xxxnt problem, please help!

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project94

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hey everyone, i have two xxxnt team losi rc cars, one is probably 7 or 8 years old, the other probably about 4 years old. i don't know much about these that is why I'm here. First problem is they both haven't been ran in a long time and both have the os mach 15 engine. should i rebuild the engine? where can i get a kit? when they stopped working it was like the engine just ran freely when i tried to accelerate. the car wouldn't move but the engine would rev. i thought i might have a differential problem but i pulled my car out the other day, took it apart and the differential, from what i could tell looked fine. neither car had more than a gallon of fuel ran through them. could i have a problem with the gear that is mounted to the engine? it spins freely, I'm guessing the thing next to that gear, the knurled piece, is the flywheel? if so it spins freely also. i dont know if this is normal? i dont know what else to check! any help is greatly appreciated, i miss jumpin this bad boy! :)

thanks
 
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olds97_lss

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I don't believe OS made a "mach 15" engine. They made a CV-R 15. Either way, I'd just buy a new engine, OS18CV-R(x). Not too expensive, plenty of power for your rig and durable/long lasting.

Could be a few things causing loss of power to the drive train. Flywheel loose on crankshaft, loose slipper, burned up slipper pad, broken/burned up clutch shoes, stripped monster gear (main diff gear in the trans) or stripped alternate gear in trans.

When you rev it, see what spins. If the spur/cb spins, it's not the clutch or flywheel. If the shaft the spur is connected to spins, then it's something inside your trans.

Could also be the ball-diff is jacked up. In the older XXX-NT RTR, they used to use a micro-nut to hold the thing together. The nut is easy to strip as is the plastic holder that holds it and keys into the axle cup. They now use basicaly the same thing, but the nut is molded into the hub that keys to the output shaft.
http://www.horizonhobby.com/Products/Default.aspx?ProdID=LOSA2911

This is the screw, nut, spring...
http://www.horizonhobby.com/Products/Default.aspx?ProdID=LOSA2908

This is the older version that sucks:
http://www.horizonhobby.com/Products/Default.aspx?ProdID=LOSA2909

They didn't have the newer version 6 years ago when I had a xxx-nt. I found a full alloy hunk/nut from hammad ghuman (or something like that) but they don't seem to really exist anymore.

EDIT:
I may be wrong... it looks like that newer version is made for the electric losi's... if it were mine, I'd try it though considering it's price. Better design if it fits.
 
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project94

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alright it took the engine out of both cars, one of them has a little bit of resistance when i try to spin the flywheel, the other spins freely, I'm thinking it may be this copper collar that goes behind the flywheel, appears that this is supposed to hold the flywheel tight making it spin with the motor. i went ahead and ordered that and the clutch, as i said i opened up the differential and everything looked fine, no stripped gears, and it all spins freely hopeing this will take care of it
 

beason

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sounds like you figured it out. as long as you didnt break something inside the engine. i would take the clutch assembly off and see if the flywheel nut is tight or not. see if the crank itself will freespin.
 

project94

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thanks for the input guys, like i said i took the diff apart everything, from what i can tell, appears fine. when it stopped running the engine would rev, but the car wouldn't move. the flywheel would just spin so i ordered this flywheel collet http://www.horizonhobby.com/Products/Default.aspx?ProdID=LOSA9376 i also ordered the clutch shoes just in case. hoping this makes sense.
 

project94

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yep, replaced that and it works great now!
 

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