Why use 10K differential oil in the rear diff?

[Maskle]

Just a little question for all of you with more experience than me.

I am currently running stock diff oil in the front and rear as well as a center diff. So I think my current set up is 30K/500K/30K. Why do some people run a lighter 10K diff oil in the rear diff? I imagine this would cause more unloading between the rear wheels when cornering. Does it handle or corner better as a result? Does it mean the rear end stays on the ground more?

Please enlightening me.

I'm currently bashing mostly on grass.

Thanks.

[87 GN]

That is alot of diff.. 10k, I'm running 120k F&R. 500k is the center diff, never used one, but I don't get why you would need or want one unless you are racing. idk

[Maskle]

GN why did you move away from 50k front and 30k rear? I would be interested to hear.

[87 GN]

I don't want that much diff(ing).Revo. BL has so much power it will cause the diff(ing) so easy anyways. I'm not a racer,if I want a tight turn I slide the rearend around..

In my Sum~Revo I locked the rear diff (JB weld) & put 700k in the front.
make sure you get all the bubbles out I didn't & had to redo the diff.
http://traxxas.com/forums/showthread...=1#post4899891
locking the diff
http://traxxas.com/forums/showthread...=1#post4990707

[Maskle]

Thank you for those links. That 700.000 wt sounds like a nightmare to work with! Did the diff not function as predicted with the bubbles?

[ducati777]

I think stock for the center is only 50.....


Lately I've become a believer in thick front, and thin rear diff oil. I used to go the other way, thick in the rear, which gets the truck to oversteer a lot. Thats fun for bashing...

But if one is racing, or running onroad especially, I like super thick up front and loose in the rear. Handling improved for me. What was happening is the truck would accelerate out of a corner, and unweight, or even lift the inside front tire off the ground completely.

When that happened, it would allow the rear wheels to break traction and spin more easily, since there was effectively zero resistance coming from the front.

Then I went to 500k up front, and loose in the rear. It'll stick pick up that inside front tire, but now it has to fight the diff, and send power to the outside front, which still has good contact. That helps pull the front of the truck, and keep it from oversteering.

In general I'm not a fan of center diffs... so none of my cars have them.

[87 GN]

Thank you for those links. That 700.000 wt sounds like a nightmare to work with! Did the diff not function as predicted with the bubbles?

correct the air (bubbles) let it diff, like there wasn't even any fluid in the carrier...

[Maskle]

I thought it might take some stain off the drive-line and maybe result in less breakages......

[LaTuFu]

I have not been running a center diff in my Revo. But I do in another truck.

I like the fine tuning you can do with a center diff.

500k or 700k in the center should give you good MT transmission like performance, while still giving you some diff action.

I like heavier front than rear to reduce front end ballooning under acceleration.

[bentrocker]

How does the heavier oil in the front diff help with ballooning ? Do you mean so one wheel isn't unloading? I am thinking of installing a center diff in my e-slayer ,just trying to learn as much as I can before.

[LaTuFu]

The heavier the oil, the more energy the diff needs to turn.

Heavier oil up front will mean that the front diff spins "slower" than the rear diff, all other things being equal.

The effect will be the front diff will be slower to balloon under acceleration.

Heavier oil in a center diff also makes it easier to wheelie than a light oil.

[bentrocker]

A ha that makes a lot of sense. I wasn't taking into account the split from front to rear with the center diff. It must affect the steering though. I imagine the thicker front oil leads to some pushing in the corners. Or does the center diff help with that too ?

[Maskle]

How does the heavier oil in the front diff help with ballooning ? Do you mean so one wheel isn't unloading? I am thinking of installing a center diff in my e-slayer ,just trying to learn as much as I can before.

I would think that when cornering the heavier oil in the front would cause more power to go to the tire with the most traction (outside tire) compared to a lighter oil. This could be beneficial when cornering while accelerating when the front has a tendency to lift of the ground. The heavier oil could cause less pushing through the corner as the outside tire has more power. A center diff should also help with cornering by keeping the front down more when accelerating and thus the truck gets more steering traction.

[LaTuFu]

A "rough" guideline (I am no expert, so definitely research other sources)

• Changing the oil in the front diff affects overall steering response.
• Changing the oil in the center diff affects the front-to-rear drive.
• Changing the oil in the rear diff affects cornering traction and overall steering.

For example, thinner oil in the front diff will increase steering into corners (off-power). Thicker oil will increase stability into corners during braking, and increase steering on-power exiting a corner.

In the rear diff, thinner oil will increase cornering traction and steering into the corner. Thicker oil will decrease rear traction cornering and reduce wheelspin.

Center diffs, thinner oils will cause the front end to balloon more under acceleration, thicker oils will give more all wheel drive action.

Most of this is really only a major concern if you're seriously racing buggies and truggies, where fine tuning your diffs will make a big difference in handling on a particular track setup. If you're just bashing, it's more likely you just want to control ballooning and traction.

In other words...play around with different setups to find what you like.