Manual Tranny Upgrade for the 289 Ford

[Saddle Tramp]

To clarify the Overdrive works with the Spicer 18 Transfer Case . See Busa’s picture, I circled the Overdrive . So if you do the Overdrive today and want to change to any Transmission that will take your Spice 18 Transfer Case , such as a T-18 Transmission later, the money you spend today will not be lost on the later Transmission swap. Assuming the original Transfer Case is in your jeep from 1965 most likely you have a “big hole” case which has the best and strongest components used during the Spicer 18 run.

(Don't be confused by all of the “18” numbers as we are talking about two different cases, the Transmission we have been referring to is a T-18 and the Transfer Case is a Spicer 18 .)

You will have another shifter nest to the Transfer Case shifters; makes you feel like an old time trucker.

 

[steve1973]

Why not try a ZF S5-42 5 -speed out of a 4x4 F150 or F250? Granny low and the Overdrive in one tough aluminum case.

ZF first introduced the S5-42 in 1987 and was used in the Ford F150 5.0 I6, F250, F350, F450 and Super Duty until 1994.

All gears on the S5-42 are fully synchronized with an input torque rating of 420 ft-lb

Standard gear ratios on the ZF S5-42:
Close Ratio

1st Gear:​

4.14

2nd Gear:​

2.37

3rd Gear:​

1.42

4th Gear:​

1.00

5th Gear:​

0.77

Rev Gear:​

3.79 Wide Ratio

1st Gear:​

5.72

2nd Gear:​

2.94

3rd Gear:​

1.61

4th Gear:​

1.00

5th Gear:​

0.76

Rev Gear:​

5.24

Close Ratio

1st Gear:​

4.14

2nd Gear:​

2.37

3rd Gear:​

1.42

4th Gear:​

1.00

5th Gear:​

0.77

Rev Gear:​

3.79
Close Ratio
1st Gear: 4.14
2nd Gear: 2.37
3rd Gear: 1.42
4th Gear: 1.00
5th Gear: 0.77
Rev Gear: 3.79
Wide Ratio
1st Gear: 5.72
2nd Gear: 2.94
3rd Gear: 1.61
4th Gear: 1.00
5th Gear: 0.76
Close Ratio

1st Gear:​

4.14

2nd Gear:​

2.37

3rd Gear:​

1.42

4th Gear:​

1.00

5th Gear:​

0.77

Rev Gear:​

3.79 Wide Ratio

1st Gear:​

5.72

2nd Gear:​

2.94

3rd Gear:​

1.61

4th Gear:​

1.00

5th Gear:​

0.76

Rev Gear:​

5.24

 

[coldair]

What we are all trying to say and i should have said that i remembered that your year of jeep has a dana 18 Transfer Case you can put an over drive in it this pretty much give you a 5 speed so to speak. what i mean by that is the 3rd gear in your Transmission is a 1.1 ratio most 5 speeds have a 1.1 4th gear then the 5th is the over drive so to speak. does that make sense?

 

[Sasquach]

Go here and read up, Overdrives

As I said a freind of mine has a Willy's wagon with the OD and it works nicely, he also has a ford motor in front of his T-90 Transmission coupled with the Spicer 18 Transfer Case .
If you are just trying to make the CJ more road freindly and not sink lot's of $$ into it this would be a good choice. try shopping around for a used one too.

 

[BusaDave9]

Let me summarize:
Option 1: Get an Overdrive for your Dana 18. Yes, this will add a separate lever to your Jeep. When it is disengaged your jeep will run just as it does now: high RPM on the highway. If you stop and engage the Overdrive all 3 gears will be taller. Even 1st gear will be taller so this might be an issue starting out. If you replace your tranny with another model this Overdrive will still be used as long as you retain your Dana 18 TCase.
Option 2: the next best option would be to get a 5 speed Ford Tranny AND matching TCase. It must be a 5 speed to get a higher top gear. There are no 3 or 4 speed Overdrive transmissions. You have a Ford small block so it should be easy to find a tranny and TCase.
Problems you will encounter if you go with this option: The Drive shafts will need to be modified for length. Don't expect to find a tranny and TCase just as long as what you already have (possible but unlikely).
If the Ford tranny you find has the wrong lengh input shaft you will need the bellhousing that came with the tranny.
The Clutch linkage may be an issue. Older ford transmissions my use clutch likages that could work with your clutch pedal but newer transmissions may be hydraulic. This means you will need the bellhousing that is mated with the tranny you get from the junkyard. Then you will need to swap in a hydraulic clutch pedal.
Option 3: Get a ford tranny and an adapter to mate it to your TCase and maybe to your engine. I don't like this option because it is expensive. Do not buy any adapters. They will only add to your expenses.

If you get an Overdrive keep in mind that the 2nd best option entails replacing the Dana 18 TCase (and the Overdrive ). So if you get the Overdrive as a temporary solution then you may end up throwing it out if you get a ford tranny/TCase combo.

This may have been confusing but Sasquach had it right from the beginning: you may just want to get an Overdrive . I agree this may be the cheapest and easiest option.
Getting a Ford drivetrain with an Overdrive tranny may be the best but most expensive option.

 

[BajaEdition]

I run an overdive in my 70 CJ6 and yes it really is nice, I now have choice of 6 forward gears, can do 80 down the freeway with no stress at all.
so I still have the ability to use the low gear in my 3 speed tranny, and can go up 25% in any gear I am in.
that is as good as any modern tranny but I get the solid strength and performance of the BW tranny I run with no headaches getting it to fit the D 18 case.
as far as the D 18, it is a super strong t case with a 2.43 to 1 low range which is a good range for every day wheeling, plus you can get a 4 to 1 low gear kit for it.
Plus you can get a PTO for the D 18 and can install it with the Overdrive , they make that kit.
So unless you just want to have conversion headaches for days, I would stick to an old topload BW that bolts direct to the D 18 you have and save some serious dough.

 

[BajaEdition]

Good god, this just continues to crank closer and closer toward that 3 grand mark, if it isn't already past it. Is there no way to do this more affordably? I'm just a lowly worker bee... Perhaps I'll just have to make do with the three speed for now? I think 2k would be the most I could ever really put into this project, at least for this particular purpose. The T-90 is just so relatively inexpensive, I figured there would be something out there that could replace it a close to it's cost. Guess there's just too many incompatibility issues... Thoughts?

get the Overdrive , it is about 650 dollars and I think the gear that you need to change is around 55
no other changes needed