more gears for a '77 cj5?

[raser13]

hey guys new here and new to jeeps. me and my wife just got a project '77 CJ5 .

cats jeep pictures by javelin1974 - Photobucket

it originally had a AMC 304 in it but along the way some one got a conversion bell housing to convert it to a ford 302. we're going back to the AMC 304 ! i have one laying around to put into it so it's cheaper than finding a 302. my main question here is right now it has the stock 3 speed stick (T-150 is the designation i think). with the AMC 304 i'm going to have the auto pilot set for every gas station as it is, and i'd like to keep the rpm's down to lower the wear and tear on the engine. so i can keep an eye out at the j-yards for a future upgrade is there a stick tranny that will bolt up to the AMC 304 that has more gears?? i'm hoping for a five speed. but i'm just hoping to at least find a little better of an upgrade to keep fuel costs and rpm's down. any suggestions?? thanks

 

[Petescj]

Heres a list of stock transmissions that came in Cjs. The T-5 is the only 5 speed that came from the factory.

http://www.jeep-cj.com/forums/f105/manual-cj-transmissions-12112/

 

[IOPort51]

Another guy looking for fuel mileage from a CJ!!!:laugh::laugh::laugh::laugh:

I wish you better luck than I have had over the years.

check the peak HP and torque curve on the AMC 304 and gear accordingly to your desired cruse speed.

I don't know if I would put a T-5 in front of a V8 but that's just me.

 

[raser13]

i'm not looking for great fuel economy, just a little better. i mean come on the thing has 33X12.5X15 inch tires for goodness sake. so i'm just talking some tweaks to eek out a mile or two more out of every gallon. i'm not expecting to get a 10-20 mile a gallon boost, i'm a realist here. plus if i can get more gears that lowers the rpm's on the motor at highway speeds. which equals out to be less wear and tear on the engine, thus leading to a little longer life.

if you don't recommend the five speed is there a strong four speed you would recommend? i'm not going off roading in this very often. mostly enough to get to camp sites. so i don't need something that is built like a tank but i do need something that can take a little abuse.

 

[Petescj]

The T-176 was used behind the last AMC 304 powered Cjs. They are a decent medium duty Transmission .

 

[CJ]

~~~ if you don't recommend the five speed is there a strong four speed you would recommend? i'm not going off roading in this very often. mostly enough to get to camp sites. so i don't need something that is built like a tank but i do need something that can take a little abuse.

the three and four speed both have a final drive ratio of 1:1 so you will not see any lower rpm,s at highway speed. Short of using a five speed or changing ring and pinions there are very few other options that would not require a lot of work.

 

[Saddle Tramp]

The T-150 is a good Transmission behind a V8 it just doesn’t have a low granny gear but from what you state low gearing isn’t what you are looking for. I’d check and see what your current differential gearing is first. If a 1976 it could be 3.54 but they could be most anything too as who know what a previous owner may have done. Look for a tag attached to the differential cover bolts. Really your only choices for improved mileage are to change your tire size or change up the differential gearing to something taller (numerically smaller) as the problem with swapping to an Overdrive Transmission in a CJ5 is the overall length of the boxes and the amount of remaining space for the rear drive line. In addition the 1977 Cjs came with a Spicer/Dana 20 Transfer Case and the only OEM Overdrive Transmission used in a CJ, the T-5 , bolts to a Dana 300 . This means you need to change to a Dana 300 Transfer Case or adapted the T-5 to your 20 Transfer Case ; the 300 is more money of course and the 20 isn’t a possible option as the T-5 to 20 adaptor combo makes the rear driveline too short. I’m not sure the T-5 will hold up long behind a V8 anyway.

Another option would be to fuel inject your motor. Not sure just how much of an improvement would be had but it must be better than a carburetor.

 

[raser13]

thank you guys for all the use full information. i was hoping that the more gears would help it out. oh well. sounds like the best set up is the one that i have.i knew this monster wasn't going to be to fuel efficient. i was just hoping i was just hoping to eek out a few more mpg. i think that the AMC 304 and the 33 inch tires that are on the cj kind of did that in. once again i thank you for all of your wisdom.

 

[IOPort51]

Don't give up!! just because we can't get better mileage doesn't mean you cant. The better it runs the more efficient it is. The better you drive the more efficient it is.

The big problem is cost justifying any changes. It is not mathematically a good idea to install a $1500 fuel injection system to gain 2 MPG. you can but a lot of gas for $1500.

keep thinking about it, if you come up with anything we would all just love to know about it.

thank you guys for all the use full information. i was hoping that the more gears would help it out. oh well. sounds like the best set up is the one that i have.i knew this monster wasn't going to be to fuel efficient. i was just hoping i was just hoping to eek out a few more mpg. i think that the AMC 304 and the 33 inch tires that are on the cj kind of did that in. once again i thank you for all of your wisdom.

 

[fgarrett]

There is one other option but I don't know if the price would justifiy it, Ford had a RTS Overdrive four speed 4th is 33 percent O.D. Herm the Overdrive Guy is who I got mine from.