Vacuum shift actuator

[Papimotors]

hello

Does anybody know where to get new Vacuum actuator Motors for front axle and transfer case ?

Are they both the same ?

[rmick]

They are different. You could lock in the front and change the vacuum plumbing to shift on the fly if you can't find a replacement.
http://amceaglesden.com/guide/Front_Axle_Lock

[Artmodels]

And isn't it that the ones that have the select drive button can be towed by front tires  tow dolly if it is in 2wd mode?

[Taylor]

The only way to flat tow any 4wheel drive vehicle, would be to place the transfer case in neutral. None of the Eagle’s have that capability. It can be done if the drive shafts are removed.

[Artmodels]

If you put the dash selector into 2wd, from what I see in the t case, the throughput to transmission still spins the output shaft of the transmission, but the front drive chain in the t case is not engaged and not spinning.  Wouldnt this be the same as just driving in 2wd mode, if rear tires are turning without being engaged to the front axle?  Then, it would be like any regular vehicle tow, where you put transmission into neutral?

Or is there something else that is happening inside the t case that I'm missing?  I know there is the silicone limited slip unit, but if chain is not spinning anyway in 2wd mode, isn't it immaterial if front wheels are also spinning(like when you are regular driving?)


What am I missing?

[MIPS]

My concern would be that without the engine running the transmission has no way to pump fluid for output shaft lubrication. AMC themselves stated in the TSM that unless you are going to tow with the rears on tow wheels, the driveshaft has to be disconnected. They wouldn't tell you to do that really annoying step unless they had good reason.

Are your motors bad with leaking diaphragms or are they just seized? You can free them if you have a vice and some penetrating oil.

[Artmodels]

No, we are picking up an 82 eagle in idaho and towing it 800 miles home.  Just didn't want to have to get a heavy flatbed type of trailer.  Probably easiest to just disconnect the rear u joint and tie up the driveshaft after we get it on the 2 wheel dolly.

[MIPS]

[Papimotors]

ok, thanks, so the vacuum shift motors are different, does anybody know where to get new ones ?

Yes, i know the shift to fly conversion

[AMC of Houston]

No new ones available.  NOS ones do pop up on Ebay occasionally; usually for around $100 each asking price.   Not sure what year you have; but here's the part number breakdown from the AMC parts books:

Axle shift motor:  8153621 (or J8153621) '81 thru '83;  8133621 (or J8133621) '84

T. Case shift motor:  3240125 (or J3240125) '81 thru '83;  53004597 '84;  53004596 '85 thru '88

Just because the part number is different year-to-year doesn't necessarily mean the part won't work the same year-to-year.  But I don't know for sure if they do indeed interchange.

[Illeagle1984]

I have heard of places that rebuild vacuum actuators or sell rebuild kits going back to 100 year old vehicles, ranging from headlight, wiper, HVAC, even vacuum door lock actuators (73-80 Mercedes). I wonder if they have coverage for these.

[Badvibes258]

Just food for thought I don't know, however the system uses pull rods, if you know the distance needed to pull them, you could uses electric actuators in theory. Making mountings might be an issue but might solve the issue?

Something like this might be a thought

Would need experimentation.

https://www.thewireszone.com/products/heavy-duty-power-door-lock-actuator-motor-12-volt-for-car-door

Another option
https://www.linak-us.com/products/linear-actuators/la12/

Likely the best.

https://www.ebay.com/itm/385205696988?chn=ps&var=653083095869&_trkparms=ispr%3D1&amdata=enc%3A1uETRfKxgQ0iA_d-Zlt-Pzw53&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&mkscid=101&itemid=653083095869_385205696988&targetid=1583904486362&device=m&mktype=&googleloc=9033181&poi=&campaignid=15275224983&mkgroupid=131097072938&rlsatarget=pla-1583904486362&abcId=9300697&merchantid=6296724&gclid=EAIaIQobChMIg7rxncjk_AIVcQitBh0Q1A6VEAQYBCABEgINvvD_BwE

[rmick]

Ive thought about that as well using solenoids. Most are a one shot pull would have to make sure it could handle a constant 12 volt. or have it reduce voltage to a holding power after initial 12 volt shot.

[Badvibes258]

I don't believe they need a "hold". Considering the use of vacuum I believe it will stay engaged until disengaged. Otherwise the transmission would overpower the vacuum.

It uses a 2 way vacuum.

Based on the direction the switch is moves which side of the diaphragm it is applied.

And based on how weak a vacuum Is I don't believe there is a need for "holding"