Vacuum Disconnect. Replace With Solenoid?

I dont plan on doing this till summer, the only place I have to work is the driveway which is covered in snow.
But, I figured I would ask this to get some ideas...

Has anyone replaced the Vac disconnect with a Solenoid? I was thinking just replace the vacuum motor with a solenoid powered by a relay and have a switch in the dash for when you need to lock the front. You would also have the advantage of essentially having 2lo when the solenoid is not activated, because the front axle isnt locked and no power is going to the ground in front.

What do you guys think? Anyone have specs on a solenoid that would work, or specs on the length of throw/shaft length/shaft diameter for the vacuum motor?

Thanks

Not a bad idea.

I have an Aussie Locker in front, and a Posi-Lok cable so I can disco during normal street driving.

Before I put in the Aussie Locker/Posi-Lok I simply "locked" the axle, which is what Jeep did post-91 with the non-disco D30 with the NP/NV231 XJs anyway.

JP Magazine did an article on drilling the fork and using a 1/4 bolt/nut to lock the CAD collar. I simplified the process by taking a shock bolt sleeve of the appropriate ID, cutting it off with a chop-saw to the correct length (a little grinding and clean-up filing) and then put the collar in the engaged position, slip the "spacer" and the shift rod together in the housing, re-install the "E" clips and all done.

Nighttime Bump..
Anyone have any info?
Maybe the Vacuum Motor specs?

honestly i dont know half the shhh ya do joe and still ya make it sound easy!!

BTT This idea sounds pretty good... Not sure if it's been done before, but I was thinking about doing the same thing. The one concern I have is how would the solenoid hold-up when wet?

Yuri said:

BTT This idea sounds pretty good... Not sure if it's been done before, but I was thinking about doing the same thing. The one concern I have is how would the solenoid hold-up when wet?

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There must be solenoids appropriate for "harsh" environments that are suitably sealed to the elements.

Why not just run with a cable/posi-lok style disconnect? Simplifies it, and no electronics involved.

Johnnie Walker said:

Why not just run with a cable/posi-lok style disconnect? Simplifies it, and no electronics involved.

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As posted earlier, I have the Posi-Lok and it works great, and someone recently posted a write-up for a "Po Man's Posi-Lock", but an electrical activated one could be quite cool, and probably cheaper--switch, wire, solenoid, sweat. I say go for it. Hell, if the price is right it could be his key to retirement, but D30 CAD axles are a dying breed so that means a limited market.

If I remember correctly the throw is only about an inch or less, and from my limited knowlege the ability to ' lock unlock" could be a benefit for some people. The vac motor itself is very weak. I could get it to work with my hand vac unit. An electric would be neat. I like to think that you dont allways have to do what others are doing.

The real problem with solenoids is the constant current draw - they heat up pretty nicely once you are just holding something in place with the same current you use to pull the actuator in. A good solenoid controller applies full current to move the actuator, then holds at a much lower current to keep it in place. Personally I would use a worm-drive motor driving a lead screw far before I would use a solenoid - a worm drive will result in the actuator staying where you put it (and requiring nowhere near the same torque from the motor) and the lead screw makes linear motion easy. You could probably hack something up reasonably quickly with an old wiper motor, they're high torque and cheap. Heck the rear wiper motor even comes with a little "return to park" switch setup you could modify... it's riveted shut though so it might be hard to work with, and would need weatherproofing and armoring.

EDIT: if you want cable driven, a return spring and a cruise control actuator (electronically activated vacuum solenoid) would be a good choice, and easily procured at a junkyard.

kastein said:

The real problem with solenoids is the constant current draw...

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<--brain fart... Yea, I should have thought about that. Not something you want in an evironment that gets wet. But the 'cruise control parts' may be worth investigating further.

I think the worm drive would be cool, eliminate the draw issue.

Converting to use a cruise actuator is really a step backward--you would just be adding an electrical component to what is already a vacuum system, and those cruise actuators are no way as stout as the original vacuum motors so you would have to "armor" it--no gain IMHO.

True. I was thinking use the cruise actuator in stock form and have the actuator itself mounted in the engine compartment with the cable leading down to the axle, but yeah, it's a solution looking for a problem. Really I'd suggest screwing around with some old wiper motors or even power window motors for a while and see what you come up with.

worm drive would also have the advantage if you slotted the worm. You could then lock the axle in with a screwdriver if the eletrics fail.

Personally, I'd just do the homebrew posi lock. It's not hard, you just have to drill some holes in your vac disco unit after you gut it.

I just ended up lockign the actuator over after getting stuck in a stupid situation for the 3rd or 4th time over the winter.

I have seen the solenoid done before, but I cant find it anymore. Someone did it on a Wrangler With a CAT fuel shutoff solenoid.

ok, how about this... Could you power the stock disconnect actuator with air pressure instead of vacuum?

the reason I ask is: I'm swapping a disconnect HP30 into my TJ. I was going to convert it to a solid shaft, but found a 95YJ disconnect shaft (big U-joint) in the junkyard. So I figured that I'd try and make the disconnect work. If it fails, then I'll go solid shaft and be done. The only stock vacuum stuff I have is on the axle end (nothing on the T-case).

You can also find non-disconnect big U-joint shafts in certain year ABS-equipped XJs before 95/96 or so (as usual I forget the exact year split), and in all XJs from that year on.