Converting the AMP MT to a Circuit ST (to race!)

i_r_beej

Well-Known Member
Supporting Member
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902
Yeah! The ECX cars are definitely excellent platforms for upgrading/modding/tweaking. Please post any photos of work you do on your car!
 

i_r_beej

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Supporting Member
Messages
902
I'm glad you're getting some useful info out of this thread.
I did look into sealing the differential. I believe the original link/how-to was posted on the now-defunct UltimateRC forum. It involved using a countersunk drill bit to remove material from the outdrive holes to allow the fitting of an o-ring. It had to be held in place with automotive gasket sealant. While a neat hack, I personally didn't feel the truck was worth the hassle. I packed the diff with a thick grease (30,000cSt) and called it good. I believe @Jeb uses a marine axle grease? I feel the thick grease is the most cost effective solution for reducing the amount of slip provided by the ECX differentials. You'll notice some weeping around the outdrives-- this is okay. Just keep the car clean if you run in dirty/dusty environments.

Please share photos of your truck here!
 

Tama

Active Member
Messages
33
Ti turnbuckles have arrived. The rest of the chassis material, and body from HH should get here in the next day or two (hopefully!). The power system likely some time next week. I'll be cutting it close since Feb 18 will be Race Day for the "AMP'd" Circuit.

Last night began removing the RTR electronics and cleaning up the chassis.

Here's the AMP MT as it is currently (with RPM steering bellcranks, Traxxas Big Bore shocks, Turnigy 1258TG servo):
View attachment 1543

Here's a look under the hood:
View attachment 1544
Traxxas Big Bore shocks in the front with stock ECX springs. I've found the Traxxas dual-stage springs to be a little too stiff for the AMP chassis. Like the Boost, this chassis design has a SERIOUS rear weight bias and I'm still struggling to get proper sag at the front end. The longer suspension arms have better leverage on the shocks so there IS a tiny bit of sag but tuning for the track will be that much more difficult.

Here's the chassis with the stock power system removed:
View attachment 1545

I removed the upper suspension links and began installing Hot Racing front spindle carriers, and serviced the stock transmission. I briefly considered just buying a set of metal gears for the transmission but in the interest of science I decided to see how long I could go before the stock gears go KABLOOEY on me.

I'll be running a shorty battery pack for a couple of reasons: remove weight from the rear and provide enough juice to the motor. I'm trying to figure out a way to attach a battery stop to the OEM battery strap. This is not a primary consideration due to the time constraint so I may just use a foam block.

Next up will be finishing up the chassis upgrades and suspension tweaks once those parts arrive. I'm waiting for the weather to get above 50-deg F so I can paint the body.
How did you fit the TBR front bumper?
Did u make new screw holes as i find they don't quite match up and did u cut the xtra length. Pls help as I'm still some what new to this. TIA👍
 

Jeb

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Messages
328
Location
West Glover, VT
How did you fit the TBR front bumper?
Did u make new screw holes as i find they don't quite match up and did u cut the xtra length. Pls help as I'm still some what new to this. TIA👍
Not sure what you mean. I’ve done 2 amps with TBR bumpers and the stock screws are the correct length and line up perfectly. 5AC9361A-1F34-4D80-9961-21CB580F4AD0.jpeg
 

Tama

Active Member
Messages
33
Thanx for getting bak 2me. Found the difference, using ur pic as reference. They sent me out the 4x4 TBR thrasher/circuit bumpers not the 2wd type like ur's. 😞
Modding time ahead for me and my screw up. Thx again 4 ur reply👍
 
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MaX-D

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Messages
79
Location
Coral Springs, Florida
This thread has been very beneficial to me is I'm converting a 2wd torment to a circuit to race at my local track. I will probably start a different thread for my truck, but the biggest thing I took away from this was the shocks as I had planned on using an extra set of Traxxas Ultra shocks with Losi Springs that I had laying around. I will definitely invest in the ECX aluminum shocks for this truck.

I had tossed around the idea of buying a Traxxas rustler to convert to racing as a good friend of mine (Razor RC) had done this with his Rustler, but I figured since I already have all of the ECX parts and extra sensored ESC and 13.5 T motor and whatnot, I figured why spend the money if I don't have to. I'm not a serious racer, as I just go out to drive for fun. I do plan on using a new jconcepts p2 stadium truck body that was designed for the rustler. It's hard to find rear motor bodies these days as everything has gone mid-motor. I'll keep you posted
 

MaX-D

Well-Known Member
Messages
79
Location
Coral Springs, Florida
Cool! I'm looking forward to seeing what you do with the car!
BTW, with your 13.5 t motor, what size spur and pinion were you running? The old 13.5 motor that I had bit the dust so I'm either going to invest in the new Hobbywing G3, Tekin Redline Gen3, or the Reedy S Plus. I'm running a Reedy 8.5 T Mach 2 in my tlr 22sct 2.0 and it's a rocket. I've had good luck with Reedy Motors, and Tekin. The hobbywing G3 from what people have said, is a little soft on the low end. I don't know if it's because the G3 is a two-pole motor, not a 4 Pole. I would rather have a 4 pole motor and just turn down the punch in the ESC . Have a great weekend.
 
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