Dana 20 problems

T

Thunder Scout

Member
Im brand new to the forums so excuse me if im doing anything wrong. So we decided that it was time to get the four wheel drive working on our Scout that we picked up. The previous owner said the transfer case was just makeing some noise when it was engaged. So just going on the notion it would be as simple as grabbing another transfer case and putting it up in it would be done. So we go to test it and put it in 4 high and it makes noise and it seems like in low speed it stays in but as soon as you get to higher speeds it keeps poping out. Im not sure if its because its not going in all the way or what. I have not tried puting it in 4 low though but I have been driveing it just fine in 2wd. Pleas any advice would sorry for any lack of information in my description
 
Welcome to the forum. You did just right coming here with your question. There really isn't much you can do in the way of adjustments or band aid applications to the Dana 20. If it's popping out of gear or trying to pop, it probably needs to be pulled for a rebuild. That is unless you've got some crazy lift on this rig that is putting the drive shafts into a severe bind. One thing that is helpful whenever posting questions is to provide some specifics about your ride. If you're planning on a swap instead of a rebuild, you should know that there are two different gear pitch angles with the d20's. The early versions, approximately '66 thru '72 have one gear pitch angle, and later years have another. If you install a d20 that is a mismatch for the output gear on the back of your trans, it will work...for awhile. It will be very noisy and damage will eventually ensue if it is used often enough.
 
Well its a 1975 with Dana 44s front and back. SOA with a one inch or two inch body lift not sure I would like to take them off but I belive its 9in of lift total and im running 35s. I went and got the transfer case that I have right now used from IH parts and we went through it and it was in good shape. I think this is the earlier d20 like you mentioned because the transfer case on my 73 matches it.
 
Those are important details. That much lift makes for some pretty extreme prop shaft to differential angles. Have there been any provisions made to the shaft ends (cv joints etc) to alleviate the binding there? Where is the fill plug on your t-case? Is it in the rear of the case or facing the passenger frame rail?
 
The fill plugs at the rear and yes I have lots of paper work from the previous owner showing that he had purchased a (custom cv drive shaft) and (yoke 1310 cv 10 spline Dana 20) from IH-parts and pleas excuse me for anything I might be leaving out im doing my best to give you information....I could send u pictures if you pm me your number im even willing to meet up with someone who might have an better idea than me and the one mechanic who ive have been working with to try to get it going. He thought the front might have been geared diffrently from the back because in the paper work it shows lots of work done to the front and rear end....im also having premature wearing in the rear end on the ring and pinions and I recently thought my rear end was out when oil was coming out of a small pin hole in the rear like something blew up in it but it makes no noise and no major chunks of metal were found. I was told but the gear oil had mettalic in it though and when you swirled your finger in it you could see but didint seem too bad... I think the previous owner might have had difficulties because I see over haul kits purchased for the Dana 44s and a recepit from Jeff and the boys installing the ring and pinions but that had a long list of things they did.
 
Different gear ratios front to rear would certainly be an issue in 4x4. A '75 would have come with 44's front and rear, so a swap there is unlikely, but still worth examining to be sure the ratios match. I know the IHPA guys wouldn't let anything leave their shop that wasn't done correctly. Rear fill plug indicates an sii version of the d20, so you should be good there. You have a lot of variables to work through because of all the aftermarket modifications.
 
Popping out of gear is usually weak poppet springs, they hold in a metal ball that seats in notches on the shift rails and act as a detent to hold the stick in the desired position. The output shafts ride on tapered roller bearings, and a bad bearing can cock the shaft enough to cause it to come out of gear. I would check for end play on the output shafts, and drop the oil pan and look for metal, if the oil looks like neverseize it's time for new bearings. Bent shift forks can cause the same thing too. When you're in 4wd either hi or lo, be sure it's done on soft ground and not hard pavement. These 4wd's get bound up from unequal turn radius's between the front and rear and need soft ground for the tires to "slip" a bit and relieve the stress.

but the gear oil had mettalic in it
Click to expand...

Not a big deal if the differential is equipped with a limited slip. The clutch plates in a limited slip will shed a little with use, and as the material is metallic; you'll see some flakes in the oil. All is well though as that metal is way softer than gear or bearing steel.
 
Maybe a stupid question, but are you running this thing at "higher speeds" on a dry, high traction surface? These old beasts need a semi slippery surface for 4wd.
 
Sorry you're still having issues with this. Have you tried shifting into 4hi on the fly? You want your hubs locked in and you don't want to be on pavement or any other hard, dry surface when you attempt this. As I stated previously, shifting between 2hi-4hi and 4hi-2hi is generally best achieved when the rig is in motion. That's not to say that you shouldn't be able to go back and forth while stopped or barely creeping with the trans in neutral, just that it might work better to be rolling in gear with mild acceleration as you go into 4hi and coasting in gear to go back to 2hi. I've found through my own experimentation with the engine stopped, that there are definite sweet spots in the front prop shaft rotation arc that will allow relatively easy front axle engagement and disengagement. Conversely, there are other sour points that will stubbornly prevent the shift lever from being moved in either direction.
 
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