Center Differential

AWD Center Differential

Background:

The center differential uses 2 spider gears to hold the power between the front and rear differentials. These small spider gears are extremely brittle and under extreme loads they can break causing major damage to the transmission if parts of the broken spider gears leave the center differential housing. If you drive the car like it should be you will not break these gears. I've done 6k clutch drops many many times without breaking the center differential, I just upgraded to make sure I wouldn't in the future. (My car weighs in at under 3000 lbs with driver and full tank of gas though)

Pics of broken Spider gears. The tranny this happened in needs all new bearings and syncros. ($700 in parts)

There are a few ways to eliminate this problem:

1) Drive like a sane person with a stock car
2) Don't do clutch drops at high rpm's
3) Keep the power of the car under 300 hp.
4) Weld the center Diff ( $50 - $300)
5) Install a modified differential with 4 spider gears ($300 - $600)
6) Buy an aftermarket LSD center Diff (Huge $$$$)

Benefits of Welded Center Differential

1) It will not break if done properly
2) The tranny becomes 4WD, the front and rear differentials will always turn at the same rate
3) Great for drifting in the snow and on dirt roads

Drawbacks of Welded Center Differential:

1) It can produce severe oversteer in any situation
2) Tight turns and Parallel parking is really hard on the drivetrain and the tires will be squealing
3) The center diff is no longer the weakest link, it's a $150 item to repair where the next weakest link is the transfer case ($600 used), rear differential ($500-$750 used) or cv shafts ($100 each). The tranny itself should handle the extra load since the front differential is pretty much bulletproof.

Pics of Welded Center Differential:

The Viscous coupler splines are welded together (Viscous coupler is no longer used...)

Both inside splines for the front differential and transfer case output shaft are welded to the center differential casing. The Front diff splines are the hardest to weld since it's in a deep galley. Don't even attempt to have an amateur weld this, it will break. Most people weld the spider gears in as backup measures but the person that welded this differential builds Superbikes and we have no doubts at all that it will hold. The bearings had to be removed from the Differential to prevent distortion during welding.

Pics of upgraded 4 spider gear differentials:

The 4 gears with the new machined cross shaft

The housing after being bored out on a cnc machine

The new spider gears ready for spacer measurements.

Here's another page for more info on the welded center diff: http://www.geocities.com/spencerhut/talon/center_differential_repair.htm

This page was last edited 10/12/2001 02:07 AM