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Transfer Case Upgrades and Modifications

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oldtime View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote oldtime Quote  Post ReplyReply Direct Link To This Post Posted: 16 Sep. 2018 at 10:09pm
Quote    This is a great compilation of Transfer-Case information.
Thanks but it's certainly not exhaustive and I'll be adding some "cool" D20 details as soon as I get with it.

Quote From this, I just learned that if I have a rear-shift Warn overdrive, then I must have a small-hole transfer-case Case ?
You read that WRONG...
The later design Warn units with a  rear shift shaft will fit either large or small hole D18 transfer case units.
It is the early vintage front shifting 27 tooth Warn units that can only be mated to small hole transfer cases.
That's because the large middle area bulge of a big hole case will directly interfere with the Warn front shift rod.

Quote   Do you feel I may be able to purchase the input bearing from Napa ? or should I be looking elsewhere  ? 
I will only recommend OEM parts that means NOS "deep" stamped Timkens made in USA.
I mainly purchase  known old stock bearings from eBay
Here's link to CJ bearing chart I posted several years back.........
That old chart does not have the D20 bearings it.

Quote  do you have them backed-up on a Thumb-Drive (flash-drive) ?
Actually No I don't even own a  computer myself and have zero back-up on anything that I post.
 I just hang out here on the Old Jeep web cause its a real bad habit.. Ha  Ha Ha !
Currently building my final F-134 powered 3B .
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Unkamonkey Quote  Post ReplyReply Direct Link To This Post Posted: 17 Sep. 2018 at 12:15am
Oldtime, you do well working off of a library computer. I believe there was people that wanted to buy you one over on ECJ5. Keep up the good work.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ol' Unreliable Quote  Post ReplyReply Direct Link To This Post Posted: 17 Sep. 2018 at 2:37am
I once bought new kingpin bearings from 4WD Hardware.  I told them I only wanted Timken bearings.  I got Timken bearings--made in Brazil....  Unhappy
There's a reason it's called Ol' Unreliable
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Post Options Post Options   Thanks (0) Thanks(0)   Quote oldtime Quote  Post ReplyReply Direct Link To This Post Posted: 17 Sep. 2018 at 4:07pm
Honestly there are other good taper bearings besides the Timkens.
Willys Overland, Willys Motors, Kaiser Jeep Corporation and AMC Jeep Corporation all used Tmkens.
Also many times you may find original old Bower taper bearings in the remaining few unrestored Jeeps. 
Obviously at one time Bowers were also exclusively made in USA. 
But anymore being genuine USA made is merely a patriotic preference.

For myself I always preferred he old Timkens in lieu of old Bowers. 
To me the Bowers seem to be a tad harder or perhaps they just suffer more readily from lubricant failure. 
Not a huge difference but that flaking or chipping  condition was often noted.
I would often clean the old bearings and inspect their condition.

When it comes to ball bearings Jeep mainly used MRC and in earlier years they used Fafnirs.
I tend to like both those USA bearings  about equally well but lean toward old stock Fafnirs if I can find them.
Fafnir was bought up by Timken and they obviously went international.
MRC is now owned by SKF and SKF does also make excellent ball bearings.

I don't care much for the modern laser ink method used to I.D. the bearings.
The laser stamp can wear off quickly and then you have no good way to identify the bearings SAE number.
Currently building my final F-134 powered 3B .
T98-A Rock Crawler using exclusive factory parts and Approved Special Equipment from the Willys Motors era (1953-1963)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote thefixer Quote  Post ReplyReply Direct Link To This Post Posted: 19 Sep. 2018 at 7:42am
Jack O'Brien built two transfer cases for us, a 3.6 D18 for me, and a D20 configured to an 18 with the 4.8 gear for my son. Both have his tapered roller bearing intermediate gear. I am also running a warn overdrive on the 3.6. The bowl gear that Jack makes for the Warn overdrive is a work of art. Jack built both of them personally in his garage, he is the real deal. The D20 case is around 18 pounds heavier than the D18 case which translates to a significantly stronger case. The 20 he built for my son has twin stick shifters and looks just like an 18. Jack cuts the top out of the case and welds a 1 inch thick block on that is machined on the inside to allow for clearance of the larger gears.This also strengthens the case. We got lucky in that Jack lives about 90 minutes away from us. As was mentioned, Jack's tapered roller bearing kit is twice the size of the one offered by Advanced Adapters. I'm trying to post some pictures. These really work well. Our Jeeps spend most of the time on the Rubicon trail so they are not babied by any means, and we are very happy with Jack's product, service and friendship.

