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Brake pedal become soft

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rigasr

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Discussion starter · #1 ·
I recently started noticing that I have to depress my brake pedal all the way to the floor when needing to brake hard. My brake pedal travels quite a bit before you feel the treg braking. The pedal is not spongy, still firm but have to press it quite far for brakign effect to start.
The brake pads and rotors are still good. There is fluid in the reservoir.

Would you think a brake fluid flush is needed here? Or brake lines need to be bled? Or some other possible problem?
 
Discussion starter · #3 ·
Mine goes all the way to the floor, cant go any further. Kinda scary as my treg just stops at that furthest point. Its never been like this, gradually got worse.
I will try bleed the brakes this weekend but any other advise I should try / look at?
 
#4 ·
rigasr said:
Mine goes all the way to the floor, cant go any further. Kinda scary as my treg just stops at that furthest point. Its never been like this, gradually got worse.
I will try bleed the brakes this weekend but any other advise I should try / look at?
Click to expand...
Sounds pretty dangerous. I'd keep my driving to a minimum and take it to VW to have it looked at.
 
Discussion starter · #5 ·
I'm avoiding the stealership. Going to bleed the brakes this weekend and see if that helps however I understand if there is air in the system it should feel spongy. Mine doesnt but I'll do it anyway. It's time to flush the brake fluid anyway.
 
Discussion starter · #7 ·
Flushed the break fluid and bled all the brakes, no luck still the same problem.
I suspect as per NKAWTG's post, the seal in the master cylinder is leaking.

Anyone know a part number for a seal kit for the master cylinder?
 
Discussion starter · #10 ·
I am open to any other suggestions to what else it could be. My numerous google searches (not specific to the Touareg) all point to the master cylinder. There is really not much else left in the equation here on what it can be.

That part is $265 after 15% discount. I will replace it myself with help of a buddy but I'm sure going to the stealership, this would be around $700.
 
#11 ·
You need to do a full trace down test. You need to pull the wheels and check the mechanical brakes to be sure that there isn't an issue with them. Have you been leaking brake fluid? If not, then even a weak master cylinder cup between circuits would still provide enough force to allow for safe braking in normal driving. I believe this master cylinder reservoir has a low fluid alert in the MFI, so has that gone off?

Just changing parts is likely to lead you to an expensive bill. You need to trace thru the system first, eliminating elements before wholesale changes. Frankly, in my professional view, relatively few current design master cylinders need early replacement. This would be an early replacement. Even with poor brake fluid maintenance, comparatively little internal rust particulates build in these modern aluminum based brake designs, so they last for a good long while. It's iron based components that are prone to a failure cycle of 7-10 years, 100,000 miles, etc. from internal rust corrosion, abrasion, and pitting.

Good luck!
 
#12 ·
There are lots of subcomponents!

rigasr said:
I am open to any other suggestions to what else it could be. My numerous google searches (not specific to the Touareg) all point to the master cylinder. There is really not much else left in the equation here on what it can be.
Click to expand...

Actually, the are lots of hydro-mechanical devices within the Touareg brake system due to EBD, electronic brake force distribution. This is far from simple to button hole.

Do the trace down, check the mechanicals for something out of position, or a missing item, like a brake pad, silly as that may sound to many folks here.
 
Discussion starter · #13 ·
Thanks for the input QPower1. We've pretty much gone through all described above. Everything appears to be in place. There is no brake fluid leak.
I suspect the seal in the master cylinder is leaking..... meaning, not leaking out but leaking back into the reservoir when the brake is pressed.
When you pump the brakes and press, it is stiff but slowly sinks to the floor when keeping pressed. From all I could research, it pointed to master cylinder internal seal leak where the brake fluid leaks past the internal seals back to the reservoir at high pressure instead of keeping the pressure on the calipers.
 
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