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Old 07-22-2006, 03:10 AM   #1
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buggy diff fluid advice anyone??

hi i am running an x-ray xb8 and am planning on racing it and just need some advice on what thickness fluid i should use and what the different thickneses would achieve .
yes i am newb at this so i ask the question any one with any advice? im looking for a good diff set up that will be good for a quiet small track with 1 straight to wind out on but thats it no more then its straight into a corner with med traction and med bumpy track.
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Old 07-22-2006, 03:40 AM   #2
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Personally I don't run an Xray, but I have friends who do and 5-5-3 seems to be a very driveable set-up, especially since your new, this will make the buggy very forgiving and tame it down, plus it will corner well. Using the 5 in the center will keep the buggy from overpowering the track, or breaking loose so easy. When people list diff set-ups they always refer to them from Front to Rear of the buggy. So thats 5000-Front, 5000-Middle, and 3000-Rear. Good Luck!!
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Old 07-22-2006, 04:02 AM   #3
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Default diff fluid

ok thanks for the advice so guessing from your advise in sayin the 5k in mid will tame it a bit this means the advice i was givin from another person was wrong he said the more thicker the fluid the more it will pull or push for that diff i asked the question again to clarify this am i right in saying he is wrong and that the thicker the fluid means the slower it makes that diff (slightly)
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Old 07-22-2006, 05:40 AM   #4
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The two hot set up's for the XB8 right now for diff's are 3-3-5 or 3-3-3. I personally run 3-3-5.


That's my set up that I was asked to post by a few of the local racer's. Try it out. It's a fairly agressive set up. The harder you drive the car, the better the set up works.
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Old 07-22-2006, 07:00 AM   #5
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This is from another thread...

Diff Oil Explanation

1st remember and this is all you have to remember is that a diff's job
is to transfer torque to the side of the diff with the least amount of
traction, ie least amount of weight transferred, ie least amount of
traction (This is opposite a torsen by the way).

Center diff fluid:
Say you accelerate, weight transfers towards the rear (your buggy
squats - how much depending on several factors such as rear antisquat
plate, how hard you are on the gas, etc), a center diff with very light
oil will "diff" more towards the front to try to balance the load and
stabilize the buggy. This is great on a slick or maybe a tight track
where you want to feel the front diff pulling your car a little more
and keep you from "spinning out."

Now, say you put in very thick center diff oil in your center diff.
You accelerate, weight transfers towards the rear, a center diff with
very thick oil will "diff" less towards the front but will give you the
most torque at the rear of the buggy, ie more acceleration. This is
great for high bite tracks but on a slick track you may find your rear
end swinging around more.

BUT, straight line acceleration is but one aspect of a center diffs
purpose. Say you are on a track and you approach a woop section. a
car with very light fluid will transfer more torque to the front of the
buggy as soon as the front tires begin to loose contact with the apex
of the woop, hence your rear end feels less power and consequently the
front of your buggy's nose comes down nice and fast ready for the next
woop. your center diff is constantly "diffing" to keep the car
balanced through the woops. Now, if you had very thick oil in the
center, the nose of the buggy would come down a little slower because
it will not diff towards the front so fast. This can cause your buggy
to get out of shape easily because your front tires are not in contact
(think steering) as much with the ground.

Also, center diff oil can even depend on what engine you are running.
if you have an OD MOD, and you go too light on the center oil, you will
find your front tires ballooning to the point of almost flying off the
wheels down the straight away, so you may increase the center oil
weight a bit.

Ok, now for my 2 cents on front diff fluid. This will control torque transfer from the left to front tire and vice versa.
Let's say you have very thick front center fluid and you exit a left
hand 180 on the gas. Your right front tire has the most traction and
hence, if you want the tightest steering, you would want most of the
torque to stay on that outside tire, and hence you would use heavier
front diff fluid. However, if you want more turn in (which happens at
the very beginning of the turn up until the point where your car has
transferred more weight to the outside tire), you could use lighter
front diff fluid.

BUT, the front diff is not just there for turning. Let's say you hit a
bump with only the left front tire of your car. With light front diff
fluid, more torque will transfer to the tire with the least amount of
traction than with thicker oil, ie the right tire starting to come off
the ground due to the chassis lifting, hence the front will stabilize
itself more than a car with thicker front diff fluid.

The rear diff follows the same principle of the front diff.

I know this was long and boring and winded, but i just wanted to get my
feelings out there as an alternative point of view. I am also a rc
photography fan and I love watching and photographing diff action on
buggies. So i am always noticing how much different buggies including
mine are diffing by watching and photographing their tires at different

What I said above is not the be all end all gospel but just my

Oh yeah, the front diff thing is also a reason you find some buggies
(at least mine) will have more front steering with a front swaybar on
some of the faster corners. The bar keeps the car from transferring
too much weight to the outside tire, thus reducing the front diff
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Old 07-22-2006, 10:50 AM   #6
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Front Thinner · increases steering into corners (off-power)
· if oil is too thin the steering may become inconsistent,
especially it can lose forward traction
(and steering) during acceleration out of corners

Front Thicker · increases stability into corners during braking
· increases steering on-power at corner exit

Center Thinner · front wheels unload more during acceleration
· decreases on-power steering (reduces oversteer)
· easier to drive on rough tracks
· if a high-power engine is used you could waste too much
power and sometime “cook” the oil in the center differential
because it “overloads”

Center Thicker · more all-wheel drive effect
· better acceleration
· increases on-power steering (reduces understeer)
· better suited on high-bite, smooth tracks
· car can be more nervous to drive especially if a high power
engine is used - you might need to be smooth on the throttle

Rear Thinner · increases cornering traction
· increases steering into corner

Rear Thicker · decreases rear traction while cornering
. reduces wheelspin
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Old 07-22-2006, 04:52 PM   #7
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thanks for the advice guys much appreciated it helps alot...................
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Old 07-22-2006, 07:04 PM   #8
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Thanks Tres for posting that. I have posted that several times now, maybe it need to be a sticky somewhere.
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