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  • November 26, 2022, 06:51:43 AM

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Author Topic: Vacuum shift actuator  (Read 325 times)

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Offline Papimotors

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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

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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
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Offline Artmodels

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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?

Offline Taylor

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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.
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Offline Artmodels

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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

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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

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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

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Re: Vacuum shift actuator
« Reply #7 on: October 10, 2022, 10:19:49 PM »

Offline Papimotors

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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

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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.
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Offline Illeagle1984

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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

 

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