T-maxx Idles/Revs but wont move.

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Bill

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Hey guys! So I pulled the truck apart a few weeks back and put on the a set of new RPM Tru-track A-arms at that time I also took the motor off and cleaned everything up before re-install. Anyways, I was wanting to test out the suspension today so I went and started it up motor sounds good, good smoke, idles at good rpm but when I hit the gas the truck wont move. Motor revs up but truck will only ever so slightly move...

I'm thinking I could have a bad clutch spring or worn clutch? (only thing I didn't look at when motor was off)

Does this sounds like a plausible cause??


Thxs!
 
Hey guys! So I pulled the truck apart a few weeks back and put on the a set of new RPM Tru-track A-arms at that time I also took the motor off and cleaned everything up before re-install. Anyways, I was wanting to test out the suspension today so I went and started it up motor sounds good, good smoke, idles at good rpm but when I hit the gas the truck wont move. Motor revs up but truck will only ever so slightly move...

I'm thinking I could have a bad clutch spring or worn clutch? (only thing I didn't look at when motor was off)

Does this sounds like a plausible cause??


Thxs!
There is several things that can cause that!
Not a broken clutch shoe spring!

1. could be a loose spur gear.
2.drive shaft or axle pin.or set screw,which ever your truck has.
3.something inside of transmission is broke.
4.foward & reverse shifter is not set right causing trans to be in a neutral position.

Idlely,you want to check all of the easy stuff first before tearing into trans.
I would check the forward & reverse linkage first!
 
Lift it when you rev it and see if the wheels spin. If they spin in the air but don't pull on the ground, my first choice would be the slipper clutch. Second choice is a drive shaft or axle pin.
 
When you installed the new RPM arms, did you mess with the diffs? If you accidentally flipped one (and I have done it... don't ask ), it can also cause the problem. You can easily tell if you rev the throttle with the wheels in the air and the axles spin in different directions.
 
There is several things that can cause that!
Not a broken clutch shoe spring!

1. could be a loose spur gear.
2.drive shaft or axle pin.or set screw,which ever your truck has.
3.something inside of transmission is broke.
4.foward & reverse shifter is not set right causing trans to be in a neutral position.

Idlely,you want to check all of the easy stuff first before tearing into trans.
I would check the forward & reverse linkage first!

Thanks for the advice! It turned out to be just a loose spur gear.
Looks like when I replaced the last stripped out spur gear I forgot to torque down the nut all the way.. oops!

Fired it up yesterday and blasted around my little park like a champ! I must say that since upgrading to RPM front arms and RPM tru-track rear arms, the Tmaxx handles going air born so much better now. Much more composed and stable in the air.
 
I'm Back!

I finally believe that I have a nice tune on the engine right now. When its on the ground it idles nicely for however long I want it to. When placed on the stand it idles without wheel spin. Both good things!

Problem arises when I place the truck on the ground and try to go forward. Motor revs up great under throttle but will only move forward a little. Switched it over to reverse to see if anything was different and the results were the same. So I placed it on the stand to ensure that there was no binding anywhere. Under throttle all the wheels spin freely with good torque.Braking is great with immediate throttle response & wheel spin.
That tells me that the drive-train is all good, correct?

I know my spur gear is tight and my clutch shoes look good.

What should be looking at next?
Thanks!
 
Now you need to leave the body off, hold the truck stationary on the ground so the wheels won't move and rev the engine to see where the power stops. Something between the flywheel and wheels won't spin. Could be a sheared pin in the trans since it doesn't sound like a front or rear only problem.
 
If power is coming out of the trans, next you'll have to look for a snapped or missing pin somewhere in the drive train. There's a few places you might have missed during re-assembly. Pins in the driveshaft from the trans mission, pins to the diffs, pins on the axle ends or pins in the wheel hexes.
It will ALL spin when it's off the ground just due to friction but on the ground there's too much of a load to move it.
 
Tested it back on the ground and still couldn't figure anything out..

I will go ahead and take it back apart and inspect carefully for broken pins and report back..

Thanks for the help!
 
You really don't have to take anything apart, yet. Put it on the ground and turn the CB. Is it turning your slipper/spur gear?
If the car is trying to move forward (all wheels are trying to pull) you'll need to take apart the clutch at the flywheel since it's not fully engaging when running or it's slipping badly under load.
If, while turning the clutch the spur turns, put a finger on the output shaft from the transmission. If it's NOT turning you have an issue either inside the trans or the pin that locks the driveshaft to the trans is sheared or missing. Do this till you find out where the drive train is no longer engaging.
 
Tested it back on the ground and still couldn't figure anything out..

I will go ahead and take it back apart and inspect carefully for broken pins and report back..

Thanks for the help!

