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s4dc3
08-13-2010, 07:41 PM
00 1.8t quattro i was wondering what the split between fwd and rwd in the quattro system, i read somewhere that its a 80% fwd 20% rwd and is it possible to change that? thanks

Kyle H
08-13-2010, 07:44 PM
40/60 front/rear

you can change it with different washers. search for 'diff washers'

s4dc3
08-13-2010, 07:45 PM
thanks

walky_talky20
08-13-2010, 08:40 PM
40/60 front/rear

you can change it with different washers. search for 'diff washers'

This is not completely correct. Our quattro system (generation 4) uses a Torsen T1 center differential and has a completely dynamic torque split. Stock, it has a Torque Bias Ratio (TBR) of about 2:1. It defaults to a 50/50 torque split when traction at the front and rear wheels is equal. If the traction at the axles differs, it can send up to about 66% of the torque to the front or rear axle (whichever has better traction). So it can give a torque split of up to about 66/33 or 33/66, depending on the conditions. Due to the slightly nose heavy nature of our cars, the actual torque split under normal driving conditions is about 55/45 front/rear, because the front wheels have more traction due to the weight of the engine. Under heavy acceleration, the torque is sent more rearward as the available traction is better due to the rearward weight shift. At that point you will probably have about 40/60 front/rear.

The TBR can be changed with the diff washers to make it about 4:1. That would equate to a maximum torque split of around 80/20, or 20/80 depending on the situation.

Kyle H
08-13-2010, 08:57 PM
oh, that's right.

s4dc3
08-13-2010, 08:57 PM
nice, i wud love to have mine 20/80 but i suppose the comp in the car changes it up depending on the condition its driving in

walky_talky20
08-13-2010, 09:00 PM
There is absolutely no computer control over the quattro system, period. Including the torque split. Quattro (in the B5 chassis) is a completely mechanical system.

The only computer controlled aspect is when the traction control kicks in when you get wheel slip. And even then, the computer is only working the brakes via the ABS pump. Nothing to do with the transmission or center differential.

Audi TT quattro or A3 quattro, or other modern transverse Audi/VW chassis use a completely different AWD system that is indeed computer controlled.

Kyle H
08-13-2010, 09:03 PM
Some information on our center diff (pdf):

http://www.torsen.com/files/Torsen%20Performance%20Technical%20Sheet.pdf
http://flashoffroad.com/features/Torsen/Torsen_white_paper.pdf
http://www.vehicledynamics-expo.com/06vdx_conf/pres/day_3/sacchetini.pdf

[:)]

s4dc3
08-13-2010, 09:07 PM
ahhhh i seee, thanks guys

onemoremile
08-13-2010, 11:16 PM
Yep. EDL (electronic diff lock) applies light braking to a spinning wheel but it only works at speeds under about 35 mph.

If you want to play with a fun AWD system try a Subaru STi. They have limited slip diffs front and rear and the center's bias is adjustable via a knob by the ebrake. We have a Torsen in the center and open diffs front and rear.

I have had the center diff mod for a couple years and it is better than stock for sure. Even more fun in the winter.

flynnr
08-15-2010, 08:21 PM
how difficult is the center diff mod to do? worth it?

k0mpresd
08-15-2010, 09:24 PM
how difficult is the center diff mod to do? worth it?

its pretty easy. i used to have a picture reference thread about the topic. then my psycho ex girlfriend deleted my photobucket.