Dana 20 rebuild

[motorider]

Jeff suggested I post some pictures of my transfer case gears to see if these need to be replaced prior to ordering a rebuild kit. This a single stick Dana 20 from a 1970 800a w/304 and 4 speed manual.

The rear sliding is the worst with about 4-5 teeth looking as in the pictures. The idler is next with all the teeth looking like those shown in the pictures. The front sliding is the best looking of the three.

The reason for the rebuild was the transfer case coming out of low range into neutral under a load. The shift forks, shift bars, and all bearings look good. Also the front bearing retainer (picture 11) has a broken lip. Should this be replaced?

Please let me know if you think these parts should be replaced.
Thank you.
Tom

 

[Michael Mayben]

Nice pics, that certainly helps describe the condition of what you have!

As to what to do about it...I'd have to say that depends upon your budget! And your tools. And your skill level as a dentist!

We're always going to replace all the bearings, seals and gaskets of course if we're gonna call this a "rebuild". And ya need to look closely at the bearing surface of the intermediate gear shaft as it's surface serves as the inner race for the roller bearings.

As for the gears...all the wear is see is on what I call the "dog" segment of the tooth. That leading angle is what takes all the abuse when the lever moves the sliders, every time ya hear the grind, you are now seeing the results! And all of these items must wear inna similar pattern over time unless the transfer case was never shifted!

Sure, if you have tons of cash (and we sure don't mind ya spending it with ihon!), you could replace every worn gear. But there is an alternative which is very attractive based upon what you consider your time is worth to play with this stuff. However, in some cases, some of those parts you will only find as "used" and May be no better than what you have now!

What I do is use my assortment of pneumatic handpieces/die grinders, and most often an inexpensive dremel flexible shaft handpiece with various grinding stones, carbide cutters, and high speed sanding attachments to return each leading edge of the worn teeth to the oem configuration. If you have no gears which have a nice, original profile for reference, just ask and I'll post some pics of what they should look like.

Reshaping these gear teeth is tedious, boring, and repetitive. It's also very inexpensive! If ya scruu up one or two teeth in the learning process, so what...that is not a deal breaker at all.

The "jumping out of engagement" is an extremely common issue with these transfer cases...and every time it jumps, then the dogs involved in the gear train in whatever position was engaged take all the abuse. Root cause of the "jumping" if you have verified that the shift forks are not bent/worn and all endplays and bearing preloads are correct, is the loss of tension of the detent springs. Those should always be replaced when overhauling a d18/d20.

As for the damaged bearing retainer...I can't explain the damage. It's possible that the bearing failed in some previous life, or possibly the front yoke was loose on the shaft or a u-joint failed/broke allowing some "whipping" to occur?? We have a decent stock of good used parts for the d20, but at my location I do not have a front bearing retainer, maybe Jeff has a used one at hq!

 

[motorider]

Michael,
thank you for your advice.

we're always going to replace all the bearings, seals and gaskets of course if we're gonna call this a "rebuild". And ya need to look closely at the bearing surface of the intermediate gear shaft as it's surface serves as the inner race for the roller bearings.

I intermediate gear shaft has a very small lip and I am going to replace.

what I do is use my assortment of pneumatic handpieces/die grinders, and most often an inexpensive dremel flexible shaft handpiece with various grinding stones, carbide cutters, and high speed sanding attachments to return each leading edge of the worn teeth to the oem configuration. If you have no gears which have a nice, original profile for reference, just ask and I'll post some pics of what they should look like.

I like the idea of reshaping, however how do you replace the lost material? I.e. A tooth that has a chunk missing. A picture of a good gear would be helpful.

The broken bearing retainer was from me removing the seal incorrectly. I will call Jeff tomorrow to order the rebuild kit, intermediate shaft, and bearing retainer.

Thanks again for your help.
Tom

 

[Michael Mayben]

Hears a pic of all three gears you referenced in your pics.

From the left you see the 18-8-56 intermediate gear, the 18-8-26 rear sliding gear, and the 18-8-28 front slider.

