machining advice req'd dual trans (1 Viewer)

[cody c]

I want to make a dual trans adapter, for part of this I am looking at cutting an input shaft down on one case and the output for another, the output for either trans are both splined the entire length, but the input is only splined at the tip for the clutch.

My plan is to use a transfer case gear, machine off the outer gear and connect it to the un splined input shaft of the rear transmission. Also the input is a narrower diameter then the t-case gear...

My question is: what is going to be the strongest but most reasonable way to connect that gear on the end of that smaller unsplined input shaft?

Im not saying which transmissions or transfer cases to keep this direct tech and to keep all the know it all negative nancy's out of the thread, but for those with a machining background perhaps you have some ideas?

 

[StevoJonesFJ60]

I want to make a dual trans adapter, for part of this I am looking at cutting an input shaft down on one case and the output for another, the output for either trans are both splined the entire length, but the input is only splined at the tip for the clutch.

My plan is to use a transfer case gear, machine off the outer gear and connect it to the un splined input shaft of the rear transmission. Also the input is a narrower diameter then the t-case gear...

My question is: what is going to be the strongest but most reasonable way to connect that gear on the end of that smaller unsplined input shaft?

Im not saying which transmissions or transfer cases to keep this direct tech and to keep all the know it all negative nancy's out of the thread, but for those with a machining background perhaps you have some ideas?

Ok, the way you proposed would be pretty tough considering the 2nd trans input shaft is smaller than the output shaft of the first. This also raises a red flag in my mind due to the increased torque the input of the second trans will see.

how much smaller is the input than the output?

 

[cody c]

Just smaller then the splines, the first case will not likely go into the lower gears unless the transfer case has first been put in low, and then the lowest gears will be used not at heavy throttle.

The input is marginally smaller at the shaft, the splines are on a thicker section of it, but just think of the shaft being 1/16" smaller diameter then the t-case gear.

 

[StevoJonesFJ60]

1/16th of an inch is too large of a difference to play with for this application for my personal comfort, there is a reason why gears typically have interference fit. But if you are set on using the transfer case gear you "technically" could cut multiple keyways in the input shaft and gear then insert keys to space it out. But you would have to make sure you get the machining done by a very qualified shop, otherwise it would not be centered an could start destroying bearings and other transmissionn parts

The tricky thing would then be mating the gear on the input shaft to the output shaft.
What were your ideas for that?

 

[cody c]

1/16th of an inch is too large of a difference to play with for this application for my personal comfort, there is a reason why gears typically have interference fit. But if you are set on using the transfer case gear you "technically" could cut multiple keyways in the input shaft and gear then insert keys to space it out. But you would have to make sure you get the machining done by a very qualified shop, otherwise it would not be centered an could start destroying bearings and other transmissionn parts

The tricky thing would then be mating the gear on the input shaft to the output shaft.
What were your ideas for that?

Side tracking, but the trans gear on the input shaft should slide right over the output of the other trans, and as the output is splined the entire length it should just slide over it at what ever length I cut it to.

In terms of aligning them, my plan is to CAD both surfaces and then get two flanges cut, burn flatbar on one flange only to connect them, then stack the two vertically with the input connector slid onto the output so they are aligned, and then weld the other flange onto the flatbar.

In other words, the adapter aligned in place by the shafts connected, and then welded.

Perhaps I should just cut the input to length and then take it to a shop, they may have to machine and weld an intermediate (spacer) between the shaft and the transfer case gear, which may involve lathing part of the gear splines to make a smooth surface.

Any other thoughts? Small peg in a larger splined hole?

 

[StevoJonesFJ60]

ok i think I have a clearer picture of what you are trying to accomplish.

What I would do is get the transfer case machined so the teeth are removed, then have a shop make a flanged piece that can be pressed onto the input shaft of trans #2. That has the same OD of the modified gear. Once the piece is pressed on align the modified transfer case gear and weld the perimeter where they meet.

I would have the machine shop bevel the mating sides for a stronger weld then have them clean up the weld on a lathe to help with balance.

 

[cody c]

ok, perhaps I should also hold onto a piece of the old transfer case shaft for them to use to mate them together as well and just pull the input shaft with it marked as to where to cut it.

Thanks for the input.

 

[StevoJonesFJ60]

Yep that sounds like a good idea, the more pieces you have the better it will be for the machinists.

 

[69rambler]

I would cut the input shaft off the second transmission and have the just the remaining input gear wire EDM'd with the internal splines for the front transmissions output shaft.

design and mill a spacer from solid aluminum that connects, seals and aligns both transmissions.

 

[StevoJonesFJ60]

I would cut the input shaft off the second transmission and have the just the remaining input gear wire EDM'd with the internal splines for the front transmissions output shaft.

design and mill a spacer from solid aluminum that connects, seals and aligns both transmissions.

The only problem with doing that is the transfer case gear is going to be to narrow to hold both the output of the first trans and the input of the second, with the reduction coming from the first trans I would make sure to have an overlap of at least the diameter of the shaft on each side.

 

[69rambler]

The only problem with doing that is the transfer case gear is going to be to narrow to hold both the output of the first trans and the input of the second, with the reduction coming from the first trans I would make sure to have an overlap of at least the diameter of the shaft on each side.

What I suggested would totally eliminate using a transfercase input gear.

The second transmission would no longer have an input shaft, just an internal spline to accept the first transmissions output shaft.

It totally depends on the transmissions design really. I can picture a lot of transmissions that this would work on and some that couldn't work this way.

 

[StevoJonesFJ60]

true story, I was stuck on that transfer gear. That would make the most sense, Wire EDM can be pricey, but simpler is always better

 

[BC40]

^That would be the way to go assuming the input shaft bearing on the second trans is larger diameter than the output shaft of the first. I'd think that remaining gear might need the bearing for support of the main shaft behind it.

 

[Tin basher]

I have seen a transfer case input adapter tig welded to the input gear of a second transmission
To mate two transmissions together
Sounds weak but was in a truck with a mid mounted
460 c6 205 that fed into the two 465 transmissions coupled by this tig welded coupler
Seen it spin all 4 44 boggers on pavement many times