1986 AMC Eagle

[89 MJ]

There were three main rear axles found in the Jeep XJ, all of which should be fairly easy to swap into our Eagles. The three options are as follows:
AMC/Dana35
Chrysler 8.25 (available in both 27 and 29 spline axle shafts)
Dana 44
There are four gear ratios found in these rear axles that would be fairly available. They are as follows, along with the engine/trans combo they came with:
3.07: 4.0, manual trans
3.54: 4.0, automatic trans and 4cyl, 4 speed
3.73: Some early (1984-1986) XJs had these. Not sure on engine/transmission combos
4.10: 4cyl, 5 speed

Note: a Jeep MJ Comanche has the same width rear axle, but the perch width is different and they are spring under axle, not spring over like XJs and our Eagles are. Comanches did also have an AMC20 rear axle available in the 1986 model year only.

I had previously read that the XJ axle swap is bolt in, with the exception of the shock mounts. This is both true and not true. The axle itself is a bolt in swap, other than needing to move the shock mounts, but there are some things to be aware of.
1. The pinion snout on a D44 or Chrysler 8.25 is 1" longer than that of an AMC/D35, so the driveshaft will need to be shortened. I was able to just barely get away with not shortening the shaft as my car has roughly a 3" lift in the rear.
2. The diameter of the axle tube for a D44 or Chrysler 8.25 is larger than that of the stock rear axle. You will need the U-bolt plates out of your donor vehicle for this swap.
3. The brake line t fitting is on the other side of the rear end. On an XJ, the t for the lines/hose is roughly in the middle on the left side of the axle. The t for an Eagle is near the right side axle perch.
4. I read that the pinion angle is correct using XJ perches. I do not think that it is, the pinion is pointed towards the floor a little bit more than I would like. That said, my car has a lift, so that may not be the case with a stock height Eagle. I will also say, even with this pinion angle not being 100% correct, it is not far enough off to the point that I worry about the pinion bearing not getting enough oil. I've also had my car up to 80 since the swap with no driveline vibration. I didn't dare push it any harder than that  
5: I personally did an 8.25 swap in my car and would do it again. Even the u-joint was the same size.


What axle is right for you? That depends. I'll lay out the pros and cons of each below.

Dana 35:
Pros: Easiest swap. The axle tube is the same size, so the Eagle u-bolt plates and be reused. These also do not have the longer pinion snout, so the driveshaft will not have to be modified. It will also be the easiest one to find. Closest to the stock Eagle rear end.
Cons: It is the weakest unit of the three that I listed. There were two styles: one with c-clips and one without c-clips. The change happened sometime around 1990. Neither are very good. I personally would not do this swap. I do not believe that the ease outweighs the weakness of the axle.

Dana 44:
Pros: Its strong. Dana 44s are used in new Wranglers and were found in a lot of trucks from the 60s-90s. I would also call it the most "correct" upgrade since they were found in Jeeps from the same era that the Eagle was in production.
Cons: These things are expensive, I looked for one for 3 years and never found a reasonable one. They are also expensive. Most I've seen have gone for $400-$600. You will need different u-bolt plates as the axle tube is larger. The pinion snout is 1" longer, so your driveshaft may need to be shortened.

Chrysler 8.25:
Pros: Plentiful, these came in a lot of Cherokees from the mid 90s-2001. They aren't that expensive either. I picked mine up for $75 and it came with wheels and a front axle. It looks very similar to a Dana 35, so many people cannot tell them apart. If you're building a sleeper Eagle, this may be a good option if you want your car to look stock underneath. These were available in 27 and 29 spline. Before 1997, all 8.25s were 27 spline. Starting in 1997, all 8.25s were 29 spline. The 29 spline is better, but either are an upgrade. Almost as strong as a D44 for a fraction of the price. This will live behind a mild V8 or stroker I6.
Cons: You will need different u-bolt plates as the axle tube is larger. The pinion snout is 1" longer, so your driveshaft may need to be shortened. It isn't period correct. These came out in the 90s, years after Eagle production ended.

Why not just swap in a Ford 8.8?
My Dad built a YJ with an Explorer 8.8 and my Comanche has an Explorer Sport-Trac 8.8. They are great axles, however they do have some drawbacks.
Pros: They are strong and plentiful. IIRC, the Sport-Trac one is a little bit wider than the Eagle rear end, so it will make the track width almost the same as the front. Some 8.8s had disc brakes.
Cons: Most 8.8s (exception being the Sport-Trac) is narrower than the stock rear end. The center section is very large. You need 35" tall tires on an 8.8 to have as much clearance as a vehicle with 31s on a D35. The driveshaft flange is different. Every single bracket will need to be cut off and replaced. The highest gear ratio commonly found in 8.8s is 3.55. The highest gear ratio in a Sport-Trac (the only 8.8 I'd recommend for an Eagle) is 3.73.


