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  • August 17, 2022, 08:43:53 AM

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Author Topic: Viscous coupling failure?  (Read 3756 times)

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Offline Jward408.jw2

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Viscous coupling failure?
« on: January 31, 2021, 08:51:02 PM »
Hello, I just bought a museum kept 1981 limited wagon from a gentleman in Atkins Virginia who claimed to have hauled the car down from Ohio on a tow dolly. Is this a likely reason the car is slipping in 2 wheel drive? If there’s a post covering this I apologize but I’ve been reading for a few hours now and haven’t found anything relevant. Should the cars with viscous coupling be hauled on a flatbed?

Online Taylor

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Re: Viscous coupling failure?
« Reply #1 on: January 31, 2021, 09:10:54 PM »
Flatbed, definitely. They only way to use a tow dolly is to remove the driveshafts.
2010 Toyota Rav4 Sometimes Commuter (better mileage and family beater)
1985 AMC Eagle Limited Wagon 🖖🏼🦅 Eats Audi quatros for breakfast😎 Official Member of the Land Rover recovery team.
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Offline Jward408.jw2

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Re: Viscous coupling failure?
« Reply #2 on: January 31, 2021, 09:43:31 PM »
So this would explain why it’s slipping now in 2wd and working as it should in 4wd?

Offline Jward408.jw2

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Re: Viscous coupling failure?
« Reply #3 on: January 31, 2021, 09:47:53 PM »
And if so, what needs to be done to correct the problem?

Offline rmick

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Re: Viscous coupling failure?
« Reply #4 on: January 31, 2021, 10:38:14 PM »
When you say slipping in it tries to move or doesn't move at all. Could be the actuator is not moving completely and is in false neutral on the transfer case. You can manually move the lever from under the car from one position to the other to insure it is not sticking in mid position.
72 Javelin AMX
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Offline rmick

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Re: Viscous coupling failure?
« Reply #5 on: January 31, 2021, 10:43:19 PM »
Here is a guy sounds like he had similar problem http://forums.amceaglesden.com/index.php?topic=46228.msg357923#msg357923
72 Javelin AMX
72 Javelin SST
72 Gremlin with 4.0
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Offline Jward408.jw2

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Re: Viscous coupling failure?
« Reply #6 on: February 01, 2021, 12:30:05 PM »
It goes but there’s obvious slipping. When I try to pull a hill I hear it Erving but I have to put it in 4wd to get up the hill.

Offline Jward408.jw2

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Re: Viscous coupling failure?
« Reply #7 on: February 01, 2021, 12:46:50 PM »
Reving*

Offline 4x4jollyr

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Re: Viscous coupling failure?
« Reply #8 on: February 01, 2021, 01:28:10 PM »
I thought 1981 eagle was 4WD all the time, no shifter??

Offline Jward408.jw2

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Re: Viscous coupling failure?
« Reply #9 on: February 01, 2021, 01:30:34 PM »
Mine is 1981 and has select shift on the dash.

Offline AMC of Houston

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Re: Viscous coupling failure?
« Reply #10 on: February 01, 2021, 05:28:37 PM »
Hear any noise from the rear right side??   Could be the dreaded busted right axle (axle spinning in the hub).
George G.
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Offline Jward408.jw2

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Re: Viscous coupling failure?
« Reply #11 on: February 01, 2021, 05:50:41 PM »
Yes there was a noise coming from the rear sounded like a bearing going out. So a roaring type noise.

Online Still Pat

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Re: Viscous coupling failure?
« Reply #12 on: February 01, 2021, 06:00:21 PM »
I thought 1981 eagle was 4WD all the time, no shifter??

My first Eagle was an '81. It was full time, no switch. I bought it NEW off the dealer's lot, so I know it was factory!
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PREVIOUS AMCs:
'72 Gremlin X 304/3 speed
'81 Eagle Kammback 258/4 speed (Purchased new)
'82 Eagle wagon 258/5 speed Ordered new, traded Kammback)
'86 (I THINK) Eagle wagon - BlackBird 258/auto. (Got hit/totaled)
'83 Eagle wagon - White Eagle 258-auto. (Front subframe was rotted out - sold for parts)

Online vangremlin

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Re: Viscous coupling failure?
« Reply #13 on: February 01, 2021, 07:41:18 PM »
I thought 1981 eagle was 4WD all the time, no shifter??

They changed to "switch-able" 4WD part ways through the 1981 model year.
1981 Kammback 258 - "Pepe"
1980 Coupe 258 - "Ginger
1972 Gremlin X 304
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Offline Jward408.jw2

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Re: Viscous coupling failure?
« Reply #14 on: February 01, 2021, 09:03:12 PM »
I’ll check the axle out and keep everyone posted. Thanks for the info.

Offline Jward408.jw2

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Re: Viscous coupling failure?
« Reply #15 on: February 02, 2021, 04:59:54 PM »
Ok so the noise is definitely coming from the right rear hub area. Is there anything specific that I need to know before axle replacement? I know a lot of things vary from year to year, model to model. Should I be looking for a specific axle or are these pretty much universal throughout the eagle family?

