TMAXX transmission help

[fight4fredm]

Ok first off this is my first thread on here. I have been in the r/c world for 20+ years and mostly with nitro outboards and outriggers. I recently purchased a couple of TMaxxs' one is powered with an OS21RG and the other is a 3.3.. Both have stripped gears inside the transmissions. My problem is the tmaxx that is powered by the OS21 has a larger transmission than the 3.3??? What is it?? The 3.3 is a grey cased with a 56t gear and the older OS powered one has a 72t gear on it. The case ia also much larger... Any help would be greatly appreciated....

 

[cwal1774]

The older one probably has reverse or had reverse at one time. The 3.3 with the grey cases is forward only. A lot of people ususally get rid of the reverse gear as it makes the transmission weaker. Traxxas got rid of reverse all together when they came out with the 4908 model.

 

[Snook Man]

There are several versions of Tmaxx transmissions.

The black transmission came with the pro.15 and the 2.5 Tmaxx models and all were forward and reverse equipped.
The grey forward and reverse equipped transmissions came with the 2.5R and the 1st 3.3 Tmaxx model # 4909
The grey tranny model 4908 and 4907are forward only and use a 6mm output shaft compared to all the others which use a 5mm output shaft.

The grey models have a better slipper clutch system and use a different type spur gear than the early (black tranny) friction peg style slipper clutches. There is a slipper upgrade kit available for the black transmissions to convert the slipper clutch to the 3.3 style.

The brake system was also changed between the .15/2.5 and the 2.5R/ 4909 models.
It was again changed between the 2.5R/4909 and 4908/4907 models.

Internal gearing was also changed and re-arranged between the black and grey transmissions. The grey transmissions have the option of close, standard, and wide ratio gear set of 1st and 2nd gear.

 

[ThEnItRo1]

The older one probably has reverse or had reverse at one time. The 3.3 with the grey cases is forward only. A lot of people ususally get rid of the reverse gear as it makes the transmission weaker. Traxxas got rid of reverse all together when they came out with the 4908 model.

do u know exactly how to get rid of the reverse??

 

[Snook Man]

do u know exactly how to get rid of the reverse??

Install the forward only conversion (FOC).

 

[cwal1774]

Yep! forward only conversion kit. They are pretty cheap I've seen them on ebay for about 8 bucks. They remove a lot of rotating mass from the transmission and moving parts. Less moving parts means less that can go wrong.

 

[b-rian]

I bucked up and bought the robinson racing steel foward only conversion.so far so good!

 

[MaxxJTmasheR]

good buy for sure, its one of the first things i bought too, also the Robinson steel spur gear