T-18 ratio ID

[threepiece188]

You could disconnect the rear drive shaft, put the transmission in first gear, put the transfer case in 2-HI, remove the coil wire, pull a spark plug out and put that cylinder on top of compression stroke. While cranking the engine you could then listen for three compression strokes escaping from the plug hole while watching the rear output yoke. It should have turned a bit over one revolution.

It would be interesting to know of a close ratio T-18 in a factory built FSJ. I doubt they would have gone through the expense of another input shaft and deal with the associated increase in confusion of an already confusing array of T-18 input shafts.

Please be sure the transfer case is in two wheel drive before going under the truck and cranking the engine. I would recomend a test crank before going under.

[Dumpy]

Originally Posted by tgreese

Not correct. Both ratios use the same case with the same cast-in numbers - no difference.

Never said it was a different case. Didnt know that about the T18A, but as from everything I've read the 1B was Granny only, correct? I haven't found any info on a close ratio T18-1B, but did it come in both ratios, too?

[tgreese]

Originally Posted by Dumpy

Never said it was a different case. Didnt know that about the T18A, but as from everything I've read the 1B was Granny only, correct? I haven't found any info on a close ratio T18-1B, but did it come in both ratios, too?

I thought you were talking about the numbers in the case? The case has to be different to have different numbers. Pre-79, all T-18 cases are the same part number, 940495. This is a Kaiser era PN. They are not going to cast a separate case with the same PN for different ratios. That's what the tag is for.

The tag will be different, with a different part number. However, I believe the close-ratio transmission will say "T18" on the tag. I've never seen or heard of a T18-1B. The tag will also carry a Jeep PN and a Warner Gear number (maybe 13-01-000-023 or similar). If you have the tag, you can look up the PN. But tags are often lost.

[Dumpy]

We are on the same page. My T18 is a 1B and has the 6:32. I think it's Jeepforum where it's covered a lot. Mine came out of a J20.

[Southern Gorilla]

Okay, let me see if I understand this.

The difference between the CJ T-18 and the FSJ T-18 is the adapter on the front of the case which moves the transmission rearward to put the shifter in an accessible position in the cab. Right?
In order to compensate for this adapter the input shaft also has to be longer, obviously. And the input gear is integral to the input shaft, so you can't just swap a different gear onto the shaft to change ratios. Right?
So if it turns out that my T-18 really is a close-ratio it means it has to be a factory unit because there is no way to shadetree fab such a piece.

I'm not yet certain that's the case. But if it is that makes this Cherokee something unique. Is there any way of tracking its history? If I stumbled onto something of some historic significance I'd rather restore it as stock as possible. I have another '76 I can "enhance".

[tgreese]

Originally Posted by Southern Gorilla

Okay, let me see if I understand this.

The difference between the CJ T-18 and the FSJ T-18 is the adapter on the front of the case which moves the transmission rearward to put the shifter in an accessible position in the cab. Right?

Only for the V8 FSJs. The pre-'79 6-cylinder FSJ T-18 transmission is the same as the '71-75 CJ transmission, except for the ratios. The '76 CJ T-18 is a little different, but still close ratio.

In order to compensate for this adapter the input shaft also has to be longer, obviously. And the input gear is integral to the input shaft, so you can't just swap a different gear onto the shaft to change ratios. Right?

Correct.

So if it turns out that my T-18 really is a close-ratio it means it has to be a factory unit because there is no way to shadetree fab such a piece.

Also correct - assuming you have the long adapter and a T-18.

I'm not yet certain that's the case. But if it is that makes this Cherokee something unique. Is there any way of tracking its history? If I stumbled onto something of some historic significance I'd rather restore it as stock as possible. I have another '76 I can "enhance".

Well, if it's a close ratio, that does not mean it's unique. Unusual yes, and we don't know of any other examples. But if one exists, others will too.

Tag numbers.

[Southern Gorilla]

Originally Posted by tgreese

Well, if it's a close ratio, that does not mean it's unique. Unusual yes, and we don't know of any other examples. But if one exists, others will too.

Tag numbers.

It would have to be extraordinarily rare if nobody has ever heard of one in the roughly four decades since these trucks first appeared.

But I'm not excited about the possibility yet. It seems far more likely that somebody has put tall gears in the diff that make it hard to start out in second and make first usable for regular driving.

I'm heading out in a little. Will see what I can learn either later today or tomorrow.

[threepiece188]

[quote=tgreese]Only for the V8 FSJs. The pre-'79 6-cylinder FSJ T-18 transmission is the same as the '71-75 CJ transmission, except for the ratios. The '76 CJ T-18 is a little different, but still close ratio.

The lengths of the input shafts are also different. The 6 cyl. FSJ T-18 input shaft is about 3" longer than the CJ-T-18 shaft.

