Will a D-18 Bolt Up to a T-15 ?

I did a search and found it (D-18) needs to have a bigger hole to mate to the T-15 or ?? I didn't really understand it though.

Question, will a D-18 T-case bolt up to a 1974 T-15 trans ? The D-18 is currently bolted up to a T-98 trans.

I don't know and looked but really don't want to separate the two different trannys/t-cases until I know more.











I have a '48 frame w/11" drums and an offset rear/locking hubs etc.

I do have another (two others) '48 w/centered rears and 10" drums/factory to that year.

I would like to use the '48 that is already setup and beefed up etc w/the offset rear if I can.

Yes the T-15 is still mated to the D-20 w/the PTO setup.

D-18 tag.


Thanks,
Jim

 

There are two different sizes of indexing hole for the 18 transfer case. The numerical measurements of the hole sizes escape me right now but one is large and one is small hence large or small hole transfer case. The Dana 20 is the large hole. Only size they came in. Dana 18's that were mated to the T-14 or T-86 were the large hole variety. If the T-98 is a factory Jeep unit from behind an F or L head then the 18 transfercase should be the small indexing hole afaik. If you can remove the transfercase without removing the transfercase input gear it is a large hole. If you can't it is a small hole. If the transfer case is bolted to a T-90 then It should be a small hole. I can't read that tag but if it says Brown-Lipe it should be a small hole.
You cannot bolt a small hole transfercase to a transmission that requires a large hole without machining the case or putting the guts of the 18 into a large hole 18 or 20 case. Another way to id a small hole transfer case is if the intermediate shaft is 7/8" or 1 1/8" diameter it came from the factory as a small hole transfer case. If it has a 1 1/4" intermediate shaft it could be either depending on application.

One other thing, 10" drums were not factory on a CJ in '48, 9" drums were. Drum brakes are measured on the inside of the drum where the shoes ride, not the outside. Neither was a centered rear axle in a 4 WD CJ of that year. Centered axles weren't used until '72 and they came factory with 11" drums.

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Thank you very much. I will measure it today.

If not then maybe sell the T-98/18 and use the T-15/20 out of my son's '74 CJ5 and a different rear which I don't want to do.


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Small hole is 3-5/32" index and large hole is 4" index.
Yes all original Jeep T-98 adapters plates bolt onto small hole transfer cases and original Jeep T-18 adapter plates bolt onto large hole transfer cases.

No such thing as 7/8" intermediate shaft transfer cases.

3/4" intermediate shafts from 1941- 1945 (MB, GPW)
1-1/8" intermediate shafts from 1945 -1954-1/2 (M38, M38-A1, CJ-2A, CJ-3A, CJ-3B)
1-1/4" intermediate shafts from 1954-1/2 -1975 (M38-A1,CJ-3B, CJ-5, CJ-6)

 

I couldn't remember if the MB/GPW were 3/4" or 7/8" for sure. Thanks for the clarification Ken.
Just to extend the information, all Dana 20's and Dana 300's up through 1986 including the IH Scout versions also used the 1 1/4" intermediate shaft.


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Thank you-will let you know the intermediate shaft size.

Might have to run the T-15/D20 combo/PTO out of Jr's '74 304.

 

Question-

How much does a T-98 go for ?

How much does a D-18 go for ?

 

That is true only for CJ's .
Some J trucks used T98 with big hole transfer case adapters.
Also there were no big hole cases prior to invention of the Dana 20 (AKA silent type transfer case) (1962)
Small hole cases were used on all CJ's excepting Dauntless V-6 from 1941-1971.
All post 1971 cases are D-20 since D-18 became obsolete.

Value of t18 or T98 depends on application (input and output shafts) and generally range from $250- $750
Basic D18 and D20 transfer cases generally range from $50 to $200

 

Thanks-Seem I will be selling them (Unit).

It is just easier to put Jr's old T-15/D-20 combo PTO in the Willy's.

Thanks,
Jim

 

Your first pic shows a Brown / Lipe (early) transfer case.
So that case definately has a small index hole unless machined/ modified.
In that pic I can see the factory Jeep T98 adapter plate but I cannot see the transmission input.
T15 is a very good 3 speed.
If you want to use Jeep T15 then I suggest you buy or build a D18 with a large hole case.
You must use 1-1/4" intermediate shaft with big hole D18's.
No adapter will be needed between T15 and big hole D18.
Now ain't this getting fun ?

 

What engine -bell-housing you plan on bolting the T-15 to?

 

Question: where will the PTO mount in a T-15/Dana20 combo???

 

On the bottom, you remove the inspection cover and bolt the unit on in it's place. Early Broncos and Scouts(with 20's) were also like this.

 

Duh! I knew that...brain-methane, I guess.

 

I have a AMC 304 in the garage that needs to be built as well as a AMC 360.

The T-15 was mated to a '74 AMC 304.

After I get this figured out then I have some frame to get rid of and axles etc.

 

Question, is the plate on the right if this D20 for a PTO or will the D18's output shaft fit so I can have an offset rear?

Thanks?
Jim







[video=youtube;qd64zIO2tb4]http://www.youtube.com/watch?v=qd64zIO2tb4[/video]


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Rollbar,
The bolt patterns of the D20's are the same as the D18 bolt patterns.

You can certainly use the case casting of the D20 with appropriate D18 parts being installed internally.
The D20 case with its original components removed then becomes a "big hole" D18.
You can build the D18 with either a single stick control or with twin stick controls.
Note... the D20 and D18 big hole cases are a little stronger than the small hole D18 cases.

 

Thank you-I was told this:

How hard is it to transfer the internals from the D18-to D20?

Is it something I can do in a regular garage or do I need to mic things etc. I did hear the D20 case would need some grinding etc.

Maybe I can find someone but if I'm to use any of the Willys rears then it has to be done-unless someone wants to swap for a centered rear etc.

Thanks again,
Jim

 

The late D20 (post 1971) cases had the oil bunge plug moved to the rear.
You can relocate (re-drill and re-tap) that if you have the required tools.

That entails the complete D18 rebuild procedure.
There should be lots and lots of information posted for complete D18 rebuilds.
Basic tools will get you by but precision measurements are best, especially for those without previous experience.

 

Thank you.


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