4 speed 4 75 cj

I am gonna chime in here as I just finished putting a Jeep T18 in my 75 CJ. I like the 4 speed so much better than the stock 3 speed. It is the best upgrade I have done so far..

First, find a Ford T18, it is the most common one out there and the easiest to rebuild. Be sure to find one with the really low granny [like 6:32] .. I understand there are like 3 different granny ratios on the T18's.
I made the mistake of finding a Jeep T18 and man it was a real hassle to rebuild.. Lots of issues. There is also a Scout T18, and it is the least desirable and most expensive to use.

Novak in SLC has a ton of info on their website.. It's not that big a deal to swap a tranny in if ya do the research first..
http://www.novak-adapt.com/knowledge/t18_t19.htm

 

As your tires get taller, you might wish you had a lower first gear to start out in. Especially on the street in high range

 

I also put a Jeep T-18 in place of my factory T-15. I have a T-18 out of a 73 cj so it bolted right in. Note: The Jeep T-18's are very long! If I was to do this swap again, I would use the T-19 with the syncronised granny gear, much easier to shift and a couple inches shorter in a very crowded Jeep. The best part of the 4 speed swap is the low reverse gear. But if your engine is a little under powered, the jeep T-18 with the 4-1 low gear is great for uphill starts on the street tying to tow. So many options???? Good luck!

 

If I were to do it again, I would look for the tranny with low 2nd gear and short overall length including the adapter. At this point I would bite the bullet with the bell housing issues and go with the SM465 with a Dana 20 (3.58 second gear, 13.0" with Novak adapter) or a SM420 with a Dana 300(3.6 second gear, 13.9" with a Novak adapter.)
The t18 plus adapter is only 12.9" long, but second gear is only 3.09.

 

i am really ignorant on all these swaps.
where would be the best place for me
to read up on this information?
what i'd like
is the same gears i have now,
but a 4th gear for the highway
so engine doesn't rev
gas consumption is down.
the best of both worlds!!
thanks
iowa

 

First start doing a web search. I used Google.. Also the Novak site I linked has a ton of good info.. I kept a file in my favorites labeled 4speed stuff, and added all the links there.. Parts Mike also has some good stuff on his site.

Second, the best you are probly gonna do is to add a low granny gear.. All the rest of the gears stay the same.. But believe me that is worth it..

 

I have no idea how relevant this is, but I had a factory original 1984 Dodge Ram 100 with a factory overdrive 4-speed transmission behind an inline slant 6 motor. I'm sorry I don't remember the trans model, etc. It was a very good unit - no trouble for at least 150K miles. Probably too long for a JEEP swap, but someone here may be able to rule it in or out, perhaps.

 

i gotta ask, and forgive me if I missed it, but....Did anybody see any actual RPM's? Just because the engine sounds loud doesn't mean it is running fast. Need to get an idea where it is actually running. As for the Ford trans taking a stock adapter, the answer is yes. You need to redrill the back of the trans and replace the output shaft. used a combination of Ford and Scout trans parts. I did this swap many years ago, It was fairly simple after spending some time researching it. I belive the trans timgr is talking about was a medium duty four speed adapted off the RUG trans. These were actually a three speed with an overdrive. They did this by recasting the third gear and countergear as an overdrive, then flipping the shifter over to make third and fourth shift backwards. They ran side linkages and were found in(if I remember right) mid 80's cars and light trucks.

 

iowa, what's your axle final drive ratio and tire height? Didn't we went through this with you before? The outcome will likely be the same.

 

Of course.

 

I have the same problem, I have an I6, t-14 and dana 20 x-fer case,3:73 gear, really feels like the jeep is struggling at highway speeds. my question is has anyone run a 3:08 gear with this combo? all the ratio calcs say I should be at about 2600 rpm. Jeep very seldom goes off road. do you all think this gear is too tall?