[urq] V8 Brake swap for UrQ - bad info worse than no info.?

[Patrick Carlier]

Ben , my guess is that you're missing some part from the booster .
That sawtooth nut can be used and re used . Just use a vice grip to tighten 
it .
I've rebuild boosters on various occasions , but never changed the nut or 
the copper washer .

There's a page somewhere with a list of all parts needed , o-rings and seals 
with dimensions
for both the alloy and the cast brake booster .

There's also a PDF for the alloy booster only .
 http://www.quattro.ca/Urq/Brake_servo_guide.pdf

The cast brake booster has a few more internal parts then the alloy one .
I'm afraid I 've lost my bookmarks , so I can't find it right away ,
but I' m sure someone on this list must have it .

Pat






----- Original Message ----- 
From: "Ben Swann" <benswann at verizon.net>
To: <urq at audifans.com>
Cc: <benswann at verizon.net>
Sent: Saturday, September 18, 2010 6:47 AM
Subject: [urq] V8 Brake swap for UrQ - bad info worse than no info.?



I have been in process of upgrading rear brakes to V8 calipers, carriers and 
rotors.
That part went fairly well and except for having a little mixup with the 
rotors - that
looks great!

There were several "suggestions" from folks I put high credibility in 
information I get
on this list -  that in order to utilize the larger diameter rears I needed 
to also use
the V8 or 200 master cyl.  Good suggestion I thought - pretty trivial to 
replace that -
albiet a bit or a PITA.    One ought to presume that unless additional 
information is
given to the contrary that a swap is a simple swap.

Now this is where someone should have provided a clue that this was not a 
doable swap
for mere mortals or at least there was more to just swapping the master 
cylinder out.
If there was BTDT on this I should have been advised..

OK - The line hookup needed to bend the lines  and reconfigure the hookups - 
old MC had
lineson bottom and sides - new MC had a V configuration. That is not t a 
real big deal,
but should have been mentioned.  Not everyone presumes things need to be 
bent or ...

Here is what frosted me..

The original master cylinder bore is less diameter than the V8/200 MC  that 
is where the
disaster started.  There was a plastic sleeve in the hydraulic booster that 
the master
is pressed into - or so I thought it was a sleeve.  It  was held by captive 
bolt at
bottom - O should have also figured that since it was a sawtooth grip nut - 
one way only
- to stop there and re install my otherwise good working "original": MC.

Yes -   I should have stopped there, but being is no caveats based on BTDT 
were issued,
presumed this was not a problem.  So I removed the bolt - with difficulty it 
came out.
The 'sleeve' was also captive by friction until I helped it free.  Free it 
did!
Hydraulic fluid, spring, O-ring seal, carrier/retainer, all let loose.  It 
was not a
sleeve but a complex shaped seal holding captive - shim, O-ring, 
veeerylooongspring,
shaft, retainer and hydraulic fluid under pressure!

I collected the parts, cleaned my face and figured that the V8 MC should fit 
in - It
did, but there would be no seal.

Finding that there was no ready way to use the V8 master in the original 
booster, I
reassembled the original components as best as I could.

So now I'm left with a mess and a car I can't drive  - the funky sawtooth 
nut is a
special seal bolt that is one use only.  I tried to seal with copper 
washers, o-rings -
hard to hold captive 3000 PSI!   So what do I need to do now - replace the 
booster?
Arghhhhhhh!  Where does one get that special seal bolt?  What a big waste of 
time - I
could have just used and aftermarket proportioning valve, instead of 
replacinG the MC.

I'm venting now - a little less than I did a few wasted hours past,  since 
this cost me
not only money, but  a lot of unessessary time and aggravation.  I look to 
this list a
source of reliable information and if there is a potential problem with a 
safety system,
I expect a little warning.  Here-say is not a good way to disseminate 
information -
either you did the job and know the details(BTDT) and provide them, or 
please don't lead
someone to do a job that is fraught with major difficulties, especially when 
it involves
critical saftey components.

If I had known this all before, I would have simply installed two new stock 
calipers.

I know - caveats for the info. provided on this list, but then  - why 
bother?  That's
all for now.

Ben


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