TRX-4 Swapping diff servos.
 

So I have had my TRX4 for a few hours now, and I decided that I wanted the rear diff to lock, then the front and rear together. It was rather simple after I tracked down the RX wiring.



It was a fairly simple swap. Channel 4 and Channel 5.
http://nebula.wsimg.com/6ad9d3e2768f...&alloworigin=1

No diffs engaged
http://nebula.wsimg.com/c18dc5a93ffc...&alloworigin=1

Rear only engaged
http://nebula.wsimg.com/efe02eef0d80...&alloworigin=1

Both diffs locked
http://nebula.wsimg.com/cb7f1af81d5b...&alloworigin=1

I'm not really sure why traxxas wanted the front diff to lock, and then both front and rear. It seems completely backwards to me.

Re: TRX-4 Swapping diff servos.
 

I mentioned that in the big thread that it should be that easy as swapping servo wires (and maybe servo and or horn orientation), and assume Traxxas did it that way so the thing doesn't flip over backwards as much for the newb drivers.

Good.

Re: TRX-4 Swapping diff servos.
 

Well...it isn't this easy. Either I didn't pay enough attention or something else is going on. The switch on top runs in the opposite function now...., and the front still is the one that only locks.

Re: TRX-4 Swapping diff servos.
 

Servo reverse switch or flip the servos 180 and flip the horns 180. That's all I got for now. And yeah, the switch will be the other way around, you're throwing the opposite servo.

I'd do just one servo at a time to make it easy for my brain.

Re: TRX-4 Swapping diff servos.
 

The Summit uses a module to control the diffs. Part TRX5697... not sure if they are using the same setup on here or not. Doesn't look like it based on that diagram ...but since it doesn't work... might be worth a look. I do know that my toggle switch only controls 1 channel...so the module makes sense.

Re: TRX-4 Swapping diff servos.
 

After more reading, and help from the facebook group, it seems I need to swap channel 4 and 5 at the RX, and reverse the servo throw in the radio.

Maybe tonight I'll get time to reconfigure it all.

https://scontent.xx.fbcdn.net/v/t31....00&oe=59A39D9D

Re: TRX-4 Swapping diff servos.
 

The reasoning for Front lock and open diffs over rear lock and open front is to pull you up and over. If you lock the rear it will push causing roll overs backward on hill ascents. Both ideas have merit, but in general a locked front is safer and more useful than a locked rear. I think they chose the right way for a trail driver and some comps honestly.

Re: TRX-4 Swapping diff servos.
 

This has been a topic of debate for decades in the 1:1 world. Generally, if you are only going to lock one end, the front is better on high-traction surfaces like rock, the rear is better on low-traction surfaces like gravel, snow. I'm not aware of any 1:1 truck where the front locks first. Almost all have the following 3 selections: both open, rear locked, or both locked. Also never heard of a truck coming with a factory locker only in the front. The better option here would have been to just make them independently controllable with 2 switches.

Re: TRX-4 Swapping diff servos.
 

it's always easy to spot who actually wheels rigs vs rc-only guys. lol.

fronts always get locked up first, because it's easier to pull weight than push it. ;)

Re: TRX-4 Swapping diff servos.
 

I think this is what I'm going to end up doing.

"thumbsup"
I agree, but I drive on slippery low traction surfaces more than high traction surfaces.

Re: TRX-4 Swapping diff servos.
 

So I finally figured out what I like. "thumbsup"

Both channel 4 and 5 are reversed.

So this means ....
Switch in rear position: Rear diff locked only.
Switch in center position: Both diffs locked.
Switch in front position: Front diff locked only.

This is without swapping channels 4 and 5, and I think it is GREAT.

I forgot I had a Traxxas link in my e-maxx so I swapped the module over to my TRX-4, updated my app for the TRX-4, and starting messing around. It made changing the servo directions a snap!

I feel this is the simplest solution to my dilemma.

Re: TRX-4 Swapping diff servos.
 

This is really cool thanks for testing this out for us duddeee.

Are you saying you can switch it around using just the Link or you used the Link and switched them physically?

Also I agree the order is reversed from what I would want.

edit: Ah I read above that irl they do lock up the front first on I guess more serious rigs. My Tacoma had I think an open front and rear but a nice low range (non-trd model) but I thought the TRD model had a locking rear and open front. and Ive been in a few f250/350s that have locking rears but I'm pretty sure open fronts? So I was surprised to read that. Also I don't mind sketchy camp roads and class3s but the one time I tried a more rocky and serious trail I got scared half way up and had to back all the way out no way to turn around lol.. it feels a lot different in real life when your truck is pitched sideways on a rock haha.

