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Author Topic: Vacuum shift actuator replacement?  (Read 3969 times)

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Offline txjeeptx

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Re: Vacuum shift actuator replacement?
« Reply #15 on: July 18, 2012, 10:14:00 AM »
I was thinking exactly the same thing - a power door lock solenoid may be a decent replacement - easy to wire up, and reliable.
'82 Eagle SX/4 "Golden Eagle", '89 YJ rock-crawler, '79 Jeep Cherokee Golden Eagle "FSJ", 'o7 F150 Supercrew FX/4 daily driver, 'o8 Solara Convertible - and a very happy wife - she left me, total surprise, her loss.

Offline carnuck

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Re: Vacuum shift actuator replacement?
« Reply #16 on: July 18, 2012, 11:43:55 AM »
I have a used one in my for sale stuff
Price drop! I'm too sick to work on them.

FOR SALE
'87 Comanche 4.0L AW4/NP242 3.73 gears, lifted 5" on near new 33" tires $2500 obo Needs spare trans I have put in, but it's still drivable

'82 Eagle Wagon (Brown Betty) 4.2L/727/NP229 with 8.25 XJ rear axle and soon a non-vacuum 3.08 front to match. 235/75/15 tires. It's down to minor body work (someone creamed my driver's door but I have another in good shape) almost zero rust, but needs interior work (seats are worn and carpet torn). $2000 but about to go up due to more work being done.

Pics of my other for sale stuff http://tinyurl.com/jimsclads

Offline captspillane

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Re: Vacuum shift actuator replacement?
« Reply #17 on: July 18, 2012, 08:02:06 PM »
I doubt an electric solenoid will work. A car window doesn't fall if you disconnect the battery. It has a natural resistance to movement that lets the motor turn on for movement and then off once the movement isn't needed. A door lock is similar. The motor just gives a push and a pull to mechanically mimic the motion of your hand pushing the lock. Indents in the lock mechanism are still critical to keep it engaged.

In contrast the vacuum diaphragm is designed to pull steady pressure on the linkage at all times. If the vacuum is disconnected the transfer case will pop out of gear. This is why I doubt you can use a Jeep cable shifter with our transfer cases. You would have to rely on the indent on the handle to hold enough pressure to keep in gear. Even if it would work for a little while any slack in the system that develops would leave you stranded. All the other available Jeep transfer cases, like the NP242 or NP231, stay in gear on their own and just need a push to pop to the next gear. Once it indents inside the transfer case it stays there on its own.

If you run a solenoid to electronically actuate the shifter you would need one that has an internal brake that switchs open during movement and closed when stationary. Such a beast exists, but it is much more complex and bulky than what you are imagining.

Look at the electonic solenoid on the back of an SX4 hatch. It is pretty large and bulky. If you run electricity to it for more than about 2 minutes it will melt all the insulation around the internal wires, in turn destroying it and starting a fire. A smaller solenoid will last even less time switched on. They are designed for a very tiny duty cycle.
« Last Edit: July 18, 2012, 08:09:03 PM by captspillane »
Currently Inspected and Insured as of Jan 2013:
-1985 Eagle Station Wagon 258 T5 Stickshift
-1980 Eagle Station Wagon 258 Auto Fuel-injected with GM TBI

Minor Repairs Underway:
-1982 Eagle SX4 258 T5
-1981 Kammback 2.5L Iron Duke T5

Restoration Efforts Near Completion:
-1982 SX4- 401 NV3550
-1983 SX4- 4.5 MPI NSG370 (6 Speed)

Restoration Efforts Underway:
-1985 SW- 4.0 MPI AX15
-1982 SX4- 4.0 AW4
-1981 SX4- SD33T NV4500 (Turbodiesel 5 speed)

Future Rescue Efforts- '85 Maroon SW, '87 Limited SW, '84 Limited SW, '87 4 door Sedan, '81 2 door Sedan, '88 White SW, '77 4 door Hornet, '74 2 door Hornet, '79 Spirit AMX, '81 Kammback.

RIP- Red '81 SX4, '84 4dr Sedan, '84 SW, '81 SW, '80 Spirit, '83 SW, '83 4dr Sedan

Offline captspillane

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Re: Vacuum shift actuator replacement?
« Reply #18 on: July 18, 2012, 08:13:46 PM »
A generic door lock actuator pulls or it pushes when you push your door lock button. It doesn't apply any force when you're not pushing the button. It will not apply the necessary constant pressure.

Push a car lock down, it stays down. Pull it up, it stays up. There is something else keeping it from moving. Likewise an XJ transfer case handle gets pulled up to shift, but then you let go and it stays right where you left it. That's not how our Eagle transfer cases work.

