Dana 20 TC questions

Dana 20 TC questions

Jason S

2008 Audi TT 3.2 Quattro,
1994 Chevy S-10 4x4 4.3L,
1976 CJ-5 304 T-150 D20 3.54 with Trac-Lock AMC 20
So my new 5 is supposed to have an issue in the TC, broken tooth according to the PO. I am at a figurative fork in the road as to how to deal with it. Pull it apart and rebuild it with the Novak rebuild kit and replace whichever gears are bad. -OR- Bolt in a working Dana 20 (with fluid change) saving the other one for a rebuild and gear reduction at a ater date.

I only have about a month and a half to get this and several less severe issues sorted or this would be a no brainer. I can get an IH Scout 2 Dana 20 locally for about $100. Would it bolt straight in w/o modification? If not, could I take the internals out and swap them into my Dana 20 ?
I think I'd rebuild the one you have. Something about the IH stuff being different IIRC.
As MyLittleCJ5 pointed out you want to stay away from the IH Dana 20 . Much different. Won't fit.
As for your TCase: if the gears need replacing I would go with a Terra Low kit. It replaces all the gears and gets you a 3 to 1 low instead of a 2 to 1. Granted you probably don't need to replace all the gears but it may be hard to find the correct gears you need. And you wont know what you need until everything is torn apart and your jeep is out of commission.
MylittleCJ5: Thanks for that pdf. I havent taken a moment yet to order the FSM for this yet. It also saved me from 'discovering' the hard way that the tranny and TC share oil. I had figured that I could ease the TC off of the jeep w/o pulling the tranny as an effort to dodge the MAW address the clutch while I'm this far. I still might address the clutch.

BUSA: I'm considering it. Just haven't decided yet. For the next month or so I can have this Jeep down and apart. I just need to have it back together enough to be able to be towed by mid december before I head to sea again. I'm moving cross country shortly after I get back and wont have time to work on the jeep. My goal is to have this thing driveable and legal so I can ship my car, and trailer or dolly the cj behind the uhaul that I will inevitably get stuck driving.:(

Brock: I think I may have read through just about everything on the net regarding rebuilding Dana/Spicer 20 TCs. Yours was definately among them. It helped me to decide that rebuilding the TC isn't a big thing. I actually have that rebuild guide from novak bookmarked. I was also planning on buying their rebuild kit. It seems like every discussion about this model TC that I have seen also includes mention of Novak and their parts.

I wonder if it would be too much to ask, to pull the pan off the bottom of the TC and find a giant neon sign saying "Hey dummy this part is broke its p/n is:":rolleyes:
Yes, Novak has a good rebuild kit for the Dana 20 but it doesn't include any gears. (sounds like you already realized that).
I agree you really should remove that bottom plate from the Dana 20 . You might see what gears are bad. Remember, if you see a gear that is missing a tooth then the gear that it meshes with will most likely need to be replaced too.
If you get a Terra Low kit it won't matter what gears are bad. You will be replacing all the gears, the idler shaft and, if I remember right, all bearings. It is the most complete rebuild/upgrade you can do on a Dana 20 but it is expensive. It's almost $1000. The best price I have found for it is $800. Check out this link:
Low Range Kit, Dana 20 TC with Manual Transmission [2112020] - $799.00 : Mad 4 Wheel Drive
Well, I drained the oil out of the TC tonight. I had planned to go further and pull the skid plate and TC cover, but I didn't have a spare jack stand to help support under the bell housing. I have the cj up on jack stands to give me a little extra room to work underneath.

While I let the oil drain, I went to work on the exploded muffler. I had to do something with it so that it wouldn't cut me to ribbons while I'm moving around underneath the cj. Leather work gloves and some PB blaster made that task almost effective, but not quite enough.

After about 20 mins or so the oil is done draining.and at a quick glance it actually looks good. Nice, semi-transparent green, it looks and smells about like fresh gear oil. If I wasn't awae of a problem, I would never have taken my 3/8ths extension and given it a stir. :eek: The oil starts to take on an olive green color with a fine metal flake added in. I think once I saw a 60's or 70's mustang that was painted about the same color. :down: There was also what looked like a metalic paste built up on the inside of the plug.

Depending on how long/far it was driven like that, the damage could be more extensive that just the gear/gears that got ground up.

Tomorrow I'll pickup another jackstand, and get that cover pulled.

