alloy.

I don't understand why I had to release the electric handbrake manually using the foot brake? The car was still warm after travelling 40 miles to my friends 30 mins prior. But more importantly why have my brakes failed?

[Guest 2]

If certain conditions aren't met then the handbrake will require manual intevention from the driver to release, ie on a de/incline.

Take it to Audi and see if there any faults stored, if not then I'm guessing it'll be down to driver error as you should've really been on the bite with the clutch whlie releasing the handbrake.

[AJB Audi]

Isn't this the Achilles heel of the electronic handbrake system when you are driving a manual car?

You effectively need three feet to complete this without rolling forward or back - one foot on the clutch, the second giving the revs and then you suddenly need to apply pressure to the brake pedal so that you can release the electronic handbrake. But as soon as you take your foot off the accelerator you lose the revs, and as soon the electronic brake is released you start to roll forward or back until you can get back on the revs again?

If you can do it quickly you minimise the risk but that's easier said than done when, like the OP, you are close to a wall!

I've only driven a couple of courtesy cars with this facility and was glad I never found myself in this scenario. I thought the problem was eliminated if you had the hill hold assist option but that this wasn't always fitted. Or possibly I'm completely wrong and I was not told how to use it properly?

[Hugie11]

Yes, its manual and it doesn't have the hill hold assist. I'm use to getting the bite using the clutch and the gas pedals together, especially on hills. Given the incline, I didnt think power in the clutch alone would be enough to get me to reverse up the hill, when I had to put the foot on the brake to release the electric handbrake. I think i've unwittingly put myself in the worst case scenario with this type of handbrake system.

What bugs me more is why the foot brake failed. Past week or so, I'm having to press the brake over an inch at least before the brakes react in any way. My wifes Zafira has better brakes. Is this normal for an Audi??

[Embisix]

Seems to me that you have a fundamental (and potentially very dangerous) problem with your brakes. The weight of your foot on the middle pedal alone should stop the car rolling, no matter what the angle of the slope (ok, slight exageration, but VWAF brakes are traditionally very responsive at the top of pedal travel, some would say a bit too grabby!). Your middle pedal should never go soft and should never require concerted effort to apply the brakes.

Get this checked out asap, you could be looking at more than a scraped wing otherwise.

Going back to the scenario with the e-brake. If you dis-engage the brake as instructed but keep the car in neutral with your foot on the brake pedal, then re-engage the e-brake and then put it in reverse and raise the clutch, the e-brake should automatically dis-engage. Manual dis-engagement was required here because you'd just started the car.

[Doctle Odd]

The clutch at biting point can hold any car easily

[zollaf]

.This week, i've been noticing the brakes have been going soft and at times ihave to really press the brake to get them working.




this is worrying. your car has some problem with the brakes, so rather than do anything about it, like stop driving it, you do nothing.

[Zenerdiode]

It's in the handbook that in this situation, you get the clutch bite; then click down on the parking brake switch. The e-brake releases as normal. In this situation you do not need footbrake pressure to release, just the engine to sense torque which it will at the clutch bite point.