bearing, speedometer gears and vent question

[Pete]

Good Morning all, I have a few questions

1. I have a np435 with the adapter for the d-20 transfer case. When I bought the adapter a year ago I think that the guy said that I needed a bearing for the spud shaft to sit in. The bearing would be on the transfer case side? Is this correct? Where can I get one of these?

2. What speedometer gear or tooth ratio should I use. I plan on running 33" tires.

3. Anyone know or have any suggestions on how to replace the vent that is next to the speedometer hole on the transfer case?



Thank you for your time. Pete

 

[DDGETHS]

OK I did a search for the vent. I did a search for the speedo gear but here is my problem. I will be starting from ground zero. I don't even have a speedo cable. Just trying to figure out which gear to run.. thanks Pete

 

[70_Steve]

3. Anyone know or have any suggestions on how to replace the vent that is next to the speedometer hole on the transfer case?

The vent on the t-case is pressed in.When I rebuilt my D20, I planned on installing a remote breather. If you finally manage to get the old breather out (it took me a while!) the hole that's left is the perfect size for a 1/4" NPT thread tap! I installed a brass fitting with hose barbs. Then ran 3/8" steel tubing up inside the engine compartment.Connected the two with rubber fuel line.

 

[Broncobowsher]

1: Don't remember
2: Since you are starting fresh, try a 16 tooth. Worked very well for me when running 4.10s and 33's. It is also the smallest that you can get. So if the speedo is still fast, you will need a convertor box $$$.
3: Press fit. Vice grips and pull it out. My hole was a little large for a perfect fit with a ¼" tap, but I did it anyway and used a good amount of pipe dope to seal it up. Works good. Had to run a 90° right off the top to clear the floor. Then used a barb and rubber line.

Have a vent system ran through the old plastic fuel line from the back axle to the front. Vent is up by the master cylinder. Both axles and the transfer case have the same fluids, so I have them share a vent as well. Put that old plastic fuel line to use too.

As for sealing up the NP435, I remember that it vents through the shifter hole. Makes it a little more difficult. My plan when I had that trans was to use an old motorsycle inner tube. slide it over the shifter and hose clamp each end to the case and the shift handle. Pull the valve stem core and place a hose over the nipple for a remote breather. Went automatic before I got to try it.

 

[72Sport]

To remove the vent take an 11/16" open end wrench and slide under the vent. Take a chisel or old large screwdriver and use as a wedge to go between the output housing and the wrench sides. Take a hammer while you hold the wrench and wedge with one hand and tap on the wedge. Try to get it out straight. Tap a little on each side until it pops out. I have removed two on the bench and one in the vehicle using this method with no damage to the vent or housing. Just don't hit the vent with the wedge.

 

[brutis72eb]

Broncobowsher-did you say you have the same fluid in the tcase and axles???? How does that work???? Your axles need dopen and your tcase uses atf. I have never heard anyone do that. Does it work well??? Just wondering;D

 

[DirtDonk]

Not to step on Broncobowshers answer here Brutis, but I figured I'd add my 2¢. Your year transfer case (Dana 20) was never spec'd to use ATF. At least in my experience. Lots of people have used it in lots of transfer cases, so it may not really be a problem, but all the books I have (except for ''73-'79 Chiltons) calls out for 50w ENGINE OIL. And that one calls for 140w in ALL boxes! From what I heard recently, this is a typo.
Regular gear oil can be acceptable as long as you don't go too thick. I use 75w/90 synthetic gear lube in all locations on my '71 as it's pretty thin initially. I used the 50w engine oil for years though.
I don't KNOW that you shouldn't use "too thick" of a lube, but my understanding of the D20 is that is uses splash to lube the upper output bearings and other things, and that thicker oil, though offering more cushion effect, may not get up there as efficiently? Just assumption on my part. But it probably would make it slightly harder to shift sometimes. Especially in the cold weather. And that's not desirable either.

Paul

 

[Mr Joe]

Just to add.... My '73 Owners Manual calls for SAE 30 below 10* for the D20....

 

[brutis72eb]

So you all use the same fluid in your diff's???? Im a tranny mechanic and whenever we do R&R's (remove and replace) we put atf in the tcases and have never had any complaints. I cant say that I have ever put fluid in a D20, so I could be wrong about that. When I pulled my D20 a couple of weeks ago there was atf in mine from PO. And when I rebuilt my Ford 9" I used dopen. Just wondering.

 

[Skuzzlebutt]

ATF is very commonly called for in newer t-cases, but back in the '70s and earlier GL was usually required.

 

[DirtDonk]

Yeah brutis, our shop books from the oil companies almost always called out for ATF (even back in the seventies) for use in chain-drive cases (NP203's and the like) and gear lube in the gear drive cases. But they also called for the gear lube in the D20 and that was the one that called for 50w engine oil in other books so there's obviously more discrepancy than usual with regards to fluid recommendations. From one oil company to another and from one aftermarket manual to another, they seem to vary in choices. I haven't had the pleasure of factory manuals in most cases though, but I would like to see what they say.
We never had any issues with AFT either and in spite of it's seeming lack of cushion and lubricity, is quite the tough stuff. After all, if it can work in an auto tranny and live for many thousands of miles, it's got something going for it.
We even used ATF in NP435's for years with no obvious ill effects. We figured it was for ease of shifting and more likely a way for the manufacturers to squeak the last tenth of a mile per gallon out of their pigs...er, I mean trucks.
But most gear drive boxes, I would imagine(I'm sure not all of them, but...), were originally designed around gear lube type oils and that's what I'm comfortable using.
I seem to remember hearing the term "dopen" before, but I don't remember what it means. Where did it come from? Is it just another term for gear lube, or is it a different stuff all together? Just curious.

Paul

 

[Broncobowsher]

I have been avoiding the computer this weekend, but to answer the question, I run the same Mobil 1 gear oil in both diffs and the transfer case. ATF in the transmission (now automatic)

The gear oil recomend came with the new Tera-low gearset.