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Old 04-18-2006, 07:48 PM   #1
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Default xxx nt sport diff

I got a Nt used from a friend with the diff out of it.I rebuilt it and drove it about 50 yards and it stopped pulling...I tightened it up and same results.I went and bought a new screw kit and same thing.Has anyone had this prob and how do you keep it from doing this?
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Old 04-18-2006, 09:26 PM   #2
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Your probly going to need to rebuild the diff. Here is what you need to pick up.
Diff gear
Diff balls
Diff washers
thrust bearing.
you can use the screw assembly and outdrives still.
A can of white greese. It will come like wd-40. Costs about 1.50 at wal-mart.
build the diff over a towel so you don't lose parts.
Place the diff balls in the diff gear.
give each side of the diff gear a tiny squirt of greese, very little. If you use too much it will slip.
Now you need to give the thrust bearing and the two washers around the thrust bearing a bigger squirt. It's ok if this has a lot of grease on it.
Now assemble the diff again.
Once you have it tightened down so that it becomes more dificult to rotate the diff by hand put it back in your truck. Now, put your car up on a stand. A shoe box or something so that the wheels don't touch the ground.
Grab a wheel and give it throtle for about 5 seconds.
Now do this to the right side.
Repeat this about 5 times.
That will break in the diff.
Now tighten your diff up some.
Now take a piece of cardboard and wedge it between the spur gear and the clutch bell.
put the truck on a table and grab the rear wheels. Rotate the wheels in reverse. If the front end lifts up the loosen the slipper about an 1/8th a turn.
You are going to repeat this untill the front end doesn't life up.
If the front end didn't originaly lift up then you need to tighten the slipper up some so that it does lift up and start with the process of loosening it.
That will set your slipper so that your transmission lasts a long long time.
Now, to set your diff.
loosen the diff. about 1/8th a turn and spin the wheels while the spur and clutch bell are locked again. If the slipper slips then loosen it another 1/8th a turn. and check to make sure the slipper is slipping.
Once you loosen it to the point when the slipper no longer slips and the diff slips then tighten it back down 1/4 a turn.
Now, your end result should be a great transmission.
The diff should be able to rotate in oposite directions with out too much resistance, smooth resistance, nothing grainy. The slipper setting will allow you to drive the car fast but it won't tear up the transmission. About once a week you will need to spray a bit of white greese in the outdrive on the side w/ the thrust bearing. You don't even need to break it down. Just give it a squirt. Every so often hold the spurt gear and spin the wheels to make sure that the diff isn't slipping and that the slipper is slipping instead of the diff. Your diff should last you a long time. If it feals grainy when you spin it then the thrust bearings need more grease. If it feels notchy then the balls need to be replaced.

When the diff slips it creats lots of friction which will melt the diff gear.
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Old 04-18-2006, 10:01 PM   #3
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Default losi diffs

another good thing to have is a robinson diff gear. it is aluminum and wont allow diif balls to grind into the plastic diff gear and thus become useless. also use only r/c greases and lubes, but i will say that team birdman diff lube is the best to use and team associated black grease is best for the balls on the thrust bolt. another thing to check after a rebuild is the collet. that is the brass ring on the output shaft of motor under the flywheel, if it has been loose and has benn spun it will slip causing loss of forward drive.

good luck and have fun
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Old 04-19-2006, 02:48 AM   #4
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An aluminum gear is bad...aluminum conducts heat and will cause more problems that it will good. If the diff is slipping and you have an aluminum gear, you could have BIG issues.

Your best bet is to tear the tranny apart; if you don't have the manual for the truck, you can download it from the Losi website, www.teamlosi.com. Really, the best materials you can use for the diff are exactly what Losi sells for their purposes. I use Team Associated Black Grease for the thrust assembly, out of habit, and Team Losi's diff lube for the balls and rings.

Follow the instructions to a T to assemble the diff and the truck. Once the truck is put back together, start the truck and apply ~1/4 throttle to get the rear tires spinning. Hold one tire for 20-30 seconds, then the other, 5-8 times for each wheel. Crank your slipper nut all the way down. Hold the right rear tire and your spur gear with your right hand, and try to turn the left rear tire. If you can turn it, you will need to place a small allen wrench through the slot in the outdrive, and the slot in the diff screw, and turn the opposite wheel clockwise to tighten the diff, try 1/4 turn at a time. Repeat the above test until you cannot turn the left wheel.

Back the slipper nut off five full turns and try the test again. You should be able to turn the left tire now, with some effort. You should see the slipper nut, spring, and assembly turning as you turn the left rear tire. If not, your diff is too loose.

Test your diff and slipper adjustments each time you want to run your truck..it takes a few seconds, but can save you even more time and money. When your diff and slipper are properly adjusted, your diff should last a long time.
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Old 04-25-2006, 12:32 PM   #5
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I ahve to disagree with the above comment. I was always having diff issues with my modded cvr in my drake. I bought the robinson gear and haven't had any problems since. take it all apart, put it together nice and check the tension before every tank. Hold the spur and one tire and rotate the opposite tire. Should be a little stiff and smoooth. If it feels gritty or "grabby" or really llose, time to take a look.

The good thing about the robinson gears is that things can get sloppy or the diff can loosen up over the course of a day and your not going to melt the spur gear.

I would have to say that the robinson was one of the best upgrades to my drake.
just my 2 cents worth.
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Old 04-25-2006, 03:59 PM   #6
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Aaron is 100% correct, you really don't need an aluminum diff gear if you built the regular diff correctly. Just like he says, if you build it right and adjust it properly it will last. A metal diff is a waste of money and will cause other problems if not adjusted properly.

Mine usually out lasts the outdrives and I run 1/2 hour heats. The outdrives wear out first and then I have to rebuild the diff when replacing them.
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Old 04-25-2006, 06:22 PM   #7
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True, you'll never melt the metal diff gear.

But if you allow the diff to slip (which is the only reason why a diff will fail, plastic gear or not) and you have a metal diff gear, you will flat-spot the balls and destroy the diff rings. The diff balls will also bind on the metal diff gear (especially as the diff lube is flung to the outside of the gear over normal use) and your diff will not operate as smoothly as it should.

If a metal diff gear was the answer, it would come that way in the kit!
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Old 04-26-2006, 08:07 PM   #8
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I had the same problem with my sport,must have rebuilt that diff 7 or 8 times.. Same thing 2 maybe 3 laps,I came to the conclusion that it was the sport gears(They are not the same as the Drake)I bought the gears that come with the Drake2 and I have had no more problems.
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Old 04-26-2006, 08:16 PM   #9
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The gear shouldn't have anything to do with it...it's all in how you adjust the diff.
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Old 04-26-2006, 08:30 PM   #10
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I had talked at lengths with Adam about this.I think my problem was with the top of the gears melting.. I did not have a problem with melting the center part of the diff..Aaron,I might suck as a driver but I do know how to build a diff..
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Old 04-26-2006, 08:40 PM   #11
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Haha ok...I haven't heard of that problem at all yet! Sorry for the confusion..
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