Edited by thefixer - 19 Sep. 2018 at 8:04am
41 MB Slat Grill, 44 GPW, 46 2A, 48 2A, 51 M38, 54 3B Kubota diesel
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Post Options Post Options   Thanks (0) Thanks(0)   Quote oldtime Quote  Post ReplyReply Direct Link To This Post Posted: 19 Sep. 2018 at 4:56pm
Yes no doubt Jack certainly provides a great product.

Quote The D20 case is around 18 pounds heavier than the D18 case which translates to a significantly stronger case. 
I find this may be very misleading for most readers 
Big hole cases certainly do not weigh 18 pounds more than any small bore case does. 
Your figures seem to represent the transfer case assembly and not the castings alone.

In fact the actual weights of various stripped down case castings are very similar.
There has often been talk of extra thick castings being used for D20 assemblies  but that is simply speculation without fact.

I have several clean bare cases at present and can weigh them to provide some real world  weight comparisons.





Currently building my final F-134 powered 3B .
T98-A Rock Crawler using exclusive factory parts and Approved Special Equipment from the Willys Motors era (1953-1963)
Zero aftermarket parts

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Post Options Post Options   Thanks (0) Thanks(0)   Quote oldtime Quote  Post ReplyReply Direct Link To This Post Posted: 20 Sep. 2018 at 1:08am
I weighed 4 totally stripped and ready to assemble case castings  today.

#1 is a small hole case from a known 1960 3B  = 26-1/4 pounds
#2 is a big hole case from a known 1967 IH Scout = 24-1/4 pounds
#3 is a big hole case from what I believe to have been a 1971 CJ = 24-1/2 [pounds
#4 is a big hole case from what I believe to have been a 1976 FSJ = 26 pounds

As you can see the #1 small hole case happens to out weigh them all.
The #2 and #3 cases look to be virtually identical and neither were tapped for clutch control.
The #4 case was tapped for clutch control and it has the rear fill plug.


I find it of little consequence to be concerned with the exact weights. 
Having sufficient metal thickness in stress areas is what really counts.

If weight alone is a major concern then I suggest grinding off that excess portion on a big hole case where it's sometimes tapped out for attaching the clutch control pivot stud.
If your Jeep does not have a clutch pivot tube then the bossed area is just another 2 ounces of dead weight hanging on the side of the case. Ha Ha Ha!

Here's sneak peak at my other big hole that's previously been assembled as a  "SUPER D18".




Edited by oldtime - 20 Sep. 2018 at 1:15am
Currently building my final F-134 powered 3B .
T98-A Rock Crawler using exclusive factory parts and Approved Special Equipment from the Willys Motors era (1953-1963)
Zero aftermarket parts

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Post Options Post Options   Thanks (0) Thanks(0)   Quote bobevans Quote  Post ReplyReply Direct Link To This Post Posted: 22 Dec. 2018 at 3:56am
Not sure if I bring back this thread or start a new one, but for those of us doing Tera Low gears, I have a couple of questions.  If we are using a large hole case, let’s say from a 70s CJ, what do we need to do to the case itself?  If the fill plug is in the rear, we will need to leave that plug ( maybe grind it for clearance?) and then drill and tap the side of the case for a new fill hole?  If so, should we drill through the boss on the side of the case?     
Also, I would like to leave my relatively recently rebuilt stock 18 as spare/original.  (Maybe use the brake backing plate from it).  What parts do we need that are unique to the D18?
I’m thinking we will need shift rods (maybe short rod is the same?), front bearing retainer/output housing, rear retainer, main shaft, clutch and hub, at least one shift fork.
What am I missing?
'48 CJ2A

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Post Options Post Options   Thanks (0) Thanks(0)   Quote oldtime Quote  Post ReplyReply Direct Link To This Post Posted: 22 Dec. 2018 at 4:27pm
Posting more questions and comments right here is certainly fine by me.
I actually never really completed this post. 
I never got around to any of the details concerning the D20 modifications.
So is anyone interested in the D20 mods ?

The big hole case castings with rear fill plug were not around prior to the 1970's.
As you know  the D20 became standard on Jeep CJ's in 1972.
And so around this time the side fill plug big hole cases were no longer being cast.