All of the dog segments on the teeth show very little wear, in fact the sliders are near perfect and probably came from d20 that was rarely shifted.

Notice the "rounded" leading edge of the teeth, those are the points of discussion regarding the condition of the gears you have currently.

If the edges of a few teeth are missing, I don't feel that is a real issue, though it's not "perfect". You can use the dremel or whatever tool ya have to smooth out and clean up those teeth. Once the case is shifted and locked into any drive position, that entrance angle doesn't matter.

After rebuilding the unit using new detent springs correctly installed, it should not be popping out of engagement under load again, so by repairing that point, you will have solved your problem. No doubt the "jumping" has been going on for quite some time depending upon how often and how hard low range was being used. Make sure the shift rails that the detents work on are in good condition also!

 

[motorider]

Michael,
I understand on repairing the gears. I am going to repair the two better gears and replace the main sliding gear. You are correct the transfer case has been jumping out of gear for some time. My wife is getting tired of her foot on the gear lever, hence the rebuild. The shift rod looks very good, so the springs must be week. I ordered the parts today. I appreciate you helping me.
Tom

 

[Michael Mayben]

michael,
I understand on repairing the gears. I am going to repair the two better gears and replace the main sliding gear. You are correct the transfer case has been jumping out of gear for some time. My wife is getting tired of her foot on the gear lever, hence the rebuild. The shift rod looks very good, so the springs must be week. I ordered the parts today. I appreciate you helping me.
Tom

Dam! This one was too ez!

Let us know how this turns out. And to test the system, you and your wife need to meet up with us at the Sierra Fall Rallye over the hill from carson city, yawl can take the off-road route to dobbins!

Most of the kidz up here rig a permanent ratchet strap on their tc shifter, or a turnbuckle to lock the lever down. Most wives/girlfriends/kidz git tired of that duty real quick, especially on those long, grinding uphill pulls!

Thanks for doin' bizz with ihon!

 

[motorider]

I received my parts today from Jeff and the rebuild kit did not come with the shift rod springs or poppet balls. Does anyone know if I could source these parts locally? Napa?
Also the IH service manual calls for the poppet springs to be the same, however the old springs are clearly different. Any idea on which spring goes to which rod? Or maybe this is not important.
Thanks in advance.
Tom

 

[Michael Mayben]

I received my parts today from Jeff and the rebuild kit did not come with the shift rod springs or poppet balls. Does anyone know if I could source these parts locally? Napa?
Also the IH service manual calls for the poppet springs to be the same, however the old springs are clearly different. Any idea on which spring goes to which rod? Or maybe this is not important.
Thanks in advance.
Tom

The information regarding these transfer cases that is spread around can be very ambiguous, including the Scout II service manual as it contains service process for both variations of the d20 used in the Scout II. And the drawings in the manual are taken from spicer-produced data that was also generic originally. This is especially so regarding the shift rail detents! So that page in your (and all!) service manual is wrong and is causing the confusion for ya.

And...the step-by-step process in the service manual for the re-installation causes more confusion because it uses different terminology for the same dam thing when compared to the parts list! However, step #8 that describes re-installing the poppet springs and balls is correct regarding the position of the "heavier" spring.

While the drawings used in both the parts list and the service manual are identical, the part callouts in the service manual are incomplete, this is not unusual in the technical publications produced by ihc and all other oem. This stuff was originally produced by two entirely different departments within these companies (but the root information was produced and handed to ihc by spicer) and they did not coordinate with each other regarding quality control and verification...I used to be in this business and fought this battle constantly dealing with this same thing with Nissan, honda, fuji/subaru, GM, and isuzu technical publications groups in both japan and the u.s.!

I am attaching a .pdf of the Scout II parts list for this unit (single stick Scout II) that is correct. Note that there are two part numbers for the detent springs, reference #12, one for the front, one for the rear. The balls themselves are common 3/8" loose ball bearings.

