How to fix AMP steering linkage design issue

xlDooM

Well-Known Member
Messages
682
When you're making a lowish speed turn on a high grip surface, the turning circle is just massively better for a left turn. This can not be fixed with trim or an upgraded servo as far as I can tell. The problem is that the part of the servo horn that goes over the servo's outer drive gear collides with the underside of the steering arm, effectively stopping the rack from turning further.

So, I fixed it...

Here's the problem:

armcollides.jpg
You can clearly see how on full right lock, the horn and the bottom of the steering arm collide, making it impossible for the servo to move over further.

How to fix the AMP steering linkage



This is the steering arm (still attached to the front cage of the chassis). As you can see it is fairly sturdy and it wouldn't hurt to take off some material.

armbefore.jpg

So I took a cutter to it and took off a good chunk:

armcut.jpg

The issue is now gone, there is come clearance between the two parts at full right lock:

armfixed.jpg

I tested it on my lawn and the difference was immediately clear. I can now do figure-eight tracks either direction around the jump, as it should be.
 

X

Conspiracy of One
Staff member
Supporting Member
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1,054
Nice work! Thanks for figuring this out.
 

xlDooM

Well-Known Member
Messages
682
I was contacted by a Horizon employee to look into this problem, which he could not replicate on his own truck. So not all cars may be affected. Either way it's good to see Horizon taking concerns like this seriously.

If you have an Amp or a Circuit, you could contribute by making both a left and right circle at (very) slow speeds and seeing if yours turns markedly better to the left than to the right, as mine did.
 

X

Conspiracy of One
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Supporting Member
Messages
1,054
You don't even need to take the RC out really. If you have it on the bench and you turn lock to lock you will notice that the servo can fully turn left. If you turn right you will hear the servo whine as it is attempting to continue turning but is running into resistance. My Amp does this. Haven't checked my circuit yet, but it is 4wd and has a completely different steering servo setup. I suspect this will only be an issue with the 2wd models.

BTW, this also occurs with the RPM servo saver eliminator.
 

Mxkid261

Well-Known Member
Messages
95
I didn't run into this problem with my RPM eliminator, but I'm running a ProTek servo and metal arm which probably makes a difference. I have full lock to lock steering clearance and little to no play. I never even ran the stock servo as I had the ProTek laying around from a boat
 

nimbuzz

Well-Known Member
Messages
83
Location
Bay Area, CA
I don't have an Amp here at home to check but I ask; 1--How many here have this problem? 2--Does it affect other ECX models than the Amp? 3--Did Horizon resolve this issue? My kids and I have bought 8 Amps in the past three months and I didn't notice it = am I dumb or is it fixed??
 

X

Conspiracy of One
Staff member
Supporting Member
Messages
1,054
As noted above, my Amp had this issue. I've never seen an official fix from Horizon. Theoretically, all 2wd 1/10 scale ECX RCs might show this issue, as they all have the same steering servo setup.
 

xlDooM

Well-Known Member
Messages
682
I have two Amps, and both have this problem. The problem was worse on my first one than on the second. There is some variation in how the top part bolts onto the front of the chassis (some of the holes are slots) which may account for the difference.

If you want to test it, drive slowly on tarmac, make circles left then right, check for difference in turning circle.
 

Tamyosho

Well-Known Member
Messages
96
Mine stops 1mm short of touching, I think it's dependant on the length of the turnbuckle.
 

Jeb

Well-Known Member
Messages
328
Location
West Glover, VT
I had to extend the length of the steering turnbuckle to acheive the full throw of the steering. Also, you may notice that when the front steering arms are at full droop the steering knuckle arm binds on the a arm. I better servo helps with this. I also shortened the front shock length by putting a nylon spacer inside the shock under the piston cap. No more binding.
 

MaX-D

Well-Known Member
Messages
79
Location
Coral Springs, Florida
I just converted a 2wd torment to a circuit. I have the RPM Eliminator but still have this problem. I'm using a Spektrum dx4c radio and a tactic tsx55 servo. I started the steering travel at 100%, and got it up to 124% to the left, but had to back the right down to 93% because the servo stopped moving. I'm going to take a look at this tonight when I get home. Am I missing anything?
 
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