Controlling Hi/Low Range and Front Axle Lock From a Shift Knob

[Lieutenant Dan]

So yesterday I had the deuce out in the evening at my wife's relatives and her one uncle said to me something very cool and interesting. He's been a truck driver for many years.

He said about using a eaton fuller 13 spd shift knob on the truck and using the air switches to control the Hi/Low Range and the front axle lock for 6x6. I thought that was an awesome idea and was thinking before I even got my deuce about putting a air switch in and using a air cylinder to shift the transfer case in and out of Hi/Low.

If you look at the picture of the shift knob the front switch is for the Hi/Low splitter and the side red switch is used for the Hi range splitter. Both are air switches and use 5/32 dot air line and the push to connect fittings.

now for me it would be nice to control all drive line operations from the shifter. It would be easier to split shift and if your offroading flipping in and out of 6x6 or 4x4. You could also use the switches for air lockers or maybe and air operated exhaust brake.

The shifters aren't expensive. On ebay I found a dorman replacement for $34. Idk if it comes with the push to connect fittings but they can be had cheap at grainger for a few dollars a piece and it needs 4. Air cylinders are cheap through mcmaster for maybe $30 and would just have to fabbed to mount under the truck and push on the selector shaft. I would make it so it is a single throw cylinder and it would constantly push out to keep the transfer case in hi range so if if there ever was a leak or a problem with the system you could still get home. When air is applied the cylinder would close and pull the transfer case into low range. Very simple operation.

What do you guys think about this? I think it's good idea and I'm going to give it a whirl.

 

[ATPTac]

To start, this is solely my opinion based on my use of my trucks. That being said:

Sounds like a good idea in theory. I think it might get overly complicated once you really start diving into the project. That's a lot of air lines and potentially a lot of headache if things start acting squirrely. The only thing that I think could be beneficial is switching from low to high on the fly. But even then, I don't really haul anything heavy, so I've never even really used low range. Plus I'd be skeptical about having an air cylinder engaging/disengaging low to high.

As far as the 4x6 to 6x6 switch, I don't think reaching over and flipping the current switch is that big of a hassle, not big enough to justify making a mod for it. I guess it really boils down to what you use your truck for. For instance, I do nothing but city/highway driving with our trucks, so I have yet to need to engage the front axle. Now I'm not saying I'll never need to use low range or engage the front axle, but if/when I do, it will be rare enough to where I'm ok with its current set up. If you plan to use yours off road quite a bit then this could potentially be beneficial if you can get it to work. Its your truck, if you want to do it and think you can get it working, go for it.

 

[Another Ahab]

Simple works already, as is. But interested to see where this goes. Subscribed.

 

[Stan]

Not for me but kinda neat. Something to think about is the volume of air needed to operate the cylinders and what kinda restriction the 5/32 line would create. The current air switch has something like 3/8 line. This could make for very slow shifts. Maybe an air relay, (??) low volume air controls high volume air to actually do the work.

 

[m-35tom]

yes, you would need a controler

 

[Lieutenant Dan]

True didn't think of that. Those are easy enough we use them at work on trailers in the air lift bags on a steerable lift axle.

 

[m16ty]

I see no reason why it wouldn't work. It would take a pretty complicated cylinder and linkage setup to also have a neutral in the t-case though.

 

[Lieutenant Dan]

I don't really see a need for neutral in the transfer case. Atleast not in my truck. I don't have a pto winch and never plan on it. I don't even know how that works or if the transfer case would need to be in neutral for it to work.

 

[m16ty]

The main reasons you'd need a neutral would be for a t-case PTO or if you flat tow the truck. If you do add a air shifter I'd keep some means to shift it manually if needed.

 

[Lieutenant Dan]

Ok so the shifter came today..... looks great and fits my hand even better then the ball I have. It will need to be modified internally because the side red switch is for the high range splitter and won't let me engage 4x4 with the front switch in the low range position. Easy enough though just grinding some plastic away.

I also got the air relays from work. They They will work perfectly. They use a 1/4 npt ports and I'll use 3/8" dot air line. It has a supply and delivery port then the signal port from the shifter. When it is plumbed NC it will exhaust the pressure back though the valve which I will run a line up to the filter housing. Then when I send a air signal to the valve it closes the exhaust and sends the supply to the delivery out to the transfer case. Should work good.

I'll also have to weld a bolt onto the shifter lever to adapt to the knob.

 

[rustystud]

Lt Dan I think this is pretty cool ! I'm all for it ! As an older member with a bad back and shoulders, trying to shift the transfer case on the fly, splitting the gears is really hard for me. The idea of having this on the shift knob is really a body saver. I hope this works out and that you will show us how you do it .
Thanks,
rustystud.

 

[61sleepercab]

Keeping eyes on road instead of head down while reaching in floor for transfer shifter ? You know switches on shifter must be a good idea or high/low switch on Eatons would be on dash!!

Keep up project and take pictures along the way. Mark

 

[Lieutenant Dan]

I surely will.... probably continue more in a few weeks as the bed comes off and the truck gets re plumbed

 

[Lieutenant Dan]

I got the fittings today and the line and cylinder should be here tomorrow.

I'm going to do it a little different then what I wanted to. Idk if the cylinder will fit in the tunnel above the transfer case but I'm hoping it will. If not I'm going to put it in the cab and enclose it like the tunnel. I'm going to cut the lever down and use a clevis to push/pull on the lever. I got a single acting bimba cylinder 1 1/6" and it says it will push 105 lbs of force. In resting mode it will be in and have the transfer case in high. I will probably have to use some sort of return spring to help pull it back into high. When I put the switch down for low it will fill the cylinder with air and push the transfer case into low. I went out and was playing with it yesterday evening a little and it measured 4" of travel at the floor. Where the lever comes through.

If this isn't enough I will get a dual acting cylinder and keep a constant air pressure of about 40 psi regulated to keep it in high. Then when I throw the switch it will overpower the 40 psi and push out into low range. I thought the shifter would control a dual acting cylinder but it won't.

 

[Hainebd]

With air shift transmissions, they use very short throws and must be in neutral before shift happens. Not doing so will wear syncros out quickly. I agree reaching down to split is a pain. I thought of extending or bending T case lever but would be longer throw. I am interested and believe small bore cylinder with short air runs.

 

[Lieutenant Dan]

I think it's going to work great. The front lock won't be a problem since it's already air operated and I just changing the switch. The hi/lo will be the challenge but I think I can get it to work.

 

[Seth_O]

Interested in this one - I have a TC that likes to pop out of high, it would be cool if this solved that. The current bungee-cord solution has lost its novelty........

 

[zebedee]

Like the mod. Only down side I can see will be all the "You put an 18 speed in there! Wow. How did yuh do that?", comments.

I went for the simpler transfer lever extension... came across a load of spare knobs - had to do something with em!

 

[bonedoc]

Sounds like a cool idea! Looking forward to seeing it progress

 

[welldigger]

Interested in this one - I have a TC that likes to pop out of high, it would be cool if this solved that. The current bungee-cord solution has lost its novelty........

You will destroy the shift fork doing that. You need to open your transfer case up and put new synchronizers in.