My .19T Mach 2 T-Maxx (former TRX 2.5 T-Maxx)

[EMH]

3/16/2021 Updates

New Fast Eddy bearings in the clutch bell (x2), the steering bell crank (x4), and throttle post (x2).

Sonic-Tronics 3800ma 2.5" Glow Plug Ignitor


3/9/2021 Updates

Alright - since I have gotten back into the hobby, my 2.5 T-Maxx has had a few changes. Yesterday, I installed a brand new Dynamite 19T Mach 2 engine with new Traxxas pull start (going to try this over the EZ-start), a Dynamite air filter, new suitable THS performance exhaust system, and a Dynamite electronic failsafe. Weather in NYC is just starting to warm up and would like to break in the new motor on a nice sunny 70+ degree day (Adam Drake engine break in method).

Original Post:

Bringing my old 2.5 T-Maxx Back to Life!

Although I think the engine is worn out and needs to be replaced, I am having a lot of fun trying out different things to squeeze out any remaining life. Took it apart and cleaned it pretty good. Using budget minded fixes where needed and testing the results is a lot of fun. Really enjoying the tinkering as much as the driving! Will be updating with what I have done so far. What a great hobby.

-EMH

 

[WoodiE]

@EMH what engine are thinking about replacing the stock engine with?

 

[EMH]

@EMH what engine are thinking about replacing the stock engine with?

Hey WoodiE = I am not really sure. At first I was convinced I would trade the 2.5 for the 3.3 but after much reading I am very concerned that the 3.3 will shred up the stock drivetrain and I might as well just buy a new 3.3 T-Maxx for just under $500. So maybe I will put in another 2.5 or 2.5R or just do the 3.3 and hope for the best. This truck has sentimental value to me and I do not want to get rid of it.

What do you think I should do?

Thanks

 

[monstertruckier15]

Hey WoodiE = I am not really sure. At first I was convinced I would trade the 2.5 for the 3.3 but after much reading I am very concerned that the 3.3 will shred up the stock drivetrain and I might as well just buy a new 3.3 T-Maxx for just under $500. So maybe I will put in another 2.5 or 2.5R or just do the 3.3 and hope for the best. This truck has sentimental value to me and I do not want to get rid of it.

What do you think I should do?

Thanks

I have the 3.3 engine in my one trucks. it will be fine if you replace the stock spur gear with a metal one. You can put a new 2.5 engine block in with no carb for $65. A good steering servo with 150 oz is a good upgrade. The trade in program is a joke.

 

[johnnydmd]

I would use a Dynamite .19, you won't regret it.

 

[WoodiE]

I'd say for the price a TRX 3.3 would be hard to beat.

 

[monstertruckier15]

A new 3.3 engine is $135 block only.

 

[Exc3l]

2.5 is MUCH more reliable than 3.3. The bearings on the 3.3 leak A LOT. I have a Revo 3.3 and it was a blast but before I could take it off-road, it died. I think the fuel tank is leaking and I know that the exhaust coupler is cracked.

 

[monstertruckier15]

2.5 is MUCH more reliable than 3.3. The bearings on the 3.3 leak A LOT. I have a Revo 3.3 and it was a blast but before I could take it off-road, it died. I think the fuel tank is leaking and I know that the exhaust coupler is cracked.

The bearings are the same in the 2.5 and 3.3 blocks. If you didn't use a fuel filter than that would have been the problem.

 

[EMH]

I would use a Dynamite .19, you won't regret it.

A tempting offering. For $109.00 I may get it just to try it out. Just need to make my air filter fit snuggly onto the dynamite carburetor.

 

[EMH]

I'd say for the price a TRX 3.3 would be hard to beat.

Seems to be the case!

2.5 is MUCH more reliable than 3.3. The bearings on the 3.3 leak A LOT. I have a Revo 3.3 and it was a blast but before I could take it off-road, it died. I think the fuel tank is leaking and I know that the exhaust coupler is cracked.

Ah that stinks - hopefully more of an isolated issue...

 

[D3MON]

i would recommend the Dynamite or the 2.5, for a new engine, since traxxas "revised" the rods in the 2.5 and 3.3 models they have been known to split pretty easily, the 2.5 doesn't have as much power so it saves the stress on the rod a bit more. the .19 is about as powerfull if not more so than the 3.3, and has higher port count which helps it a bit on top end for power. everything from the 2.5 should bolt over from it, including ez-start, and it comes with everything that doesn't swap over from the 3.3 (clutch nut and exhaust mount) and all for 110$. Dynamite is based off SH which has been around for a really long time and make good engines.
one of the first biggest upgrades i recommend would be a new pipe, plastic absorbs and muffles the pressure pulses from the exhaust where aluminum will transfer it more cleanly to the tank to get the proper pressure

 

[EMH]

As of 3/16/2021


Engine:

Dynamite .19T Mach 2 with Traxxas Pull Start

+Dynamite Air Filter


Servos:

Bought two Traxxas 2075X servos on ebay for about $33 each. These are now on my truck for the steering and throttle (love the extra output). Moved over
a Traxxas 2055 servo over to the transmission control (Reverse/Forward).

