D18 Questions

So I've got two D18's. One is from my M38A1 with the 1-1/8" Intermediate and the other is from a later 226-something. It has the 1-1/4" Intermediate. Is one better than the other. I'm kinda of wanting to rebuild the M38A1's case. Is the only difference with the internals the intermediate shaft and the bearings? Are the gears ID the same? So, the questions is could I take the good gears and shafts out of the newer case and put them into the older one if I use a 1-1/8" intermediate shaft and bearings?

Is there any easy way to pull the bearing off the main output shaft? I'm talking about the roller. I haven't even looked at the internal bushing. I wonder if it would be better to just get a new output shaft since I haven't even looked at the "good" one. No one seems to sell a complete overhaul kit for the D18 like they do with the T90.

The newer case doesn't have an ebrake. I know some guy's ditch them but I'm still on the stock 9" drums. Might switch to 11" drums but I haven't looked into it much. From the looks of it I can swap the rear housing. When did the CJ5 go to rear brakes with the integrated parking brake and ditch the transfer case drum? '69 with the refresh?

Thanks

 

This is a good place to start: https://www.novak-adapt.com/knowledge/transfer-cases/model-18/

 

"MD's case" ? Not sure what you mean.

"Are the gears ID the same?" No, the gears are not the same.

I think Jeep CJ5 went to 11" rear brakes with parking brake in 72. I may be off on the exact year, but when I convert an older Jeep to 11" brakes I use the wheel cylinders, shoes, drums and hardware for a 72-73 CJ5. Earlier Dauntless Jeeps had 10 1/2" rear brakes, and 11" front brakes, but still had the drive line parking brake.

Finding 11" rear backing plates with the parking brake for a Dana 44 is the problem. Since they were only used 2 or 3 years they are very scarce. When I convert an older Jeep to 11" brakes, which I do with pretty much every Jeep that comes into my possession, I rebuild the drive line drum parking brake, and use front 11" backing plates all the way around. The front backing plates are also getting scarce, but I find them a lot more often than the rears.

The 11" Bendix brakes are self actuating, and self adjusting, which makes them better brakes with less maintenance, but the 9" drum brakes will lock up the wheels if they are kept in good condition and adjusted regularly.

 

Yeah, I've read that a few times over but it doesn't mention if they're interchangeable. Also the newer case had two yokes and no flange. The rear output housing isn't milled for an eBrake either. I missed this page though, https://www.novak-adapt.com/knowledge/gear-table/

MD as in M38A1.

So, according to this, https://www.novak-adapt.com/knowledge/gear-table/. The gears have different tooth counts but the intermediate gear ID is the same on for 1-1/8" and 1-1/4". So does that means I would be able to use all of the shafts and gears from the 1-1/4" in the 1-1/8" as long as I get a rebuild kit for the 1-1/8"? I'm torn with wanting to reuse as much of the military parts but also if the newer stuff is better then I'd rather use that. I have confirmed that the newer Tcase has a 29T gear and not 26T. Probably be better to just use the newer case and put the front and rear output housings on the new case?

Another question, is the drive gear for the speedometer the same and just the smaller gear tooth count different? The transfer case came from a 226 so I'm guessing it had 4.88 gear or higher. My M38A1 has 5.38's so the speedometer gear is different. I think it's 15T. Can I just drop in my 15T?

A friend of mine said he's got a complete set of brakes for converting to 11" drums. I haven't seen it yet though. I'd like to put the ebrake back on the newer tcase though. Looks like to do that I'm going to have to possibly shim the output housing though. I'm guessing the tolerances aren't exact enough to just swap the shims over?

 

The speedometer gears can be swapped, but you have to swap both the drive gear and the driven gear.

The tail shaft housing will interchange. Your guess is correct, you don't just "swap the shims over", shims are used to set the end play, which can vary widely between one transfer case to another. You will have to assemble and measure to determine what you need in the shim pack. This is covered in the Factory Service Manual, and if you don't have one you need to get one.

"The gears have different tooth counts but the intermediate gear ID is the same on for 1-1/8" and 1-1/4". So does that means I would be able to use all of the shafts and gears from the 1-1/4" in the 1-1/8" as long as I get a rebuild kit for the 1-1/8"?"

I think you need to do some more study on this.

The main reason for the larger shaft and bearings in the later case was to make it run quieter and last longer. In that sense it is a better option. IMHO you would be better off to just rebuild the later case without swapping the internals from one to the other, which presents some problems that can result in disaster. As I said above you can swap the tail shaft housing and use the drive line brake. The only outward difference between them is the intermediate shaft being slightly larger, and nobody will care enough to crawl under to measure that, and nobody will likely notice it isn't the military unit.

 

Got into the transfer case again. Pulled the interrupt out of the shifters. Swapped the yokes over to the but installed the drum since the bolts have shoulders and probably wouldn't work without new bolts. I swapped the speedo gears. Both of them. They are in fact matched. What's up with the speedo gear just sitting on the output shaft? I guess it gets pressed on with the yoke. The other thing I found is that the case is really loud in low range. I'm not sure if it's normal or not. Some people have said it's normal for straight gears. https://youtube.com/shorts/q5ORLjnaE48?si=8sqrKt4WuuecVUP1 I'm not used to straight gears. I've got a NV231 and an Atlas 2.

I'll eventually take it all out again and rebuild it properly but I'm trying to just get it running. I'm still wondering how to get the bearing off the main shaft though. It fits snug on there and there's not much to grab onto.

 

"What's up with the speedo gear just sitting on the output shaft? I guess it gets pressed on with the yoke." Yes, another correct guess.

Have you obtained a Service manual yet ?

 

As for noise level, I think you need to brush the rust off the gears and put the sawdust in.
Here's mine, you can here the gears on the little uphill sections but yes it normally sounds like a bee hive... it's not much better in high range.

And here is my in-laws


Here's another of mine, compared to kids with outside voices.

 

Nope, I'm going in blind as a bat.

Okay, yeah, that's the sound in the first video. I've driven a few but never in low range. Only when I took apart the D18 did I realize how it all worked. None of the Jeeps I've driven have the plaque or sticker on the dash.

 

"Blind as a bat" It is your Jeep, so whether you want to guess your way through on working on it is up to you.

The first thing I get when I start working on a vehicle is an appropriate service manual, but I haven't always been this way, it was something that was influenced by learning from my mistakes.

I was probably in my twenties before I discovered you could get new parts for old cars in boxes.

 

That was a bit of a joke. Some of my questions are just to reaffirm my suspicions. It's just easier to get an answer sometimes.

The Jeep, while complete isn't really original. From what I can gather, the military changed some things. The engine seems to be newer. MD 58XXX. I'm guessing the 58 is the year. The body is a '52 according to the tag. The T90 is an M-Series. At first I thought the transfer case might be a civilian case but I think it might be from an M38. It was definitely green. It doesn't have the right ebrake but I was reading that the M38 has the CJ style brake. I'm guessing this was all done in '58 when it was repainted red oxide. There are some numbers on the fender that say 58 as well. The PO also did some changes as well. Has some weird vacuum booster added to it. Carb is wrong. The wiring has been hacked into as well. Though I don't plan on using any of those Packard or Douglas connectors. Really though, it's pretty easy to work on compared to the other vehicles I've worked on. All other POs never really got the Jeep running. The last owner to get it running was from 4 owners back. I'm the 5th.