Seeking thread-die specs for T-Case shaft

[chilidavid]

VEHICLE:
Daily Driver: 1971, S2a, 88, LHD, 2.25 petrol, Soft-top

Note: I've also inquired about these thread specs directly to the RoamerDrive guys, but I think that they're trying to take a few days off during the holidays. (The thread specs referenced below relate directly to the installation of the RoamerDrive SS unit.)

PROBLEM:
Went to install my new RoamerDrive SS and encountered a SERIOUSLY FROZEN "castle nut" on the transfer case gear shaft. (This castle nut holds the one gear that needs to be removed in order to install he RoamerDrive SS coupling, and then the complete overdrive housing can be installed onto the back of the T-Case. Sounds quick and easy, right?)

With the help of a friend with an acetylene torch, we finally got the carefully heated (R.H thread) castle nut to come off the shaft. (I'm guessing that the PO must have, for some reason, went crazy on the nut in the past, but we can't be sure. The nut is supposed to be just somewhat "snug" up against the gear.) But now, after finally removing the castle nut, the first two or three threads on the gear shaft are distressed - just enough to where I don't dare try to install the SS coupling on the shaft now, and end up forcing the brand new hex nut onto the shaft to secure the coupling, ending up damaging my new hex nut too!

Does anyone know the thread specs of the transfer case shaft in question? If not, I'm sure the RoamerDrive guys will get back to me soon.

And... I'm going to visit my local machine shop today and hand them the "RoamerDrive HEX NUT" that is extremely anxious to be installed onto the shaft, and maybe they can determine (using their closest sized tap?) what thread die I should utilize. Of course, I prefer to procure the Genuine Specs, and then order the Correct Die for the job. (What a wild and crazy idea!?)

If you have any info, I would appreciate hearing from you...otherwise, I'll try to maintain myself, and continue driving my old Dodge truck to work...BORING!

Thanks!

Dave
(A shade tree mechanic who doesn't even have a shade tree.)

[SafeAirOne]

Though it's easier to figure out using the threaded shaft, if the machine shop can't tell you the thread specs using the nut, it's probably time to find a new machine shop.

[I Leak Oil]

That nut is supposed to be torqued to 100 ft.lbs. If you simply snug it up against the gear you will be disappointed when it backs off and trashes your tranny.

[SafeAirOne]

That nut is supposed to be torqued to 100 ft.lbs. If you simply snug it up against the gear you will be disappointed when it backs off and trashes your tranny.

Tell me about it. I dodged a bullet when, after 8 years, the locking washer failed and my mainshaft nut backed off. Fortunately, it happened just as I was backing out of my driveway. Amazing how violently your truck stops, even when backing up at 3 MPH, when that nut backs off and jams into the PTO cover plate while the mainshaft is turning.


Also, I'd be careful about acetylene torching anything in there, lest you anneal something that is supposed to be hardened.

[ignotus]

Hi,

I think you are talking about the nut on the end of the gearbox main shaft not a "transfer case gear shaft". I just measured mine on the outside of the threads I get 7/8" or 22mm, the thread tpi is 16. Another nontypical LR use, typical 7/8 tpi would be either 9 or 14, and metric for a 22 are 2.5 or 1.5(the latter being close but no cigar to the 7/8x16).
Ray at Globalroamer will set you right!

Hmm a quick Gooooooooooooooooooooogle finds; http://www.tracytools.com/7-8-x-16-tpi

[chilidavid]

Thanks. You're correct.

Technically, the small "transfer" gear (that I was finally able to slide off the shaft) was inside the transfer case, but was actually on the transmission main shaft. My shade-tree background is showing through.

I did make the effort to use my calipers on the shaft end, as well as on its small threaded section, and came up with a 13/16" x 16 TPI number - and I now suspect the 13/16" that I quickly got is probably more like 7/8" in reality, as you suggested.

To estimate the thread count, I placed a lump of kneaded eraser onto the shaft threads, and then compared those thread impressions to an SAE bolt that I had laying around. The 16 TPI bolt did seem to match up to the thread impressions on the soft eraser. Your numbers are most likely right on the money! I am definitely even more hesitant now to clean up threads using my own guesswork and sloppy measuring.

Global Roamer will provide me with their numbers this week (Maybe even today). More than likely, their numbers will match up with yours!

In the meantime, I ordered two (2) Tri-Gauge Combo Tools (inch and metric) from Thread Tool Supply Company (threadtoolsupply.com) so I can get ahead of any thread count questions in the future. Oh...and I have discovered that there are several companies that sell individual thread dies (solid and split-die types) that I will be considering: Newman Tools, and Victornet.com just to name two.

Thanks for the input! I'm going to use your numbers this morning to initially locate the thread die that I might need. When Global Roamer confirms those numbers, I can order the die ASAP.

I prefer to obtain a split-die, hex-nut version, because the distressed threads in question are at the very beginning of the threaded section. It is possible that even a standard thread die could be mis-aligned when placed (started) on damaged threads. My mission is to do this right, so that the next (third) owner doesn't have to deal with this 50 years from now. (Joke! More like 4 or 5 years from now.)

Dave

[chilidavid]

THREAD-COUNT-QUESTION UPDATE:

Ray at Global Roamer just confirmed that the thread specs for the end of the tranny main shaft are in fact 7/8" x 16 TPI, so "ingnotus" was right on the money with his measurements.

I ordered a HEX-NUT-shaped thread die from www.drillsandcutters.com for $24.64, plus shipping.

Before I chose a hex-nut-shaped die, I revisited the threads on my tranny shaft again, and made sure that the new HEX NUT provided by Global Roamer was able to turn freely - at least a couple of turns - on the thread-damaged shaft before the nut stopped. Since I have a couple of beginning threads that are OK, and I'm not re-cutting a new shaft, I don't need to use a round thread die with a leverage handle. And I don't have space for a handle anyway. The hex-shaped die will work fine to "clean up" a few damaged threads, and I can use a large socket wrench to turn the hex-shaped die (carefully, of course; and backing off after each half-turn or so as if I were cutting brand new threads.)

Oh...and I am reminded that I need to always use cutting oil - to make sure that no threads are "torn", or in any way damaged by the cutting surfaces of the sharp die.

After that, it's GO TIME...next week. Time to install my new SS model Roamerdrive!

Thanks to all for the input. I need all the help I can get. And after driving this Series to work each day for going on 6 years, I think I deserve an overdrive!

Dave