TRANSFER CASE ??????????????
- Thread starter WRECKTHOSECARS
- Start date
Its a Dana 20 w/ factory twinsticks. Most likely out of a 65'-69' Scout 800.
WRECKTHOSECARS
Member
Thanks, I would like to get the correct shifter knods and boot. Do you carry them? Is this good case or is there a better option without spending a lot of money.
Yes we carry both the correct knobs and boot.
This is a good case especially since it has the factory twinstick. Just be sure to use the correct bullgear(input gear) that came with it as later Dana 20's had a slightly different pitch to the gear set.
This is a good case especially since it has the factory twinstick. Just be sure to use the correct bullgear(input gear) that came with it as later Dana 20's had a slightly different pitch to the gear set.
WRECKTHOSECARS
Member
This case was in my project "hemi Scout" on your forum. How do I know if it has the correct gear or if it needs to be rebuilt?
Michael Mayben
IHPA Tech Moderator - Retired & No Longer Online
Wreck, Jeff should be in the air right now on the way to loweryankeeland.
There is a Dana/spicer part number on the input (bull) gear you have. Can you post that number and we can determine which one you have?
The pitch of the input gear, and the pitch of the main drive gear in the tc must match. The "early" gear has a pitch angle of a nominal 17*, the later gear set has a pitch of a nominal 22*.
I have an "early" gear here that is mounted onna borg warner slushbox out of a Scout 800, should be the same gear as what you currently have.
There are many different gears that were available depending upon which oem the tranny and tc was installed in since the early '50's. The part number defines the spec for each gear and also the spline count which varies.
The "early" gear is a d-s p/n 18-8-31 and is a 6 spline.
The sii "late" gear is a d-s p/n 18-8-56 and is a 23 spline.
There is no definitive info on "when" IH actually started using "which" version of the d20....and after all these years many of these have been mixed and matched so that the bom is no longer valid for the most part though it is a key to "original". If your transfer case still has a tag on it, that will be the Dana/spicer "bom" number, same as for the axles. If you can post that number, I can research what it came with originally but that will take a few days, gearman dave has the old references for this stuff and I have to get with him, if we can't find info in the paper, then we call dave's contact at Dana.
There is a Dana/spicer part number on the input (bull) gear you have. Can you post that number and we can determine which one you have?
The pitch of the input gear, and the pitch of the main drive gear in the tc must match. The "early" gear has a pitch angle of a nominal 17*, the later gear set has a pitch of a nominal 22*.
I have an "early" gear here that is mounted onna borg warner slushbox out of a Scout 800, should be the same gear as what you currently have.
There are many different gears that were available depending upon which oem the tranny and tc was installed in since the early '50's. The part number defines the spec for each gear and also the spline count which varies.
The "early" gear is a d-s p/n 18-8-31 and is a 6 spline.
The sii "late" gear is a d-s p/n 18-8-56 and is a 23 spline.
There is no definitive info on "when" IH actually started using "which" version of the d20....and after all these years many of these have been mixed and matched so that the bom is no longer valid for the most part though it is a key to "original". If your transfer case still has a tag on it, that will be the Dana/spicer "bom" number, same as for the axles. If you can post that number, I can research what it came with originally but that will take a few days, gearman dave has the old references for this stuff and I have to get with him, if we can't find info in the paper, then we call dave's contact at Dana.
Michael Mayben
IHPA Tech Moderator - Retired & No Longer Online
One more thing...in your jpeg #1018 above, that part number cast into the case is the part number for that part, not the transfer case assembly itself. Each d/s part normally has a part number on it somewhere, in the case of the gears, the number is sometimes vague but can be raised through the use of heat and dykem blue.
The actual bom number for the case is onna stamped sheetmetal tag under a retaining bolt for one of the retainers. That is the "critical" number. And a d18 and d20 share many parts also.
The actual bom number for the case is onna stamped sheetmetal tag under a retaining bolt for one of the retainers. That is the "critical" number. And a d18 and d20 share many parts also.
WRECKTHOSECARS
Member
Thanks for the info. Is there any reason to find the number on the gear, if the tc was already installed and functional behind the 727? How will I know if the tc needs to overhauled?????
Michael Mayben
IHPA Tech Moderator - Retired & No Longer Online
Unless some kinda hokuspokus has taken place, the 727 output gear would have to be the 23 spline item with p/n I referenced above.
A 727 never was used with the 9 spline gear that would have been used inna "early" twinstick d20, that tc would been behind a manual tranny or a borg warner slusher.
Many times we find the input gears and the main gear in these setups are not matched as far as the tooth angle!!!! Ya can imagine the consequences of that! It will "mesh" kinda but is noisee as hell and somethin' will break in short order.
It's difficult to determine the tooth angle unless ya got the two different parts side-by-side.
