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Author Topic: 4wd switch?  (Read 9091 times)

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Offline caleb_fleming

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4wd switch?
« on: February 17, 2012, 06:27:28 PM »
I'm trying to find a way to get around the vacuum 4WD switch.  I want to change it over to a manual shift.  Has anyone done this?  If so would the shifter from a jeep work or do I need to make the shifter from scratch?  The main reason I'm trying to get around the vacuum operated shifter is the line keeps falling off the the fitting on the intake and I think the diaphragm might have a hole in it or just not working for some reason.   :banghead:

Offline JayNaga

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Re: 4wd switch?
« Reply #1 on: February 17, 2012, 06:47:49 PM »
There is a write up in eaglepedia

Offline DaemonForce

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Re: 4wd switch?
« Reply #2 on: February 17, 2012, 06:47:59 PM »
I know someone from the Florida Keys has done this to their Eagle but it's probably the vacuum+mechanical shift combination that I have in mind involving the NP229. If you have ANYTHING else, you could probably just take the shift housing from an 85 Wagoneer and append it to the floor shift housing on an Eagle. I'd try this out with the one that has been sitting in the picking yard for the past year but I can't really afford to be going into the yards lately. I know SOMEONE has done this before without engineering a clever seat lever so I know it's possible.

Oh yeah, Eaglepedia link. :/
« Last Edit: February 17, 2012, 06:50:12 PM by DaemonForce »
1983 Limited
AMC 258C {R2:27.Jun.13}
Carter 2681 {R2:28.Oct.12}
TorqueFlite A998 {R6: -20.Apr.12}
NP129 {R2:28.Apr.12}
M35-273 {???}
Compression: 0
Corrected Idle: 0RPM

Rebuild:
???

Offline eaglefreek

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Re: 4wd switch?
« Reply #3 on: February 17, 2012, 09:53:53 PM »
I know someone from the Florida Keys has done this to their Eagle but it's probably the vacuum+mechanical shift combination that I have in mind involving the NP229. If you have ANYTHING else, you could probably just take the shift housing from an 85 Wagoneer and append it to the floor shift housing on an Eagle. I'd try this out with the one that has been sitting in the picking yard for the past year but I can't really afford to be going into the yards lately. I know SOMEONE has done this before without engineering a clever seat lever so I know it's possible.

 
The floor shifter from a full size jeep is only for low range. It still uses the same vacuum switch that an Eagle does to shift from 2wd to 4wd. It wouldn't be too difficult to do with a heavy duty push pull cable.
1986 AMC Eagle Wagon 4.2L/4.0L head, AW4,NP242, Chrysler 8.25" rear.
1981 AMC Eagle Wagon As Seen On TV  Lost In Transmission


 

"I know he'd be a poorer man, if he never saw an eagle fly,
Rocky mountain high"  John Denver
Click for Fayetteville,TN Forecast" border="0" height="100" width="150

Offline mr.mindless

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Re: 4wd switch?
« Reply #4 on: February 17, 2012, 10:30:03 PM »
That's not entirely accurate, the shift lever does engage and disengage the front driveshaft.  There's just also a vacuum actuator that takes care of the CAD on the front axle...

I haven't quite figured out yet what that switch on the dash does.... just the CAD? or does it do something at the tcase as well? And from the full-time application I assume there has to be a center diff, but that would have to be locked out in 4x2 mode.

I guess I should catch up on Eaglepedia, huh? :)
Michael Maskalans
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'98 Dakota - tons & 42s
'97 Ram 3500 - 13sp RoadRanger

'87 Eagle Wagon 258/auto "Saint Michael" - Daily driver status.
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Offline JayNaga

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« Last Edit: January 08, 2019, 09:29:04 PM by Taylor Williams »

Offline captspillane

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Re: 4wd switch?
« Reply #6 on: February 18, 2012, 01:59:50 AM »
The AMC Eagle was designed to be all wheel drive. There is no appreciable difference from 2WD to 4WD. If someone tells you otherwise its because they've driven solid axle vehicles like the XJ their whole life. Its totally unnecessary to ever put an AMC Eagle in 2WD. AMC added it for only one reason; they realized that some people would only buy the car if they saw a 2WD mode available. Its a consequence of the Eagle existing before any other all wheel drive car existed.