Our Eagle transfer cases need a steady one pound of pressure to stay in gear. If they do not they absolutely will pop into a "false neutral." In between gears the car cannot move and damage absolutely will occur. The transfer case will be ruined if you let it pop out too often.
Currently Inspected and Insured as of Jan 2013:
-1985 Eagle Station Wagon 258 T5 Stickshift
-1980 Eagle Station Wagon 258 Auto Fuel-injected with GM TBI

Minor Repairs Underway:
-1982 Eagle SX4 258 T5
-1981 Kammback 2.5L Iron Duke T5

Restoration Efforts Near Completion:
-1982 SX4- 401 NV3550
-1983 SX4- 4.5 MPI NSG370 (6 Speed)

Restoration Efforts Underway:
-1985 SW- 4.0 MPI AX15
-1982 SX4- 4.0 AW4
-1981 SX4- SD33T NV4500 (Turbodiesel 5 speed)

Future Rescue Efforts- '85 Maroon SW, '87 Limited SW, '84 Limited SW, '87 4 door Sedan, '81 2 door Sedan, '88 White SW, '77 4 door Hornet, '74 2 door Hornet, '79 Spirit AMX, '81 Kammback.

RIP- Red '81 SX4, '84 4dr Sedan, '84 SW, '81 SW, '80 Spirit, '83 SW, '83 4dr Sedan

Offline jim

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Re: Vacuum shift actuator replacement?
« Reply #19 on: July 19, 2012, 12:41:30 PM »
I think txjeeptx answered the original question, which is that the front axle acuator will not work on the tc without a lot of hassle, so maybe it will be ok to hijack this thread.
I have wondered about a 2 cable system, one to pull the lever either way as needed and lock.
My preferred method would be a solid rod linkage system of some sort.
It's moot for me because either one would be too much for me to fabricate.
I'm right 98% of the time, and I don't care about the other 3%.
"The constitutions of most of our States assert that all power is inherent in the people;
that... it is their right and duty to be at all times armed."
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Offline BenM

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Re: Vacuum shift actuator replacement?
« Reply #20 on: July 19, 2012, 04:27:01 PM »
If you use a lock actuator you would need some kind of over-center spring. It is possible to attach a spring to a lever in such a way that it will pull the lever to either side as long as the motor can overcome the lever and the spring tension to pull the lever to the center and then past it. You would attach the spring so it goes parallel to the lever when the lever is centered.

There are "liner actuators" or "linear motors" that hold in position, but I have no pricing on one or any idea how it would hold up under a car.
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1987 AMC Eagle Sedan -- 1976 Pacer Coupe -- 1968 Pontiac Tempest Custom S -- 1940 Mercury (& a 2002 Jetta Turbodiesel, 5 spd., the Wife's Daily Driver)

Offline philotomy

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Re: Vacuum shift actuator replacement?
« Reply #21 on: July 20, 2012, 08:39:45 AM »
I think when the time comes I'll buy a decent used one from a full size jeep,for now I think a cable tied off (or bungee cord)will have to do.
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Offline carnuck

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Re: Vacuum shift actuator replacement?
« Reply #22 on: July 21, 2012, 07:14:44 PM »
I think txjeeptx answered the original question, which is that the front axle acuator will not work on the tc without a lot of hassle, so maybe it will be ok to hijack this thread.
I have wondered about a 2 cable system, one to pull the lever either way as needed and lock.
My preferred method would be a solid rod linkage system of some sort.
It's moot for me because either one would be too much for me to fabricate.

There is a company that makes them for XJs and others for @$130. I made my own for my FSJ for $40 in parts including a PTO cable from NAPA. (mind you, I got discount on them)
Price drop! I'm too sick to work on them.

FOR SALE
'87 Comanche 4.0L AW4/NP242 3.73 gears, lifted 5" on near new 33" tires $2500 obo Needs spare trans I have put in, but it's still drivable

'82 Eagle Wagon (Brown Betty) 4.2L/727/NP229 with 8.25 XJ rear axle and soon a non-vacuum 3.08 front to match. 235/75/15 tires. It's down to minor body work (someone creamed my driver's door but I have another in good shape) almost zero rust, but needs interior work (seats are worn and carpet torn). $2000 but about to go up due to more work being done.

Pics of my other for sale stuff http://tinyurl.com/jimsclads

Offline 85AmCfreak

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Re: Vacuum shift actuator replacement?
« Reply #23 on: July 22, 2012, 11:08:50 PM »
Do you have a part number casper? Maybe someone could try this out and do a write up??
I Don't know why. But everybody's always talking about their STI or That guys EVO, I think I'll stick with my old, but reliable AmC. Did I ever tell you I was Full blooded Eagle?

