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Discussion Starter #1 (Edited)
You know, I built this setup a long-ass time ago for my current buggy and was thinking about selling it as a kit. Sicne then I've lost the time to do so so I figured I'd just throw the idea out there for ya'll to copy. I have no pics right now. I'm not even sure that I can get any. But rest assured, the idea works. I've been using it for almost a year now with zero failiures. I can shift in and out of 4wd on the fly with the flick of a switch. Sometimes after switching the rear I need to flip the auto trans in and out of rev once or twice to release gear mesh tension to get it to flick over, but it flicks with the reassuring solid thud of a shift rail pounding in its race. In fact, I prefer it to a manual shifter so much that I'll never go back. It should work on about any t-case that uses shift rails. You just need to know the throw of each rail. I use a Ford NP205 and the throw between positions on it was .5".

Obviously, you have to have OBA. I run mine at 85 psi, but it could be higher. I'll discuss the setup for a single shift rail because it is exactly the same for the other one.

For one shift rail you need 2 .5" stroke pnumatic rams. (I used 3/4"
bore from Clippard.) This is important. The stroke must match the stroke of your t-case shift rails. The rams are then tied together at the back side, or in other words, the ram bodies. The rams I got from Clippard were threaded at the back end of the ram body. I just welded 2 appropriately sized nuts together and screwed a ram into each side. So now what you have is a double ended ram with 3 positions. The three positions are both rams fully extended, both fully retracted, and one ram entended while the other is retracted. This corresponds the the 3 positions of throw in your shift rail. (High, Neutral, Low) Important note: You can't just get a single double ended ram for this because it has no internal stops that would correspond to the 3 positions of your shift rail.

No now you have this double-ended ram made out of two single ended rams with clevis mounts at both ends and 4 air ports, one for each end of the piston in each ram. You will take this ram and mount one end directly to the shift rail. You will take the other end and stationary mount it somewhere straight in front of the shift rail. It must be mounted so that, in each of its three positions, it synchs with the three shift rail positions. In other words, with the shift rail fully extended, the rams must both be fully contracted. With the shift rail in neutral, one ram will be fully extended, the other contracted (it doesn't matter which) and with the shift rail in the t-case as far as it goes, both rams must be fully extended. Once this is done, you are ready for the brains of the operation.

Using a 3-way pneumatic toggle switch from Clippard and some handly little valves which I will provide part numbers for later, you plumb the rams to the valves and switch so that the rams do what you need them to do in accordance to switch position. This is the complex part which I will explain later once I get all the valve part numbers.

I don't know if I have explained any of this clearly at all. But what you end up with is no shifters in your passenger compartment and two toggle switches on your dash. One switch operates each axle. When it shifts, it does it with a positive-sounding clunk that is way better than the grinding that soemtimes happens with hand-operated shifters. It's super-bling and so convenient. With hose and everythign, I spent about $300 doing this. It ended up being way easier than making shift linkage in tight buggy-space and I'm not banging my knees on shifters, either. It's a lo-buck Lovell 205.

One thing is important though. You must have done your twin-stick the correct way so that you can not shift front-high-rear-low or vice versa. This setup will allow that to happen if there is no internal stop within the t-case. And we all know what happens when that happens.

J. J.
 

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Oh, c'mon.... spill it already. I was just looking at doing this last weekend. I found some 3/4" bore Speedaire cylinders I had stashed in the garage was thinking about an air setup. I didn't think of putting to cylinders back to back to create a 3 position cylinder. I was thinking of using the cylinders and some springs to pull it off, but it created a potentially dangerous situation, so I scrapped that linkage idea.

So, on your 4-way, 3-position air control valve did you use an open center or a closed center?
 

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Hmmmm , between this mod and a 3:1 lomax gear set Im thinking my 205 could use extreme make over :evil:

Cant wait for some more info....
 

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I thought my home-brew McMaster-Carr cable shifters were kind of clever, but this trumps mine by a mile. This would certainly clean up my interior a lot.



It'd be a really easy retrofit too, the majority of the bracket work is already in place...

Dammit. I hate it when I want to upgrade things before I even finish building and wheeling the original idea. :cry:
 

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Discussion Starter #8
I'm at work right now and the list of part numbers is at home. I won't be home until late tonight, that's why I can't post them until then. I also have crappy hand-drawn diagram that I will scan and post that will show you how to run the lines. Sorry I can't tell you much until then.

J. J.
 

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Umm.... it appears your interior and the exterior are one in the same. :flipoff2:
Precisely, you can obviously see the benefits this air-shifter setup would offer!

It'll be sealed up and skinned when it's "done" anyway.
 

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Discussion Starter #10
Awesome idea man, i really want to see your setup...



