what do I have?
- Thread starter sweetpeet
- Start date
SteelHeadz
Super Moderator
If thats a factory engine V8, that should be a 304. I could be wrong, but i think it's paired up with the t-176 or t177 trans. and a dana 300 t.case.
Bounty__Hunter
Super Moderator
Dana 300 didn't come around until '80 or so, before that it was the Dana20 I believe.
Saddle Tramp
New member
If it is a stock 74 CJ5 and a V8 it should be an AMC 304 mated to a T15 with a Spicer/Dana 20 x-case. Dana 300 x-cases made their debut in 1980. In fact 1980 is the only year you can get a V8 and the 300 in a CJ from the factory.
Although Jeep offered a T18 transmission in CJs during 1974 (available from 1972 to 1979) the only year the T18 was mated to a V8 from the factory was 1979, all others years the T18 only came behind an I6. 1977 to 1979 T18s are the wide ratio 6.32 first, all others are close ratio.
Although Jeep offered a T18 transmission in CJs during 1974 (available from 1972 to 1979) the only year the T18 was mated to a V8 from the factory was 1979, all others years the T18 only came behind an I6. 1977 to 1979 T18s are the wide ratio 6.32 first, all others are close ratio.
SteelHeadz
Super Moderator
Ahh see there! thanks for the correction. I thought it was the dana 20 but i wasn't sure on that either.
Rubiconrich
New member
I'd find a t18 to go behind your V8. And research a 1980 Dana 300 out of a scout. same bolt patterm as a 20 but it's a 300.
David
New member
IMHO, there's no reason to replace the 20 with a 300 unless you really need the deeper gearing. Not disputing that the 300 has its advantages, but the 20 is a solid, stout transfer case--if it ain't broke, don't fix it. You can also regear the 20, but that's expensive. If you need deeper gearing, I'd go for the T-18 transmission, or a similar wide ratio transmission.
mrhc
New member
From Saddle Tramp: "the only year the T18 was mated to a V8 from the factory was 1979, all others years the T18 only came behind an I6. 1977 to 1979 T18s are the wide ratio 6.32 first, all others are close ratio."
So if I have a 79 CJ7 with a factory V8 304 then the transmission is more than likely a T18? And please explain to a novice what that means.
So if I have a 79 CJ7 with a factory V8 304 then the transmission is more than likely a T18? And please explain to a novice what that means.
Saddle Tramp
New member
The 1979 standard transmission was the T150 three speed, the T18 4 speed was an upgrade. The T150 is a good sturdy transmission but there is no low "granny" gear. The T18 has a low first gear in either 4.02:1 or 6.32:1 depending upon year. In CJs, 1972 to 1976 were all 4.02:1 first and 1977 to 1979 were all 6.32. What this means is if you have a 1977 to 1979 T18 the 1st gear is 6.32:1, for every one complete revolution of the output (rear) shaft the input shaft from the motor has to turn 6.32 times. The top gear, 4th, will be 1:1 as this transmission has no overdrive, meaning for every one revolution of the input shaft the output shaft turns once as well. On newer transmissions with an overdrive, usually 5th or 6th, the output shaft will actually turn more than one complete revolution for every complete revolution of the input shaft. The T150 has a 2.99 first gear so the engine only turns about half the revolutions in first gear that it would with the T18 making it harder to go slow without lugging out or killing the motor.
Diehard crawlers, guys/gals who like to navigate rock based terrain whether boulders or slick rock, look for a low transmission first gear coupled with low transfer case gearing and low differential gearing as it is necessary to "crawl" through/over what lies ahead. Speed tends to be the enemy here leading to a loss of traction and/or destruction of the machinery. That doesn't mean there isn't ever a time to goose it but on balance slow and steady is the way.
Mud & sand tends to be just the opposite; you need all the speed you can get at the tires as forward momentum comes more from being able to push the mud/sand behind you without allowing your tires to dig too deep. In this case, rock crawling low gearing tends to be a hindrance rather than a help as in order to get the tire spin you need your motor will be redlined or just unable to obtain the necessary tire spin without going up a gear. When I first got into jeeping I spent hours on the sand dunes of the Oregon coast with a bone stock 1972 CJ5. (AMC 304, T15 3 speed, Dana 20 x-case, and 3.73 gears in the differentials) other than Armstrong Rhino tires and never had a problem, but this jeep would have been next to worthless on the rocks.
Having said that, there are times things just seem to cross over. I know of dirt roads that even when dry are too rough to just idle along with a V8, non granny gear low, and low range on a Dana 20 x-case, with 4.56 differentials. Also, if you use your jeep for a daily driver as well a weekend wheeling or you have to drive your jeep a long ways on asphalt to get to the fun, road manners become important and a balance between the two may need to be achieved; screaming down the road at 3500 plus rpm but only doing 50 mph is not my idea of a good time.
In the end, it all comes down to crawl ratio and what is best for you and your needs depending on how you want use your jeep.
Diehard crawlers, guys/gals who like to navigate rock based terrain whether boulders or slick rock, look for a low transmission first gear coupled with low transfer case gearing and low differential gearing as it is necessary to "crawl" through/over what lies ahead. Speed tends to be the enemy here leading to a loss of traction and/or destruction of the machinery. That doesn't mean there isn't ever a time to goose it but on balance slow and steady is the way.
Mud & sand tends to be just the opposite; you need all the speed you can get at the tires as forward momentum comes more from being able to push the mud/sand behind you without allowing your tires to dig too deep. In this case, rock crawling low gearing tends to be a hindrance rather than a help as in order to get the tire spin you need your motor will be redlined or just unable to obtain the necessary tire spin without going up a gear. When I first got into jeeping I spent hours on the sand dunes of the Oregon coast with a bone stock 1972 CJ5. (AMC 304, T15 3 speed, Dana 20 x-case, and 3.73 gears in the differentials) other than Armstrong Rhino tires and never had a problem, but this jeep would have been next to worthless on the rocks.
Having said that, there are times things just seem to cross over. I know of dirt roads that even when dry are too rough to just idle along with a V8, non granny gear low, and low range on a Dana 20 x-case, with 4.56 differentials. Also, if you use your jeep for a daily driver as well a weekend wheeling or you have to drive your jeep a long ways on asphalt to get to the fun, road manners become important and a balance between the two may need to be achieved; screaming down the road at 3500 plus rpm but only doing 50 mph is not my idea of a good time.
In the end, it all comes down to crawl ratio and what is best for you and your needs depending on how you want use your jeep.
Turbogus
Active member
Hiya Saddle Tramp, thanks for mentioning the T150 IS good and sturdy, mag editors have much maligned this transmission over the years and most recently I think I saw yet another remark in line with this in JP Magazine~so much for objectivity. Although I would like to upgrade to a T-18 w/6.32 1st, I'll wait until I break (if that ever happens) my T-150
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