Mojave Mojave 6s Servo mount flexing

[5mall5nail5]

Hey all - recently picked up the Arrma metal diff housing and put earplugs in it - so nice. While I had the truck apart I was playing with it with the body off and noticed that the steering servo shifts a decent amount while steering. I saw an EXB aluminum steering servo mount but I also saw a HR aluminum servo mount - is one better than the other in terms of future compatibility/etc.? I am inclined to get the EXB/Arrma one for "factory" sake but if there's some reason I should consider the HR I'd be open to that too.

Thanks!

 

[Jon NC RC]

Hey all - recently picked up the Arrma metal diff housing and put earplugs in it - so nice. While I had the truck apart I was playing with it with the body off and noticed that the steering servo shifts a decent amount while steering. I saw an EXB aluminum steering servo mount but I also saw a HR aluminum servo mount - is one better than the other in terms of future compatibility/etc.? I am inclined to get the EXB/Arrma one for "factory" sake but if there's some reason I should consider the HR I'd be open to that too.

Thanks!

Honestly good sir I've never had that problem with mine, but I'm interested to see what people say so I'll jump on this thread to see what others will relate to you! Good question......are you sure all screws are tightened appropriately?

 

[5mall5nail5]

Honestly good sir I've never had that problem with mine, but I'm interested to see what people say so I'll jump on this thread to see what others will relate to you! Good question......are you sure all screws are tightened appropriately?

Yep, all right. The plastic holder is flexing under torque. Not enough to really prevent the truck from steering but flex is power loss. I'll take a video.

 

[Sargent_Horse]

If it's the same as the Kraton EXB mount, then the EXB one has a metal plate but still has plastic arms/risers. The HR aluminum mount is all aluminum components. I have not had any issues with my HR servo mount in my Kraton. I'll be putting a carbon one from @HotdogCustoms in my MEXB though, since I have it sitting around.

 

[5mall5nail5]

@Sargent_Horse do they have a web store available? Here's a video of my current situation.

 

[Sargent_Horse]

@Sargent_Horse do they have a web store available? Here's a video of my current situation.

Easiest way to contact him is to send him a PM on the forum I think. Either the HR one or the Hotdog customs one would help solve your issue. If you want to try a DIY fix, some people just replace the screws that hold the servo mount with the longest ones that fit to help stiffen up the risers. With the flex eliminated, it becomes a bit more important to properly set your endpoints, just keep that in mind.

 

[jondilly1974]

As a quick fix, you can simply use much longer screws to mount the servo mount to the chassis. The longer screws will take out some of the flex by reinforcing the legs from the inside. Not as good as an alloy mount, but it will improve its rigidity.

 

[Jimbobjr]

Get rid of the rubber servo grommets and the stock is pretty solid. The very best servo mounts are one piece. GKA makes a nice one. On the smaller/lighter wheeled trucks the stock one works fine. I even use the plastic one on the talion and as @jondilly1974 said run longer bolts. Plenty stiff enough for the Katars.

 

[Jon NC RC]

@Sargent_Horse do they have a web store available? Here's a video of my current situation.

Interesting. I will give you definite kudos for this.....
Many times people come on to the forum and describe the problems they have, but including a video was definitely helpful! Thank you for doing that!!!

I am absorbing what the people are suggesting, and when we get back home from a brief getaway, I will monitor my Mojave to see if I need to do any adjustments.....

Well done

 

[Jimbobjr]

I watched the video again. Are your end points adjusted? Looks like the flex is coming at the end of the throw both directions. If you do decide to get a servo mount maybe get the heavier servo saver spring too. That will be the next weak point in your steering.

 

[5mall5nail5]

I watched the video again. Are your end points adjusted? Looks like the flex is coming at the end of the throw both directions. If you do decide to get a servo mount maybe get the heavier servo saver spring too. That will be the next weak point in your steering.

I'll check, but slowing the footage down I can see the assembly reposition before it reaches the endpoint. Especially changing directions. I don't have any binding noise or anything, but its worth a check.

 

[Jimbobjr]

I'll check, but slowing the footage down I can see the assembly reposition before it reaches the endpoint. Especially changing directions. I don't have any binding noise or anything, but its worth a check.

I checked the talion today with the plastic mount. It moves maybe half as much but I do have the long chassis screws in it. The hr and stock mount move much less (I have both in other cars) but there’s only so much those tiny screws can hold and they still will flex slightly. My other brand trucks with plastic servo mounts/receiver holders do not budge. They rely on the rigidity of the receiver box as well as larger mounting bolts. Imo that way or having them mounted horizontally is better but we have what Arrma decided to go with and it does work ok...

 

[joeshow750]

I'd probably do this one before the HR one--it's one piece, has a cutout for your servo wires (some servos can be a pain to get in and out), and only costs a little more.
https://justbashitrc.com/shop/arrma-6s-servo-mount/

 

[Burt37]

Yep, all right. The plastic holder is flexing under torque. Not enough to really prevent the truck from steering but flex is power loss. I'll take a video.

You are 100% correct. Flex is power loss or in this case "Kinetic energy"...

Now, if you are a racer and are more interested in performances than longevity, than I agree with you. You should try to remove the "flex" out of the servo mount. But all you are really doing is just transferring that flex elsewhere in the system... No matter what you do, something will have to absorb this flex...
Linkages, servo saver spring, plastic gears inside the servo... That's normally the price you pay for performances, as you will need to replace those parts more often...

If you are just enjoy yourself with your car, then perhaps, the servo mount is exactly where you want this flex to happen.. Is probably the cheapest part in the chain of the steering system...

I guess what I'm saying is that the servo mount (including the rubber mounts) are doing their job of absorbing the "flex" that otherwise would impact more expensive parts in your car.. It is not a defect. It was built to work that way.. But if you want (need) to improve your lap times, and money is not an issue, an aluminium mount, will definitely cut the flex down at the servo (you will also need to remove the rubber), and improve your steering response...

 

[5mall5nail5]

I watched the video again. Are your end points adjusted? Looks like the flex is coming at the end of the throw both directions. If you do decide to get a servo mount maybe get the heavier servo saver spring too. That will be the next weak point in your steering.

So I went out to do something else but took a min to check this. I have a FlySky Noble NB4 - I set the EPA on the steering input to like 40% and it does the same thing. It's exacerbated whenever the servo arm is further away from perpendicular to the servo body because at that point there is both the resistance of the steering mechanism but also torque being applied in the linear vector with respect to the servo body. So, yeah, the plastic does flex a fair amount. As to whether or not things would start breaking if moved to the HR mount or not... we'll have to find out!

 

[SrC]

@Sargent_Horse do they have a web store available? Here's a video of my current situation.

Get rid of the rubber grommets. Don't use them at all. Buy some alloy servo specific washers with Flat head screws. ( of longer lengths)
And use longer screws on the stocker plastic servo mount. Makes the plastic mount much more rigid. I also feel you also might have Endpoints over extended. What I see in the video at least. I don't feel alloy mounts are always truly necessary if using longest screws that will fit. I have half of my 6s rigs with HR alloy servo mounts and the the rest using plastic mount with longest screws that fit. (all 8 screws) Both chassis side and servo screws. Works for me. But overextended endpoints will stress any mount whether alloy or stock plastic.