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Author Topic: Looking for np128 to replace np129  (Read 3811 times)

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Offline djdelee421

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Looking for np128 to replace np129
« on: March 09, 2017, 12:17:58 PM »
On my 83 sx4 I was just cruising around the other day and all of a sudden this loud whining and metal on metal sound happened. So I got home jacked the rear end up rotated my tires in drive and sure enough the np129 is done the viscous coupling to be specific. So I found out that my dad's 86 wagon has the np128 with the open differential and my questions are is a swap easy and is it worth it and ultimately where can I find a 128? Let me know my last resort will be a jeep tcase because I really don't want a hole in my floor.
83 sx4 driver
83 wagon limited (project)
85 wagon limited (parts)
86 wagon driver
73 VW beetle (project)
68 Kaiser jeep (project)
85 GMC Sierra (project)
98 24valve Cummins work truck (beast)
94 suburban daily driver
93 freightliner FLD 120 (beast)

Offline eaglefreek

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Re: Looking for np128 to replace np129
« Reply #1 on: March 09, 2017, 03:55:17 PM »
A 128 is a direct swap. Easy is a relative term, based on your mechanical ability and tools. With a lift and the right tools, it's probably a 1-2 hour job. On kickstands and on your back a bit longer. 128's were a one year only thing and not easy to come by. I've had both and the 129 seemed to do a bit better in the snow than the 128, but not enough difference to worry about.
1986 AMC Eagle Wagon 4.2L/4.0L head, AW4,NP242, Chrysler 8.25" rear.
1981 AMC Eagle Wagon As Seen On TV  Lost In Transmission


 

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Offline djdelee421

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Re: Looking for np128 to replace np129
« Reply #2 on: March 10, 2017, 12:34:30 AM »
Would a 128 last longer than a 129 and if you did do a jeep t case which one goes in easiest or can jeep parts be put in a 129 I just have no idea what to do I want my eagle back out there so bad
83 sx4 driver
83 wagon limited (project)
85 wagon limited (parts)
86 wagon driver
73 VW beetle (project)
68 Kaiser jeep (project)
85 GMC Sierra (project)
98 24valve Cummins work truck (beast)
94 suburban daily driver
93 freightliner FLD 120 (beast)

Offline djdelee421

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Re: Looking for np128 to replace np129
« Reply #3 on: March 11, 2017, 12:08:14 AM »
Ive decided to try and find a T4 or 5 with a transfer case behind it hopefully a 242 or 231? I'm not sure but I'm going to the junkyard tomorrow and will see what I can find only got a couple hundred bucks so I'm hoping for a good deal. Anybody think it's a good idea? I haven't done much research but the T5 seems like a common trans I'm just not sure what t-case will most likely be on it.
83 sx4 driver
83 wagon limited (project)
85 wagon limited (parts)
86 wagon driver
73 VW beetle (project)
68 Kaiser jeep (project)
85 GMC Sierra (project)
98 24valve Cummins work truck (beast)
94 suburban daily driver
93 freightliner FLD 120 (beast)

Offline vangremlin

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Re: Looking for np128 to replace np129
« Reply #4 on: March 11, 2017, 08:05:31 AM »
From what I have read, the T4s are prone to breaking up down by people shifting incorrectly.  And I would imagine a T5 would be very hard to find.  You have an automatic in there now?  Fairly big undertaking to make the transformation to a manual transmission.
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1972 Gremlin X 304
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Offline djdelee421

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Re: Looking for np128 to replace np129
« Reply #5 on: March 11, 2017, 09:16:57 AM »
True I just don't know what the easiest option will be for me what would you recommend?
83 sx4 driver
83 wagon limited (project)
85 wagon limited (parts)
86 wagon driver
73 VW beetle (project)
68 Kaiser jeep (project)
85 GMC Sierra (project)
98 24valve Cummins work truck (beast)
94 suburban daily driver
93 freightliner FLD 120 (beast)

Online mudkicker715

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Re: Looking for np128 to replace np129
« Reply #6 on: March 11, 2017, 10:00:41 AM »
A manual trans swap will be a royal pain in the as s. Plus eagle specific needs for that to be done. I swapped to a manual once. Just swap the transfer case.



Manitowoc WI

Offline eaglefreek

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Re: Looking for np128 to replace np129
« Reply #7 on: March 11, 2017, 04:34:06 PM »
You will not find a T4 or T5 with a 242 or 231 behind it. There were only available in Eagles and Jeep CJ's and I think a very few FSJ with the 6 might have had a T5. You'll only find a 129, 128, Dana 300, 229 or 228 behind one. The 128 should technically last longer since it doesn't have a viscous coupler. A 229 or 228 would be the easiest Jeep transfer cases and closest to a bolt in swap with no driveshaft changes needed.
1986 AMC Eagle Wagon 4.2L/4.0L head, AW4,NP242, Chrysler 8.25" rear.
1981 AMC Eagle Wagon As Seen On TV  Lost In Transmission


 

"I know he'd be a poorer man, if he never saw an eagle fly,
Rocky mountain high"  John Denver
Click for Fayetteville,TN Forecast" border="0" height="100" width="150

Offline djdelee421

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Re: Looking for np128 to replace np129
« Reply #8 on: March 11, 2017, 07:21:09 PM »
So I don't want the 229 because of the viscous coupling personally I don't want anything to do with them so what all will have a 228 I know some XJs have them anything else? And also will they last me a while I like off roading quite a bit haha
83 sx4 driver
83 wagon limited (project)
85 wagon limited (parts)
86 wagon driver
73 VW beetle (project)
68 Kaiser jeep (project)
85 GMC Sierra (project)
98 24valve Cummins work truck (beast)
94 suburban daily driver
93 freightliner FLD 120 (beast)

Offline Prafeston

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Re: Looking for np128 to replace np129
« Reply #9 on: March 11, 2017, 07:35:18 PM »
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Offline djdelee421

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Re: Looking for np128 to replace np129
« Reply #10 on: March 11, 2017, 08:25:08 PM »
So I found someone that rebuilds np231s and sells for $400 so I know people have put these on an eagle so how hard is the swap and is it a good price?
83 sx4 driver
83 wagon limited (project)
85 wagon limited (parts)
86 wagon driver
73 VW beetle (project)
68 Kaiser jeep (project)
85 GMC Sierra (project)
98 24valve Cummins work truck (beast)
94 suburban daily driver
93 freightliner FLD 120 (beast)

Offline acct21

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Re: Looking for np128 to replace np129
« Reply #11 on: November 24, 2023, 11:39:53 AM »
Reviving an old thread, but for any of the New Process VC cases of the era (119/129/219/229), as long as the VC failure doesn't result in pieces of the coupler shell damaging other parts of the case, the VC can be removed and replaced with the open differential inside of the VC itself.  Once the large snap ring is removed, the shell comes apart and the differential can be removed from the core. 

Once the side and rear output shafts are reassembed with the open differential, the case can be resealed, and it is now a 118/128/218/228 -- exactly as they came from the factory.  You lose the limited slip function, but gain the confidence that the VC isn't going to fly apart and detonate your case.

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