Changing out gears in a Manual Transmission

[Shawn76]

Is it possible to change the 1st gear ratio in a 3speed manual Transmission ? I have a 81 CJ7 AMC 258 i6 / 4.2l with a 3 speed. It is great on the highway, but have to ride clutch a little too much when taking off. It may be in another thread but I can't find it if it is. Instead of doing a Transmission change out I thought I might just rebuild Transmission and replace 1st gear with a little lower ratio. Any help will be greatly appreciated!

 

[Torxhead]

Wow, that is one I have never heard of. I would suggest the T-176 4 speed and hopefully it will bolt right up.

 

[Shawn76]

I think that is what came factory in it, but its been changed. It works really good just a little too high in 1st. In 4 low i have to ride the brake to creep around in the woods

 

[mtnwhlr]

I've never heard of anyone doing that either. You can put lower gears in the Transfer Case though. That will only help when in 4WD.

 

[Shawn76]

I thought I could, but it wont really help my normal driving. I just thought that surely I could get a different gear for the Transmission . Im not sure though. Just wishful thinking maybe. lol

 

[Posi]

If the tranny is Jeep chances are you have the Dana 20 (81 should be Dana 300 ).

 

[Saddle Tramp]

I don’t think we can give you any solid suggestions without knowing what you already have for a drive train. We know you have an AMC 258 i6 / 4.2l , unsure about the Transmission , Transfer Case , axle gear ratio, and tire size. Some pictures will go a long way but try to get the numbers off of the boxes/tags too and let us know.

The VIN should also be of some help, at least for what it should be in the jeep stock. In your case the 4th position should be a C for the AMC 258 i6 / 4.2l but what is the fifth position letter? That is the important Transmission /Transfer Case one.

 

[BusaDave9]

In a word, no, this can't be done. You can't replace just the 1st gear. You would also have to replace the gear that it meshes with. That would be the idler gear in the bottom of the Transmission . This idler gear isn't a simple gear. It's also a shaft with other gears on it. It is used for shifting into every gear.

This is why companies like TeraLow can't just sell one gear to give your Transfer Case lower gearing. To lower the gearing of your TCase you must replace ALL the gears.

If a company wanted to sell a kit to lower the first gear for your Transmission they would need to manufacture a new first gear and an new idler gear that still meshes with the other gears.

 

[harleydragon]

If you have a spring over then I am guessing that you are running a good bit taller tires than stock..you might still have the original gearing in your axles making it too tall of gearing for taking off

 

[Shawn76]

Thanks for all the input guys! Ok, here is what I know so far, my vin# is 1JCCM87A8BTO14467, the number stamped in the drivers side of my Transmission is 2603347, the number on the metal tag on rear of my Transfer Case is 300596-125 on top of tag and on bottom is 5357020. Thats what I have in it now, but I think it came factory with the T-176 and the Dana 300 , but im not sure.

Thanks again Guys!!

 

[Saddle Tramp]

The VIN decoder says- you have AMC 258 i6 / 4.2l with a 4 speed Transmission , a CJ7 , 3750 lb GVW, and a 1981 Model Year. My bet is you had a T-176 and a Dana 300 but the Transmission could have been an SR4 as they were used behind some AMC 258s.

Hard telling what you really have; need pictures.

 

[Posi]

the number stamped in the drivers side of my Transmission is 2603347, the number on the metal tag on rear of my Transfer Case is 300596-125 on top of tag and on bottom is 5357020.

2603347 = T-150 3 speed
300596-125 = this number has been found on Dana 300 and Dana 20 , post up the casting numbers found on the case. Should be sometime like C18-15-24 for the Dana 20 , or C300-15 for the Dana 300 .

 

[harleydragon]

more so that the tranny and Transfer Case ,I think you need to determine what the gear ratio is and then match it to the size tires you are running