Tmaxx engine is fine but barely moves

[jlobbia]

I have a tmaxx with a big block kit and a XTM457 engine. I just got it for around 130$ yesterday and just finished tuning.
I took it to the street where I pulled the trigger to open the carb fully, but the truck barely moves. The spur gear is moving very fast rpm while idle and while running. The spur gear moves freely when spun with my finger. There is no friction whatsoever. When pulling the trigger, the engine gets very fast and the spur gear moves very fast, but the truck goes around five mph. I am about to take apart the tranny, as I read somewhere it is unhealthy for the engine to run at such high rpm when there is no resistance to the pinion gear. Also when I move the spur gear with my finger the wheels do not move at all. Please help.

 

[tntpoof]

have you checked the clutch shoes and clutch bell?

 

[Twiztid420]

I don't see a spring on that spur gear. Am I missing it? It looks like a piece of rubber or something.

 

[Twiztid420]

Your spur gear is part of a slipper clutch system that that protects your car from sudden shocks to the drivetrain. It also slips a bit when under heavy torque if it is set correctly. If it is to lose it will spin freely and you will get this effect. There is supposed to be a spring behind that nut that allows you to adjust the tension in your slipper clutch. I believe your problem lies there.

 

[D3MON]

agree with the above, it looks like they just put a piece of fuel tubing instead of the spring, which will not hold shape/tension enough to work correctly.
should looksomething like this:
https://www.ebay.com/p/1701020764?i...zPgO-Nv5nOaC8G7t9JrevLpZtRze_ULhoCsRUQAvD_BwE
btw nice score there, you got the XTM big block kit on that T-maxx, really hard to find nowadays and getting pretty pricey if you can even find them used.

 

[olds97_lss]

Yep, without that spring, your just melting your slipper pegs. Probably a good idea to order a new set of pegs along with the spring as the pegs are likely melted down quite a bit because of it:
https://traxxas.com/products/parts/4685

This was my old BB maxx with an RC Solutions steel spur:

 

[jlobbia]

Your spur gear is part of a slipper clutch system that that protects your car from sudden shocks to the drivetrain. It also slips a bit when under heavy torque if it is set correctly. If it is to lose it will spin freely and you will get this effect. There is supposed to be a spring behind that nut that allows you to adjust the tension in your slipper clutch. I believe your problem lies there.

Thanks! I'll try to see if that is the problem. Thanks in advance.

 

[Twiztid420]

agree with the above, it looks like they just put a piece of fuel tubing instead of the spring, which will not hold shape/tension enough to work correctly.
should looksomething like this:
https://www.ebay.com/p/1701020764?i...zPgO-Nv5nOaC8G7t9JrevLpZtRze_ULhoCsRUQAvD_BwE
btw nice score there, you got the XTM big block kit on that T-maxx, really hard to find nowadays and getting pretty pricey if you can even find them used.

Yeah I got jealous as soon as I saw it! And for $130! Sigh...

 

[jlobbia]

agree with the above, it looks like they just put a piece of fuel tubing instead of the spring, which will not hold shape/tension enough to work correctly.
should looksomething like this:
https://www.ebay.com/p/1701020764?i...zPgO-Nv5nOaC8G7t9JrevLpZtRze_ULhoCsRUQAvD_BwE
btw nice score there, you got the XTM big block kit on that T-maxx, really hard to find nowadays and getting pretty pricey if you can even find them used.

Thanks! I'll see if I can get my hands on that if it is the problem.

 

[jlobbia]

Yep, without that spring, your just melting your slipper pegs. Probably a good idea to order a new set of pegs along with the spring as the pegs are likely melted down quite a bit because of it:
https://traxxas.com/products/parts/4685

This was my old BB maxx with an RC Solutions steel spur:

I'll look into it.The guy had a steel spur gear included in the bags of parts, andthat one had decent pegs, so i don't think i'll need to buy anymore. Thanks!

 

[Twiztid420]

I'll look into it.The guy had a steel spur gear included in the bags of parts, andthat one had decent pegs, so i don't think i'll need to buy anymore. Thanks!

The fact that is is moving some tells me that the transmission is probably working. At least first gear is. It would be making some crazy noise if the gears were grinding or slipping. I am fairly positive that you will fix your problem when you rebuild that slipper clutch.

 

[jlobbia]

UPDATE:
I have replaced the old tubing with a misc spring, just have to wait for the actual traxxas one to arrive. I took apart and reassembled the tranny to find that the pawls were backwards. That explains why it wasn't catching at the high rpm. I will test it tomorrow.

 

[jlobbia]

UPDATE:
I have test ran it after switching the pawls back to their correct positions and installing a spring. IT STILL IS THE SAME!!! It barely moves, and when it does it goes about two mph max on full throttle. What???? Please reply if you have any suggestions.
FYI found out that moving the spur gear and the wheels not moving is normal, as it has to reach high rpm for the pawls to flip out and catch.

 

[Twiztid420]

UPDATE:
I have test ran it after switching the pawls back to their correct positions and installing a spring. IT STILL IS THE SAME!!! It barely moves, and when it does it goes about two mph max on full throttle. What???? Please reply if you have any suggestions.
FYI found out that moving the spur gear and the wheels not moving is normal, as it has to reach high rpm for the pawls to flip out and catch.

You have the correct spring on and it's tightened correctly?

 

[cbaker65]

Have you checked the other stuff to make sure there is no binding in the running gear ,wheel pins ,hexes ,wheel hubs
are not adjusted right ,were they would put a bind on axles ,center drive shafts set screws tight? Things like that will
hender the performance!

 

[olds97_lss]

Got a video of it?

Even if your two speed was broken, it would still go faster than 2mph at WOT as it should be in first gear. Unless your 2-speed one way bearing is slipping badly, which it could be. I never had one go bad, but your still running a black transmission which means that thing is old... so it could be the lube in the OWB is dried up and causing it to not engage properly or something.

When the spur is spinning, is the shaft the spur on spinning as well? Or do you see the spur spin while the shaft is more or less stationary?

 

[Twiztid420]

The reason I asked if you had the correct spring is because it is a thick heavy spring you can't just throw any spring on it. That being said, if you are sure it is done correctly then I would move on to the areas that olds97 has just mentioned.

 

[jlobbia]

Have you checked the other stuff to make sure there is no binding in the running gear ,wheel pins ,hexes ,wheel hubs
are not adjusted right ,were they would put a bind on axles ,center drive shafts set screws tight? Things like that will
hender the performance!

Yes, everything is working correctly.

 

[jlobbia]

Got a video of it?

Even if your two speed was broken, it would still go faster than 2mph at WOT as it should be in first gear. Unless your 2-speed one way bearing is slipping badly, which it could be. I never had one go bad, but your still running a black transmission which means that thing is old... so it could be the lube in the OWB is dried up and causing it to not engage properly or something.

When the spur is spinning, is the shaft the spur on spinning as well? Or do you see the spur spin while the shaft is more or less stationary?

The spur moves along with the shaft, there is no slipping.

 

[jlobbia]

You have the correct spring on and it's tightened correctly?

It's a different spring, but I tightened it down pretty good. It should suffice.