Tim.. about your hybrid 18/20 transfercase

[DanStew]

Is your transfercase offset or cetnered? I cant see your pics of your axles to see if you have an offset rear. I am getting a set of waggie axles from a Qtrack waggie so the rea is offset. I was pondering putting them in teh commando, but i am running a 20 in the commando, so i was thinking about if i can convert to be an offset. i have plenty of dana 18 parts to make it happen. is it possible?? Which way did you make the case a hybrid.

[53Flattie]

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! :oops:

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: )

[DanStew]

hehehehe.. sorry bout that ;)

When I get the commando lifted it will be easier for me to get under it and map out what to do. i ahve plenty of the 18 parts to make it owrk, so that is good. i was thinking about what to do with a set of waggie axles. At time i keep forgetting the rear is offset so i was thinking ir was a good fit for the commando, but my friend who is gonna give them to me kept setting me straight and saying they are offset and i would have to change the transfer, so if i can turn the 20 into an offset, then that is what i am gonna have to do.

Thanks!! And happy profile changing!!! :)

[gte636p]

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

[nickmil]

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.

[gte636p]

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

[nickmil]

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:

[DanStew]

Hey Nick,
to change over the 20 to make it an offset, do i use the 20 gears? or do i have to swap everything from the 18 into the 20 case and use it like that?

[gte636p]

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

[cj51969]

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.

[cj51969]

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

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.

[nickmil]

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

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. :beer:

[gte636p]

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

[vanguard]

btt.

[Boyink]

;)

Got it now?

[vanguard]

Nope. :shock: :D 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:


The large hole d18 and the d20 share the exact same case casting.

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


Interchangeability between complete transfer cases is quite good, although it is not always desirable or possible to replace a Model 18 with a Model 20. The longer rear output section on the engine certerline of the Model 20 usually causes driveshaft problems if its use is attempted in a short wheelbase Universal Jeep, even if the offset rear axle housing is changed to a "centered" type.

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


Generally speaking, all Model 18 transfer cases are interchangeable as a unit. The proper input gear must be used for the transfer cases case being used. Match up holes in gaskets with the transmission and transfer case when using stock Jeep transmission as these sometimes differ and may cause loss of lubricant from the transmission into the transfer case.

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

[Boyink]

This looks like a case (ug) for Nickmil.

Unless I've misunderstood reading this in the past, the outer case between the large hole D18 and D20 is the exact same thing, meaning I can look for either one, swap my guts in along with a bigger intermediate shaft and related parts, and end up with an offset output, large hole, 1 1/4" intermediate shaft transfer case.

I don't want a centered output tcase.

I can't tell from Novaks diagrams if the case itself is different or not.

Nick?

Patrick - isn't this what your dad did - use a 20 case to build a large-hole D18?

[Boyink]

http://www.earlycj5.com/index.php?name=PNphpBB2&file=viewtopic&t=10244&hig hlight=hole+d18+d20

http://www.earlycj5.com/index.php?name=PNphpBB2&file=viewtopic&t=5380&high light=hole+d18+d20

http://www.earlycj5.com/index.php?name=PNphpBB2&file=viewtopic&t=1531&high light=hole+d18+d20

[gte636p]

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

[Boyink]

Thanks Chris - I'll let you know on the 'case. I may have gotten one as part of a deal with Herm the OD guy...;)

[nickmil]

The advantage of using a 20 housing vs a large hole 18 housing is the 20 housing is slightly beefier in the intermediate area and is MUCH more available for most people. If you have access to a large hole 18 housing than by all means use it. All the castings, meaning front and rear outputs, will interchange from one case to the other. One thing I should note here is you cannot make a centered output 20 out of a large hole 18 case as there is an extra relief and extension in the 20 for the longer shift rail in the 20 for the front output where the 18 uses a short one and does not need the relief. That's why the 20 has two relief caps in the back of the case that are pressed in and the 18 only has one that is cast as part of the case. One other thing that has been mentioned before, make sure if you use a 20 case you get one with the fill plug on the side, as some had the plug on the rear and can't access it with the 18 rear output housing in place. Or you can drill and tap the case on the side for the fill plug. Nickmil.

One other thing I should add here. The procedure for putting the 18 guts and outputs in a 20 case is EXACTLY the same as rebuilding a stock 18. There are NO mods required unless you need to drill and tap the housing for the clutch linkage pivot on the driver's side or you have a case with a rear fill plug and need to put it on the passenger side of the case. Nickmil

[Boyink]

Thanks Nick....I have Herm checking his stock.