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post #1 of (permalink) Old 09-05-2000, 08:22 PM
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D18 swap and rear axle

I like old jeeps, and think Willys did it right the first time around, but I also have a respect for newer jeeps and have one as well, a 79 CJ7. I have not done much with it yet but it does have a 360 and T18 tranny with D20 transfer and 20 rear axle. Here is what I have been thinking, get rid of the D20 transfer and put in an D18 instead, cause of its classic and simple mechanics and also you can add a lot of toys to it. I have an extra D18 laying around and am thinking i can use the 20 case and swap the innards and get twin sticks at once. Is this possible? Is it just this simple? What rear axles would drop in rather easily, hopefully better than the 20, what about a 44 from a J truck or wagoneer with the Q track?? Width difference?
has anyone on this list done similiar?
Any and all input is appreciated

Two many jeeps to count, I think 5 1/2 and a trailer or two. Who knows what to come!!
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post #2 of (permalink) Old 09-06-2000, 09:52 AM
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Re: D18 swap and rear axle

I got a little confused about your question but here's your option.
First if you want to use the Dana 20 transfer with the Dana 18 guts(must be a late model after 56-58 with the larger center gear shaft(same size as the Dana20)) then you will need an extra gear. This gear can be found in late 60's Bronco Dana 20's. Many people will do this to get lower gears in the Dana20(2.46). You will also have to do a little grinding on the 20 case to get the larger gears to fit and slide. It's easy, I did it in about 20 min with an air grinder. There's an article on Offroad under Jeep stuff that outlines the swap. They say the you need a certain gear from a Bronco 20 but I've found that that gear was also stamped with other numbers that work. Check the spline and tooth count. That's whats important.

Yes you can also pull the shift rail plug thing and graft the twin sticks onto the 20. Theres an article on the Binder Bullitin about this.

Last If you use the Dana20 transfercase you could keep the AMC20 and upgrade to 1 piece shafts ($300) or look for a 72-75 CJ with the Dana44. It's a bolt in swap after moving the spring perches.

If you were to go to the Dana18 you will need to get a new rear end. Dana 20's from a CJ7 auto would work after moving the perches and upgrading the shafts if desired. A AMC20 from fullsize trucks or Wag's with the Auto I believe have the one piece axles already but they are wide and if you want to retain the stock width you will have to cut them down.

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post #3 of (permalink) Old 09-06-2000, 10:38 AM
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Re: D18 swap and rear axle

Hey -

I already have the setup you're considering and it's great! '79 CJ-7, 360, T-18, Dana 18, Warn OD, and offset Q-trac AMC 20. Yes - just assemble all of the Dana 18 components into the Dana 20 case and bolt it up. Leave out the interlock pill between the shifters and you'll have the rear-wheel drive low-range you need with a front locker.

I LOVE - did you hear? L-O-V-E this setup and my friend Greg has the same thing except 258 and T-19, but still Dana 18 with offset AMC 20 and he loves it too. Having the pumpkins lined up is really nice off-road. The rear driveline angle is better on the 18, and the twin-stick setup is great off-road - especially with lockers. On top of everything else, you get 2.46 low-range instead of 2.03, and no, you won't need any extra gears, that's only for building a 2.46 Dana 20 which is not what you're after. I have the Warn OD on mine for long trips and that's also great - it's super as a gear splitter on steep mountain roads since the gears are so wide on a T-18.

We both run Q-trac CJ-7 AMC 20 rears with a welded on truss, welded tubes, one-piece axles, lock-rites, and 3.54 gears. Neither of us has ever had a problem with these, and they're easy to get, cheap to build up, and strong with the mods I've listed. Plus, they match right up to your front axle in width and gearing, and the offset is just right for the Dana 18.

Do it - it's great. - Chuck

Chuck Hadley
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post #4 of (permalink) Old 09-06-2000, 12:53 PM
Matt M38A1
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Re: D18 swap and rear axle

These guys have it. Just to clarify Pigpen. He saying the gears from the D18 with the 1 1/8 center shaft will go into your D20 case (it has the 1 1/4 shaft). You just need to use the roller bearings from the D20 center gear. If your D18 has a 3/4" center shaft, forget it. If you have the D18 with the big shaft, everything should just swap. The hangup will be the input gear, and getting one with the correct spline count for your tranny.

FYI I have an offset AMC20 for sale cheap!!!

post #5 of (permalink) Old 09-06-2000, 12:56 PM
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Re: D18 swap and rear axle

This sounds great, I think I might have read about you jeep awhile ago and that is where this crazy idea came from. I am just looking at this from the perspective that I know the 18, I like the 18, the 18 is simple, the 18 is cheap, and you can do more with the 18 ie the overdrive you have or a pto or both. do you have any pics of your rig? I would love to see them.

Two many jeeps to count, I think 5 1/2 and a trailer or two. Who knows what to come!!
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