News: Putting FUN and FRIENDLINESS, FIRST into owning and learning about AMC small bodied cars, primarily Eagles, Spirits and Concords as well as vehicles built in AMC's Mexican subsidiary, VAM.

The AMC Eaglepedia can now be accessed using the buttons found below  This is a comprehensive ever growing archive of information, tips, diagrams, manuals, etc. for the AMC Eagle and other small bodied AMC cars. 

Also a button is now available for our Face Book Group page.


Welcome to the AMC Eagles Nest.  A new site under "old" management -- so welcome to your new home for everything related to AMC Eagles, Spirits and Concords along with opportunities to interact with other AMC'ers.  This site will soon be evolving to look different than it has and we will be incorporating new features we hope you will find useful, entertaining and expand your AMC horizons.

You can now promote your topics at your favorite social media site by clicking on the appropriate icon (top upper right of the page) while viewing the topic you wish to promote.


  • March 28, 2024, 10:25:41 AM

Login with username, password and session length

Author Topic: Vacuum shift actuator  (Read 1610 times)

0 Members and 1 Guest are viewing this topic.

Offline Papimotors

  • Hatchling
  • *
  • Posts: 8
  • Thumbs Up 1
Vacuum shift actuator
« on: October 09, 2022, 04:00:36 PM »
hello

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

Are they both the same ?

Offline rmick

  • Eagle Sport
  • ****
  • Posts: 386
  • Thumbs Up 40
Re: Vacuum shift actuator
« Reply #1 on: October 09, 2022, 11:10:42 PM »
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
72 Javelin AMX
72 Javelin SST
72 Gremlin with 4.0
81 SX 4

Offline Artmodels

  • Eagle
  • **
  • Posts: 55
  • Thumbs Up 4
Re: Vacuum shift actuator
« Reply #2 on: October 09, 2022, 11:39:18 PM »
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?

Online Taylor

  • Administrator
  • Eagle Sundaancer
  • ******
  • Posts: 851
  • Thumbs Up 34
Re: Vacuum shift actuator
« Reply #3 on: October 10, 2022, 09:21:15 AM »
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.
2010 Toyota Rav4 pack mule
1985 AMC Eagle Limited Wagon 🖖🏼🦅
2020 Honda Africa Twin the long haul trucker

Offline Artmodels

  • Eagle
  • **
  • Posts: 55
  • Thumbs Up 4
Re: Vacuum shift actuator
« Reply #4 on: October 10, 2022, 11:26:53 AM »
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?
« Last Edit: October 10, 2022, 11:31:17 AM by Artmodels »

Offline MIPS

  • Eagle Sport
  • ****
  • Posts: 449
  • Thumbs Up 44
Re: Vacuum shift actuator
« Reply #5 on: October 10, 2022, 02:38:49 PM »
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.
« Last Edit: October 10, 2022, 02:42:11 PM by MIPS »

Offline Artmodels

  • Eagle
  • **
  • Posts: 55
  • Thumbs Up 4
Re: Vacuum shift actuator
« Reply #6 on: October 10, 2022, 05:20:24 PM »
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.

Offline MIPS

  • Eagle Sport
  • ****
  • Posts: 449
  • Thumbs Up 44
Re: Vacuum shift actuator
« Reply #7 on: October 10, 2022, 10:19:49 PM »

Offline Papimotors

  • Hatchling
  • *
  • Posts: 8
  • Thumbs Up 1
Re: Vacuum shift actuator
« Reply #8 on: October 11, 2022, 04:47:25 AM »
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

Offline AMC of Houston

  • The only thing we learn from history is that we don't learn from history.
  • Global Moderator
  • Eagle Sundaancer
  • *****
  • Posts: 893
  • Thumbs Up 86
    • American Motors Club of Houston
Re: Vacuum shift actuator
« Reply #9 on: October 11, 2022, 05:02:36 PM »
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.
George G.
'81 Eagle Sundancer
'85 Eagle Waggie
1960 1902 Rambler Replica
'64 American
'70 AMX (Big Bad Blue), '70 AMX (White)
'77 Gremlin
'78 Pacer Coupe, '78 Pacer Wagon
'79 Pacer Wagon
'73 Jensen Interceptor
'86 Audi 5000 Turbo
'98 Aston Martin DB7
'09 Nissan Titan
'10 Nissan Maxima

Offline Illeagle1984

  • Manic Mechanic
  • Premium Member
  • Eagle
  • *****
  • Posts: 111
  • Thumbs Up 13
Re: Vacuum shift actuator
« Reply #10 on: October 11, 2022, 06:55:19 PM »
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.
It's getting crowded down here:
1973 Ford Mustang "Rustang"
1984 AMC Eagle Sedan "IllEagle" 183k
1984 AMC Eagle Wagon "Eagle 2"
1996 Cadillac Eldorado 178k
1998 Oldsmobile Eighty-Eight 239k
2002 Cadillac Eldorado Doral Edition
2005 Chevrolet Silverado 1500 179k

Offline Badvibes258

  • Hatchling
  • *
  • Posts: 5
  • Thumbs Up 1
« Last Edit: January 26, 2023, 01:05:14 AM by Badvibes258 »

Offline rmick

  • Eagle Sport
  • ****
  • Posts: 386
  • Thumbs Up 40
Re: Vacuum shift actuator
« Reply #12 on: January 25, 2023, 11:01:35 PM »
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.
72 Javelin AMX
72 Javelin SST
72 Gremlin with 4.0
81 SX 4

Offline Badvibes258

  • Hatchling
  • *
  • Posts: 5
  • Thumbs Up 1
Re: Vacuum shift actuator
« Reply #13 on: January 26, 2023, 12:40:19 AM »
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"

« Last Edit: January 26, 2023, 01:17:38 AM by Badvibes258 »

 

SMF spam blocked by CleanTalk