[Carnuck]

My '83 Honcho has a spacer, but not nearly as long as I recall on my '77 and '76, but then it has a NP208 on it and not Dana 20 like they had. (I'm still contemplating the Ranger gear splitter O/D setup in place of the spacer)

[tgreese]

Originally Posted by threepiece188

The lengths of the input shafts are also different. The 6 cyl. FSJ T-18 input shaft is about 3" longer than the CJ-T-18 shaft.

Not sure which years or combinations you are thinking of. There was no domestic six cylinder FSJ T-18 after 1979. Through 1979, the bell-to-transmission plate adapter for the 6-cyl FSJ and an intermediate CJ are the same PN, 992667. The bellhousing is the same, 3215152. Same length.

Take a look at my '77 J-10 with a T-15 as an example. If it had a V8, it would have an adapter/spacer. As it is, it has no spacer. Same transmission and same input length as an intermediate CJ. The T-18 in a 258 FSJ is set up the same way - just like a CJ.

The '76 and later CJ T-18s are different, but '77-on is wide ratio not close ratio. '76 is an oddball, since it has its own input shaft and bell, but is close ratio ('76 was the big transition year for CJs). The Ford T-18s also have a shorter input shaft, about 6" stickout compared to 7"+ for the intermediate CJs.

[threepiece188]

[quote=tgreese]Not sure which years or combinations you are thinking of.

I have two T18's from 1970's CJ's one is a wide ratio 1979, the other is close from 1974. Both have short input shafts and bellhousings. I also have four T-18's from 6 cyl. FSJ's 1976-1979. They all have a longer input shafts and deeper bellhousings. They also have a 15/16" iron spacer between the trans and bell.

[tgreese]

Originally Posted by threepiece188

I have two T18's from 1970's CJ's one is a wide ratio 1979, the other is close from 1974. Both have short input shafts and bellhousings. I also have four T-18's from 6 cyl. FSJ's 1976-1979. They all have a longer input shafts and deeper bellhousings. They also have a 15/16" iron spacer between the trans and bell.

The '74 CJ transmission should be the same OAL as the 258 FSJ transmission. They use the same bell and the same plate. Take a look at the parts book - it's there in black and white - I quoted you the part numbers above. The plate is thin, maybe 15/16", but it's the same part for the 258 FSJ and the CJ. The input shaft for this app is longer than the Ford T-18, since both the bell is deeper and the plate is there. If your '74 CJ trans is not like this, then it's likely been converted, and has a Ford input shaft. This is a very popular conversion for the CJ.

The '79 CJ is different, and is wide ratio. A '79 is a late CJ-5, and different from the '72-75 intermediates that got the same trans setup as the 258 FSJ. Not sure about the stickout on the '79 CJ T-18, but the whole setup is different from the earlier CJs or the FSJs. These transmissions '77-79 are quite sought after by the CJ crowd, but you need the whole setup including the bell to make it work.

I believe you are mixing parts from different applications if you don't see this. There's also a long spacer that's used with the T-15 in V8 FSJs, in addition to the spacer for the V8 T-18 FSJs. These too use the T-15 bell (3215152).

I worked in a Jeep dealership parts department during the '70s, and I've seen the mid-70s stuff first hand. Not all of it is still in my memory, but some ...

[threepiece188]

Originally Posted by tgreese

The '74 CJ transmission should be the same OAL as the 258 FSJ transmission. They use the same bell and the same plate. Take a look at the parts book - it's there in black and white - I quoted you the part numbers above. The plate is thin, maybe 15/16", but it's the same part for the 258 FSJ and the CJ. The input shaft for this app is longer than the Ford T-18, since both the bell is deeper and the plate is there. If your '74 CJ trans is not like this, then it's likely been converted, and has a Ford input shaft. This is a very popular conversion for the CJ.

...

I don't see how the 1974 close ratio T-18 could be converted with a Ford input shaft if the tooth counts are different.

I've been conversing from a 10 year old memory here. I guess I'll have to take a look at my transmissions again. God help me if I'm wrong because it seems clear as glacier water.

[tgreese]

Originally Posted by threepiece188

I don't see how the 1974 close ratio T-18 could be converted with a Ford input shaft if the tooth counts are different.
...

You're right - it can't. It would have to be a wide ratio transmission that was converted. The V8 FSJ transmissions, with the Ford input shaft, are common swap for these Jeeps. Or you can, with some hole drilling and plugging, combine the main shaft and adapter from the Jeep transmission with the rest of a Ford T-18; this would have a Ford front pattern and stickout, and a Texas TC pattern.

[threepiece188]

Well the 1974 does indeed have the longer input shaft just like you said Tim.

Please everyone keep me in your prayers. You wouldn't want me to start scrapping FSJ parts because I thought they were left-overs from my buddys Ford projects would you?