All Eagles should have the front axle disconnect in the fully locked position at all times. That's true even if you insist on using 2WD. The factory agreed with this too and eventually eliminated the front axle disconnect without changing anything else. That is why later Eagles are called "shift on the fly." The disconnect was a reliability disaster without any worthwhile effect. It also required the car to be sitting still in order to shift. To disconnect it permaneantly you simply need to remove the cover and use a hose clamp to keep the shaft in the fully extended postion. I included a picture of the last one I did.

At the transfer case you should just remove the vacuum diaphragm and eliminate all the troublesome vacuum lines to the whole system. The vacuum diaphragm does more than shift, however, it also holds the transfer case in gear and prevents it from popping into neutral. You need to use rope to pull tension against the shift lever once you remove the diaphragm. For 4WD the top of the shift lever is tied forward to the transmsiion. I also included a picture of the last one I did.



« Last Edit: February 18, 2012, 04:02:12 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 eaglefreek

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Re: 4wd switch?
« Reply #7 on: February 18, 2012, 08:41:43 AM »
That's not entirely accurate, the shift lever does engage and disengage the front driveshaft. 
Which lever are you taking about? The factory vacuum switch or the FSJ floor lever?
1986 AMC Eagle Wagon 4.2L/4.0L head, AW4,NP242, Chrysler 8.25" rear.
1981 AMC Eagle Wagon As Seen On TV  Lost In Transmission


 

"I know he'd be a poorer man, if he never saw an eagle fly,
Rocky mountain high"  John Denver
Click for Fayetteville,TN Forecast" border="0" height="100" width="150

Offline eaglefreek

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Re: 4wd switch?
« Reply #8 on: February 18, 2012, 10:51:40 AM »
Actually the first AWD car was the 1907 Dernburg-Wagen.
1986 AMC Eagle Wagon 4.2L/4.0L head, AW4,NP242, Chrysler 8.25" rear.
1981 AMC Eagle Wagon As Seen On TV  Lost In Transmission


 

"I know he'd be a poorer man, if he never saw an eagle fly,
Rocky mountain high"  John Denver
Click for Fayetteville,TN Forecast" border="0" height="100" width="150

Offline captspillane

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Re: 4wd switch?
« Reply #9 on: February 18, 2012, 02:49:21 PM »
I'll add "mainstream" to the sentence so its still valid. The Eagle came out before Subaru coined the term "all wheel drive." Subaru offered part time four wheel drive in 1974 but did not come out with full time "All wheel drive" until 1986. The AMC Eagle called it "Full time 4WD" but did not offer any other mode in 1980, making it the first mainstream all wheel drive car before there was such a thing as all wheel drive. Who cares? Point is that they added the 2WD mode as an after thought to boost sales. It was well engineered to be fine without it.

The Borg Warner 1339 transfer case actually made a Jeep full size truck and a CJ7 full time four wheel drive in 1973 through 1979. Only AMC offered that unit and it was bizarre. I don't call them all wheel drive because they had solid front axles that do not perform any where near as well as an AMC Eagle's CV shafts and independent front suspension. A "Quadratrac" CJ7 will have slightly less fuel mileage and more front axle wear than a CJ7 with a normal Dana20 and disconnecting front hubs. I refer to that as full time 4WD and the Eagle as AWD because thats the precise modern meaning of those terms, even if it took a few decades to iron out what means what.

The term "Full-time 4WD" in a "Selec-trac" Cherokee is completely different than the "Full-time 4WD" advertised with the Eagle. In a Cherokee the solid axle Ujoints create a surge in the wheel when you're in four wheel drive. It causes resistance and considerable undue wear, even on wet pavement.  That also causes a drop in fuel mileage. In a Grand Cherokee the system is better but there is still turning resistance. Many Grand Cherokee owners swap their Full time NP249 transfer case for the 242 and they notice a very tiny difference in fuel mileage. The Eagle, however, has a completely different front end directly equivalent to the modern All Wheel Drive cars available. They have no appreciable difference or undue wear.

