help with doubler build

[Crashtest84]

This may need to be moved but I was wondering about how much torque the 2 piece shaft that you have to build for a doubler has to handle as kinda need to know how strong it needs to be built I read the two post in the tech and there wasn't much said about really how they made them other then it seems better to weld then to press that brings me to my next question on the old trans output shaft was it just cut off at the end of the splines and welded to the sector shaft or would it be better to turn down the output shaft so that is would fit inside the sector shaft and then weld it by the splines and at the front of the sector shaft to ? I guess what im just trying to ask here is what would be the best way to make the shaft ?

 

[kunar]

pretty sure they need to be turned so they are pressed together, then welded. they are hardened so welding takes extra steps. i dont know how much torque they handle but i have heard of a few that have broken.

 

[Evan]

From my updated writeup:

"[The central sector shaft] is probably the weakest link in this doubler setup. When welding the shaft [after it's been pressed together], it's important to heat both pieces of steel to around 500 degrees F prior to welding. After the welding is complete, allow the shaft to slowly cool in a preheated 500 degree oil bath.


Additionally, do not put the doubler case in LO and the transfer case in HI. This puts excessive strain on the doubler sector shaft. If you want to use single LO range, use the transfer case.


If you abide by the above rules, you should have no problems. I've had my doubler in for about a year, and have had the skinny pedal to the rug many times; snapping axle shafts and drive shafts. The doubler shaft has stood strong."

 

[4x4junkie]

What engine do you have?

If you take the 4.0L's 225ft-lbs, multiply it by 3.40 (4.0L 1st gear ratio), you get 765 ft-lbs of continuous torque load.

You also have to factor dynamic loads into it as well though (such as bouncing up & down while on the throttle).
I would double the number to allow a safety margin for dynamic loading (or transient loads up to 1530ft-lbs). Of course hard use on the clutch can cause the load to exceed that as well.

 

[Evan]

I forgot to mention, having lower gears in the axles makes it easier on the doubler.

 

[metalmacguyver]

This may need to be moved but I was wondering about how much torque the 2 piece shaft that you have to build for a doubler has to handle as kinda need to know how strong it needs to be built.

I read the two post in the tech and there wasn't much said about really how they made them other then it seems better to weld then to press.

that brings me to my next question.

on the old trans output shaft was it just cut off at the end of the splines and welded to the sector shaft, or would it be better to turn down the output shaft, so that is would fit inside the sector shaft, and then weld it by the splines and at the front of the sector shaft too?

I guess what im just trying to ask here is what would be the best way to make the shaft ?

holy punctuation batman! 2 question marks in the entire paragraph and no periods. it makes reading painful. lol

i fixed it up for you


how strong to make it? ---- as strong as possible

how to make it?------- well as the above posts have said, typically they are made by turning down the output shaft to a press fit with the sector shaft. they are then welded together.

the shafts are usually made this way because it is the easiest way to do it, not because it is the strongest.

i read somewhere about someone that i believe took the sector shaft turned it down and resplined it. if not then they may have made a completely new shaft. this sounds like the strongest way to make it because it is all one piece and you dont have to worry as much about it changing shape during the heat treating process. the down side is that resplining a shaft is much much more difficult than turning a shaft and pressing and welding it. it also requires a specialized machine (either a horizontal mill or a dedicated splining machine) and tooling.

if you have the resources to make a one piece shaft then thats the best way to go. however for most people the press/weld method is really the only practical way to make it.

i hope this helped and i didnt confuse you with my late night rambling

 

[Crashtest84]

holy punctuation batman! 2 question marks in the entire paragraph and no periods. it makes reading painful. lol

i fixed it up for you


how strong to make it? ---- as strong as possible

how to make it?------- well as the above posts have said, typically they are made by turning down the output shaft to a press fit with the sector shaft. they are then welded together.

the shafts are usually made this way because it is the easiest way to do it, not because it is the strongest.

i read somewhere about someone that i believe took the sector shaft turned it down and resplined it. if not then they may have made a completely new shaft. this sounds like the strongest way to make it because it is all one piece and you dont have to worry as much about it changing shape during the heat treating process. the down side is that resplining a shaft is much much more difficult than turning a shaft and pressing and welding it. it also requires a specialized machine (either a horizontal mill or a dedicated splining machine) and tooling.

if you have the resources to make a one piece shaft then thats the best way to go. however for most people the press/weld method is really the only practical way to make it.

i hope this helped and i didnt confuse you with my late night rambling

"Punctuation" YES, thanks for the reminder! I knew I forgot something, I talked to a few machine shops yesterday and seems like they all want to charge about $200 to make the thing. I was unsure of to say the best way to make it. But I have a better idea now back to the shop now

 

[Jim Oaks]

There was someone here that found someone to make a new 1-piece sector shaft instead of pressing and welding the 2-pieces.

I'd actually like to know who it was because I could use one.

The info was lost on the old forum.

 

[4x4junkie]

There was someone here that found someone to make a new 1-piece sector shaft instead of pressing and welding the 2-pieces.

I'd actually like to know who it was because I could use one.

The info was lost on the old forum.

Duffy at D.D. Machine was making new one-piece chromoly shafts, although I don't know if he was selling then separate from his kit or not.

 

[Jim Oaks]

Seems like someone close to NW Ohio was doing it.

 

[metalmacguyver]

http://www.rrorc.com/forums/showthread.php?t=21585&highlight=doubler

has some info about the one piece shaft.

 

[Jim Oaks]

Did you guys see Patov6 did a doubler with a D20/BW1354?

 

[Evan]

You can't turn down the existing shaft and respline it. Because the shaft is hollow, it becomes too weak.

 

[metalmacguyver]

Did you guys see Patov6 did a doubler with a D20/BW1354?

i have seen some pics of it. people have had difficulty finding out info about it though.