I provided pre modification information under the heading, TRANSFER CASE PROGRESSION:


That said a big hole case with rear fill plug can easily be modified for building of D18 assemblies.
It is impractical to use the rear bung opening for D18 applications.
The rear plug may be sealed anyway that you desire.
The D18 bung should be drilled and tapped at the normal right side location.

This pic shows the only parts that are virtually identical for both D18 and D20 assemblies.
(Also a couple of the Timkens will interchange....)
(and gears must be interchanged as matched sets....)


If a person wants to go from D18 single stick to D18 twin stick they will need these parts plus levers:


If a person wants to add parking brake to their D18 0r D20 transfer case they wil need these parts:




Edited by oldtime - 22 Dec. 2018 at 4:47pm
Currently building my final F-134 powered 3B .
T98-A Rock Crawler using exclusive factory parts and Approved Special Equipment from the Willys Motors era (1953-1963)
Zero aftermarket parts

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Post Options Post Options   Thanks (0) Thanks(0)   Quote 3A Steve Quote  Post ReplyReply Direct Link To This Post Posted: 22 Dec. 2018 at 9:32pm
Thanks for the information on the different overdrive fitting between the small and the big mouth D-18. On another CJ2a posting I was expressing my confusion about why my ATV O/D worked in my original small mouth D-18 and in my replacement Tera Low big mouth case and why a Saturn O/D would not fit in my big mouth. The Saturn (Warn) is almost .4 inches wider than the ATV. Now I am "un-confused".

Thanks again,

3A Steve
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Post Options Post Options   Thanks (0) Thanks(0)   Quote oldtime Quote  Post ReplyReply Direct Link To This Post Posted: 22 Dec. 2018 at 11:05pm
This pic shows clearly why the D18 rear bearing cap will not work with a rear bung hole.
Either welding of the rear bung hole or installing a flush fitting plug will be  acceptable...
Currently building my final F-134 powered 3B .
T98-A Rock Crawler using exclusive factory parts and Approved Special Equipment from the Willys Motors era (1953-1963)
Zero aftermarket parts

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Post Options Post Options   Thanks (0) Thanks(0)   Quote bobevans Quote  Post ReplyReply Direct Link To This Post Posted: 23 Dec. 2018 at 2:33am
Thank you!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote oldtime Quote  Post ReplyReply Direct Link To This Post Posted: 23 Dec. 2018 at 8:52pm
Quote  Thanks for the information on the different overdrive fitting between the small and the big mouth D-18. On another CJ2a posting I was expressing my confusion about why my ATV O/D worked in my original small mouth D-18 and in my replacement Tera Low big mouth case and why a Saturn O/D would not fit in my big mouth. The Saturn (Warn) is almost .4 inches wider than the ATV. Now I am "un-confused".

3A Steve,
Now you have me confused.
I'm not really sure what statements you may be referencing.
I have no Advance Adapter nor any ATV. overdrive experience.
So I doubt that I made any comments on those units
AFAIK this is the only comment I made concerning O.D. units and it specifically relates to WARN units....
Quote
Thirdly > The D18 readily accepts the famous  Jeep Approved Special Equipment Option;  the  Warn overdrive unit. (since 1964)


That said if your D18 is a built using a big hole then your O.D. unit must be the late type: having rear shift.
The early front shift O.D, units will only mate to small hole transfer cases.

Above.....I'm merely stating that  rear shift O.D. units are required for use on any big hole casting.
This is due to the larger "big hole"case dimensions near the O.D.shift rail.
I don't have any of the early Warn rear shift units otherwise I'd take a pic showing why it cannot be used with a big hole case.
Early Warn front shift units have 27 tooth mainshaft gears.
Late Warn front shift units have 29 tooth mainshaft gears.

Special bowl gears are always required if installing aftermarket low gear sets.

Currently building my final F-134 powered 3B .
T98-A Rock Crawler using exclusive factory parts and Approved Special Equipment from the Willys Motors era (1953-1963)
Zero aftermarket parts

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Post Options Post Options   Thanks (0) Thanks(0)   Quote 3A Steve Quote  Post ReplyReply Direct Link To This Post Posted: 23 Dec. 2018 at 9:43pm
Sorry to be confusing.  

As a last shot at not being confusing (then I'll give up), I bought a used ATV O/D to use with my 3A's transfer case. Worked fine. After a trip to Moab in 2017 I went to a big mouth D-18 to get lower gearing. Kept the same O/D as in the small mouth D-18. Worked fine in both T-cases. 

