84 4kq locking differentials

[Huw Powell]

> Huw,  When I engage the center differential lock the car feels like the 
> front axil is locked.  You can't even make a tight turn without the 
> front crow-hopping like a old Ford with locking hubs.

Locking the hubs on a 4wd vehicle doesn't lock the differential (I can 
get my F250 stuck with just one wheel spinning... needs LSD).  But in a 
tight turn the front and rear turning radii are different (well, in any 
turn, but a tight turn makes the difference larger), so the center being 
locked will causing that scrubbing.  Heck, my F250, and I think my 
Blazer, scrubs with no lockable diffs, in 4wd on a tight turn.

Basically, if you have enough traction to feel the scrubbing, the diff 
should be unlocked.

> I ought to disconnect 
> the system, my son wants to play ralley drive with the axles locked, he 
> just going to put it off the road or hurt someone.

Yikes... is he at least taking it out into some mud?

>>> Why does the selector switch on my 84 4kq lock the front 
>>> differentials first?  If I switched the vacuum lines to lock the 
>>> rears first would that harm the quattro system?.  If I drove with 
>>> only the rear differential locked would that work.
>>
>>
>> It makes sense to me - before locking the rears to each other, you'd 
>> prefer to simply keep the front and rear in sync (meaning you have to 
>> spin two wheels, not one, to be "stuck").  That would be the "going 
>> down the road" option - center locked only.
>>
>> Then in a real jam, you go further and lock the rears, making it so 
>> that three wheels have to spin for you to be stuck.  Not a good way to 
>> drive, however, unless you are in really low traction situations.
>>
>> Analogizing to the next generation, with the automatic "torque 
>> sensing" center diff, the car takes care of the middle for you, 
>> hopefully at the right times, and the rear can be locked manually, but 
>> undoes itself at 15 mph.
>>
>> By the way, just for clarification, you aren't locking the "front" 
>> differential - it's the center one.  The front diff. can't be locked.

-- 
Huw Powell

http://www.humanspeakers.com/audi

http://www.humanthoughts.org/