Hitec servo arm compatibity

[Asuckaphish]

Just picked up a TRX4 kit last week and going to put a Hitec 7950 in it. Doing some forum research it looks like there are potential clearance issues depending on the servo arm used hence a few manufacturers making TRX4 specific arms. Looks like nobody is making specific ones for Hitec's 24t splines. Anyone have any suggestions for Hitec compatible arms that keep the stock geometry intact? Looks like the hole in the stock arm is at 22mm. Unfortunately nobody ever lists the hole distances in various servo arms

[ScoJac]

They are a few on here that run Hitec servos and will more than likely chime in in soon. You might reach out to Samix RC, they just came out with specific TRX4 horns but right now they are in the 23 and 25 splines. I’d imagine they are will drop a 24 also. Give them a hollar Samix RC/TRX4

[Asuckaphish]

Thanks for the suggestion. I'll look into the Hudy one.

Has anyone run the Vanquish horns. My LHS has those in stock. Something I can pick up locally is preferred. I'd hate to have to pay shipping for just a servo arm unless I need to lol

[imprezapino]

https://rover.ebay.com/rover/0/0/0?m...2F162440366491

I have a 7954 with this one ;)

[drtrydr2000]

Not sure if this will be an issue with this particular servo but I fried mine and had a Hitec 645MG laying around. I went to mount it in my TRX and the mount was different. The "4 ears" did not line up at all. I mounted two screws perfectly and the other two fit in the slots by the hole but not in the holes. Not even close.

I hope that made sense...

[28offroader]

Originally Posted by Natedog

I used a Hudy offset aluminum arm like this but it has three hole options instead of the two that this has, clearance is great for everything and I have full steering in both directions:
https://www.hudy.net/xhudy/news/news...&kategoria=127

The Hudy horn in your link doesn't look like it has enough drop to clear the panhard bar during full suspension compression. Have a picture of your actual horn or know where to buy it?

[binaryterror]

Originally Posted by 28offroader

The Hudy horn in your link doesn't look like it has enough drop to clear the panhard bar during full suspension compression. Have a picture of your actual horn or know where to buy it?

It shouldn't have drop, that what causes a panhard to hit in a Traxxas. The servo horn needs to be opposite of the norm and remain tight to the servo case.

I have these on order for mine currently based on Natedog's suggestion and reviewing the geometry.

[svt923]

Tekno makes a very good low profile clamping servo arm. I have one on my Ascender which needs maximum clearance between the panhard and servo arm.



It seems the 24T version is getting more difficult to find these days unfortunately. Since Hitec has switched their newer servos over to 25T splines, there must not be much demand from racers for a horn to fit older servos.

[RayB]

My friend is running a Hitec servo with a Vanquish horn. He only gets half to 3/4 suspension compression as the pan hard bar hits the horn...

[Asuckaphish]

Originally Posted by RayB

My friend is running a Hitec servo with a Vanquish horn. He only gets half to 3/4 suspension compression as the pan hard bar hits the horn...

My buddy has a vanquish horn on his and checked his last night. He said he was loosing about an 1/8" in travel at full compression but no travel loss from when compressing side to side.

[Schs2013]

VP makes one I'm pretty sure

Sent from my FRD-L14 using Tapatalk

[o0wiz0o]

Originally Posted by drtrydr2000

Not sure if this will be an issue with this particular servo but I fried mine and had a Hitec 645MG laying around. I went to mount it in my TRX and the mount was different. The "4 ears" did not line up at all. I mounted two screws perfectly and the other two fit in the slots by the hole but not in the holes. Not even close.

I hope that made sense...

There's a technique to solve this. Don't tighten the screws. Put them all in loose and you'll find they all work and tighten down fine. No need to Dremel the servo tabs.

[28offroader]

Originally Posted by binaryterror

It shouldn't have drop, that what causes a panhard to hit in a Traxxas. The servo horn needs to be opposite of the norm and remain tight to the servo case.

I have these on order for mine currently based on Natedog's suggestion and reviewing the geometry.

Servo horn upright is drop. I guess installed it would need lift.

[binaryterror]

Once these Hudy come in I bet I'll be done finally.

The stock truck I am using a 23T so not much option. I just used a standard (Robotronic, Vanquish, Pitbull, Integy, etc) and then spaced the servo up. In my case with a Robotronic it was exactly 2.5mm that was the issue.

My other Class 2 build has just TRX-4 Axles but I'm using a TRX-4 specific servo due to the electronics fitment. It's the SSD and works well but I'm also modifying the CVD's and portal boxes to increase steering, so I will likely need more throw than the SSD offers.

[drtrydr2000]

Originally Posted by o0wiz0o

There's a technique to solve this. Don't tighten the screws. Put them all in loose and you'll find they all work and tighten down fine. No need to Dremel the servo tabs.

I didn’t dreamel anything. I’ll snap a picture of it. I’m saying it’s not even close.

[rockhugger]

Originally Posted by svt923

Tekno makes a very good low profile clamping servo arm. I have one on my Ascender which needs maximum clearance between the panhard and servo arm.



It seems the 24T version is getting more difficult to find these days unfortunately. Since Hitec has switched their newer servos over to 25T splines, there must not be much demand from racers for a horn to fit older servos.

I'm using this arm with a 24t hitec and it works very well, I did have to change the panhard around a little. I get full steer and articulation both directions. I called them to see if they will be making anymore and they rudely said no, we are driving the industry to the 25t standard. have a nice day. It sucks because it really is the besty 24t option.