[T2] Disc brakes dragging

Bob accessys at smart.net
Mon Aug 17 08:40:27 PDT 2020



FWIW I have had bad parts right out of the box so I wouldn't "trust" that 
a new part, any part, is working until inspected and tested

Bob


On Sun, 16 Aug 2020, Erik Burtis wrote:

> "Thanks for all the input. All the parts are new save the steel brake
> lines"- these coil be rusting from the inside out and causing a blockage,
> but since the symptoms go away with the booster disconnecting, I don't
> think this is your issue.
>
> " 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?"
> Yes, it's the one by the manifold.  As Bob suggested, make sure it's
> installed in the right direction.  Memory is a little fuzzy but I think the
> bentley has it backwards.  Search the samba for the bentley mistakes
> thread.  The check valve should hold a vacuum for several minutes after you
> turn the car off, overnight in some cases.  So if you go back 5 min after
> turning the bus off, press the brakes and the pedal should go down easi=y
> for the first cycle or two.  Then it'll become more difficult.
>
> " AND one more thing. In perusing the forums on the Samba I found a post
> complaining of exactly the problem I'm having"  Shoot the PO a message and
> see if/how he solved it.
>
> There are some problems that show up with the new boosters verse rebuilt.
> Call your vendor, maybe they have some suggestions?
>
>
> On Sun, 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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