What I did and Why:
For my Eagle, I chose the Chrysler 8.25 with 3.54 gears. I did have to regear the front to match, but that was part of the reasoning behind changing the axle. I wanted lower gears. I chose the 8.25 because it is strong and it was cheap. From my prior research along with sale prices I've seen for these axles, the 8.25 has D35 pricing and D44 strength.

Would I change anything?
The only thing I would change would be getting some shims to get the pinion angle a little bit better. Other than that, I am very happy with the swap and I would do it again. The 3.54 gears seem perfect behind the 258, even though I do not have overdrive. If a person does a lot of highway driving, I'd recommend 3.08 gears. With 3.54 gears and 225/75R15s, you are turning roughly 3,000 rpms at 70. I've had my car up to 80 briefly and it was completely fine.

 

 

 

Now back to the regularly scheduled program. 

 

I have a long story with this car. It was given to me by my employer when I was 12. It needed a motor, so I bought a parts car and swapped the motor. 

I then sold the car to buy my MJ. I don’t regret selling it for the MJ, but I had to jump on the opportunity to get it back. 
 

Here is everything that I had done to the car along with pictures when I had it before. 
 

1986 AMC Eagle Station Wagon

258 Inline Six

3-speed automatic transmission

Shift-on-the-fly transfer case

2:73 gears

106,000 miles on body

105,000 on engine from a 1985 Eagle

Rust free body from down south

Interior in good condition-a few tears in front seats, tiny hole in rear seat- about an inch in diameter

Spare front bumper, window trim, and transmission

 

New parts:

Axels

Starter solenoid

Vacuum lines

Spark plug wires

Heater hoses

Brake lines around master cylinder and on rear end

New fluids in transfer case, engine, master cylinder, and transmission

 

I have no idea how many extra parts are still with it, but the guy also said that he has a bunch of parts too 

Edited December 8, 2023 by 89 MJ
Adding technical info to the first page. Easy for others to reference in the future

[neohic]

Rad. I’m a sucker for these cars. 

[89 MJ]

20 minutes ago, neohic said:

Rad. I’m a sucker for these cars. 

It’s going to be a fun build too, although it’ll stay mostly stock. Maybe a 2” lift and 235/75R15 tires with 3.54 gears. 

[89 MJ]

Here is the current state. 
The car is in PA. I am in WI. I am looking into some shipping options. If I can’t get it shipped reasonably, we are planning to drive there and back the weekend of the 19th. Since I sold the car, the owner says he has done nothing with it. He is planning on getting it fired up this weekend and will try to send me more pics then. 
 

This car is going to be my year round driver. When I get it back, I want to take it apart and fix any rust (was an AL car, so it is very solid) and then rust proof the ever living snot out of it so it will survive. I will also have to keep it clean in the winter.
 

I want to lift it a couple of inches and run 235/75R15s in an All Terrain flavor. I also want to modify it in a period correct 80s kind of way. 
 

It isn’t going to be painted anytime soon either. The red may get redone, that is TBD when I get the car back. 

[Romain]

I'll love to see her restored.

[89 MJ]

1 hour ago, Romain said:

I'll love to see her restored.

Believe me, so would I. Being 17 though doesn’t give me much extra time, space, or money to have 20 restored 80s vehicles plus a newer daily driver for winter duties. 

[JMO413]

I LOVE those cars! Helped a buddy build one way back in the day. It was a 2 door 4 speed. Lifted a little with a ton of trimming to fit 31/10.50/15.

[neohic]

Have you considered getting a donor XJ for a full drivetrain swap? 

[89 MJ]

3 hours ago, JMO413 said:

I LOVE those cars! Helped a buddy build one way back in the day. It was a 2 door 4 speed. Lifted a little with a ton of trimming to fit 31/10.50/15.

They are a ton of fun! This car has a ton of stories during my 2 years of ownership, maybe I’ll have to tell some. 

[89 MJ]

2 hours ago, neohic said:

Have you considered getting a donor XJ for a full drivetrain swap? 

I have, and it is not out of the picture, but you can’t find a Cherokee around me with less than 200,000 miles on it for less than $1,500. 

[89 MJ]

When I had this car the first time, we took it out in the snow once I got it running. We jumped it through a snowbank and drifted it around in the yard. My cousin even took out a tree with it while slaloming in the yard. No damage was done to the car. We had a ton of fun with it and part of the reason I want it back is for the sentimental value.
 

Here is the look I’m going for in terms of wheels and tires. 2” rear spring lift, 1” coil spring spacers, and 235/75R15s with some fender trimming behind the flares. I will trim on the fenders, but not the flares. 

