[T2] Disc brakes dragging

Chris Dreike cdreike at gmail.com
Sun Aug 16 19:57:57 PDT 2020


Hi Guys,
I tried 1/32 shims. Still working. Tomorrow I'll try 1/64th. Looks like
things were on the edge of working. These are small differences.

And thanks David. I'll scuff things up tomorrow and re-bed as you suggested.

Cheers,
Chris

On Sun, Aug 16, 2020 at 6:42 PM david raistrick <keen at icantclick.org> wrote:

> I'd start with a fresh bed-in and get them hot.  that might sort out the
> balance.  or scuff the pad surfaces and the rotors, then re-bed.
>
> On Sun, Aug 16, 2020 at 9:14 PM Chris Dreike <cdreike at gmail.com> wrote:
>
>> Thanks to you guys I installed 1/16" thick shims between the booster and
>> the M/C. Problem is gone! I'll try some thinner shims until the problem
>> returns and go with something thinner than 1/16. As it is now the pedal
>> goes WAAAY down to about 1.5" above the floor. I'll lengthen the pedal to
>> booster rod back to spec too.
>>
>> Now on to the next problem, the brakes pull to the left. I know that the
>> driver disc got pretty hot one time before I realized the brake drag
>> problem. The passenger side didn't get quite as hot. How can I remedy
>> this?
>> Have the disc turned? New pads?
>>
>> Success, of sorts, at last.
>>
>> thanks again.
>> Chris
>>
>>
>> On Sun, Aug 16, 2020 at 1:33 PM Chris Dreike <cdreike at gmail.com> wrote:
>>
>> > 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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