Offline AMC of Houston

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Re: Viscous coupling failure?
« Reply #16 on: February 02, 2021, 06:19:20 PM »
All Eagle rear axles are the same; year-to-year, and side-to-side.   But it has to come off an Eagle; other AMC passenger car axles won't work (even tho some Hollander mis-info says otherwise).  If you get a left side axle (preferred), you'll still have to press off the hub to get the backing plates swapped out (and of course put a new bearing on it while you're at it).    Also going back together be sure to set the axle end play per the TSM (no shims go on the right side; only the left).  You'll find that usually will have to reduce the shim pack thickness due to normal wear on the diff spacer block).

And don't put the new bearing on backwards!!   I've seen it done by AMC-inexperienced shops!!   Outcome wasn't pretty.....

Good luck finding an axle (they're out there).
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 MIPS

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Re: Viscous coupling failure?
« Reply #17 on: February 03, 2021, 12:35:15 AM »
For curiosity sake (you can't really drive the car right now anyways), raise and support that corner with a jackstand and then give the wheel a good wiggle and pull. If the break is on the outside portion of the shaft the wheel and drum should pull right off.

Offline Jward408.jw2

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Re: Viscous coupling failure?
« Reply #18 on: February 04, 2021, 01:27:32 AM »
It’s actually drivable in 4wd the front axles are popping so I’m sure they’re due for replacement also but it drives fine. Even in 2wd it does excellent until a hill. I can’t find an axle for the rear anywhere though.

Online vangremlin

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Re: Viscous coupling failure?
« Reply #19 on: February 04, 2021, 02:16:14 PM »
I can’t find an axle for the rear anywhere though.

You could try car-part.com.  They sometimes have those hard to find parts available used.  Good luck!
1981 Kammback 258 - "Pepe"
1980 Coupe 258 - "Ginger
1972 Gremlin X 304
1978 Gremlin 4 cyl 121 - sold
1964 TBird 390 - sold

Offline Thack

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Re: Viscous coupling failure?
« Reply #20 on: February 04, 2021, 09:51:22 PM »
There is one more option for what’s going on, the transfer case is in 4WD and the diaphragm in broken. When you select 2wd the axle disconnects and the viscous coupler is supplying power to the rear but losing power to the open front. It would make taking off and loads feel like it was slipping. Changing the selector to 4WD would close the open power loss and would drive pretty much normal. To confirm this look at the transfer case lever in both 2wd and 4WD to see if it has moved.

Tom H

Offline rmick

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Re: Viscous coupling failure?
« Reply #21 on: February 05, 2021, 01:48:15 PM »
ATTACHEMENT
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72 Javelin SST
72 Gremlin with 4.0
81 SX 4

Offline Jward408.jw2

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Re: Viscous coupling failure?
« Reply #22 on: February 06, 2021, 03:28:37 PM »
Ok, I feel like such an idiot for this but the selector lever wasn’t locking fully into 2wd. I’d like to apologize and thank everyone for their advice. I was poking and prodding around under there yesterday and took the transfer case cover off to see the selector better and cleaned it really good there was debris caked up on the lever/nut and the rod didn’t seem to be getting the vacuum it needs to fully shift it.

Offline AMC of Houston

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Re: Viscous coupling failure?
« Reply #23 on: February 06, 2021, 04:14:14 PM »
Glad it was an easy fix!!    Here's hoping you never experience the dreaded right axle failure!!
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 Jward408.jw2

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Re: Viscous coupling failure?
« Reply #24 on: February 06, 2021, 04:15:48 PM »
Manually locked it into 2wd and took it through a gravel parking lot. It’s definitely locked in.

Offline Jward408.jw2

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Re: Viscous coupling failure?
« Reply #25 on: February 06, 2021, 04:17:21 PM »
Good news is I located a 1988 parts car nearby good motor trans vtc and diff.

Online vangremlin

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Re: Viscous coupling failure?
« Reply #26 on: February 08, 2021, 11:15:58 AM »
Glad it worked out for you.  You're not the first one to experience that problem!

That parts car will come in handy!
1981 Kammback 258 - "Pepe"
1980 Coupe 258 - "Ginger
1972 Gremlin X 304
1978 Gremlin 4 cyl 121 - sold
1964 TBird 390 - sold

Offline MIPS

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Re: Viscous coupling failure?
« Reply #27 on: February 09, 2021, 01:19:21 AM »
I found that after 35 something years it's worth the time to remove both SelectDrive actuators, clean and lubricate the shafts. The front one especially as it has a vent that allows road dirt into the shaft cavity can and will seize it up. Likewise inspect the rubber grommets that connect the various rigid plastic lines to the steel lines. I've had a set which were deformed and swollen from soaking up too much rubber softening engine additives over the years.
The system runs off manifold vacuum and uses a vacuum reservoir as a booster. Neither actuator needs a strong vacuum to operate, just a constant vacuum. Take a small piece of vacuum line and you should be able to operate both using your mouth. ;)
« Last Edit: February 09, 2021, 01:27:53 AM by MIPS »

Online vangremlin

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Re: Viscous coupling failure?
« Reply #28 on: February 09, 2021, 11:23:45 AM »
Take a small piece of vacuum line and you should be able to operate both using your mouth. ;)

May I suggest using a piece of "fresh" vacuum line?   :rotfl:
1981 Kammback 258 - "Pepe"
1980 Coupe 258 - "Ginger
1972 Gremlin X 304
1978 Gremlin 4 cyl 121 - sold
1964 TBird 390 - sold

 

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