4 speed 4 75 cj

what was the four speed transmission
that was optional for the 75 cj?
i finally figured out that the 3 speed
i have is a T 14 (used in I-6's)
thanks
iowa

 

T-18. Close ratio. To swap one in, you need a diffferent bell housing (t-150 or 176 works). Plus you need the bull gear off a t-15 or t-18 for your transfer case. The one on the T-14 will not work on the T-18. You also need an adapter plate to mount the Dana 20 t-case to the tranny. If you can find a Jeep T-18 then it will probalby have this plate on it already.

Point of note. The 4 speed tranny gives you a granny low not an overdrive.

 

If we are talking about the stock 4-speed from 1975, it is indeed the close-ratio T-18. The OEM transmission uses the T-15 bell and a plate adapter. If you swap in a Ford wide ratio T-18 from a pickup, then you need to adapt the rear of the transmission to your transfer case and can use the T-176 or T-150 bell, which is a Ford pattern. You can also use a T-18 from a Jeep truck - this will bolt up to your transfer case. You must then substitute an input shaft from a Ford T-18 and redrill the 150/176 bell to match the Jeep pattern. The truck transmissions will have a 6.32:1 granny 1st.

AFAIK the close ratio T-18, with a 4.02:1 1st, was only used in 6-cylinder CJs and Commandos. There may have been a few years where this transmission appeared in Wagoneers... that's controversial.

 

I just went through this myself. Check out this thread for details.

 

thanks guys!!
really helps
iowa

 

You're right on the Wagoneer application. I remember a 74 Wagoneer with a 360 and a CR T-18 at a place I used to work at.

 

am i right in thinking that if i did put the
above mentioned 4 speed in my jeep
that the 3rd and 4th gears would be the same?
the extra gear is only the granny low?
iowa

 

No. All the gear ratios are different, except for 4th (top) gear, which is 1:1. The ratios are given in the sidebar "Jeep T18 ratios at a glance" here: http://www.novak-adapt.com/knowledge/t18_t19.htm

<edit> Also here: http://www.jeeptech.com/wiki/index.php/Transmission/Factory/T-18

 

Oh.. are you asking about in comparison to your T-14? The T-14 ratios are here: http://www.jeeptech.com/wiki/index.php/Transmission/Factory/T-14
Then it would be (T18:T14)
6.32 : n/a
3.09 : 3.1
1.69 : 2.6
1.0 : 1.0
R7.44 : R3.1

So you'd have a higher 2nd (T18 3rd) and much lower reverse.

 

Question: The AA site was not clear on this. On the back end of a Ford T-18, Can you bolt on a Jeep Texas style adapter as used on the Dana 20 T-cases. I would assume some drilling and tapping, but that's no big deal. The AA kits are awfully expensive. I already have some proper mainshafts and a couple Texas pattern adapters.

 

I have not, but Nick says you can. You need to plug some holes and drill/tap others. You can use the main shaft and adapter from a Texas pattern T18, ie Jeep or IH. http://www.earlycj5.com/forums/showthread.php?t=4449

 

forgive my ignorance,
so this means that my T14's 3rd gear
is the same ratio as the T18's 4th gear?
the reason that i ask,
is that it sounds like the engine is
revving pretty good when in 3rd gear
and going about 40-50 mph!
thanks
iowa

 

Per the table above, you are correct.

You can go to this link and do a side-by-side comparison of the two transmissions. After calculating, the bottom chart will tell you what RPM you are (or will be) turning at a specified MPH for each gear.

 

Thankyou much Tim. That thread answered every question I had.

 

which trannie would i put in
so the engine won't rev so much
in high gear?
iowa

 

do they make OD's for the T14?
and if so, where do i get one?
4wd?
thanks
iowa

 

No, your only change to get an overdrive is to use a transmission where the top gear is an overdrive gear. There are several 5-speed transmissions available with an overdrive top gear, but they aren't an ideal choice - they are often expensive, long, require expensive adapters.

The only 4-speed transmission that I know of that has an overdrive top gear was made by Ford, and was called the SROD (single rail overdrive) transmission. They aren't very common, but you can buy an adapter from R&P 4WD. I expect you'd have to change to the Ford style bellhousing (from a T176 or T150) as well.

What's your axle ratio? These Jeeps only came with 3.73 (std) or 4.27 (opt) axle ratios, and they are fine for the street. Even if you have short tires (28") and the 4.27 axles, you're only at 3330 rpm at 65 mph, which may sound fast but is fine. Adding some floor mats and padding will quiet your Jeep on the highway.

 

I agree with Tim. Your engine should be able to run all day long at 3000 rpm. Your other option would be to install taller road gears and then install a Teralow conversion for offroad. Personally 3.73 is the tallest gears I would ever consider running. I run 4.27 in mine with 32 inch tires and I want, no make that need, a Teralow.

 

i'm back on this topic again!
sounds like i might as well
keep my T14 and maybe just
get some taller tires?
iowa