# Brakes slip at low speed



## MaSeDoGG (Jan 22, 2004)

When I am at parking lot speeds, I will press the brakes and it will feel rock hard, but my car will still be moving. I noticed it first when I was in reverse, but it also does it in forward. 

The car is an automatic tiptronic. Has TT front brakes but it did it also with the stock rotors. Pads look fine, but braking could be improved all around. I didn't notice a massive difference with the TT upgrade. 

Does it need a brake flush or a new brake booster? Abs? 

Any ideas or suggestions would be great. Thanks!


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## VWBugman00 (Mar 17, 2009)

MaSeDoGG said:


> When I am at parking lot speeds, I will press the brakes and it will feel rock hard, but my car will still be moving. I noticed it first when I was in reverse, but it also does it in forward.
> 
> The car is an automatic tiptronic. Has TT front brakes but it did it also with the stock rotors. Pads look fine, but braking could be improved all around. I didn't notice a massive difference with the TT upgrade.
> 
> ...


First, please stop driving until you've got this figured out. No accidents allowed!

Now, it sounds to me like you may have a vacuum leak on your brake booster. I'd go get some ether (starting fluid) and spray the vacuum line from the booster to the intake manifold while the car is running. If it jumps or hesitates, you've got a leak on that line. Replace it, and check again. If that isn't it, try bleeding it. If it's not that, I'm not sure. Could be a brake booster, and I hope it's not, they're a pain to change.


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## DC Jetta Guy (Jul 31, 2004)

Look at this post...it has a pic of what is likely the problem and is easy to fix:

http://forums.vwvortex.com/showthread.php?5951521-What-is-this-hose-for


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## KG18t (Aug 9, 2006)

Is the pedal normal at higher speeds? When the pedal is like that at parking lot speeds, is there any accompanying noise? Does it pulse at all?


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## MaSeDoGG (Jan 22, 2004)

I meant to report back in this thread. I had another thread made in the MK4 section. 

It turned out the be a cracked brake booster vacuum pump hose w/ check valve. It is only on cars with automatic transmissions. The pump is located up under the subframe by the downpipe (and is sort of a hassle to get to).

Not exactly sure what the part number on my car was, but it has since been revised and updated to P/N: 1J0612041FQ


I got the hose at ECS for $67.91


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## VWBugman00 (Mar 17, 2009)

MaSeDoGG said:


> I meant to report back in this thread. I had another thread made in the MK4 section.
> 
> It turned out the be a cracked brake booster vacuum pump hose w/ check valve. It is only on cars with automatic transmissions. The pump is located up under the subframe by the downpipe (and is sort of a hassle to get to).
> 
> ...


Glad to hear it's fixed :thumbup:


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