[T2] Disc brakes dragging

Jamie jrivers at globalserve.net
Sun Aug 16 13:36:18 PDT 2020


http://www.johnstuartpowerbrake.com/

> On Aug 16, 2020, at 4:29 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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