Couple questions about the AMP MT

[Bigpoppa99]

Considering ordering two of these trucks (AMP MT) in kits for me and my son to put together and bash around. I have a few questions, and some I have read about here on the forums but just don't quite understand.

Tires: I understand the stock tires don't have foams and make poor handling of the truck. Any recommendations for tires/wheels of the same size as stock? I mostly plan to run on dirt, grass, and occasional SC track (packed dirt), occasional pavement.

Servo: By reading I can tell the stock servo is out of the question, so I plan to put in the Power HD 1501 at the time of build.

Servo Saver: A bit confused here. On weather to try it stock or go ahead with the RPM eliminator. I read where some like it, then I seen a review where a guy said he put one on and went back to stock servo saver.

Bumpers: I kept seeing Tbone bumpers mentioned, can you guys link me to the Tbone bumpers for the AMP MT you are referring to?

Power HD 1501, will that servo run fine by plugging in like the stock, or can it handle the volts from a 2s lipo? In my r/c crawlers I have my high torque servos wired straight to my 2s lipo.

Bearings: I read the stock bearings are not too good, so I may go with Fast Eddy bearing from the time of build.

 

[X]

Only thing that is a must for the Amp is a lipo battery. Everything else in my mind is a nice to have.

Let me explain the RPM servo saver eliminator review. Stock, replacing your servo saver with the RPM unit gives some benefit but only because it eliminates the stock servo saver. Gets rid of a little inaccuracy when trying to steer while on rough terrain. The problem with only installing the RPM unit is that now the chassis sends the bumps to the next weak object in line.....the servo and servo arm. These are both plastic (gears and arm). I was constantly jumping teeth on both the servo and servo arm causing me to constantly have to redo the trim. To the point where I would have to reinstall the servo arm to recenter it. Because of this I uninstalled the RPM unit because this was my son's RC. I had no need at the time to pay for a new metal geared servo and servo arm with servo saver.

 

[slowmethinks]

As far as the T-bone racing bumper, I'm pretty sure that your amp uses the circuit chassis. Without having the truck in front of me, I don't have much to go off of. But T-Bone racing makes a bumper for the circuit. I would definitely get both the front and rear.

http://tboneracing.net/19033-tbr-thrasher-front-bumper-ecx-circuit-st-2wd/

 

[Bigpoppa99]

X, so with me planning to run a MG servo with a aluminum servo horn anyway, would you still suggest the RPM eliminator?

Slowmethinks, do u have a link for the rear bumper?

 

[slowmethinks]

X, so with me planning to run a MG servo with a aluminum servo horn anyway, would you still suggest the RPM eliminator?

Slowmethinks, do u have a link for the rear bumper?

http://tboneracing.net/brands-a-m/ecx-electrix-rc/circuit-st/

 

[xlDooM]

I run the power HD 1501MG servo with a plastic servo horn and the RPM servo saver eliminator and it has been fine. Make sure you use the 25T horn you get in the extra Amp bits and pieces instead of the 23T that goes on the stock servo.

By the way I don't think you need the RPM servo saver eliminator per se. When you take the stock servo saver apart, you see that it has quite a bit of contact area to glue the two halves together. You can always try this first.

 

[Bigpoppa99]

Can the servo saver not tighten down? I can't hardly remember but on my old Traxxas Emaxx (or could have been my Losi 8 buggy) I thought I remember you could either tighten the saver down to where it takes more to "scissor" it open, or you could use stiffer springs to get the same effect. I can't remember which it was though. Can the saver on this truck not be tightened?

 

[xlDooM]

It's not adjustable. The "spring" is a metal collar around the two parts which opens up. I suppose if you made a stronger collar out of a stiffer material, that would tighten it up. But the whole steering is protected from impact by four ball joints, a plastic servo horn, and the plastic turnbuckle. On mine, it's one of the ball joints attached to the servo horn which pops off when I overcook it. If those joints were more solid, I reckon the servo horn might strip. But my experience has been that when you are crashing hard enough to do that, other stuff starts breaking faster. In my case the axle carrier and the caster block.

At one point I had a zip tie around the servo saver, it worked well but it slid off by the end of the run and it's not a very accessible place.

 

[Bigpoppa99]

Gotcha. Oh and what are these shoulder screws people say they are loosing and what's the fix for that?

 

[xlDooM]

Look at this picture:

The blue part is the axle carrier (spindle). It is attached to the caster block (the c-shaped plastic part that wraps around the top and bottom) by two shoulder screws. They have a smooth section which goes through the holes in the caster block, and then some threads at the end that screw into the axle carrier. The problem is that the threaded end is really short. It must be, otherwise it would hit the outside bearing.