+Added a Dynamite electronic fail safe in case of radio interference or loss


Receiver Power:

Moved away from the four AA batteries and put in a Venom 1600 hump pack for the 6-volt output.


Exhaust:

THS Performance Exhaust Pipe


Miscellaneous:

Put on new (longer) fuel lines and added a fuel filter.

Fuel tank was replaced not that long ago.

Put in 45 weight shock oil plus 20% stiffer springs with some spacers as needed.

New Fast Eddy bearings in the clutch bell (x2), the steering bell crank (x4), and throttle post (x2).

Sonic-Tronics 3800ma 2.5" Glow Plug Ignitor

Additional assorted tools, an open field bag to make life easier, O.S. LC3 Hot glow plugs


Learned...:

Using two year old fuel is a terrible idea that causes nothing but problems (never again!)

 

[D3MON]

good upgrades, and notes. it is really handy having a build log here in the forum to help you if you want to look back into why you did certain things or make note of others, really helps to keep track and share experiences for others that may have ran or are running into similar situations.
yes definitely fresh fuel is much better lol.

 

[EMH]

i would recommend the Dynamite or the 2.5, for a new engine, since traxxas "revised" the rods in the 2.5 and 3.3 models they have been known to split pretty easily, the 2.5 doesn't have as much power so it saves the stress on the rod a bit more. the .19 is about as powerfull if not more so than the 3.3, and has higher port count which helps it a bit on top end for power. everything from the 2.5 should bolt over from it, including ez-start, and it comes with everything that doesn't swap over from the 3.3 (clutch nut and exhaust mount) and all for 110$. Dynamite is based off SH which has been around for a really long time and make good engines.
one of the first biggest upgrades i recommend would be a new pipe, plastic absorbs and muffles the pressure pulses from the exhaust where aluminum will transfer it more cleanly to the tank to get the proper pressure

I did read and see that issue with the 3.3 rods which makes for a weakened connection so you do make a good point. Seems like you prefer the .19 Dynamite over the TRX 2.5. Definitely want to get away from the stock plastic exhaust pipe, regardless of what engine I hook it up too.

 

[monstertruckier15]

I have the resonator aluminum pipe and It didn't make good fuel pressure to the fuel tank. I went back to the plastic exhaust and the fuel pressure went back up.

 

[olds97_lss]

The 3.3 is ok, might be ok for a tmaxx, but IMHO, it wasn't a powerhouse. I doubt you'd have too many issues with it in your maxx. The older tmaxx was known to have forward/reverse primary gear issues though, even in stock form. Most would replace it with a forward only conversion, then the primary output gear was nearly twice as wide and far less likely to shred.

As for the plastic spur vs metal, I'd just fill all the slipper peg holes with new pegs on a plastic one. With good mesh, they held up fine.

One of my revo's was a 3.3 I got used. It seemed weak compared to what people said, even with an upgraded pipe. So, since it was used, I decided I'd try with a new 3.3. Break it in per traxxas instructions and see... it wasn't hardly any better. Ended up going with a 21TM.

 

[D3MON]

I have the resonator aluminum pipe and It didn't make good fuel pressure to the fuel tank. I went back to the plastic exhaust and the fuel pressure went back up.

what were you monitoring exhaust pressure exactly? not exactly sure with the traxxas aluminum pipes, but does it have the internal cone to tune the pulses? something like a THS tuned pipe is going to be so much better, they have an inner cone that tunes the pulses to increase performance in the usable power band. can usually find pipes designed to aid in the low end or high end, or one to increase performance overall.
you had retuned your engine with the resonator pipe correct?

 

[monstertruckier15]

The resonator pipe is junk I tried everything. I went back to the shorty stock plastic pipe for the 2.5 and 3.3 and it ran way better. I run 18% oil lube. I'm not going to run some expensive aftermarket pipe. My trucks are just fine stock. I now have 10 t maxx's.

 

[olds97_lss]

Were there 2 resonator's for the t-maxx like there were for the revo? One was 2 chamber, one was single chamber. I don't think either existed the last time I had a t-maxx... but I did try the dual chamber one on a 2.5R revo and it wasn't any better than the stock pipe with the stinger drilled out.