[scaleless]

Sorry if I'm a party pooper, but I think the pics you shared of it as it is right now look way better than the lifted one with XJ wheels!

[89 MJ]

7 hours ago, scaleless said:

Sorry if I'm a party pooper, but I think the pics you shared of it as it is right now look way better than the lifted one with XJ wheels!

I might run those turbine wheels, but the rear end is sitting about an inch lower than the front end, so something needs to be done with the suspension. 
I do love me a set of turbines on these cars. 
Don’t worry about being a party pooper either. I love different ideas!

[watchamakalit]

There is NO cooler vintage wheel than turbines.  Forget the xj wheels they look like poo

[89 MJ]

43 minutes ago, watchamakalit said:

There is NO cooler vintage wheel than turbines.  Forget the xj wheels they look like poo

Yeah, my car does have XJ wheels and they will be going away. I might try to get some XJ turbines to replace them. 

[eaglescout526]

You need those odd 5 spoke XJ waggy rims from 84-86. 

[89 MJ]

50 minutes ago, eaglescout526 said:

You need those odd 5 spoke XJ waggy rims from 84-86. 

If I found a set, I’d consider it, but I honestly think I like OEM turbines the best on Eagles. 

[watchamakalit]

3 hours ago, 89 MJ said:

Yeah, my car does have XJ wheels and they will be going away. I might try to get some XJ turbines to replace them. 

It wouldnt matter mj style or stock eagle style. Just keep the turbines.

[89 MJ]

21 minutes ago, watchamakalit said:

It wouldnt matter mj style or stock eagle style. Just keep the turbines.

The Eagle and MJ shared the same turbines. These were some aftermarket ones that we had laying around. 

[89 MJ]

I’m kinda digging the Jeep Golden Eagle stripe. Maybe one in maroon would look sweet on this car. I'm also digging the aluminum slots. 

[89 MJ]

For future reference in case I decide to do an AW4 swap:

 

//THE BIG AW4 INSTALL POST - very long post incoming
gonna have to break it up and caption the process with the pictures so hopefully this all makes sense. 
there are a couple small issues i need to work out, but overall this is a good picture of what it's going to take if you're interested. for what it's worth, i managed to perfectly maintain AMC's original power band and highway engine rpm speeds despite gearing, transmission and tire size changes. it's a drastically improved driving experience - still feels like a vehicle of its vintage, but with more modern throttle response, acceleration, and driveability. 
--------------------------------
So why do this? If you've ever dreamed of an automatic with overdrive, this is what you've been dreaming of. This is by far the easiest, and best, overdrive automatic to adapt and install. According to the internet, the AW4 was developed jointly by AMC, Aisin and Borg Warner - hence the Aisin-Warner name. When properly cooled and maintained, the AW4 is a very dependable and long-living unit. Its use of a standalone TCM allows it to be used behind a carbureted engine and keeps wiring as simple as possible.
First things first - if you're the kind of person that is intimidated by electrical stuff, this won't really be the task for you. You'll need to be able to read and understand wiring diagrams to correctly assemble the transmission harness and integrate it into the existing wiring where needed. 
I work on cars professionally, so while I'm attempting to write this so that anyone with minimal knowledge will understand, I will probably overlook something that is second nature for me at some point. That said, this definitely isn't a job you can graduate to after changing your own oil a handful of times - it's relatively straightforward, but a bit tricky at points.
There are a couple things I haven't totally nailed down yet. One of which is the front driveshaft. The original will be too short; the donor will be too long. I haven't bothered with the transfer case shifter since I don't have a driveshaft. I made new linkage rod for the original shifter to attach to the new transmission. It's a bit stiff getting out of park and the detents don't line up with the original shifter, so I may go with the Jeep shifter and cable at a later time.
There's enough information on forums about the various differences from year to year so I'll just link to those rather than summarize. I used a 1989 TCM, 1989 TPS, and a 1991 transmission. Up thru 1997 any year TCM will run any year transmission if you're forced to mix and match like I was.
https://www.naxja.org/forum/showthread.php?t=1053970
DONOR VEHICLE PARTS NEEDED (preferably all from the same vehicle)
-transmission AND transfer case (231 or 242)
-starter w/solenoid connector
-flexplate and bellhousing tin plates (keep all bolts)
-transmission control unit
-as much original wiring as possible with at least connectors for the TCM, TPS (read note below), and the two transmission connectors at the firewall
-both transmission and transfer case shifters with cable and linkage
-cooler lines
-throttle body
-throttle cable bracket
-crossmember
NOTE ON THROTTLE POSITION SENSOR
I recommend using the RENIX ERA throttle position sensor regardless of which TCM you use. All TCMs will use a 5v reference and this sensor will work with any system. The renix sensor is a dual sensor that is capable of reading 0v nominal at idle or 5v nominal at idle depending on which side of the sensor you use. The sensor has an arm pivot that makes it MUCH easier to adapt than the later style sensor. Connectors can be obtained new thru parts stores if your donor vehicle does not have what you need. If using a chrysler era TCM, you'll need a 5v regulator to provide the signal voltage. Renix TCMs provide the 5v signal.
WALKER PRODUCTS 20091094 - is a complete kit with sensor and both pigtails.
STANDARD MOTOR PRODUCTS TH67 - sensor only
STANDARD MOTOR PRODUCTS HP4460 - 3 wire connector for use with chrysler era TCM
STANDARD MOTOR PRODUCTS S555 - 4 wire connector for use with renix TCM

