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Thread: What's wrong with my TRX-4? High/low gear shifting problem.

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Old 09-03-2021, 11:46 PM   #1
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Join Date: Jul 2021
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Default What's wrong with my TRX-4? High/low gear shifting problem.

Hello guys, hope everyone is doing great!

I have a new TRX-4 Defender with a strange issue.

When I engage gear shift, it doesn't engage fully until I give a bit of throttle. When I give a bit of throttle, then it clicks(loud) and engages. Does anyone have the same problem? My rig is new and hasn't been out on trails yet.

It happens maybe 7 out of 10 tries.

Please take a look at this video - https://youtu.be/ot7dXYHoP4w

Any help would be appreciated.

Thanks guys!
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Old 09-04-2021, 12:08 AM   #2
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Default Re: What's wrong with my TRX-4? High/low gear shifting problem.

could be sticky shift lever, dirt/debris could be causing it to stick. Servo could be getting weak, or when you are shifting, the shift dogs are not quite alinged and it takes little turn for them to slip into place.

Its kind of normal in many cases, but you could have some sticking or weak servo issue showing up.
Just a few ideas.
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Old 09-04-2021, 01:04 AM   #3
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Default Re: What's wrong with my TRX-4? High/low gear shifting problem.

when I had my TRX4, It did this every time. I always just barely tap the reverse, it'd shift then i'm good to go. you MIGHT have something sticking like the above comment said, but more than likely there's not.

If you do decide to resolve this 'issue', then save opening the transmission for last. It is a pain in the ass to get back together all complete. Trust me, save it for last.

Last edited by ScaleLifeNewbie; 09-04-2021 at 01:08 AM.
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Old 09-04-2021, 02:28 AM   #4
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Default Re: What's wrong with my TRX-4? High/low gear shifting problem.

Quote:
Originally Posted by Timmahh View Post
could be sticky shift lever, dirt/debris could be causing it to stick. Servo could be getting weak, or when you are shifting, the shift dogs are not quite alinged and it takes little turn for them to slip into place.

Its kind of normal in many cases, but you could have some sticking or weak servo issue showing up.
Just a few ideas.
Thanks for the suggestion. I think I'll have to do some more research.
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Old 09-04-2021, 02:30 AM   #5
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Default Re: What's wrong with my TRX-4? High/low gear shifting problem.

Quote:
Originally Posted by ScaleLifeNewbie View Post
when I had my TRX4, It did this every time. I always just barely tap the reverse, it'd shift then i'm good to go. you MIGHT have something sticking like the above comment said, but more than likely there's not.

If you do decide to resolve this 'issue', then save opening the transmission for last. It is a pain in the ass to get back together all complete. Trust me, save it for last.
Cheers mate, I hope it won't cause too much issues but it's pretty annoying to see this happening in a new rig. Thanks for your input!
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Old 09-04-2021, 02:58 AM   #6
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Default Re: What's wrong with my TRX-4? High/low gear shifting problem.

This is normal, as i understand the situation.
The gears are not synchronized and there's no clutch, and so you not only should avoid switching gears when not driving (servos will die when trying to pull the lever in for a prolonged time), it is neccessary for the rig to roll.
Although the dog will not slide in when it's under load, it most certainly will not do when the wheels are not turning. In the first case, friction will hold the dog in the runnning gear so it can't be pulled out, in the second it'll come almost to rest in the other position but then the tooth won't fit and it blocks.
Try driving slowly, maybe even switch then lower throttle a bit. Loadless casting works best.

On my Summit i usually do this to show off and switch like a real car: low gear, pull Trigger and accelerate. Then gear up while still getting faster (notice it is not engaging right now), and when final low gear speed is reached, "clutch and shift": briefly release trigger and re-pull. At this moment the gears click in.
Result: Sportscar-like Acceleration, *schnick* high gear and off we go.

The manual of either car has a section about this.
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Old 09-04-2021, 05:52 AM   #7
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Default Re: What's wrong with my TRX-4? High/low gear shifting problem.

Quote:
Originally Posted by amigaman View Post
This is normal, as i understand the situation.
The gears are not synchronized and there's no clutch, and so you not only should avoid switching gears when not driving (servos will die when trying to pull the lever in for a prolonged time), it is neccessary for the rig to roll.
Although the dog will not slide in when it's under load, it most certainly will not do when the wheels are not turning. In the first case, friction will hold the dog in the runnning gear so it can't be pulled out, in the second it'll come almost to rest in the other position but then the tooth won't fit and it blocks.
Try driving slowly, maybe even switch then lower throttle a bit. Loadless casting works best.

On my Summit i usually do this to show off and switch like a real car: low gear, pull Trigger and accelerate. Then gear up while still getting faster (notice it is not engaging right now), and when final low gear speed is reached, "clutch and shift": briefly release trigger and re-pull. At this moment the gears click in.
Result: Sportscar-like Acceleration, *schnick* high gear and off we go.

The manual of either car has a section about this.
Thanks so much for sharing! I'm learning new things every day!
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Old 09-04-2021, 08:44 AM   #8
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Default Re: What's wrong with my TRX-4? High/low gear shifting problem.

Think of it like an older full size vehicle which you would have a lever inside to engage the 4wd (not one that you would have to manually turn the hub in the center of the rim). The vehicle has to roll forward to the engage. Obviously if you slam on the gas it may engage hard. My TRX4 would slam into high or low gear if I did it while mashing the throttle, but would be much softer if throttle is rolled on gently. I pretty crawl much more than trail and have since yanked the whole tranny out and replaced it with the single speed from a TRX4 Sport.
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Old 09-12-2021, 08:52 AM   #9
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Default Re: What's wrong with my TRX-4? High/low gear shifting problem.

This is normal, the trans and axle lockers are not like a modern car with synchro's. So the dog ears aren't perfectly aligned all the time. I usually give a tap in reverse or forward depending on my last direction. That aligns the tabs perfectly and makes for. Seamless engagement

Sent from my SM-G991U using Tapatalk
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Old 09-22-2021, 10:20 AM   #10
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Default Re: What's wrong with my TRX-4? High/low gear shifting problem.

It's completely normal. There is only 2 dogs in the transmission to engage, so depending on where in the cycle the dogs are when you shift, it may need a little movement to get them lined up. It's not a synchromesh transmission like a car.
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