I've "heard" that the very early tf 727 application (late 1971 production) May have a 23 spline gear with the "early" tooth angle, but the Dana info does not reference that, that is why we have to call Dana techserv directly about that kinda juju! There is much in the way of this stuff for IH that is not documented/referenced in commonly available sources, even the IH parts list can't be trusted for that.
We delt with just this same issue about a month ago regarding parts selection for another customers d20....and the same thing on one I'm building myself right now.
As for determining the "condition" of your tc, that is impossible without a teardown! The one I'm doing now, "looked" good from peeking through the big hole, but the intermediate gear set was trashed, and the input (bull gear) was wasted also. Shafts and bearings are re-useable. That was easy to see, just look at the dog teeth on it and if they don't have sharp, trapezoidal corners, then it's wasted.
If you are using the oem 727 that is married to the d20, ya must replace the seals behind the input gear! Trust me!
See this thread:
http://www.forums.IHPartsAmerica.com/transmission-tech/588-torqueflite-727-guapo.html
A 727 never was used with the 9 spline gear that would have been used inna "early" twinstick d20, that tc would been behind a manual tranny or a borg warner slusher.
Many times we find the input gears and the main gear in these setups are not matched as far as the tooth angle!!!! Ya can imagine the consequences of that! It will "mesh" kinda but is noisee as hell and somethin' will break in short order.
It's difficult to determine the tooth angle unless ya got the two different parts side-by-side.
I've "heard" that the very early tf 727 application (late 1971 production) May have a 23 spline gear with the "early" tooth angle, but the Dana info does not reference that, that is why we have to call Dana techserv directly about that kinda juju! There is much in the way of this stuff for IH that is not documented/referenced in commonly available sources, even the IH parts list can't be trusted for that.
We delt with just this same issue about a month ago regarding parts selection for another customers d20....and the same thing on one I'm building myself right now.
As for determining the "condition" of your tc, that is impossible without a teardown! The one I'm doing now, "looked" good from peeking through the big hole, but the intermediate gear set was trashed, and the input (bull gear) was wasted also. Shafts and bearings are re-useable. That was easy to see, just look at the dog teeth on it and if they don't have sharp, trapezoidal corners, then it's wasted.
If you are using the oem 727 that is married to the d20, ya must replace the seals behind the input gear! Trust me!
See this thread:
http://www.forums.IHPartsAmerica.com/transmission-tech/588-torqueflite-727-guapo.html
WRECKTHOSECARS
Member
I have removed the gears in question. The gear from the transfer case has the numbers 18 5 10 and the gear transmission has the numbers 18 8 56. Are these a match? I also need a service manual for a Dana 20, a rebuild kit and the two tail shaft seals for the 727. I hope you can help.
Ps. Will this transfer case handle 360 horse power at the flywheel or should look for something else?
Ps. Will this transfer case handle 360 horse power at the flywheel or should look for something else?
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I'll try a stab at your gear numbers.
I'm using novak adaptors' chart and interchange guide:
the novak guide to Dana 18 & 20 gears interchange
I've found this to be trusted information for all the work that I have done on d18's & d20's, it's authors are sources of work and information for the 4x4 gear biz. It does show the 18-8-56 gear to be IH specific for the tf727, and has a 17.5 degree tooth angle. The 18-5-10 intermediate gear has the 20 degree tooth angle; it is not compatible with your present input gear. You would need the intermediate gear 18-5-16 to mate with your autotransmission's gear 18-8-56. As Mike has mentioned, they will "mesh"; but not correctly and are short lived with noise and heat. Here's a rebuild guide from the same outfit, and I have found it very helpful in addition to the service guide cts 2450, :rebuilding the Jeep / IH Dana spicer 20 transfer case.
The tooth angle is the helix angle with respect to the gear's axis. Getting 2 gears with different angles to mate or mesh is like getting a 4x4 rig up a trail with 2 different but close axle ratios, it'll go some distance but close is not good enough.
I have no info on the hp question.
I'm using novak adaptors' chart and interchange guide:
the novak guide to Dana 18 & 20 gears interchange
I've found this to be trusted information for all the work that I have done on d18's & d20's, it's authors are sources of work and information for the 4x4 gear biz. It does show the 18-8-56 gear to be IH specific for the tf727, and has a 17.5 degree tooth angle. The 18-5-10 intermediate gear has the 20 degree tooth angle; it is not compatible with your present input gear. You would need the intermediate gear 18-5-16 to mate with your autotransmission's gear 18-8-56. As Mike has mentioned, they will "mesh"; but not correctly and are short lived with noise and heat. Here's a rebuild guide from the same outfit, and I have found it very helpful in addition to the service guide cts 2450, :rebuilding the Jeep / IH Dana spicer 20 transfer case.
The tooth angle is the helix angle with respect to the gear's axis. Getting 2 gears with different angles to mate or mesh is like getting a 4x4 rig up a trail with 2 different but close axle ratios, it'll go some distance but close is not good enough.
I have no info on the hp question.
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