[T2] Disc brakes dragging

Chris Dreike cdreike at gmail.com
Sun Aug 16 13:33:20 PDT 2020


Wow, Thanks for all the input. All the parts are new save the steel brake
lines. The brakes worked fine before I installed the drop spindles.
I looked up How works a brake booster. The brake fluid level is not
dropping. There appears to be a weep hole at the bottom of the M/C mounting
flange. No fluid dripping out.
Yes the brakes are working fine with the vacuum line disconnected from the
intake manifold. The vacuum check valve is new and working as I checked the
function.
The vent line is in good working order. Sadly the boot at the front of the
booster is shot after an year and a half. Anyone know where to get a new
one? I'll try Wolfsburg West tomorrow.

Later today I will add a small shim between the M/C and the booster and see
if that helps. The booster seems to be the problem. Will report back later.

Erik, Where is the check valve you mentioned earlier? Is it in the M/C? or
were you referring to the vacuum check valve in line to the manifold?

AND one more thing. In perusing the forums on the Samba I found a post
complaining of exactly the problem I'm having. New booster from Wolfburg (
I got mine from CIP1 and it looks to be the same manufacturer) and his disc
brakes were dragging. I did not see a solution on that thread however there
were a lot of posts saying to have your old OEM booster rebuilt rather than
buy a new one as the new ones are problematic.

Cheers,
Chris

On Sun, Aug 16, 2020 at 7:10 AM Jamie <jrivers at globalserve.net> wrote:

> Inside the booster, there is a valve, opens on brake application and
> allows vac to assist movement Of cylinder in master cylinder
>
> If fluid is in that area, it will hold the port open,, and keep brakes
> applied while vacuum is available
>
> and when more fluid gets in there ,,A slight tap of the pedal will cause
> the vac to depress it and pull it out from under your foot, and apply
> brakes fairly hard!
>
> Sounds to me that there is fluid that has bypassed seal on master ,,, over
> the years,, so you don’t notice a recent drop in fluid in the reservoir,,
>
> Pull the master (loosen off far enough) and field fab a dip stick from box
> board to slide into booster below the master .. see if there is fluid in
> there
> I don’t worry about a little fluid,,
>
> If there is a “lot” <relatively speaking,, I’ve devise a way to siphon/
> wet vac out the fluid ... a u shaped steel line ,,
> There isn’t much room ,,
>
> Of course , if there has been a recent drop in reservoir level,, then a
> master cyl repair/ replacement is in order
>
> My take on it,,  Jamie
>
> > On Aug 16, 2020, at 9:51 AM, Erik Burtis <ewdb92 at gmail.com> wrote:
> >
> > I was thinking about this problem early this morning.  Let's see: You
> said
> > you replaced all the brake lines, so unless dirt got into the system at
> > that time or there is a defect, they shouldn't be the issue..  The
> problem
> > went away when you disconnected the brake booster.  I think this rules
> out
> > blockage in the lines or brake fluid issues.  This sounds like a buildup
> of
> > vacuum to me and when you stop driving and press the brakes, you release
> > the vacuum.  It can happen if the check valve is in backwards; can also
> > happen if the booster vent line is blocked (did it get pinched during
> your
> > spindle work?).  Do both front brakes drag?  If so, also an indication
> this
> > is not line related.  Maybe a failed booster would hold extra vacuum, but
> > it seems to me that they do the opposite.  One of the tests for a failed
> > booster is a change in rpms when you press the brake pedal.
> > Erik
> >
> >
> >>
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