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Old 11-13-2008, 03:13 PM   #1
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Default xxxt losi melting inside of diff gear?

Hello all Im Adam and im new to this site. I have a xxxt losi with a traxxis vxl brushless motor and use a lipo and regular batt too. Im having a problem with the center diff gear eating out around the ball bearings. I check my diff everytime i run it because i know it doesnt need to get too loose and i leave my slipper a little loose 2 avoid wheeling out of corners. Is there any metal gears that will interchange with the xxxt diff gears or can i do anything that will stop this? Im open to any suggestions.
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Old 11-13-2008, 03:18 PM   #2
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sounds more like your putting the diff in backwards. the screw end should be on the motor side of the transmission. and diff should be tight before u run . a metal gear is not answer. and not made that i know of.
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Old 11-13-2008, 03:21 PM   #3
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Welcome to the site! Now with you diff problem. I am not aware of any after market metal gears for the xxxt. The reason you diff is melting due to it being set to loose. I would get a new plastice gear, diff balls and thrust bearing set and rebuild the diff. I would reccomend Bfastrc diff balls, diff rings and thrust bearing set. I have been running my set diff parts for over 4 months with a Mamba Max 4600 and 7.4v lipo and it still fills like the day I built it.

Here is a write up from the Bfastrc thread on how to rebuild and break in the diff.

B-FAST R/C PERFORMANCE
Differential Break-In Procedure

1)Clean all parts and work area

2)Follow owners manual for assembly instructions

3)Lightly Coat Diff Balls with Silicone Diff lube, thoroughly lube Thrust Bearing with AE or Losi BLACK grease. (or equivalent)

4)Snug diff screw just until gear will not turn while out drives are held.

5)Assemble transmission per manual

6)With assembled transmission in car and car on a stand, hold one rear tire while lightly applying the throttle for about 20 seconds (about 1/4 throttle, No tire swell). Repeat while holding opposite tire.

7)Tighten diff screw about 1/16 of a turn and repeat step 6

8)Repeat step 7 two more times.

9)Slowly loosen diff screw a little at a time so rear tire turns with little or no resistance while holding the opposite tire.

10)Slowly re-tighten diff screw a little at a time until resistance is felt while turning one tire and holding the opposite.

Drive car and adjust diff to suit your driving style.

Do Not let the Diff Slip at anytime!!
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Old 11-13-2008, 03:50 PM   #4
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cola, I just have replaced everything from the new cups n to the center diff and made sure the diff wasnt too loose. The owner at the local hobby shop told me the same thing so i went and got the diagram to put the diff back together and done it the way it said. The only thing i did different is put more of a light diff grease n it. Now don't get me wrong this just didnt happen as soon as i got it fixed. I mabe run it 15 times some around the yard and on a concreate oval. Do you think mabe this happend because of to much power, or speed because this thang gets scary fast.
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Old 11-13-2008, 03:57 PM   #5
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If it was built correctly it should last a long time, however if you used the stock losi parts that could be your problem. When ever I used the stock losi rings and steel diff balls I would only get a few race days out of it until it needed a rebuild. But if it is consistently eating the diff gear up it is due to the diff slipping. Did you replace the diff screw and nut when you did the rebuild? That may also be the cause of your problems.


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Old 11-13-2008, 04:05 PM   #6
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I did replace the diff screw,bearings,spring,balls,cup washers etc. And i did use team losi stuff to replace. what brand do i need to go with?
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Old 11-13-2008, 04:14 PM   #7
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I would go with www.BFastRc.com for the diff rings, balls and thrust bearing kit. I have been running the same diff parts in my truck for over 4 months and they feel like new. I would also get the Losi XXXTCR square spring instead of the washers.


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Old 11-13-2008, 05:17 PM   #8
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Suggest re tightening the diff after the first run or two. Tends to loosen up a little as everything beds in. Agree that the later CR coil spring works better than the cupped Bellville washers. The B-Fast is nice, but it shouldn't be needed to keep it from slipping, more about getting it smooth. Many run stock stuff with hot motors with no problem, but they do have to be set properly and checked occasionally.

Or if it's not for racing perhaps try the gear diff from the Desert Truck I think it is. Don't know much about it myself, but it should be lower maintenance. Might require a different tranny housing.
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Old 11-13-2008, 05:27 PM   #9
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everyone has been most helpfull. I'll let you know how everything comes out, Thanks Adam
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Old 11-13-2008, 05:54 PM   #10
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I like to use the CR diff rings in the older cars. Be sure and use the copper gaskets and use losi or Asc stealth diff lube on the outdrive between the copper ring and between the copper ring and the diff ring then build the diff as normal. This has worked very well for me since the CR rings came out. The slipper pads may be glazed and not slipping consistantly. I like to use the Asc slipper pads (white ones) and spur on my Losi.

Last edited by plumslow; 11-16-2008 at 04:28 AM.
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Old 11-13-2008, 05:54 PM   #11
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Quote:
Originally Posted by Dave H View Post
Suggest re tightening the diff after the first run or two. Tends to loosen up a little as everything beds in. Agree that the later CR coil spring works better than the cupped Bellville washers. The B-Fast is nice, but it shouldn't be needed to keep it from slipping, more about getting it smooth. Many run stock stuff with hot motors with no problem, but they do have to be set properly and checked occasionally.

Or if it's not for racing perhaps try the gear diff from the Desert Truck I think it is. Don't know much about it myself, but it should be lower maintenance. Might require a different tranny housing.
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Old 11-15-2008, 12:42 PM   #12
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Quote:
Originally Posted by plumslow View Post
I like to use the CR diff rings in the older cars. Be sure and use the copper gaskets and use losi or Asc diff lube on the outdrive between the copper ring and between the copper ring and the diff ring then build the diff as normal. This has worked very well for me since the CR rings came out. The slipper pads may be glazed and not slipping consistantly. I like to use the Asc slipper pads (white ones) and spur on my Losi.
The asc diff lube? is it a blacklube that you aren't suppose to get on any other part of your diff. A guy told me that you have to be carefull how you put that on cause if it gets in your main diff area it will cause diff to slip no matter how tight you get it. Im getting out of gas powereds and now im realizing that electrics can be a handfull of work too. lol
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Old 11-15-2008, 06:30 PM   #13
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make sure your using the clear diff lube when assembling the diff
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Old 11-15-2008, 07:04 PM   #14
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Quote:
Originally Posted by adawg1 View Post
The asc diff lube? is it a blacklube that you aren't suppose to get on any other part of your diff. A guy told me that you have to be carefull how you put that on cause if it gets in your main diff area it will cause diff to slip no matter how tight you get it. Im getting out of gas powereds and now im realizing that electrics can be a handfull of work too. lol
Correct, the black AE lube (moly based I believe) is only for the thrust bearing. The Losi stuff is brown I think.

Use the clear silicone stuff, AE, Losi, or many others, for the diff rings and balls like TNS mentioned.
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Old 11-15-2008, 07:59 PM   #15
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also try robinson racing products they make a hardened sleel gear for the diff i have a few for the XXX-NT im not sure if theyll fit but you will never melt another litttle plastic gear i belive there about $50 cdn
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