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doubler shafts


swynx

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anyone know the length of there doubler intermediate shaft, end to end?

ive been inquiring with carl jantz, from jantz engineering about having the stock transfer case shaft cut down and resplined, instead of press/weld 2 shafts together.

from the measurements that i have taken it seems that there would be plenty of room for this. (he says he cant spline right up to a shoulder, best he could do is about 3/4" away.) the spot he is talking about has, if i remember correctly 1 3/8" material before it hits the adapter plate( the large spline section that gets bored/press/welded.), i figure if he starts splining before the adapter plate all should be good and i could grind/cut off whatever excess shaft is left. and have a complete 2 1/4 shaft engagement.

the reason i am inquiring about this instead of pressing the 2 shafts together is because i have seen many threads where the 1350/1354 shreds the splines once the user hits the highway. i know there are many members here that are having no issues, so im not sure what the problem is, but id like to avoid it all together if i could. i saw on another forum where someone had the above stated issue with 2 shafts within a few hundred miles and someone posted a pic of what looked like a resplined stock shaft.

also im not sure if the oiling hole would cause any issues, but he shouldnt have to spline right up to it.
 


swynx

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no input on any of this?

one thing im most worried about is that oil galley hole being a weak link.
 

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Sorry I don't have any info. I'm watching this to see if any good info turns up. I have an extra transfer case that I would like to use as a doubler some day. But getting that shaft made is the one part of the project that scares me.
 

swynx

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4x4junkie

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no input on any of this?

one thing im most worried about is that oil galley hole being a weak link.
I researched this many years ago and indeed the hollow inside of the shaft becomes a major weak link once the shaft diameter is turned down for it to be resplined.

Avoiding the hollow part (resplining only over the solid part) would add something like 3 inches of overall length to the doubler.


As for shafts eating the splines, that sounds like a misalignment issue with the adapter plates causing the shaft to run crooked between the cases (or possibly the shaft wasn't heat treated correctly afterward).
 

swynx

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I researched this many years ago and indeed the hollow inside of the shaft becomes a major weak link once the shaft diameter is turned down for it to be resplined.

Avoiding the hollow part (resplining only over the solid part) would add something like 3 inches of overall length to the doubler.


As for shafts eating the splines, that sounds like a misalignment issue with the adapter plates causing the shaft to run crooked between the cases (or possibly the shaft wasn't heat treated correctly afterward).
i have seen a few pictures where they just had the end of the shaft splined and just ran a fullsize box. being that i have an extended cab i dont see an issue with this. i asked carl jantz about the shafts eating themselves and he said that if he pointed a finger it would be at the heat treating.

i have seen all 3 doubler shafts work well, so what do you recomend? what shaft do you have?

ive seen some of carl jantz trouble shooting and machine work, he takes his time to ensure it gets done right, and charges a bit higher prices because of this, but id rather have it done right. so i trust his work.
 

4x4junkie

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I have the D.D. Machine kit. It's just a pair of machined adapter plates and a one-piece chromoly shaft (you supply the 2nd t-case yourself).

If you were to respline a stock shaft as a 32 or 35 spline or something to fit a fullsize case, the hollow part of it likely would not present near as much of an issue.
 

swynx

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I have the D.D. Machine kit. It's just a pair of machined adapter plates and a one-piece chromoly shaft (you supply the 2nd t-case yourself).

If you were to respline a stock shaft as a 32 or 35 spline or something to fit a fullsize case, the hollow part of it likely would not present near as much of an issue.
im not sure how far down the hollow part goes, but i dont think its far. in fact i think that it stops right about where the splining would start. (theres a smaller hole) < which i assume is the end. i think this is the route ill try first if it fails ive got 4 other shafts i can try a different design with.
 

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