t18 and dana 20

I will try and get around to measuring the bearing collar and such next week.

Thanks for the offer Mike, I think i'm going to pass.

Nick: I thought I couldn't take the dana 20 gears and make it into a dana 18.
how do I go about doing this? I imagine I still need a new bull gear, would there be anything else? I got the large hole dana 18 case that I can use the front and rear outputs on.


Thanks everyone for helping, I really appreciate it.

 

Sorry, I mislead you on that.
The D20 Teraflex gear set # 2112020 is almost identical to the D18 Teraflex gear set # 211018.
The difference being that the D20 set has an additional gear.

Yes you need a 6 spline mainshaft gear and that should about do it.

 

Randy, I was only half serious anyway. I wouldn't mind seeing the teraflex gears when you start swapping them over to the D18. They are on my wish list eventually.

 

If the Dana 20 with the 3.15 Tera gears is on the back of the T-18 it should already have the proper 6 splined input gear. If you want to use the gears in the 18 transfer case behind the T-14 then you would need a 10 spline input gear.
You can put the 20 gears in an 18 case but no one does it because it gives you a higher low range. Most people want to go the other way and go lower on the low range.
3.15-1 is the lowest Tera makes for the 20 afaik. The Dana 300 kit goes down to 4-1 low range. If I had that stuff sitting around I'd convert the T-18 to fit my engine, build an 18 using the 3.15 gearset, 20 case, 18 transfer case outputs and two stick shifters, and keep my offset rear. Unless there were issues with my offset rear axle then I would source a centered 44 and keep the 20 a 20. The biggest advantage if the 20 is they are much quieter. The advantage to the 18 is better driveline/u-joint angles, twin stick shifter with factory parts, and the drivelines are in line with each other making It easier on the trail to pick lines to avoid damaging drivelines.


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oldtime: no worries it happens to all of us.
which is the mainshaft gear? I thought the bull gear attached to the t18 would be the mainshaft gear?

okay, i'm starting to wrap my head around making a dana 20 an 18.


well mike, when I get everything sorted and swap everything in, I need to bring the jeep up to Sacramento anyway.

 

yes Nick this is exactly what I was hoping to do. I'm just getting hung up on how you make the 20 case and 20 gears into a dana 18.

From my understanding I need the front twinstick output and the rear output off of my dana 18. Take out the extra dana 20 gear, and install new bull gear to convert the dana 20 to dana 18

 

Here again I guess I was not thinking clearly.
I was only thinking about your current T-14.

Like Nick said the T18 / D20 combination will aready have the correct mainshaft gear.
The mainshaft gear is often called the bull gear or the transfer case input / drive gear.
Mainshaft gear is the term that Jeep uses and it should not be confused with the mainsdrive gear.

To build a D18 with 3.15 just put the Teraflex gears into the desired bighole (4" index) case.
Omit all of the D20 rear output parts.
Add the D18 front bearing cap complete with twin sticks if you like.
Add the D18 rear bearing cap.
Add D18 parking brake if you like.

That's about it.
You can either put the rear PTO plate on the D18 or you can add an overdrive.
Overdrive only fits with special 3.15 bowl gear that is available from Herm.

 

thanks for the clarification oldtime,

I believe this is one of those things that as soon as I take it apart I will immediately understand. until then, reading it over and over seems to be working.


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With the T-18 @ 6:32x3.15x3.73 in low gear you have a pretty respectable 74:1 crawl ratio............the bonus with the Warn Overdrive attached would be having the ability to pick a better gear ( -25%) when off road.........in high gear you have all the freeway gear you need...........if you go that way and want to match that transmission up to the stock Buick Housing I can tell / show you what needs to be done with those extra bosses and the top two holes in the B&W T-18 ....not a real hard job.

 

tarry thanks for the offer, I might have to take you up on that. it would be easier to see what is done before I attempt this.


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I wasn't sure if I should of started another thread or just tack it on here.
I been thinking about it, how do I know if the bearing retainer is turned down? I tried taking bearing retainer off but it looks like I got to take off the bell housing.
(I have a limited amount of tools here in Sacramento)

Edit: I took off the bell housing carefully with vice grips... I know i'm a bad person.



from here to the tip of shaft I got 5 15/16


now here is what i'm interested in:

4" and 15/16 diameter for the bearing retainer





3" 13/16 height, and a 1" 7/16 outside diameter