Offline txjeeptx

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Re: Vacuum shift actuator replacement?
« Reply #24 on: July 22, 2012, 11:26:52 PM »
Different mfgrs have used different types of door lock solenoids over the years. I recall the 80's Dodge truck solenoids hold their own position in a latching sort of way. They also snap to between the positions pretty forcefully. Have pinched fingers messin with em on my dad's ol' Ramcharger.

I agree completely that if the solenoid doesn't somehow "latch" itself into position, you'll very quickly burn up the coil  in it (or the supply wire, or fuse, if yer smart enough to remember to include one), since it is an electromagnet, which is essentially a looped-up wire short circuit.

Sure would be cool if the auto-trans shifter cable from some common, junkyard late model application could be easily repurposed into a t-case shifter cable for our Eagles?  -just another idea. Would still need to figure out a shifter handle/lever & mounts for everything.
'82 Eagle SX/4 "Golden Eagle", '89 YJ rock-crawler, '79 Jeep Cherokee Golden Eagle "FSJ", 'o7 F150 Supercrew FX/4 daily driver, 'o8 Solara Convertible - and a very happy wife - she left me, total surprise, her loss.

Offline BenM

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Re: Vacuum shift actuator replacement?
« Reply #25 on: July 23, 2012, 11:07:47 AM »
You could use a microswitch to cut the power when it reaches the limit. It would take a small, stiff spring a part of the actuator arm to give you just a bit of play on the engagement or you'd have to be really accurate with the switch placement, but I bet a spring-loaded linkage arm is an OEM part for a ton of stuff. A two-pole microswitch could even illuminate an indicator to tell you you're in position.
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1987 AMC Eagle Sedan -- 1976 Pacer Coupe -- 1968 Pontiac Tempest Custom S -- 1940 Mercury (& a 2002 Jetta Turbodiesel, 5 spd., the Wife's Daily Driver)

Offline Softbuster

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Re: Vacuum shift actuator replacement?
« Reply #26 on: July 23, 2012, 08:53:27 PM »
Here is my Idea:  Remove the failing vacuum actuator and install this in its place.  Its a piece of threaded rod, the same size as the Hole in the original mounting bracket, with a chain link (repair-a-link for a bike chain or something) welded on the end.  (you will need the little pin from the actuator to attach it at the shift lever)
The threaded rod is long enough to be able to put the t-case in 2wd or 4wd.   Just that whenever you want to change it you have to crawl under the car with two wrenches and loosen the nuts, move to the desired position and re-tighten the nuts against the mounting bracket on each side.     Or just leave it in 4wd forever!

I like things to be simple and Work every time I want it to.

Question....   should I install this in place of the failing actuator to sell the car or let the buyer decide what to do??





« Last Edit: July 23, 2012, 08:55:57 PM by Softbuster »

Offline mach1mustang351

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Re: Vacuum shift actuator replacement?
« Reply #27 on: July 23, 2012, 09:35:11 PM »
What if someone went with a old school style stick shift and made some kind of detent setup. 

Something that works like if you push the stick to the right it comes out of the detent, pull into 4wd and then let it move back to the left to lock the stick and linkage in place. 

It all makes sense in my head... i'll try to draw a picture
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1987 AMC Wagon 4.0L, 3" Body lift, AX15, NP242
1981 AMC SX4 Sport
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Offline carnuck

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Re: Vacuum shift actuator replacement?
« Reply #28 on: July 24, 2012, 02:12:35 PM »
I'm putting an FSJ lever under my seat.
Price drop! I'm too sick to work on them.

FOR SALE
'87 Comanche 4.0L AW4/NP242 3.73 gears, lifted 5" on near new 33" tires $2500 obo Needs spare trans I have put in, but it's still drivable

'82 Eagle Wagon (Brown Betty) 4.2L/727/NP229 with 8.25 XJ rear axle and soon a non-vacuum 3.08 front to match. 235/75/15 tires. It's down to minor body work (someone creamed my driver's door but I have another in good shape) almost zero rust, but needs interior work (seats are worn and carpet torn). $2000 but about to go up due to more work being done.

Pics of my other for sale stuff http://tinyurl.com/jimsclads

Offline jim

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Re: Vacuum shift actuator replacement?
« Reply #29 on: July 24, 2012, 07:27:37 PM »
I'm putting an FSJ lever under my seat.
Attached to what how?
I'm right 98% of the time, and I don't care about the other 3%.
"The constitutions of most of our States assert that all power is inherent in the people;
that... it is their right and duty to be at all times armed."
--Thomas Jefferson to John Cartwright, 1824. ME 16:45
What part of "shall not be infringed" do they not understand?
08 Impala
01 Yukon 4X4
(There's more to life than fuel mileage)
83 Eagle wagon; shared responsibility as daily driver
88 Eagle white woody wagon; shared responsibility as daily driver
86 wagon parts car
Click for Little Rock, AR Forecast" border="0" height="100" width="150

 

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