[200q20v] 20v turbo in '88 90

[Derek Pulvino]

Hey all,

Been busy, so a little late getting back on this topic.  I've heard that 
unequal length driveshafts are a contiributing factor in torque steer, but 
does anybody know why?  Believe or not, this is not a trick question.  Best 
ideas I could come up with was the different torsional rigidities of the 
differing lengths of metal, and/or a different summing of the force vectors 
related to uneven angles of declination between the drive flange and the 
hub.  Seems the first could be compensated for from a strength of materials 
perspective, but not sure on the second one.  At any rate, does a cartesian 
break down of forces really apply to a torque (excluding the "right-hand 
rule")?

I think another factor in the front-wheel drive torque steer equation is the 
relation of steering axis to the centerline of the wheel, aka basic front 
end geometry.  Two cases in this point are the changes noted in torque steer 
when using wheels of different offsets on the same front wheel drive 
vehicle, and Audi's front suspension design as first seen on the A8.  You 
know the one that includes multiple ball joints (or whatever you'd like to 
call them) to create a "virtual steering axis" further away from the vehicle 
center line than the termination point of the suspension.
My understanding is that a big part of the reason for this design was to 
"eliminate or minimize torque steer."  It apparently works well, since even 
in the front drive A4's, torque steer is said to be fairly well gone.

This second part, several modded quattro owners testimonials, and front 
wheel drive reviews of t44's lead me to believe that our chassis setup is 
not immune to torque steer.  But this is not necessarily my point.  This is 
all been sort of a baited hook; I can't seem to figure out the mechanics of 
this either.  In other words, why does this work?  Best I could come up with 
on this was unequal traction for the different sides of the tire, and/or 
different sides of the vehicle.  But this wouldn't necessarily make a 
difference unless previous suspension architecture limitations prevented you 
from being able to get the wheel centerline to match up with the steering 
axis.  Pretty sure that's not the case.

Maybe I should have gone into mechanical engineering; probably be able to 
answer more of my own questions.

...Oh ya, and to tie it back into the 200 thread, anybody think there's a 
way to retrofit the A4 suspension into our 200's, so if we decided to run 
front wheel drive we don't need to worry about a supercharged Bonneville 
like steering feel? (slight sarcasm)

tia, (not to be confused with tna, for which you never stop thanking)

Derek Pulvino



Message: 13
Date: Wed, 22 Aug 2001 08:16:38 -0700
From: Wolff <wolff at turboquattro.com>
Subject: Re: [200q20v] 20v turbo in '88 90
To: 200q20v at audifans.com

A 4wd Golf is a different animal than a quattro since the front half shafts
are of unequal length. In a front wheel drive Golf or sideways motored
passat you can really feel it pulling sideways even if you start out with
your wheels pointed straight ahead. This is annoying to me. In a front wheel
drive Audi (excluding a TT which I haven't driven but has the motor in the
wrong way) it will go straight under accelleration if the wheels are pointed
straight. Of course as soon as the steering wheel is turned under
accelleration it becomes obvious that its front wheel drive.
Wolff
"Nobody can forget the sound." - Michele Mouton
----- Original Message -----
From: Aaron Rieke <aaron_s_r at hotmail.com>
To: <200q20v at audifans.com>
Sent: Wednesday, August 22, 2001 1:01 PM
Subject: RE: [200q20v] 20v turbo in '88 90


>Oh yeah, Derrek, you are right. Saw a video of a Dahlback equipped Golf
4wd.
>   The thing was all over the place off the line.
>
>aaron
>
>
>_________________________________________________________________

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