4wd switch?

[caleb_fleming]

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.   

[JayNaga]

There is a write up in eaglepedia

[DaemonForce]

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. :/

[eaglefreek]

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.

[mr.mindless]

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?

[JayNaga]

http://www.amceaglesden.com/~iowaeagl/guide/index.php?title=Cable_Operated_Transfer_Case_Shifter_-_Joshpit2003

[captspillane]

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.

[eaglefreek]

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?

[eaglefreek]

Actually the first AWD car was the 1907 Dernburg-Wagen.

[captspillane]

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.

[68AMXGOPAC]

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]

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.

[mr.mindless]

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.

[carnuck]

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?)

[83sx4boc]

is there any videos out there on this process?