I have some incomplete data regarding the spicer part numbers for the springs also, but the information does not delineate the springs by length/rate and crossover to the actual oem spring p/n. Since this "parts" stuff went out of production by spicer/Dana many years ago, we can't just pick up the phone and talk to 'em like we can regarding axle stuff.

Prolly your best source of info regarding replacement springs is novak, call their tech/assist and ask about replacement springs for the Scout II version d20, their p/n's might be the same as for Jeep and Ford, but might not!

Novak:

contact novak

Thanks for calling this to our attention, I'm gonna followup about sourcing the detent springs myself!

 

[motorider]

Michael,
wow, you are a wealth of information. I am working on a Scout that my grandfather purchased new in 1970, so the history/detailed mean a lot too me. I called novak and they are sending me the poppet springs as you described so I will have them this weekend. Thanks for you help. I will let you know how everything works when I am done.
Thanks again.
Tom

 

[Michael Mayben]

michael,
wow, you are a wealth of information. I am working on a Scout that my grandfather purchased new in 1970, so the history/detailed mean a lot too me. I called novak and they are sending me the poppet springs as you described so I will have them this weekend. Thanks for you help. I will let you know how everything works when I am done.
Thanks again.
Tom

Granpa's Scout???? Wonderful!

I have/work with many friends who are restoring rigs passed through 2nd and 3rd generations in the family what a great thing to have! Most of the folks dealing with the heritage vehicles learned to drive in 'em or their fathers/mothers learned to drive in 'em!

I now realize I've been thinking you were dealing witha Scout II single stick d20, I forgot it was an 800a! But no matter, at least the parts we've been talking about are the same!

Here's a correct parts list for an 800a. And I'll be dam...it actually calls out the poppet spring length!

Sorry I posted the incorrect parts breakout, we pride ourselves here at ihon in being technically correct and accurate!

 

[motorider]

I did learn to drive in this one as well as it was my first car. Good to keep in the family. Thanks for posting the second pdf. I will be able to measure the new springs to compare.

 

[motorider]

I did order the poppet ball springs from novak but the springs they sent were obviously too short. I ended up measuring the old springs and they did meet the original spec when not compressed. I also had the spring force spec at a known compressed distance, however had no way of measuring the compressed force. I ended up installing the old springs with the addition of a very small stainless steel washer between the spring and the ball to increase the compression. After what seamed like hours of shifting and thinking, I decided that this increased the compression enough.

I finished the rebuild and installed last night. I did a short test drive in 4-low under load and it stayed in gear. Seems like it is fixed.

Thanks for all your help. Was not too hard a job with the right instruction.

 

[Greg R]

I sure like reading success stories, glad it all worked out for you.
That is a very fine Scout too, congrats!

 

[motorider]

I sure like reading success stories, glad it all worked out for you.
That is a very fine Scout too, congrats!

I like the sucess stories as well.
Thanks

 

[Michael Mayben]

I sent my entire box of transfer case "stuff" (misc. Small parts) up to lyle for use in building his d18 in this thread:

http://www.forums.IHPartsAmerica.com/transfer-case-tech/589-Dana-spicer-transfer-case-guapo.html

Beginning with post #8.

Lyle brought the box back to me Saturday and when I put it away yesterday, guess what I found buried inside...all kinds of poppet springs! Didn't know they were there as all this stuff was left here by a pro gear-builder and I haven't fully sorted it!

Some of the springs are color-coded, some are not. I'll sort this stuff and see if I have what you are looking for. Some of 'em are for np 205 also, but there May be some interchange. I know it's kinda late now, but it might be needed in the future if the issue comes up again.

Thanks for posting that the springs from novak were not correct, we need to develop our own list of "nuances" that are applicable to only the IH stuff and this is one item I've not encountered before where there are different springs available...unless they shipped you the wrong items (which I seriously doubt given the quality of the novak operation!)!

 

[motorider]

Thanks for offering the springs. If I have a problem, I will contact you. Novak indicated that took the springs from another kit. I am not sure which one. Novak was very helpful, just did not work out.
Thanks again for your help.