Notorious Best diff oil weight for flat bumpy dirt / short grass

superticky

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Hello everyone !

I guess this is a basic question but I could not find exactly what I was looking for by just searching.

I'm still running stock diff oil for almost a year so it's time to do some diff maintenance and use more accurate oil weight for my needs.

I basically drive on short grass (parks) or bumpy flat dirt (abandoned construction sites).

I've always noticed the front wheels are taking way too much power that needed when spinning in the air on bumpy surfaces, more dirt than grass. I've read doing a better oil weight distribution on diffs could make more power to go rear and more resistance to front.

Which oil weight would you recommend for this ? rear/center/front.

An extra question is if this would be causing my front wheels wobbling too much or do I have a different problem there ? I already make sure everything was tighten good enough. What should be a good checklist for wobbling front wheels on high speed ? ( 40 mph since i'm on 4S )

Here is a picture of the current place i'm driving on weekends (just to show an idea).

Thank you !
 

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nino

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I drive on similar stuff, and right now I'm in the middle of a rebuild. Going 100k center, I'll see how it handles. Don't want to go too thick, not recommended for bumpy stuff. I hope 100k will send a bit more of power to the rear. With stock fluid it all goes to the front when I punch it and the balooning is ridiculous.

I'll go thicker in the front and rear too, haven't decided what weight yet. Probably 20-30 front, 15-20 rear.

No wobble problems on my Kraton. Make sure your servo saver is tightened all the way... You may need a stronger servo than stock to keep the wheels pointed where you want them. Also, the front should have a bit of toe out.
 

avogev

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Hello everyone !

I guess this is a basic question but I could not find exactly what I was looking for by just searching.

I'm still running stock diff oil for almost a year so it's time to do some diff maintenance and use more accurate oil weight for my needs.

I basically drive on short grass (parks) or bumpy flat dirt (abandoned construction sites).

I've always noticed the front wheels are taking way too much power that needed when spinning in the air on bumpy surfaces, more dirt than grass. I've read doing a better oil weight distribution on diffs could make more power to go rear and more resistance to front.

Which oil weight would you recommend for this ? rear/center/front.

An extra question is if this would be causing my front wheels wobbling too much or do I have a different problem there ? I already make sure everything was tighten good enough. What should be a good checklist for wobbling front wheels on high speed ? ( 40 mph since i'm on 4S )

Here is a picture of the current place i'm driving on weekends (just to show an idea).

Thank you !
you probably have AVC maxed out. the stock servo is not fast enough to make the small corrections on time so as it corrects, it overshoots since it cant straighten out fast enough, and as it overshoots, the gyro tries to correct it again. i had the same issue with my typhon when i upgraded my radio to something with a gyro. after switching servos to something really fast, i don't have the wobble at high speed.
 

olds97_lss

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I run 100/500/100 in my outcast and it's great for what I do, which is skate parks, grass in the park and grass bmx track. I run 3.8" trenchers that are wrapped, so they are a bit heavy compared to stock tires. I get enough unloading to the front that it's not that painful to drive if you don't go WOT off the line, but it still has some give to it for when you land badly.
 

superticky

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No wobble problems on my Kraton. Make sure your servo saver is tightened all the way... You may need a stronger servo than stock to keep the wheels pointed where you want them. Also, the front should have a bit of toe out.
you probably have AVC maxed out. the stock servo is not fast enough to make the small corrections on time so as it corrects, it overshoots since it cant straighten out fast enough, and as it overshoots, the gyro tries to correct it again. i had the same issue with my typhon when i upgraded my radio to something with a gyro. after switching servos to something really fast, i don't have the wobble at high speed.
Thanks guys both for the servo saver / servo observation.

I will check the servo saver and regarding the servo itself I'm using a standard one while I learn how to drive better. I stripped the stock one 3 times. After I know better how to handle bashing I will get one of those expensive Savox ones :) However I didn't know a cheap servo could affect the wobble front wheels but it makes sense after reading your explanation.

This is a $20 JX PDI-6221MG 20K which says Operating Speed (4.8V): 0.18 sec/60° Operating Speed (6V): 0.16 sec/60°

Would that be the problem then ? I will still check the servo saver.


I run 100/500/100 in my outcast and it's great for what I do, which is skate parks, grass in the park and grass bmx track. I run 3.8" trenchers that are wrapped, so they are a bit heavy compared to stock tires. I get enough unloading to the front that it's not that painful to drive if you don't go WOT off the line, but it still has some give to it for when you land badly.
Thank you, I see for bashing is common 100K in the center and 60K for front. For rear I see different people using 7K , 10K, 20K or 30K,

the lighter the rear oil the more power it will attract so more wheelies but less craziness in the front wheels right ?

Thank you all !
 

avogev

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hard to comment on that servo...im not sure what the stock one is but i think its around that speed as well. i think anything at or under .1sec will be good enough? mine is .065 sec...so im not really sure.
 

olds97_lss

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Thank you, I see for bashing is common 100K in the center and 60K for front. For rear I see different people using 7K , 10K, 20K or 30K,
the lighter the rear oil the more power it will attract so more wheelies but less craziness in the front wheels right ?
Thank you all !
Actually, the center weight controls how much power goes to the front and rear tires all the time. Heavier oil means less unloading to the front when on the throttle. Lighter means more unloading to the front. I run the 500k because I don't care for my front tires spinning in the air all the time and grinding the tread down at the skate park when I'm really leaning on the throttle.

Heavier in the front takes away steering but makes it less likely to unload the inside tire in a turn (I think). I'm not sure what heavier/lighter in the rear does.

I'm a basher, so running thicker oil is also less maintenance as it's less likely to leak out. As long as the power gets to the ground and there's some give in the driveline, I'm happy.

I just converted my v1 revo to a v2 which has a center diff that comes with 2M (2 million wt) in the center diff and it actually feels too light to me. lol! Not sure where to get thicker to help with that... then again, I got the roller v2 used, so perhaps the original owner messed with it.

As for the servo, I run the Savox 1210 in my outcast. With .15 sec at 6V, it seems plenty fast to me as well as 277oz at 6V seems like enough torque. It gets a lot faster/stronger at 7.4V, but I run a blx185 stock esc which only puts out 6V.

I do run a cheap servo in my ERBEv2 now, JX PDI 4806HB which isn't bad on 6V, but I think I'd try the CLS-5830HV instead in my outcast for a bit more speed and torque at 6V. Pretty decent specs for a waterproof $40 servo. I just tried the 5821LV out because it was so cheap and I was spending $100 on lipo's when I made the order, so figured what's another $15. It worked so well in my revo that I bought another to have on hand in case I have one die in another truck.
 
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Jimbobjr

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Perhaps your tires/wheels are filled up with debris causing balance issues. Venting the outside of the tires can help get water out making the foam inserts last longer.
 

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