turbo bypass valve for auto box?

[Ameer Antar]

well, i figured i'd get a few about that...but I got 7 emails saying 'don't 
do it', or 'Haven't you had problems already ?' Only one person actually 
tried to answer my question.

The tranny's on the '84-'85 5k are different than the '86-up. From my 
experience I've only heard about '86+ tranny's having problems, and even a 
200 auto tranny's having to be replaced twice! My theory is that the early 
boxes might be sturdier than the latter. Mine has 190k miles on it, shifts 
perfectly and has no delay when engaging drive or reverse. In one year of 
ownership, I've put 30k miles on it! That's quite a bit and I do drive 
vigorously. After I rebuilt the turbo I would bring it up to 1.4 bar mostly 
on highways when passing or hill climbing. So the autobox [at least for the 
'84] can handle stock boost just fine, as some have questioned.

I doubt that the tranny would fall apart instantly after doing an upgrade. 
I'm sure it will have an accelerated death, which happens w/ any car or 
tranny if you modify it a great deal. I'm sure those w/ quattros are 
accelerating the wear on their tranny's brass parts and their final drives, 
etc. What really kills tranny's and such is lack of maintenance, rocket 
launches, etc. These are 2 things I avoid. I rarely launch the car from a 
light, only using high bar boost on hills or when passing someone on the 
hwy, which means the boost is not sudden or harsh. In any case, I actually 
don't mind if the A/T dies, b/c I'm interested in converting to 
manual...b/c of the lower rpms, better accel, and such. But I don't wanna 
throw away the autobox if it's fine. But it's ok if I run the tranny into 
the ground.

My question really is would it be safer to use a bypass valve on the A/T? 
My thinking is that even on an A/T, air is still being pushed into the 
throttle body at high rates at high boost, and when I let go of the pedal 
after passing someone, or finishing a hill climb, only to find a cement 
truck going 10mph, the rushing air will slam against the throttle valve, 
and possibly damage the turbo. Any ideas, comments here? I appreciate all 
your advice, but we don't always have to agree. Thanks again.

-ameer


At 09:00 AM 11/30/2000 , you wrote:
>Please don't do this mod with an auto box, they cannot handle the detuned
>turbo engine let alone a fire breather. Haven't you had problems already ?
>
>Kevin Phillips  1990 200TQ, 1995 900SET.
>BARCO Graphics Integration Team
>40 Westover Road
>Ludlow MA 01056
>kevin.phillips at barco.com
>
>  -----Original Message-----
>From:   Ameer Antar [mailto:ameer at snet.net]
>Sent:   Wednesday, November 29, 2000 22:43
>To:     quattro at audifans.com
>Subject:        turbo bypass valve for auto box?
>
>If I do a 1.8 bar upgrade, is it worthwhile to use a bypass valve. I
>thought it would be important when I let go of the gas after pushing the
>pedal a lot. any advice? thanks.
>
>-ameer