If theres no external pins or set screws are loose or broke,then it could be in the trans.
I'm not sure about the traxxas trans ,but my Mgt trans has a few pins & set screws inside.
besides a oneway bearing.Theres a shaft that holds that & gears in which they are held
in place by pins & set screws,I think theres even a hub that houses a paw that catches
an engages the gears to rotate.
So theres a quite of few things in the tranny that could be your problem as well!
 
Tough call on it being a trans problem since it's not as likely to spin off the ground when something is broken in there. When it's in a clutch or a plastic drive shaft you still have some friction to make it spin if it's not under load.
The pawl that engages in the trans is what shifts it to second gear.
 
Well, I picked up a really cheap mint condition Revo off C-list today and swapped some hop ups from it onto my T-maxx. While doing so, I went ahead tore into the tmaxx pretty well today. Looked over ALL of the pins, set screws axles and even took the trans. apart. Every thing checked out good and rotated properly.

I think my problem was that the Trans. was somehow in a neutral position. Possibly slipped in after the last few cartwheel it preformed..
Will test this theory tomorrow.
 
Well, I picked up a really cheap mint condition Revo off C-list today and swapped some hop ups from it onto my T-maxx. While doing so, I went ahead tore into the tmaxx pretty well today. Looked over ALL of the pins, set screws axles and even took the trans. apart. Every thing checked out good and rotated properly.

I think my problem was that the Trans. was somehow in a neutral position. Possibly slipped in after the last few cartwheel it preformed..
Will test this theory tomorrow.

Cool,Ya never can have too many parts in the rc world!
The best way to learn into rc's is to dig off into them,you will find out the tricks &
to better isolate problems that accure.
I don't run reverse in my mgt trucks because its one more thing that can go wrong.
I run a forward only tranny!
The benefit of that is losing dead weight from all the steel gears inside an the durability of
performance ,of less maintenance.
 
Third time was a charm!!
I was set on figuring out the issue today so I dove into the transmission. I gained some confidence after I found a nice little thread on the Traxxas forum. Guy was having the same exact issue as myself.
https://traxxas.com/forums/showthread.php?8946132-TMaxx-3-3-Transmission-problems
I also found a nice exploded view of the transmission to help guide me.
https://traxxas.com/sites/default/f...edviews-130515_4907 Transmission Assembly.jpg

Anyways, Got everything in pieces and started inspecting. Turned out to be a small pin that went through a gear and the shaft and was secured with a metal clip..
After a victory lap, I headed down the local HS and got myself a replacement pin and gear.
Part #: 5396X https://traxxas.com/search?type=All&keyword=5396&items_per_page=40

I replaced the pin and threw in the new gears and reassembled the transmission. Just got the transmission put back into the truck and will test out the truck tomorrow and report back. I am very hopeful that I have solved my issue..

Thanks for all the help guys!!
 
Third time was a charm!!
I was set on figuring out the issue today so I dove into the transmission. I gained some confidence after I found a nice little thread on the Traxxas forum. Guy was having the same exact issue as myself.
https://traxxas.com/forums/showthread.php?8946132-TMaxx-3-3-Transmission-problems
I also found a nice exploded view of the transmission to help guide me.
https://traxxas.com/sites/default/files/4907_Tmaxx33_TQi_explodedviews-130515_4907 Transmission Assembly.jpg

Anyways, Got everything in pieces and started inspecting. Turned out to be a small pin that went through a gear and the shaft and was secured with a metal clip..
After a victory lap, I headed down the local HS and got myself a replacement pin and gear.
Part #: 5396X https://traxxas.com/search?type=All&keyword=5396&items_per_page=40

I replaced the pin and threw in the new gears and reassembled the transmission. Just got the transmission put back into the truck and will test out the truck tomorrow and report back. I am very hopeful that I have solved my issue..

Thanks for all the help guys!!

That's great!
That one of the reason I took out my reverse gears ,by doing so ,it relieved some of the rotating mass inside that relieved some of the tension
& pressure on the pins inside of tranny.
Also a lot has to do on the tension that your spur is set on the terrain you run on.
When I run my Mt out in the street ,I will loosen up my spur alittle because of the high torq. & high grip of my tires.
Too much on an off throttle out in the street with high torq & grip with out something giving will eventualy shear a pin!

But anyway ,I'm glad that you decided to dive off into it ,ts the best way to learn ,you also learn on any future issues
that may come.
 
I couldn't wait until tomorrow. I HAD to know! The cars were out of the garage so I fired little monster and away it went! Ran excellent, lots of torque and super responsive with a good little idle. Nice smoke as well. Busted out some donuts until the garage got too toxic and shut it off.
Looking forward to getting it out into the open ASAP.

Will most likely be purchasing the forward only kit here in the near future. :):thumbs-up:

While I had the transmission out for the 3rd today I replaced the single disk brake with a vented disk brake. Excited to see how braking improves.?.

Cheers!
 

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