For the record, bolting a T-18 to D18 vs. T-18 to D20

Just for the record, what is the difference between bolting a T-18 to a Dana 18 verses bolting a T-18 to Dana 20. I know the T-18 D20 package is factory, I have one in my 79 CJ5, but I was under the understanding that the D18 had the same bolt pattern as the D20. Must be a difference in input gears/drive gears? There are several good threads about granny low tranny installs on here, just wanting to get my facts straight, great web site here, my new favorite. Thanks for any and all info, Chris.

 

The D20 case and big hole D18 case are identical. (small hole D18 has the same pattern, but a smaller index hole) I put D18 guts into a D20 case when I did my conversion. The only thing I found that was different was the location of the fill plug. The D20 had it on the rear of the case and the D18 had it on the side. The original plug interfered with the D18 output housing so I replaced it with a flush plug and had a new filler drilled in the side. (the casting boss was the same). There are several different gears. Novak has a chart here. You can use whatever you like as long as all the gears in the set are compatible.

 

Thanks for the info here guys, lots of options I am seeing here. Basically If I have a F head, T-90, and a Dana 18 t-case from a 71 CJ5 what is the easiest route to getting a T-18 in between the F head and the Dana 18- I do have a Dana 20 T-case for swapping around and what not. Thanks for your time here guys, Chris.

 

Do a search of this forum. I'm pretty sure there has been some recent discussion of this very topic.

 

The three pieces you'd need are on the input end.

spacer / adapter
input shaft
bearing retainer.

Spacer / adapter can be found, but it is tough to do. You could make one - that would be fairly easy (relative to the other two bits)

input shaft - there never was an input shaft made for a t-18 to F-134 bell housing. You can't use a T-98 shaft because they are different from the t-18 shaft.

While conventional wisdom generally warns against it, I think that one could experiment with cutting off a t-90 shaft and welding it on to the stub of a t-18 gear. I have seen this done with jet engine parts that have stresses thousands of times greater than any Jeep could ever put on a part. This is not a weld that one could do at home, or even at the local welding outfit - it would require a very high end, high tech welding shop and would probably be very costly. Frankly, I think it would work.

bearing retainer - there never was a bearing retainer made for a t-18 to f-134 application. You could use a t-98 bearing retainer if you could find one. you could also make one from a common large shaft t-98 bearing retainer and a t-90 bearing retainer. I've never seen a homebrew bearing retainer, but I know that they have been made by an outfit in California.

The output side would be cake walk after you have experienced making / finding the input side.

 

Thanks for the good info here guys. I will look up some info at the three web sites posted by Lynn. I will let you know what I find out, if anything at all. One last thing. Would the SM420 or 465 be an easier install between the f head and Dana 18? I guess I will ask that question of the websites also, thanks Chris.

 

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