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
Premium Member
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1,210
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
Staff member
Premium Member
Messages
1,210
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
124
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
Premium Member
Messages
1,210
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
100
Mine stops 1mm short of touching, I think it's dependant on the length of the turnbuckle.
 

Jeb

Well-Known Member
Messages
337
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
213
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?
 

Breenus

Member
Messages
8
I agree, the steering design is not great. Even changing the servo and using as many different parts as I could didn't solve the issues, it improved them a bit though. When I look at the steering it's just not well engineered. I just bought the Hot Racing aluminum steering bellcrank and it looks like that is going to elbow to elbow to elbow situation, which definitely seems to be the weak point. I still have a bag full of servo connectors and fittings so when that comes in I am going to see what I can do to make this work right. I'll take some pics.
 

denbownium

Member
Messages
9
My AMP had this issue with the RPM saver, I know. Not sure about stock.

I was able to use the Hot Racing Aluminum steering servo saver kit for the Circuit/Torment specifically on the AMP MT. Upgraded stock servo to a SPKTRM 6180 (its metal gear out to servo arm mounting) and added Aluminum servo arm. It turns good now. The connecting arm from servo arm to servo saver gets shorter too - that helps with eliminating slop. The only mod I had to do was Dremel out the 90 degree edge of the servo cover (the black cover that connects to front shock tower and chassis) to allow for the taller servo arm. Other than that, all bolt on.

ECX AMP - dremel.jpg

Look from overtop:

overtop look.jpg


side view:

side look.jpg


now to work on tires .... at least rears for grip when accelerating. stock terrible with brushless setup.
 
Last edited:

Lephturn

Well-Known Member
Messages
206
Check out the wheels/tires for a Redcat Volcano - grippy and cheap. Seal the wheel vent holes and vent the tires.
 

weave

Well-Known Member
Messages
327
Location
San Jose, Calif
My AMP had this issue with the RPM saver, I know. Not sure about stock.

I was able to use the Hot Racing Aluminum steering servo saver kit for the Circuit/Torment specifically on the AMP MT. Upgraded stock servo to a SPKTRM 6180 (its metal gear out to servo arm mounting) and added Aluminum servo arm. It turns good now. The connecting arm from servo arm to servo saver gets shorter too - that helps with eliminating slop. The only mod I had to do was Dremel out the 90 degree edge of the servo cover (the black cover that connects to front shock tower and chassis) to allow for the taller servo arm. Other than that, all bolt on.

View attachment 6525

Look from overtop:

View attachment 6526


side view:

View attachment 6527


now to work on tires .... at least rears for grip when accelerating. stock terrible with brushless setup.
 

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