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Old 12-02-2009, 02:28 PM   #1
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Default Front diff getting more power than the rear?

Yesterday while driving my buggy around in front of my house i noticed that the power band seem to struggle to get to high speed, And it felt like the car was being pulled not pushed. Then today while driving in some thin snow i also noticed that the back end wasnt spinning around at all, instead it was struggling to turn (which is hasnt before). Then while looking at the tires the back ones had more snow on them then the front. If youve ever driven any rc car in the snow the back tires usually spin the snow off.

I think that somehow my front diff is getting like 20% more power than my back diff is there a way to correct this?
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Old 12-02-2009, 02:41 PM   #2
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Check your center diff. If the oil is shot or leaked out, it'll unload all the power to the front. Thicker oil in the center usually improves acceleration and rear end power.
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Old 12-02-2009, 02:42 PM   #3
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that sounds like a bad wheel bearing are u driving a nitro or electric
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Old 12-02-2009, 02:48 PM   #4
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Quote:
Originally Posted by Semple View Post
Check your center diff. If the oil is shot or leaked out, it'll unload all the power to the front. Thicker oil in the center usually improves acceleration and rear end power.

This was the first thing that came to my mind. The other is to make sure your diff bearings are good. If it is binding or struggling this could verry well be your problem. But most likely it is light diff in the center. When the snow packed in your back wheels it made them heavier and harder to turn so the diff throws the power to the wheels that are breaking free.

Hope this helps you.
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Old 12-02-2009, 02:53 PM   #5
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Well considering im in the nitro off road forum..

And ill check the center diff to see if a screw came loose and leaked my oil or what have you. I had to stop anyway because my engine mount came loose.

Are there any other more "physical" problems it could be? Like shims or anything in the center diff?

Ive had this buggy for 2 years and still learning the whole center diff thing
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Old 12-02-2009, 03:45 PM   #6
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Also check for any binding in the rear. Something like the rear brakes etc. If it was only one of the rear wheels, the other one should still be going hard out. Definitely check the center diff though.
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Old 12-02-2009, 04:45 PM   #7
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Thanks guys, i looked on the inside of the diff and it was pretty dry in there


I need to get a heavier weight but all i had was 3000. So now after filling it, i picked the car up and spun the spur gear and it spun the back wheels faster and before it spun the front wheels, So i guess it works! Ill have to try tomorrow.
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Old 12-02-2009, 05:28 PM   #8
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3k is pretty light for the center....i would test with that and if anything get the proper wt.
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Old 12-02-2009, 08:40 PM   #9
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Quote:
Originally Posted by Integra View Post
3k is pretty light for the center....i would test with that and if anything get the proper wt.
The last time i filled it was with 3000, ill keep an eye on it and ill get some 5 or 6 tomorrow
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Old 12-02-2009, 08:56 PM   #10
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Default Go thicker....

I would put 7000 in the center diff that would fix the problem...
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Old 12-03-2009, 05:35 AM   #11
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+1 on that 5000 or 6000 in the center..I go down to 4000 on really torn up or super tight technical tracks but never lower than that..and if the oil leaked out once replace all the o rings too cause it'll only leak again..if it's been running a while without oil I should take a close look at the internal shafts for the satellite gears as well.without oil they are likely to have some wear and better to replace them before the play develops and you rip the teeth off the diff gears...
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Old 12-03-2009, 01:45 PM   #12
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If you were low on oil, I would re-grease the outdrives. Normally when I have seen low fluid (and not visibly seen a leak like a bad gasket or loose screw) it is been due to the outdrives were dry and the pressure of the diff spinninng would push the oil out the outdrive. Also, depending on the buggy I would put between 5K-7K oil in the center diff. Basically, Losi 8 / Mugen MBX-6 / Kyosho MP9 I would go with 5K and all others I would put 7K. If you normally drive on concreate then I would increase 5K to 7K and 7K to 10K.
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Old 12-04-2009, 11:44 PM   #13
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I see that you have TT in your signature. So assuming that you race, I would recommend 7k center. If you were more of a basher, then do 10k. The higher the fluid the more 4wd it becomes. Makes for a lot of fun off the track, but if you are serious about racing, then as you go up in viscosity, the more you will have a car that has a tendency to slide around and be unstable. Lower will make a car that pulls and handles better for most drivers.

I run 7k in a lot of applications, but like 10k also. Running high in the back is where real traction issues begin.....
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Old 12-05-2009, 12:35 AM   #14
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Having too light center can make the car torque stereer like a front wheel drive car under acceleration. I too run 7-10 in the center.
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Old 12-05-2009, 01:30 AM   #15
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somewhere I have a really good diff setup guide..I can't find it on the computer so I'll have to scan it in from my R/C folder of reference stuff...I'll post it later..

here you go my printout had the link at the top.....

http://www.rc411.com/pages/howto.php?howto=24&page=1
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