[urq] Diff Locks

[Martin Pajak]

Brandon,

Louis-Alain is right, all of my cars Ur-q and 4kqs do it.
You have a stress from one driveshaft "trying" to turn the wheel backwards while another "trying" to turn it forwards (at a standstill).  That is due to difference in rolling diameter between tires, front back (load), and wear.

Think of it as turning a slow corner with diffs locked and then stopping in the middle of the turn, the stress will remain untill you start turning the other way...  it even worse with both diffs locked. :)

Hope this helps.
Martin Pajak

http://www.quattro.ca


---------- Original Message ----------------------------------
From: "Brandon Rogers" <brogers at terrix.com>
Reply-To: Brandon Rogers <brogers at terrix.com>
Date:  Mon, 6 Jun 2005 12:47:13 -0600

>yeah but it vibrates (rough idle) when the car is stationary.  I don't see how those factors can cause vibration when  the car ain't moving.
>
>Brandon
>  ----- Original Message ----- 
>  From: Louis_Alain_Richard at computerhorizons.com 
>  To: Brandon Rogers 
>  Cc: Urq List 
>  Sent: Monday, June 06, 2005 12:18 PM
>  Subject: Re: [urq] Diff Locks
>
>
>  I don't think so.
>
>  I have the same behaviour on my car. My conclusion is "drivetrain stress" or windup.
>
>  As each wheel as a different diameter (pressure, wear, weight on each axle, etc) then one axle as a greater developpment than the other. When rolling, this difference is absorbed in the slippage of each tire. 
>
>  When you coast to a stop on an adherent surface with the center diff locked, it means that one axle has a rotational load and this put a stress on the engine/transmission/diff mounts. This is the vibration you feel in the body. 
>
>  As a proof of this, if you can't have the center diff to disengage (when the car is stopped), it means there is a load on the dog clutch, CQFD.
>
>  To play with my theory, deflate your font tires to 25 psi and inflate the rears to 35 psi. Lock the diffs, roll 100 ft straight ahead and notice the vibration. Then do the opposite (35 front, 25 rear). You'll see that the vibration is a lot less present.
>
>  Louis-Alain
>
>
>   
>  -----urq-bounces at audifans.com wrote: -----
>
>
>    To: "Urq List" <urq at audifans.com>
>    From: "Brandon Rogers" <brogers at terrix.com>
>    Sent by: urq-bounces at audifans.com
>    Date: 6/6/2005 12:17
>    Subject: [urq] Diff Locks
>
>    GUys-
>    did some highway driving in our downpour over the weekend so I locked the center diff - when I came to a stop I realized I had forgotten to unlock the diffs - I could tell the diffs were still locked (other than the fact the green light was still on) because the motor was idling a little rough.  Turned the dial to unlocked and of course the roughness went away.
>
>    Does this mean I have a vacuum leak somewhere in the lock system?
>
>    TIA
>
>    Brandon
>  =
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