NOTE ON DRIVESHAFTS
If you use a slip yoke eliminator kit, you can use the original Eagle rear driveshaft. This worked for me both on this install, and an AX15 manual transmission in an SX/4. The overall length of the transmission and transfer case assembly is within an inch or so shorter of the original 998/129 assembly. However in this situation, the AW4 is longer and the 231/242 shorter which makes the original front shaft too short. Additionally, i do have an 8.25 rear axle installed which moves the pinion yoke about another inch forward which may affect whether the original driveshaft can be used with the original eagle model 15 rear axle - I'm not sure here.

HIGHLY RECOMMENDED NEW PARTS
-slip yoke eliminator kit (unless you want to have a driveline shop modify from the donor)
-USA STANDARD GEAR USA41198 u joint u bolt kit if using SYE
-large external transmission cooler
-transmission cooler hose, clamps, etc
-transmission mount
-EAGLE BRAKE SWITCH W/CRUISE and connector (if you don't already have cruise control)
-1000-1300 ohm resistor (transmission control resistor on diagram)
-fluid/filter/gaskets/seals
-misc wire/battery cable/heat shrink/eyelets
-misc sheet metal for brackets as needed

WHAT MUST WE ADAPT?

The transmission crossmember will need to have much of the middle section removed, a new section added to the rear, and reinforced appropriately. I'll credit Paul Schexnayder here for the method I used, though my work is not nearly as nice as his.

We'll need to adapt the throttle bracket to connect the transmission throttle valve (kickdown) and mount the TPS. It's discreet once complete.

We'll need to adapt the donor throttle cable bracket to properly anchor the throttle valve cable.
I've removed the original engine control module and associated wiring, so its location in the passenger kick panel and harness grommet were ideal to reuse for the TCM and the new wiring. If you're still using the original system, you'll have to find another home for it.

THE OVERALL PROCESS
Remove the original transmission, flexplate, starter with cable, kickdown and shifter linkage, transfer case vacuum lines, and cooler lines. 
[refer to pictures from here out]

[PCO6]

On 5/30/2021 at 6:59 AM, 89 MJ said:

... I do love me a set of turbines on these cars. 
 

 

I agree! 

 

[89 MJ]

45 minutes ago, PCO6 said:

 

I agree! 

 

Beautiful!

[rylee144]

not sure if you need parts or not. saw this ad and thought of you. $650 whole thing

 

 https://www.facebook.com/marketplace/item/649909605670282/?ref=browse_tab&referral_code=marketplace_top_picks&referral_story_type=top_picks&tracking={"qid"%3A"6969347107855019793"%2C"mf_story_key"%3A"1129760426234670102"%2C"commerce_rank_obj"%3A"{\"target_id\"%3A1129760426234670102%2C\"target_type\"%3A6%2C\"primary_position\"%3A0%2C\"ranking_signature\"%3A7217722880576978944%2C\"commerce_channel\"%3A501%2C\"value\"%3A0%2C\"upsell_type\"%3A21%2C\"grouping_info\"%3Anull}"}

 

[89 MJ]

1 hour ago, rylee144 said:

not sure if you need parts or not. saw this ad and thought of you. $650 whole thing

 

 https://www.facebook.com/marketplace/item/649909605670282/?ref=browse_tab&referral_code=marketplace_top_picks&referral_story_type=top_picks&tracking={"qid"%3A"6969347107855019793"%2C"mf_story_key"%3A"1129760426234670102"%2C"commerce_rank_obj"%3A"{\"target_id\"%3A1129760426234670102%2C\"target_type\"%3A6%2C\"primary_position\"%3A0%2C\"ranking_signature\"%3A7217722880576978944%2C\"commerce_channel\"%3A501%2C\"value\"%3A0%2C\"upsell_type\"%3A21%2C\"grouping_info\"%3Anull}"}

 

Thanks for sharing, but I don’t think I will be able to make it happen at this point.