Tim.. about your hybrid 18/20 transfercase

Actually, I need to change that on my profile. At the time, I *thought* I had an 18/20 hybrid (thanks in large part to the mis-information of a local offraod shop). I thought that any t-case (in an early Jeep) that only had one shifter was a Dana 20. So, when I bought the '68 CJ5 for the drivetrain, I thought it has a single stick 20. It had the correct input gear for the T-14, whereas my original Willys Dana 18 wouldn't work. I really wanted the twin stick, so I swapped the shifter housing to the CJ5 t-case. Sorry for misleading you guys!

Now, my friend who has an M38 with a 225 and a T-150 is running a Dana 20 case, with the Terra Low kit, and the twin stick housing from a Dana 18. I just spoke to him, and he said that he used the 20 case for two reasons: #1. He needed a 'big hole' case for the T-150, which was originally mated to a Dana 20; #2. Because if you run the Terra Low kit in a stock 18 case, you have to grind the heck out of the inside to fit the larger gears. He said that you could take all the gears from an 18 and put them in a 20, and make it a low output if you wanted. (All this gear talk makes my head spin :? )

Here's something I didn't know. Early on, the CJ5's had small hole 18 transfercases with a single stick and an offset output. At some point they were switched over to big hole 18's with a single stick and an offset output. (This is what the local 4x4 shop was referring to as a Dana 19???, which we thought was just a Dana 20 with a low output) This, I'm sure of b/c the CJ5 I bought for the V6 had a small hole, single stick dana 18. The '69 CJ5 that belongs to my friend's dad has a big hole, single stick, dana 18. Both are offset outputs.

So, to summerize: Yes, I have an offset rear axle; No, I don't actually have an 18/20 hybrid, only a twin stick 18; and Yes, you can make a Dana 20 an offset output with twin sticks.

(now, I'm going to change my profile! :mrgreen: )

 

since you guys seem to be in this to... i've got a transmission lined up to go in, but it's a t15 instead of my t14. guy says it'll bolt up, and i'm not questioning him on that, but could i just take the input gear currently on the 18 (ten spline for the t14) and swap out a six spline input gear top match the t15 output shaft and bolt everything back up? i'm mainly concerned about the centered output of the D20 and the issues it will cause with the driveshaft (if any). anyone ever done this kind of stuff??

-chris

 

Let me add something to the confusion here. If you are running a manual transmission or running an automatic with an aftermarket adapter with a 6 or 10 spline output then you can do the low range conversion. If you are running the stock turbo 400 adapter and shaft then you cannot do the low range conversion using the 18 gears because of the odd input gear of the automatic adapter. You can using the Tera gear set as they build a special input gear that will fit the stock turbo 400 adapter. Also, converting a 20 using 18 gears also necessitates using one gear from an early bronco model 20 (if you want the centered output of a model 20). You can put either model 20 or model 18 guts and outputs in a model 20 case. By doing so it gives some advantages, like a slightly beefier case, large hole case, and the large 1 1/4" intermediate shaft.

 

i should have tried to explain myslef a little better...i'm planning on keeping the 18, just putting it behind a T15. the jeeptech website says it's possible, but the output shaft of the two transmissions are different (the T14 is 10 spline, the T15 is six spline). from that i'm just inferring that ordering the transfer case input gear with the same tooth count, just changing to the six splines would help me to keep my little 18 in place.

i'm not concerned about the gearing factor involved so much as i am the money factor... one gear vs possible floor changes (might still have to do that) and a possible new drive shaft (centered output right?? it's higher and fuher over from the offset pumpkin). from that point of view the 18's winning out.

thanks for the insight
-chris

 

The 29 tooth 6 spline input gear # is 18-8-23. Tell whoever you get the part from what you are doing and they should be able to match it up for you. Walck's probably has what you need and so should R&P 4 WD Parts Inc. Nickmil. :stout:

 

there's a write up on that at:

http://www.off-road.com/~jweed/transfer.htm

from what i've seen it looks like a real pain to do (especially that grinding inside the case). i think that's what nick was trying to describe before

-chris

 

Just have to check here..... Is someone telling you that a t15 that is made to bolt to a AMC bellhousing bolt pattern will bolt up to your Buick bellhousing? Or is it coming with an adpter set like these - http://www.novak-adapt.com/catalog/kit_1415.htm
The t14 and t15 used in the 72-75 CJ are different than the t14 used with the Dauntless, the input shaft is longer on the AMC applications.
http://www.off-road.com/jeep/tech/trans/t14.html
http://www.off-road.com/jeep/tech/trans/t15.html
http://www.novak-adapt.com/knowledge/cj5_72-75_swap.htm

I meant to jump in on this last night and point this out but it wouldn't take my posts then.
Mike B.

 

Ignore that write up... it is for putting a Bronco gear in to get lower gearing. The large hole d18 and the d20 share the exact same case casting. And the 18 gears will go into a 20 case without a problem. The only thing I'm not sure of is what is done if the 18 gear set uses the smaller intermediate shaft... but someone here I'm sure knows how that is dealt with, or I can find out if need be.
Mike B.

 

All you need is the thrusts, intermediate shaft, and intermediate needle bearings to put the 1 1/8" intermediate guts in a 1 1/4" intermediate case. The inside diameter of the intermediate gear is exactly the same. There is no grinding or anything else needed to put the 18 gears in the 20 case. It's all bolt together. Done it dozens of times. You will want to use the 18 gears because they give you a 2.46-1 low range versus the stock 2.03-1 lousy low range of the 20. It does make a difference. Nickmil.

 

yup, i'm stupid... i thought that swap was just to get the gears in there. it all makes sense though..

as for the transmission, you've got a point there Mike. i mentioned it was behind a 225, but i don't think that really made an impact in the conversation. i knew that they came behind the AMC's but didn't think far enough ahead to check the belhousing bolt patterns (which really isn't that far... i've got my mind on other things). thanks for the warning though, i sent the guy an email asking whether or not it'd bolt up for sure.

-chris

 

btt.

 

Nope. I must be extra dense today. R)

Based on my reading I would go with a big hole 18 rather than trying to swap 18 guts into a 20.

I think the following is wrong:

Novaks guide clearly shows different housing castings (Dana 18 Part 15 vs Dana 20 part 20).

http://www.novak-adapt.com/knowledge/transfer_case_article.htm

plus

Although with a SS Dutch being a CJ-6, this is probably less of an issue, but since

I can't see why you'd want a 20 instead of a big-hole 18.

 

from the 20 case i've got sitting outside (as a result from the purchase seen in the orignal thread.... man that was a long time ago) they look identical, just with different holes patched up. if you're looking for a case i'll look into tearing my 20 down and sending it your way boyink. it's just sitting outside waiting on a phantom project to show up... but i'm on my fourth jeep, and running out of space so it's about time for me to start consolidating space.

i'll look into the front output, because i remember that being a little different and i know the shifter linkage is different (but coming out of the same place)... from what i've read over and over the insides can be swapped out no problem.


http://www.ifsja.org/cgi-bin/ubbcgi/ultimatebb.cgi?ubb=get_topic;f=12;t=000045;p=

i'll second the different gear cut angles, it's subtle but when you get the two bull gears together it's noticable (or maybe mine were worn differently??)... so don't try to mix the parts.

hope it helps
-Chris