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Old 02-25-2009, 02:20 PM   #1
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Default Purpose of a Center Differential?

Working on a project and was wondering how tuning a center diff affects performance.
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Old 02-25-2009, 04:52 PM   #2
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as a simple explaination, heavier oil = more acceleration, I don't really have any time at the moment to get more into it
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Old 02-25-2009, 06:50 PM   #3
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It affects the distribution of power between the engine to the front and rear diffs. The thicker the fluid in it, the less its wants to allow different speeds between the front and rear diffs



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Old 02-25-2009, 08:23 PM   #4
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With a center diff can you keep a consistent power transfer ratio between the front and rear? Or does it change as the load changes between the front and back wheels?
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Old 02-25-2009, 09:58 PM   #5
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The more the load/traction the more power goes to the other end of the car.The thicker the oil, the more the power goes to the end with traction.Works the same in all the diffs.Unless you have lots of traction thick oils are not the best for most drivers.I find it easier to start thin & work thicker.

Is that the awnser you want? If not download the hudy setup book for details on specific expected results for oil changes per diff.
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Old 02-25-2009, 10:23 PM   #6
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The center diff is like a slipper clutch in a way that the thicker oil you add the more power you send to the front and rear. In theory thicker would seem better but with thinner oil more often than not you have a better handling truggy. Better drivers can run 20k in the center and keep things under control with ease. But if you're new at this running 10-15k will make the truggy much easier to drive.

Just my opinion, I'm sure everyone has a different setup that they prefer.
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Old 02-26-2009, 12:03 AM   #7
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The main duty of a any differential is to "diff away" unusable traction from the tires that are hooked up. This applies left to right and front to rear. Weight transfer affects the diff action in a big way, so be sure to keep an eye on how much your chassis rolls or squats. Keep in mind if your center diff oil is too thin (you may notice your front tires ballooning), you will loose forward bight out of corners, and possibly cook the center diff oil.

- I recommend using heavier oil in the middle on high traction tracks.
- Use thinner oil if the track feels loose, or if the car feels loose in the back.
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Old 02-26-2009, 12:43 AM   #8
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this might be jacking this thread but i have a similar question. I am running a jammin x-1 truggy. Our indoor track is kinda tight and has TONS of traction. my current diff setup is 7-10-3. the thing acts like i need a baseball field to turn it, but when i ran outdoor earlier this fall I had no problem. i personally like the back end a little loose. SO, should i maybe go up to 5000wt in my rear?? thanks
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Old 02-26-2009, 01:04 AM   #9
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Quote:
Originally Posted by 1lowtaco View Post
this might be jacking this thread but i have a similar question. I am running a jammin x-1 truggy. Our indoor track is kinda tight and has TONS of traction. my current diff setup is 7-10-3. the thing acts like i need a baseball field to turn it, but when i ran outdoor earlier this fall I had no problem. i personally like the back end a little loose. SO, should i maybe go up to 5000wt in my rear?? thanks
i dont think its your fluid, somethings not right on the steering
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Old 02-26-2009, 01:17 AM   #10
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i thought about that but it has full lock steering. i even compared it next to an 8t and an rc8t and it turns about the same but on the track it is completely different. I have went upin shock oil in the rear and tightened up the sway bar in the rear and that all helped some but itstill needs to be a little"looser" for my taste. what about adjusting the droop settings?? i have neveer messed with those. they are flush with the bottom of the arms on all 4 corners. ( i didn't know it had droop adjustments until recently when i had to change out an arm)
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Old 02-26-2009, 03:27 AM   #11
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Tighter steering can be tough to find. Small things mater. Things like, more caster, less Akerman, less toe, take off the front sway bar, lighter rear diff. oil, rasing rear ride hight est. est. When you make a change, do one thing at a time. If it didn't help, put it back where it was and try the next one. Also check servo saver setting and/or a manly servo. Oh yea, it takes time but it can be found. And just think, if you find the good indoor, the outdoor will be smokin'. A tire that works is 80% of the deel, too. Good luck and good hunting.
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Old 02-26-2009, 03:38 AM   #12
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Didn't take long to jack this dudes thread.

When you are on power the diff sends the power more power to the front wheels as they begin to loose traction. This scrubs alot of speed. By adding thicker oil you are in a sense locking up the diff so it continues to send power to the rear. The thicker the fluid the more pronounced it is. Go to extreme and you will be spinning out whenever you jump on the throttle. This is a good way to control forward traction. I agree with the others that you are best to start light and work up until you see a loss in performance. Then bacl it off a bit. Its up to your comfort zone to figure out.

If you are doing some wacky project and want EQUAL power to front and rear. Just lock up the diff with some epoxy.
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Old 02-26-2009, 03:45 AM   #13
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purpose of the center diff?

well obviously its an evil plot by companies to add one extra thing that can break costing you more money out of the wallet
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Old 02-26-2009, 06:28 AM   #14
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Old 02-26-2009, 08:04 AM   #15
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A center diff is important for many reasons. The first being without it brake bias wouldnt be able to be changed. The second is when the power is applied the vehicle may want to wheelie. When the front wheels come off the ground power to the rear is lost because of the diff action which makes our cars much easier to drive. Just think truggy vs t-maxx with the same engine and which would be easier to drive.

Thicker and thinner fluids just change the amount of power being sent to the wheels with traction. When a wheel breaks loose with thin fluid power is lost to both making it easier to drive at the cost of speed. Thicker fluid sends more power to the wheel with traction because the diff fluid is causing less power to be lost to the wheel that has broken lose because the thick fluid is making an attempt to still send some of that power to the wheel with traction. When off power the thinner fluid allows the 2 wheels to turn at different rates needed to make turns easier and thicker fluid is more resistant.

This is why some companies have come out with new smart diff designs. Off power its better to have a light diff fluid to allow the car to turn easier but on power you want the power going to all the wheels to put down the power like with thicker fluid.

In rough or low traction conditions go with thin diff fluid. In smooth or high traction you can put more power down and thicker will be faster. I have switched my diffs for a rough track then forgot and gone to a high traction track and couldnt figure out why I was slower than my previous visit to the same track.
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