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2.5 trAnsmission issues

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3

3.3max

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So my boys 2.5 spur gear will spin but it only kicks in at a certain rpm like u just can't move slowly it just hits like the tranny or something is wrong so the spur gear will spin for a bit then just grab what could it be
 
if we are talking about a t-maxx 2.5 trany. its probably stuck, it has a centrifugal clutch, that engages at certain rpm, thats why with your finger you could move the spur gear, and the wheels doesn't try to move, and when you apply gradual throttle very very slowly, the t-maxx gives small "pushes" while the clutch is engaging and when the cluth its fully engaged, it moves and acelerates without the "pushes", i thing you need to disasemble the trans, and clean and lubricate all the gearing, ballbearings and clutches every thing inside it, but remember not to add oil to the asembled tranny.
 
Due to the design of the black transmission when equipped with reverse
No matter how well you clean and lubricate it, it will always “Buck” at low engine rpms.

There are only 3 things you can do to solve the issue.

1: Adjust the forward/reverse clutch pawls to engage sooner (at a lower rpm).
Caution! Doing this will often cause the transmission to get stuck in forward or reverse.

2: The “No Buck” mod.
The pins that the clutch pawls pivot on in the forward and reverse output gear are removed and replaced with a grub screw pin (the type that attach the drive shafts to the differentials). The pin in the gear then locks into the inner clutch bell preventing the Bucking.

3: Install the FOC (Forward only conversion).
Constant engagement, and a stronger/less rotating mass, more reliable transmission.
 
3.3max said:
How hard is it to do
Click to expand...

3.3max I have the same Tranny assuming we are talking about the "Black Tranny"

I have had my tranny out of my RIG 3 times now it's not a hard job to replace the gear's inside If your like me & more so if it's your son's RIG I like having Reverse myself 1 of the reasons I havent opted for the Forward only swap & I actually keep @ least 2 set's in my stock of parts. So when the gear dose throw inside the tranny I can easley replace them & not have the RIG down for a long time

I would either replace the gears inside tranny & keep a set onhand "because thay will break again over time" Or convert to the Forward Only
 
I think I will do the foc I hope it is not hard I like the reverse because my boy is only five
 
FOC is a great upgrade. I had a ton of problems until it was installed and has been smooth sailing ever since. Also i a pretty simple procedure,probably a 3 on a scale of ten imo.
 
idk maybe twenty minutes top, but most of the time is used by getting the tranny out and apart. And then when u get done u can remove the servo used to shift from for-rev.Less draw on batterys and other than the big time rotating mass uve lost in the driveline and shed a little weight off the truck.
 
I have the same tranny and going to do the FOC soon as I can for the simple reason of more reliability. My reverse servo is out anyways and have only a 2 channel reciever so all the reverse is unhooked in mine already. I have heard no negative remarks only positive about that upgrade to that tranny!

---------- Post added at 8:15 PM ---------- Previous post was at 8:01 PM ----------

Also with the foc I think it opens up the available rear brake option as well
 
Sweet I can't wait what all comes in the kit what's it look like
 
3.3max said:
Sweet I can't wait what all comes in the kit what's it look like
Click to expand...

Dont really know yet but fixen to research it online. I havnt done it yet because I been too occupied in new engines for both my RCs and other issues like servo and tuning stuff plus to start with the tmaxx has been under reconstruction and already bought new torque control slipper upgrade fuel tank bulkheads and chassis braces. Along with new dynamite engine to go on it not 2 weeks after buying a new 2.5R for my revo and front end parts for it after my cousin sent it into a tree WOT. So the FOC is gonna have to wait a bit for me.

---------- Post added at 11:28 PM ---------- Previous post was at 11:23 PM ----------

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXMJG1

---------- Post added at 11:29 PM ---------- Previous post was at 11:28 PM ----------

http://www.rcplanet.com/Traxxas_Forward_Only_Conversion_Kit_p/tra5195.htm
 
This is the correct shaft and gear for the black transmission FOC
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXCNA8&P=7
It only consists of a shaft and a gear, very easy to install.

A rear brake is only needed when you have a center differential installed in the transmission. The Tmaxx was not designed for a center diff and has no provisions to install a rear brake system like the revo has.
 
I was thinking about the FO convert after posting " my comment I like the reverse " & talked to a bashing buddy & he actually said i'd be better off with the FO convert.. He explained to me the Tranny will have LESS gear's / part's spinning inside tranny.. So I just might opt for the FO my HS has the FO's in stock.. " HS# is contact #3 on speed dial on my cell phone LOL my buddy has it #2 on his phone LOL
 
Last edited:
Snook Man said:
This is the correct shaft and gear for the black transmission FOC
http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXCNA8&P=7
It only consists of a shaft and a gear, very easy to install.

A rear brake is only needed when you have a center differential installed in the transmission. The Tmaxx was not designed for a center diff and has no provisions to install a rear brake system like the revo has.
Click to expand...

Thanks for that link snook. I thought the ones I posted had too many parts that seemed like they wouldn't fit anywhere in the black tranny. It looked more like the one for the 2.5revo tranny instead. Which if I start racing it I'm gonna want to install one in it as well. :D
 

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