Had a relatively small problem with my overdrive after using it for a year. Sent it back to ATV (Herm). Then bought a Saturn (Walck's) to replace it (thinking I would use the repaired ATV in a Willys wagon I have). As you point out, the big mouth that is now in my 3A takes a different O/D. The Saturn was just under .4 inch larger diameter panetary than the ATV unit. Wouldn't fit in the big mouth D-18. The ATV unit fits in both the small mouth and the big mouth D-18. 

In short the big mouth appears to require a narrower planetary gear assembly than the small mouth. And, from experience, the ATV unit will work in either case. I am happy that you pointed out the difference in the two cases. I was at the point of adding my experience to the things I would never be able to figure out.

3A Steve
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Joe Friday Quote  Post ReplyReply Direct Link To This Post Posted: 24 Dec. 2018 at 3:57am
I don't think there is as much confusion as there is incomplete communication.

When you normally discuss overdrives, the fitment is defined by the ORIGINAL gearing that came from the factory. There were 3 different intermediate shaft diameters, the smallest one used on the MB was mated to a 27 tooth output gear on the back of the T84 Transmission, then the larger diameter shaft was used with a 26 tooth output gear on CJ2A, 3A, and Early 3B as well as M38 and M38A1 with T90's.
The third diameter intermediate shaft use was coupled with a 29 tooth output gear. SO the only unique part of the Overdrive, whether ATV, Saturn, or Warn, is the number of splines on the transmission output shaft, and the number of teeth on the transmission output gear. this is the gear the overdrive bowl gear replaces. I have attached an example.


It sounds to me like your aftermarket "SPECIAL" Terra Low bowl gear from ATV (HERM) just happens to be 26 tooth? I think that's the only confusing part. Since the Terra Low intermediate gear is much larger, the bowl gear needs to be much smaller...

The Saturn overdrives from Walcks are made to the same standards as everyone else. There is nothing wrong with them.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote 3A Steve Quote  Post ReplyReply Direct Link To This Post Posted: 24 Dec. 2018 at 2:11pm
Yes, the ATV unit has 26 teeth. Fits both types of the D-18. And you're correct, I don't usually discuss overdrives. But despite incomplete communication, thanks to you I now understand why the Walck's unit wouldn't fit and I now know to be very careful putting an overdrive into my wagon. Also understand that I could have problems getting my overdrive serviced or repaired if anything happens to Herm.

Steve
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Post Options Post Options   Thanks (0) Thanks(0)   Quote oldtime Quote  Post ReplyReply Direct Link To This Post Posted: 19 Jan. 2019 at 9:32pm
So I just assembled another big hole D18.
This latest unit includes a 3.15 Tera Low gear set.
A tapered intermediate shaft kit.
Factory twin sticks excluding the interlock "pill'.
And a speedometer gear set for 4.89 DR.

Zero case grinding was required. But a couple items are worth noting.

Here you can see where I checked to make sure that the large Tera Low sliding gear would clear the large shift fork. Close, but no fork grinding was required.

Due to close fit the late type fork set screws are certainly preferable in lieu of early safety wire set screws.

I found that the short shift rod was very near to touching the large diameter intermediate gear with the shift rod poppet ball engaged.
So here I shortened the short shift rod by about 1/8".

This pic shows the 1/8" clearance between large intermediate gear and rod after shortening the rod.

I installed a late type 6 tooth type speedometer drive gear. 
And the early longer length companion flange was not a good match.
Here you see an early (longer) speedometer drive gear next to a late (shorter) speedometer drive gear: 

Here you see an early longer companion flange next to a late shorter companion flange:

If installing a park brake assembly I find that the drive gear must be mated to the correct length companion flange. 
Other wise the park brake drum will be out of position.

In my instance using the longer drive gear with the longer companion flange does not allow the drum to set up next to the backing plate as it should.:

Furthermore the brake shoes do not set deep enough into the parking drum by .15" distance.

Also the "hug lock" nut does not go fully onto the rear output shaft threads.

Solution .... use the correct matching parts !
Currently building my final F-134 powered 3B .
T98-A Rock Crawler using exclusive factory parts and Approved Special Equipment from the Willys Motors era (1953-1963)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bobevans Quote  Post ReplyReply Direct Link To This Post Posted: 20 Jan. 2019 at 5:34am
Really nice. And those pictures look pretty good.

Edited by bobevans - 20 Jan. 2019 at 5:45am
'48 CJ2A

'56 DJ3A

'79 CJ7

And two of them actually run!
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