Re: TRX-4 Swapping diff servos.
 

Here's a YouTube video link that may help:

https://www.youtube.com/watch?v=aT24MGifqW0

Re: TRX-4 Swapping diff servos.
 

For what it's worth, I crawled 1:1's from age 17 (1992) till age 32 (2007) culminating in competing in 2000 with a first gen Toyota pickup in Montrose CO. I lived in CO and wheeled all over the southwest, mostly northern CO and Eastern Utah and we always locked the rear first and then the front.

I had Detroits in both so I don't count, but most had rear only, rear locked and front selectable or both front and rear selectable.

Weight transfer, steering, and weaker front axle component were the reasons for our choices.

It's possible that the community has changed in the past 10 years that I've been into RC only....


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Re: TRX-4 Swapping diff servos.
 

on a 1:1 i'd much rather unlock the front, i have lockers front and rear on mine, and sometimes the only way to be able to steer worth a damn or stay out of muddy ruts is to unlock a hub. but a scale rig turns alot better than a 1:1 does with spools front and rear.

on an rc i would much rather unlock the rear. especially when going up something techy and off camber where the rear gets all the traction and wants to push the rig straight, or break loose and swing the rear into a hole you were trying to avoid.


i havent read anything really about this truck and dont own one, but does that unlocked wheel spin at a faster rate when its only putting power to one of the wheels? that could be kinda cool for the front... and for the rear you could intentionally bind the axles or portals with bushings and shims so the unlocked side could be a passive turning brake. yes it'd be hard on the drivetrain and elecs, but it could be interesting for a scale comp rig.

Re: TRX-4 Swapping diff servos.
 

I also wanted to figure out how to just lock the rear diff, My reasons are a bit different though. For me locking the rear only was for hooning around.

As you guys already figured out the Traxxas link was the easiest was to do this, as well as un-do this. Putting it back to normal is pretty important to me as I dont use it like that for long at all.
I also prefer the front being locked first for the rocks I crawl on. If I am forced to do them in a specific order I'll take the fronts first. In my backyard I have a line that's slanted and steep in which I will roll backwards when front and rear are both locked on most attempts, while having just the front locked allows me to pull my way up with almost no worries of rolling backwards.

I guess the Ideal mod for these diffs would be to get these lockers on 2 separate switches so you can lock any diff at any time. I'm guessing this would require a different transmitter though.
Any thoughts on what it would take to do that?

Re: TRX-4 Swapping diff servos.
 

In a crawler, front locked first is definitely better, and in some cases, like the other guy said, having the rear unlocked will help. In 1:1, rear locked first is definitely better, at least in forests with muddy hills etc i dont have any experience 1:1 rock crawling. On dirt/ mud, having the front locked will 1: destroy your turning circle. 2: make the front try to slide to the side when climbing a slippery hill with no ruts to guide you. 3: massively increase the risk of breaking cvs. There are two times we use front lockers: in flat mud bogs, when winching, or occasionally when descending a slippery hill to avoid locking a wheel when driving an automatic. I drive a 1:1 (samurai with rear arb locker and being a passenger in my dads cruiser with factory electric lockers-rear, then both locked- for about 10 years before getting my licence) as well as rc crawlers (venom creepers so i have plenty of experience with fiddling around with lockable diffs)


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Re: TRX-4 Swapping diff servos.
 

I drive 1:1 Suzukis in offroad competitions maybe 10-15 years only in the rear locker class.

On the TRX4 the locked front first works for me better than first rear locked.On some steep rocky hills the Truck climb better with front than both locked ,because if the rear locked tires get to much traction the rig try to wheely or tipp over . With rear open and front locked there is no tendency to tip over and the two front tires climb over the rocks with ease.;-) I dont think 1:1 rigs and 1:10 cant be compare because the rc is extreme lightweight and over powered,non 1:1 110 Defender can do such extreme climbing (even with lockers) ha ha!

Re: TRX-4 Swapping diff servos.
 

If you have a 4 channel radio laying around you can select how you want your diffs to lock. I'm running a 4 channel Futaba and can select how I want to run my diffs from all open, to rear only, front only or both. The only downside (if you want to call it that) is you don't have control over the 2 speed tranny servo anymore.

Re: TRX-4 Swapping diff servos.
 

I already swapped mine as well. I swapped channel 4 and 5 servo plugs at the receiver, the then both channels needed the servo reversing done from what they previously were. It's awesome now!