# Set me strait on center diff oil tuning...



## JammInChris (Dec 20, 2009)

I've read some conflicting information regarding the effects of oil viscosity as far as center diff's are concerned.

What does a thicker oil in the center diff do? How does it effect handling?

Same for the converse?

Thanks guys...


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## Smiley (Feb 2, 2005)

Front Diff- Controls On/Off Power Steering. The thinner the oil, The better Off-Power Steering you will have. The Thicker the oil, The better On-Power Steering you wil have.

Center Diff- Controls the amount of power/ Torque. Thinner Oil will make the car distribute the power between the Front and Rear better, Which will make the car easier to drive, Less Torque. Thicker Oil will make the car harder to drive, More Torque.

Rear Diff- Controls Rear Traction. Thinner Oil will make the rear end less stable, and unpredictable. Thicker Oil will make the rear more stable and more planted.


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## kstoracing (Oct 30, 2008)

Thanks Smiley, that was nice and direct.


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## JammInChris (Dec 20, 2009)

Smiley said:


> Front Diff- Controls On/Off Power Steering. The thinner the oil, The better Off-Power Steering you will have. The Thicker the oil, The better On-Power Steering you wil have.
> 
> Center Diff- Controls the amount of power/ Torque. Thinner Oil will make the car distribute the power between the Front and Rear better, Which will make the car easier to drive, Less Torque. Thicker Oil will make the car harder to drive, More Torque.
> 
> Rear Diff- Controls Rear Traction. Thinner Oil will make the rear end less stable, and unpredictable. Thicker Oil will make the rear more stable and more planted.


Thanks Smiley,

So by putting thinner oil in the center diff, does that send more power to the front wheels?


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## Merdith (Sep 20, 2009)

*Diff-erent things*

I usually use 7,000 in the center diff, however, in the hot days of summer I use 10,000. If the oil is too thick it gives you 4 wheel braking and makes the car push a bit under braking, along with a little too much rear power that can cause spinning out under power, so I drop to 7,000 in the colder months to avoid that. Thinner oil lets the power transfer better front and rear, but too thin and it will transfer too much on power and make the front spin out and cause irratic steering like a front wheel drive car. Thinner oil can make the center diff burn up faster too, along with the front center driveshaft. That's why I go thicker in the summer. the center diff controls where the power goes, lighter gives more to the front under power, and thicker oil gives more power to the rear or keeps it more even....Hope this helps.....


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## jasonwipf (Feb 23, 2009)

Smiley said:


> Front Diff- Controls On/Off Power Steering. The thinner the oil, The better Off-Power Steering you will have. The Thicker the oil, The better On-Power Steering you wil have.
> 
> Center Diff- Controls the amount of power/ Torque. Thinner Oil will make the car distribute the power between the Front and Rear better, Which will make the car easier to drive, Less Torque. Thicker Oil will make the car harder to drive, More Torque.
> 
> Rear Diff- Controls Rear Traction. Thinner Oil will make the rear end less stable, and unpredictable. Thicker Oil will make the rear more stable and more planted.


Yes nice direct explanation. Seems even more so the case now that I am electric too. When I was gas and bleeped/powered my way thru turns it seemed 5/7/3 was good. But now that we coast or lightly power thru the apex of our turns in electric a lighter center diff helps as it transitions the power between the front and rear better. So now I am 5/5/4. That 1k increase in the rear diff really made the rear end stick more when I am powering out of the turns. Truggy I am 7/7/4.


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## Courtney Vaughan (Apr 11, 2007)

Keep in mind, that it is also has a lot to do with how you drive, and the design parameters for your car's platform.

While thinner oil in the rear may make it a little unstable, "unstable" is a subjective word. In this case, "unstable" would mean that the rear end rotates quicker. Pending your driving style, this could be what you're looking for, and could be described as "stable" to you.

I like a lot of off-power steering and the design of my car tends to push a little, so I run thin (3K) in the front. 
I like a softer "punch" during acceleration, and my car's design carries a lot of traction under acceleration, so I run 4K in the center.
My car has a shorter chassis than some of the newer revisions, so the rear of the car rotates easily and I had to actually go up to a thicker than conventional rear oil (5K) to slow down that rotation. 

So, I run 3/4/5&#8230;&#8230;which is somewhat abnormal. But the point is, it suits the design of the and my driving style. 

As for a direct answer to your center diff question, think of it as a "punch control" or a "slipper"&#8230;&#8230;&#8230;&#8230;.that's the easiest way I can think of to explain it. The thicker you go in the center, the harder the "hit" from the wheels when you pull the trigger!

And no, thinner oil in the center will not apply more power to the front, it will apply less power to front AND rear. If you want the front to "pull" in the direction you have the wheels turned, go up (thicker) in the front diff. The trade-off is that it may hinder your steering while you're off the power and trying to steer through a slow turn.

Don't ask me about shocks though&#8230;&#8230;&#8230;&#8230;.still working on those LOL!


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