These screws can work themselves loose under repeated cornering. You cannot really tighten them hard in the stock plastic caster blocks (or even the uprated RPM ones) without stripping out the hole.

I think the best fix is getting the aluminium axle carrier from Hot Racing, as pictured above. Other solutions are possible using Associated or Traxxas parts. There is a two page thread on here somewhere.

 

[Bigpoppa99]

http://www.ebay.com/itm/Hot-Racing-...147426?hash=item58d5815ea2:g:HZEAAOSwa-dWtPFE

Gotcha. Is this the right part? Then im assuming use Blue loctite on the aluminum right?

 

[Bigpoppa99]

http://www.ebay.com/itm/Hot-Racing-...232371?hash=item43e9609f33:g:lsoAAOSwFMZWtPEx

Oops, just found this part too. Which to get? And do they have to go together or can you mix aluminum with the stock plastic?

 

[X]

http://www.ebay.com/itm/Hot-Racing-...232371?hash=item43e9609f33:g:lsoAAOSwFMZWtPEx

Oops, just found this part too. Which to get? And do they have to go together or can you mix aluminum with the stock plastic?

This, the steering knuckle, is the part with the issue I believe. I've seen people run these without the aluminum caster blocks. And yes, blue loctite should be used in the knuckle, but be careful about getting it on any of the plastic.

 

[i_r_beej]

RPM warned me that blue threadlocker (Loctite, whatever) will damage the nylon plastic in their parts. I think this also extends to just about any plastic used in RC cars. They did recommend using regular CA glue (Superglue) as a threadlocker for screws in plastic parts.

 

[i_r_beej]

The T-Bone Racing "Basher" bumper for the ECX Circuit is a perfect fit for the AMP cars. They are identical to the Circuit (and Boost) in the front.

 

[i_r_beej]

With me planning to run a MG servo with a aluminum servo horn anyway, would you still suggest the RPM eliminator?

The RPM servo saver eliminator vastly improves steering accuracy by removing 98% of the play in the steering assembly. I would classify it as a "performance upgrade" not a "durability upgrade." That said I have the RPM SS eliminator and Turnigy/Power HD titanium geared servo in my Boost buggy and have been regularly hitting the track with it with ZERO issues. ANd by hitting the track, i mean that literally. The track surface is thin ozite carpet over concrete floor and wooden jumps so the surface is VERY HARD. I have crashed into poles, barriers, Slash SCTs (and been run over by them), gone cartwheeling over double and triple jumps... just horrifying stuff and have not has a single breakage. I also use RPMs rod ends and Associated titanium turnbuckles for steering and camber links. What usually happens is that the rod ends pop off the ball studs, thus preventing any damage to the other steering components. I also carry a couple of spare 25t servo arms, just in case.

You can also try gluing the stock servo saver as a cheap alternative or placing a ziptie or two over the metal "C" spring. But the stock spring is just too soft and is easily overpowered by the big tires on the AMP.

 

[slowmethinks]

Yup, look into the Turnigy 1258TG. It's really cheap for what it is. I have that, the RPM servo saver eliminator, and T-Bone number on AMP and it handles MUCH better. When I can keep the front down, that is.

 

[xlDooM]

http://www.ebay.com/itm/Hot-Racing-...232371?hash=item43e9609f33:g:lsoAAOSwFMZWtPEx

Oops, just found this part too. Which to get? And do they have to go together or can you mix aluminum with the stock plastic?

This is the one, and like X said, you can mix it with a plastic caster block. I use it with the stock caster block on one of my amps, and with the thicker but still plastic RPM caster block on the other.

 

[Bigpoppa99]

Well, I may just get the MG servo for sure, and I might try CA gluing the stock servo saver together and see what I get with that first before just dumping all this money in at once. Might try using CA as thread locker on the stock shoulder bolts also, may upgrade that part later, especially if I see its a problem.

Just how bad are the stock bearings?? Are they really that bad? I'm getting the kit version so if the bearings are just sealed bearings, I might can try to make use of them by popping the seals off and shooting some Cow RC Moo-Slick in them or some type of grease and putting the seals back on. If you guys don't think that will work and the stock bearings are absolute junk, then I might consider getting a Fast Eddy bearing kit.

 

[xlDooM]

Honestly I think the bearings are fine. They looked very sorry a few weeks ago when I took this picture (below) of the wasted stock axle carrier (notice the burrowed-out shoulder screw hole) so I had bought new ones, but when I checked them out last week they were clean and spun freely so there must just have been a lot of crud sticking to the outside. And if they develop a little bit of play, so what, the entire car is setup with lots of play in all the joints so you will never notice as long as they spin well. Having some extra bearings on hand is always a good idea, but I wouldn't start by replacing the stock bearings on principle.