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.
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.
