Fj60 4wd T-case Vacuum switch 3D-Print (1 Viewer)

[ChaserFJ60]

So in my engineering class we have to 3D print anything, and I need a vacuum valve for my 4wd ever since I put in a split t-case that requires a vacuum shift. Below is a file of the basic idea of what im making, Im planning on adding little indents for a rubber o-rings to make a perfect seal. im planning on painting the shaft and sanding smooth to further promote a good seal. In its complete stage im thinking of a push pull type mechanism. this first file is just the core idea of what it is im planning. anyone with experience in 3d printing please leave suggestions/ideas.
(using fusion 360)

Im basing my design off of what this guy used here - LONG OVERDUE transfer vacuum valve conversion writeup

 

[NookShneer]

@NLXTACY feedback?

 

[Seth S]

You may find that the printed surfaces don’t provide enough smoothness to seal properly even with o rings.

The trick with 3d printing is to think outside the box and try a new way to do it that conventional processes don’t allow

 

[ChaserFJ60]

You may find that the printed surfaces don’t provide enough smoothness to seal properly even with o rings.

The trick with 3d printing is to think outside the box and try a new way to do it that conventional processes don’t allow

I figured that might be an issue, a possible remmedy i came up with is to make the shaft slightly larger than needed initially, then sanding it down smooth and use a hard, oil resistant acrilic paint to promote sliding and smoothness. Then coat the shaft in oil. I know this is a project that would be better milled from metal, but i get free 3d-printing at school.

 

[Cruzerman]

Educate me. I see FJ60, so why the vacuum shift?

 

[ChaserFJ60]

Educate me. I see FJ60, so why the vacuum shift?

So i did an 2fe EFI conversion, and decided to go all out with a H55F transmission. I found a used H55f with a mated tcase for super cheap online from a BJ60, the bj60's tcase didnt have a manual engaging 4wd like our fj60's, instead it was a vaccum electric solenoid switch. So now instead of using a nifty push button to engage the 4wd in the tcase like the bj60's had, i will manually get out and switch the vacuum lines. And i dont want to add any more electric to my truck, adding a whole computer system for the efi was plenty enough. To those wondering how I got a Bj60 input shaft in an fj60 crankshaft, i rebuilt the transmission and replaced the input shafts as that was the cheapest alternative at the time.

 

[Seth S]

Consider doing a rotary valve. For reference you might look for the vent selector out of a 1981-1993 Saab 900. They switched vacuum and worked very well.

 

[NLXTACY]

I would do a rotary valve instead, easier and off the shelf. Although it’s fairly low vacuum, I wouldn’t use layered filament as a vacuum vessel.

edit: Seth beat me to the rotary idea

 

[ChaserFJ60]

I dont want to buy anything as this 3d print is also for a grade in my class. but i like the idea of a rotary valve, i can make it much more compact, but it may be harder to get a
perfect seal with a 3d print. Ill mock up a new design today and post it tonight

 

[Seth S]

Keep in mind that 3D printing isn’t intended to be a one stop package. You might still need to do after machining or use gasket/seal material. It just allows you to crest geometries that may not be possible or cost effect through traditional means. So don’t lock yourself into thinking it had to be 100% 3D printed. You might consider finding an off the shelf vacuum rotary valve and taking it apart and then reverse engineering it to show how you can make it more efficiently with 3D printing.

 

[Seth S]

Here’s a recent real world use of 3D manufacturing. GE's Catalyst | GE Aviation

 

[Cruzerman]

Thanks for the info. Makes sense. Not being familiar with that setup, can it be converted back to a stick? I will take the stick any day, just like manual windows, door locks, etc. On a utility vehicle, simple = reliable = good.

 

[ChaserFJ60]

Thanks for the info. Makes sense. Not being familiar with that setup, can it be converted back to a stick? I will take the stick any day, just like manual windows, door locks, etc. On a utility vehicle, simple = reliable = good.

Yes you can! Theres a few writeups about it. you would have to remove the tcase to drill and tap a hole for a ballspring retainer part, and some linkage would have to be added.

 

[animaldevictor]

that's great, I have printed the 4WD shifter bushings with PLA, they are working great!!

 

[elripster]

that's great, I have printed the 4WD shifter bushings with PLA, they are working great!!

One note on PLA, it will start to warp/deform around 140-150 degF. ABS is generally much more heat resistant though is trickier to print.

 

[Seth S]

tell your school they need to get with the program and buy an Arcam machine. then you could make some parts out of titanium

 

[ChaserFJ60]

looked up rotary valve, it over complicates my simple 3d design, that or im not seeing the same thing you guys are suggesting. as of now my plan is to scale my design, and start to work some sealing features

 

[Seth S]

Essentially it’s a plate with some holes in it and nipples for attaching vac lines. A second plate with another hole and nipple mates against it. You turn the plate and the holes align and engine vacuum can go to the device. You turn to a second position and engine vacuum is blocked off while the device vents to atmosphere.

 

[Seth S]

this is the back of the saab switch:

and the front:

The driver turns a control knob to select the different vent positions: defrost, vent, heat, floor etc....The various vents open and close using vacuum diaphragm actuators and the switch routes engine vacuum to each accordingly. The inside it essentially just a round plate with holes drilled in it that align the appropriate ports based on switch position.


did a quick sketch in sketchup to give you an idea of how simple it could be

I've not done a full design because you should be able to figure that out you'll need to provide vacuum and figure out the switching ports. But something like this would be very easy to design for print. and if you get creative you might be able to to it all in one print.

 

[ChaserFJ60]

Wow thats very interesting, i appriciate the sketch. Because the 3d print wont be precise enough to make air tight parts im going to have to do it in pieces so i can work them. I like the way this one works but im still stuck with the venting port. I think i may stack a group of valves? Im going to have to think on it. My initial impression is that the rotary design you showed will be easier to make an airtight seal on