One of my wife's best friends owns this company, small world.
BTW, I'm not sure who it is that you know, but when I was doing all of this and working out the theory of it all and researching part numbers, Clippard was so unbelievably helpful that I have to mention them. I spoke to two different guys about it and they were not only 100% knowledgeable about their product, but also down-right into what I was doing. They were excited to be working on something completely custom that had never been done before. I can't say enough good things abotu Clippard, so you're friend definately knows how to run a company.

J. J.
 

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Id like to see some pics. :smokin:
 

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Discussion Starter #12
The crappy part is, I took pics when I was putting it all together and then my digicam died, so they all disappeared. I can't take any more right now because it is all underneath my buggy's floor board and I don't feel like tearing it all out just for pics. It's pretty trick though and very clean and compact.

J. J.
 

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Well Im in no hurry but it would be nice to see how you did it all. My hand shifters work for now but it would be nice to hit a switch.
 

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Clippard's website is the tits and it has Solidworks drawings of the cylinders.

http://www.clippard.com/store/byo_cylinder/byo_stainless_details.asp?sku=USR-12-1/2-B||W
 

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I'm at work right now and the list of part numbers is at home. I won't be home until late tonight, that's why I can't post them until then. I also have crappy hand-drawn diagram that I will scan and post that will show you how to run the lines. Sorry I can't tell you much until then.

J. J.
How about a little nugget of info until then. By "handy little valves" are you referring to shuttle valves?
 

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So, on your 4-way, 3-position air control valve did you use an open center or a closed center?
I think it depends on how it is plumbed from the switch.

Just a thought, If you had a cylinder with too much stroke sitting around, you can use a Delrin hollow shaft or welded washers or something to limit the stroke to 0.5". I do this at my work all the time.

Great idea! I can't wait to see some pics & diagrams!
 

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I think it depends on how it is plumbed from the switch.

Just a thought, If you had a cylinder with too much stroke sitting around, you can use a Delrin hollow shaft or welded washers or something to limit the stroke to 0.5". I do this at my work all the time.

Great idea! I can't wait to see some pics & diagrams!
Actually, I screwed up in that post. The 3 types of 4-way/3-position valves are: pressure center, exhaust center and closed center.



The closed center doesn't seem to make much sense in this application...
 

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Discussion Starter #20
OKOK you impatient bastards! I'm home on my lunch break and here's the skinny:

I used 2 Clippard #UDR-1281-1/2 (http://www.clippard.com/store/display_details.asp?sku=UDR-12-1/2) rams for each shift rail. Beware, the thread size on the body of the cylinders is fine-thread and difficult to find. Even my local Fastenall store had to order it.

I used these RC-1281 (http://www.clippard.com/store/display_details.asp?sku=RC-1281) clevises for the attachments. The pins fit perfectly in my shift rail holes.

You'll need 2 each of these MPA-3p pilot actuators (http://www.clippard.com/store/display_details.asp?sku=MPA-3p) to do this the cheap way. (I'll mention more on this later.)

And the brains of the entire operation, the MJV-4 4-way spring return valve. (http://www.clippard.com/store/display_details.asp?sku=MJV-4) (You need 2.)

Your new TV-4DP "shift lever". (One needed.)(http://www.clippard.com/store/display_details.asp?sku=TV-4DP)

I used these PQMC08P quick connect fittings with some 1/4" hose to plumb it all. (http://www.clippard.com/store/display_details.asp?sku=PQ-MC08P-PKG) (You need A LOT!)

And finally, the diagram: (Sorry for the large file.)



Basically, you screw the pilot actuators onto the spring return valves, which depending on if they are pressurized or not, changes which port the air comes out of on the spring return valve. Plumb it like in the diagram and that gets you your 3 positions.

Obviously, These are all Clippard part numbers. It can probably be done with other valves from other companies. I do know for a fact though that Clippard is the only company that makes a switch even remotely similar to the TV4DP listed above. I searched for days for one that had a metal instead of plastic switch and never found one. Upon real-world testing though, the plastic ones are holding up just fine.

Also, keep in mind when you order this stuff, everything listed above is for ONE SHIFT RAIL ONLY. If you are doing an NP205 or other 2-speed t-case, you will need a total of:

2x TV-4DP
4x MPA-3p
4x MJV-4
4x UDR-1281-1/2

If you are doing a Stak 3-speed, you'll need:

3x TV-4DP
6x MPA-3p
6x MJV-4
6x UDR-1281-1/2

Finally, as mentioned earlier, the valves listed above are not the only valves that you can do this with. Clippard has some air manifold valves with baseplates that could also make it work, but the baseplates are made of clear plastic and I don't trust that for on the trail. Those valves are also tremendously more expensive. They also have other brass valves with built-in pilot actuators, but they are a lot larger than this setup and also more expensive. I believe that this valve combination is by far the easiest, cheapest, and most simplistic one available at this time. Simple is important because simple = more reliable. (Which mine are.)

So basically, here's a drawing of a bird's eye view of my setup if there were no floor directly under my driver's seat:



Hope this helps.

J. J.
 
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