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Amp jump

Lephturn

Well-Known Member
Messages
51
My son did a video submission for his class project last week. Today he wanted to jump it with the Amp.


I had the Amp apart and I know it has a few ruined teeth on the spur gear. Can’t get the slipper pads to go on the new spur gear so I figure I’ll run it until it shreds.

It is stock except for a Gens ace 2S 50c 5,000 mAh LiPo. It could easily push a bigger gear ratio and tires with more grip would help.With these tires and the LiPo my kids are learning to modulate and be careful with the throttle which is good prep for brushless I figure.
 
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Lephturn

Well-Known Member
Messages
51
As a follow up to the screwed up spur gear, the slipper clutch just doesn’t slip. I keep backing it off to see if I can get it to slip on carpet but not so far. I am at least a full turn back from the 2.5mm in the instructions that come with the kit. I want it to slip to keep from chewing up the spur the rest of the way but I’ll have to back off more.

I suspect my son landing jumps full throttle with lots of wheel speed in the air is what did it.I’ve had two full 5,000 mAh Lipo charges through it and it’s not dead yet. Sounds like crap but still going. I’ve been jumping it and had some nasty landings but no other breakage. In the video I landed dead on the side - no issues. You don’t see when my son missed the ramp and ran it into the rocks wide open. This Amp is a tough piece of kit.
 

TrackJunkie

Member
Messages
13
I don’t know where they got that 2.5mm number but its way too tight. I had to loosen mine to where the nylon part of the lock nut was just on the threads still, and even that just barely slips.
 

Steve g

Well-Known Member
Messages
270
Location
Massachusetts
Take it apart and make sure the metal discs aren't stuck on the pads. 2 of my trucks get stuck, even with new pads and spur gear, at least once a month. I haven't figured out why, could be heat, but I have to take them apart to separate it to get it to work again.
Generally go by turns out from full compression of the spring by the nut. 1.5 to 2 turns out (full rotation of the nut ccw) is a good starting point.
 

Lephturn

Well-Known Member
Messages
51
I’m way back from that. I have had it apart so I know the discs aren’t stuck. Nothing in there it’s clean and the metal discs turn smoothly. I keep backing the nut off but I’ll take the whole cover off and look at where I am on the nut.
It’s tough though. I have a new 7,000 mAh 55c LiPo and it is quick and runs a long long time with it. I still have a noisy gear case with 3-4 smooshed teeth on the spur but I haven’t stripped it yet.
 

Steve g

Well-Known Member
Messages
270
Location
Massachusetts
You can test the slipper clutch as you are adjusting it without driving around. Have the truck flat on the ground, or work bench, hold both rear wheels down so they can't move, one with one hand, one with the base of the reciever, then slowly hit the throttle and the front tires should start to lift off the ground, maybe 3 to 4 inches, then the slipper should start slipping, and the front should go back down. This is a good way to do it, but you can't repeat it over and over, as both the motor, and even the slipper pads/spur gear will heat up fast. So keep an eye out for that. This works best for brushed motors, and sensored brushless motors, but doesn't work well with the typical 4 pole higher kv brushless motors. They cog too much to get it to work right. Does work on 6 pole brushless motors, but there's not many of those made. Its a good idea to check it every 10 or so battery packs, as its a wear item and will get looser the more its being used.
 

Lephturn

Well-Known Member
Messages
51
I backed it way WAY off and then eventually got it slipping. Once it glazed the pads I had to tighten it up a bit more. Hard landings from big jumps seemed to start it slipping too much, but a quick adjustment fixed that.
 
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