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  1. #1
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    Advice to correct power on oversteer

    I just installed a new rear diff and version 2 bulkhead in my Revo using 30,000wt. diff oil along with my new center diff with 50,000wt. oil (didn't touch the front diff). It now has too much drive to the rear wheels which makes it hard to control. I am guessing that I need to pull out the front diff and install 30,000wt. or thinner diff fluid to get the front wheels to do more of the work? Can someone confirm this for me or lead me in the right direction concerning diff fluids?

  2. #2
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    I would think that you would want to put thinner oil in the center diff, so more power went to the front wheels, but I don't know much about the center diffs because I don't have one
    Brushless Summit!!!!!
    Slash 4x4

  3. #3
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    I have 30000 in my Cd and still have oversteer and plan to drop that down more now that nice weather is here. For snow and ice it worked great but now that I'm hooking up more on dirt I find on power it still lifts the front end.
    Ve8
    Merv

  4. #4
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    Quote Originally Posted by Tat76 View Post
    I have 30000 in my Cd and still have oversteer and plan to drop that down more now that nice weather is here. For snow and ice it worked great but now that I'm hooking up more on dirt I find on power it still lifts the front end.
    I switched to 30,000wt. today and it made hardly any difference over 50,000wt. I am still pulling the front wheels in the air with a 2-cell lipo and my NEU 1110. Gonna take it down to 5,000wt tonight.

  5. #5
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    It is the center diff that is causing your problems. You need to go to thinner (lower weight) fluid in the center diff, so it can transfer more power to the front wheels. Right now, your rear wheels are getting too much torque.

    Dennis

  6. #6
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    Thanks, gonna go down to 5000wt. tonight and see what happens. Can't believe some people are actually running 100,000wt (it'd be like a locked diff).

  7. #7
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    The looser center diff is what allows the Merv to jump correctly on a track. If the center diff was locked, as the car goes up a jump and the front wheels go over the rise and into the air, all the torque goes to the rear wheels and that is why it is so hard to control wheelies at that point. If the center diff is looser, then as the front wheels leave the jump and start to go airborn, the center diff transferres torque to the front wheels and less to the rear so, while you are under power going up the jump, the torque automatically transferrs and you get a smooth jump instead of a wheelie and tail end landing.

    The center diff tuning is why you see buggies jumping so well, and easily controllable. So, you will need to watch how the Merv handles, and adjust accordingly. Only problem I have found with the Merv center diff, is that the fluid leaks out, changing the tune. In quality1/8 scale buggies, the diff's don't leak. At least mine do not.

    But I would say, a looser center diff with the Merv is better than trying to have it real tight. When I want that, I just take the center diff out and run it locked up.

    Please let us know how it works out. I have not tried it, but I would think that just some grease in the center diff instead of fluid, would stay better, and take all that skidding back and forth out of the back end. Just no wheelies with it that way, but easy to drive on low friction surfaces.


    Dennis
    Last edited by BigGrump; 04-15-2011 at 10:10 PM.

  8. #8
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    Am I mistaken, or wouldn't a center diff with 50k still have better handling than the original stock output gear?

  9. #9
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    Quote Originally Posted by MERVracer View Post
    Am I mistaken, or wouldn't a center diff with 50k still have better handling than the original stock output gear?
    Absolutely, the center diff with 50K would have more diff action than without a center diff. The problem is when you are looking for a greater transfer of torque to the front wheels than 50K will allow. For example, a stock Merv can give you uncontrolled wheelies, where the Merv will actually flip over backward. On a race track straight away, this is undesirable. A center diff with heavy fluid, can also flip the Merv over backward on a straight away. However, it is possible to adjust the weight of fluid in the center diff, that under full power, the Merv will not flip over backward on the straight away. So, the whole story is not if there is a center diff or not, it is rather the degree of torque transfer the center diff is allowed to make that determines the result of tuning.

    Dennis

  10. #10
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    Another approach could be to try softening your rear suspension...
    What have you learned today?

  11. #11
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    So far I havent found my CD to leak but will see how it goes now that I changed it out to 10k. Hope no rain today so I can give it a test but thinking that this should make a huge difference. Was going to change the F/R diffs to but decided to see how much of a change this makes and then go from there.
    Ve8
    Merv

  12. #12
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    Thanks for the help everyone. I went with 5K rear, 10K center and 7K front. Its raining like crazy right now but from my brief indoor testing, I am liking it so far. Still wheelies on 2S but my NEU motor is stronger than stock and carpet with JConcepts Goosebumps give more traction than anything I know of so.....I am hoping that outside on dirt/asphalt/grass it'll be OK.

  13. #13
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    Great, the important thing is if you can actually see a change from before, if so then as long as it is in the right direction, you will know what to do if you want a little more or less of what you see.

    I personally think it is great fun to read about someone going through a tuning process, then maybe getting some desired results.

    Please let us know after the blasted rain stops.

    Dennis

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