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Mechanical tech This is for the mechanical parts of a model. Gear reductions, Axles, Transmissions, General drive line


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Old 08-12-2017, 06:10 PM
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kaptain Jack kaptain Jack is offline
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Default I'm puzzled

Picked up a bargain, a high lift.The guy admitted that shifter is finicky. Brought it home, the problem is the higher gear doesn't engage, high pitch sound and nothing, lower and second ok. Took the gear box apart, seems to be ok, added grease, tested manually,works fine. Rear axle was a bit stripped, but not much, changed the parts. Same problem: upside down, all is fine shifting and engaging ok, on the floor only low and second, high slips with high pitch motor.
Any ideas?
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Old 08-12-2017, 08:23 PM
frizzen frizzen is offline
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Default Re: I'm puzzled

Kinda sounds like one of the 3rd gears snapped a cross pin / hogged out a spline holding it to either top or bottom shaft.

Pull the trans case off, run it upside down in 3rd and squeeze tires on an axle to put load on it. Should be able to see which gear slips on shaft.
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Old 08-13-2017, 08:02 PM
bigdogrod bigdogrod is offline
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Default Re: I'm puzzled

either that or the shiftier is not throwing the gear far enough to engage, see if you can get it in manually

>that's what she said!<

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Old 08-14-2017, 08:57 AM
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kaptain Jack kaptain Jack is offline
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Default Re: I'm puzzled

Thanks for coming through, on manual shifts ok, I changed the servo to a metal high torque, much better but not perfect. Just like real car, switching into third from stop, takes a lot of throttle before it takes off. Not The same as my other High lifts, but at least it moves.
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Old 08-14-2017, 10:04 AM
bigdogrod bigdogrod is offline
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Default Re: I'm puzzled

check out the servo throw, it might not be engaging enough, longer servo arm or adjust end points on radio if yours has that setting
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Old 08-14-2017, 07:07 PM
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Default Re: I'm puzzled

Found the problem: stripped the gearbox completely apart and discovered that one of the slip gears was on the wrong side and fully engaged, so when you tried to shift, no room to go.... All fine now.
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