I was thinking of using a Dana 18 transfer case for my rig. Yeah, I know, do an Atlas or NP205:rolleyes: But I like my offset axles:cool: and want to keep the build up cheap:p

This will be going behind a V8(5.0L TBI... book rates it at under 200 hp:( ), SM465, and at least a 2 to 1 gear reduction box.

I'm more of a technique wheeler than a "gas the mo-fo" type:p

Can anyone comment about the strength of the tcase(assume 1.25 inch intermediate shaft)? Do they have the habit of splitting in half like the "old" Land Crusier FJ40 cases? How about stripping out the 6 spline input gear? How about the 6 spline output shafts(front and rear)?

How difficult is it to upgrade the input gear to a 10 spline or 23 spline? Is it as simple as finding a gear with the right outside splines?

Also, what is interchangable between this and the Dana 20 aside from the housing? Intermediate gear cluster? Front output shaft/housing?

I've looked through a dozen articles and AA's Jeep book but none addressed some of the items above:( And a search here provided nothing.

TIA for any useful information.

The D18 is a pretty strong tcase. I know a lot of guys running them behind v8's with no problems. I wouldn't bother with any mods other than to make sure that the intermediate shaft is good and that the thrust washers are good as well.

Originally posted by Lil'John
Can anyone comment about the strength of the tcase(assume 1.25 inch intermediate shaft)? Do they have the habit of splitting in half like the "old" Land Crusier FJ40 cases? How about stripping out the 6 spline input gear? How about the 6 spline output shafts(front and rear)?

How difficult is it to upgrade the input gear to a 10 spline or 23 spline? Is it as simple as finding a gear with the right outside splines?

I believe the outputs are 10 spline not 6, but I don't think there's any upgrade for them. I have heard of people damaging the input gear, though it's the teeth that break off not the splines that are the problem. I have also heard of splitting the case in half, but that takes serious abuse.

Originally posted by Lil'John
Also, what is interchangable between this and the Dana 20 aside from the housing? Intermediate gear cluster? Front output shaft/housing?

You could use Dana 20 gears if you wanted to, but you would need the entire gear set minus the rear output gear. Jeep and Scout D20s have only a 2:1 low range though so while you could, I don't think you'd want to. I think Bronco D20 gears will work and they have the same 2.46 ratio. The front output shaft and housing are completely different, so no help there.

A guy in our club is running teralow 3.15:1:1 gears in his D18. Runs it behind a 4.2L/T-18a combo with no problems.

My only complaint is having to ride behind him with my crappy 40:1 crawl-ratio TJ, his 100:1 crawl ratio makes it move sloooow...


{edit}
Check this (http://www.off-road.com/jeep/tech/xfer/d18.html) out. It has some useful info on the D18
{end edit}

Thanks for the great info Grandpa Jeep. I wasn't dead sure on the front/rear output splines... it looked like 6 from the bad picture I saw :p

JohnnyJ, I know the feeling of slowing people up:D I did that for about a year with a SM465 before people finally upgraded.... well, that and I got stuck in the rear of the pack more often than not:rolleyes:

Check this out as well:
http://www.novak-adapt.com/knowledge/knowledge_gateway.htm

They have a good reference chart as well as rebuilding instructions.

Bryan

The main issue with 18's the torque is not directed straight through it. This is why the case has been known to split where a model 20 does not (as often). If you read about the 14day flattie, Tri-County gear made a 1/2" steel girdle that bolted onto the lower cover to help stiffen the case up. Seemed like a good idea to me. You might try calling them if you are interested in something like this. Overall, the 18 is a good t-case.

BTW, My original 18 grenaded the input gear many moons ago.