The shift lever on the dash sends vacuum to the shift lever at the transfer case. The vacuum enters the transfer case shift lever and then exits from another port to go to the shift fork at the axle disconnect. The "shift on the fly" Eagles eliminated the axle disconnect and used a transfer case shift lever that simply deleted the exit port that would have gone up forward to the axle. It is true than that the shift lever in the dash works both the transfer case and the front axle disconnect.





« Last Edit: February 18, 2012, 02:55:36 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

68AMXGOPAC

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Re: 4wd switch?
« Reply #10 on: February 18, 2012, 03:30:16 PM »
The AMC Eagle was designed to be all wheel drive. There is no appreciable difference from 2WD to 4WD. If someone tells you otherwise its because they've driven solid axle vehicles like the XJ their whole life. Its shear ignorance to ever put an AMC Eagle in 2WD. AMC added it for only one reason; they realized that some ignorant people would only buy the car if they saw a 2WD mode available. Its a consequence of the Eagle existing before any other all wheel drive car existed.

All Eagles should have the front axle disconnect in the fully locked position at all times. That's true even if you insist on using 2WD. The factory agreed with this too and eventually eliminated the front axle disconnect without changing anything else. That is why later Eagles are called "shift on the fly." The disconnect was a reliability disaster without any worthwhile effect. It also required the car to be sitting still in order to shift. To disconnect it permaneantly you simply need to remove the cover and use a hose clamp to keep the shaft in the fully extended postion. I included a picture of the last one I did.

At the transfer case you should just remove the vacuum diaphragm and eliminate all the troublesome vacuum lines to the whole system. The vacuum diaphragm does more than shift, however, it also holds the transfer case in gear and prevents it from popping into neutral. You need to use rope to pull tension against the shift lever once you remove the diaphragm. For 4WD the top of the shift lever is tied forward to the transmsiion. I also included a picture of the last one I did.




I enjoy reading your posts, generally full of valuable info. , but to claim the term " ignorance" while speaking of others and AMC is a little much.

68AMXGOPAC

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Re: 4wd switch?
« Reply #11 on: February 18, 2012, 03:33:32 PM »
I had one of those old Subaru wagons , it had 2wd or 4wd , and low range shifter also. I didn't see it on a later model I had. I think the first one was like an 87 or 88 , and the later one a 91 or 92 , both were standard transmission models.They sure would go, but prone to rotting out around the rear axle mounts and rear wheel bearings going it seemeed.Didn't help I carried a bunch of tools in the back.

Offline mr.mindless

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Re: 4wd switch?
« Reply #12 on: February 19, 2012, 06:30:35 PM »
That's not entirely accurate, the shift lever does engage and disengage the front driveshaft. 
Which lever are you taking about? The factory vacuum switch or the FSJ floor lever?

I was referring to the floor shifter in Jeeps and Dodges with CAD front axles and manually shifted tcases.


Michael Maskalans
Codriver, Game Day Racing - Ultra4 #571
'98 Dakota - tons & 42s
'97 Ram 3500 - 13sp RoadRanger

'87 Eagle Wagon 258/auto "Saint Michael" - Daily driver status.
'84 Eagle Wagon 258/auto "Swamp Thing" - project in need of a bath
'84 Eagle Wagon 258/4sp - parts car

Offline carnuck

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Re: 4wd switch?
« Reply #13 on: February 19, 2012, 07:33:56 PM »
CAD tcases in most XJs have a vacuum port that controls the front diff. You can ignore the port if you don't have a vacuum axle in them. If you have an Eagle tcase however, the vacuum front diff is controlled

(I just had 2 weird error messages while trying to post this. First one said POP failed, then I was told I couldn't post here?)
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Offline 83sx4boc

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Re: 4wd switch?
« Reply #14 on: January 08, 2019, 06:05:41 PM »
is there any videos out there on this process?

 

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