Right now my preference is to get the cj squared away and on the road and save the Tera Low 20 for a later down the road ungrade.

I'll know more when I get the cover pulled, and might be able get the TC pulled tomorrow night also.
My rebuild kit included some gears I needed the extras I got from Morris 4x4.
The TC section of Jeep Tech Pages had me scouring the internet and local JYs and parts houses for dana 18 gears and a particular gear from a bronco Dana 20 . All the gears (individually) and a rebuild kit are only a couple hundred less then the Tera kit. So that is a pointless rroute unless you have to do it piecemeal or can find a jeep dana 18 tc somewhere.

I'm about to head up to the garage to pull the tc. This should be fun.
I pulled mine and replaced the damaged gears all the synchros and bearings.
All ordered after I made a list of what I needed.
I ordered novaks master rebuild kit, then the other misc pieces. On reassembly be sure to use thread sealer on all bolts that go into the case where the fluid is.
I'm a bit floored right now. I got the skid plate off and found a bolt for the tranny mount and half of Eastern Washington. Cleaning as I went seemed like the right way to approach this and, considering what I found inside the TC, I think it was the best way also.

After I got the forest floor out of the skid plate I attacked the outside of the TC oil pan with a large wire brush to knock off the worst of the grit and grime around the bolts and the edge of the pan. Another good move as it turns out. Once the outside around the pan was clean, I pulled the drain plug again and let the residual oil drain while I losened the bolts. With a little coaxing the pan came right off and inside the bottom of the pan I found...nothing but oil, and maybe some tiny flakes of metal.

As a point of reference for the inspection I based everything off of what I believe to be oil holes in the intermediate gear. There are two and conveniently they are 180 degrees apart. I shifted the TC into 4lo to ensure that all gears would turn at once. Then while turning the front driveshaft by hand I started inspecting the teeth of each gear, ensuring that the intermediate gear got four full revolutions. I did this by counting each time I saw an oil hole come around. (Eight times = 4 full revolutions.) I checked the mesh of each gear this way. I found no gears with broken teeth. I felt in up underneath the gears for the rear driveshaft and also found nothing. I found no evidence of serious damage on any of the gears. These pics show the only 'abnormal' tooth wear that I found.
This bottome one gives a close-up of the holes I am talking about. You can also see that the oil looked fine for the most part.

You can see where the corners of all three gears for 4lo have all been ground down some. I believe that this is where the metal I found originated. I thought that maybe I was missing something. So I checked each gear twice. Then I went and started tracing wires to find a good place to start fixing bad places in some of the lighting wiring. After about an hour or so, I got back under the cj and checked each of the gears again. I made sure the front hubs were unlocked and checked the feel of the tc in each of the gears: 4hi, 2hi, n, and 4lo. Everything felt nice and smooth. I checked for excessive play the in bearing mesh, I did nothing scientific here, just a visual inspection while physically rocking a gear back and forth while holding the other. All of them had some but a not much.

I have a theory as to what the PO saw/experienced to make him think that there was an issue with the TC:
The tc shifts into all gears, but 4hi and 4lo are at the extreme e4nds of the range of motion for the shifter. The tc shifter linkage under the cj has a large amount of gunk caked on. The Transmission mount had no bolts mounting it to the transmission, leaving it free to flop around as directed by the motor and driver. I think that these things combined to make the tc difficult if not impossible to shift fully into 4lo or 4hi, or could have even caused it to occasionally jump out of gear. Judging by the gears, I am thinking that 4lo was where he had the most dificulty.

At this point, I think I might be ready to cut a gasket for the TC oil pan, clean any debris I might have left off the gears, reinstall the pan and fill it full of oil.
The gears are worn but not what I'd call needing a rebuild.
Check the linkage itself for worn parts/bushings, etc.
Bolt her down properly and give it a test.

Most people have a hard time getting into 4lo, on mine I had
to be rolling real slow to shift, stopped it just wouldn't go in.
I got the cover back on the TC and got it filled with oil. It's nice when a mountain turns out to be little more than a pebble.

While I have it up on stands, I am going to change the rest of the fluids in the drivelines. One thing I found for the TC and that I will use on the rest is the gear oil hand pump. That thing made filling the tc full of oil a breeze.

After the driveline, I have to dig far enough into the electrical to make the turn signals work.

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