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AMC Eagles

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Couldn't find a place that would work for a question concerning AMC Eagles, so will go here. Car has a AMC Model 15 axle. 7.5 inch ring gear. It has been suggested that the Dana 35 is basically an upgraded AMC 15 (and it too has a 7.5 inch ring gear). Will a AMC 15 ring and Pinion fit in a D35 axle? Reason I'm asking is I want to replace the Model 15 in my Eagle with a D35 from a Cherokee (with is same, spring perches same, just have fix shock mounts to make it work) and I need a 2.35 gear ratio which isn't something I can find for a D35 (Need to match up gear ratio with front axle)

 

Thanks in advance

 

Rich

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 Well, Rich, welcome to the forums!  The AMC Eagle is the predecessor to the XJ Cherokee and contributed both the chain drive transfer case concept and the unitized body design.  You're one of us!

 

As for the AMC 15 axle, this is an AMC design that shares little resemblance with the Dana 35 beyond the somewhat similar differential cover shape.  The AMC Model 20, which is the mainstay in 1980-86 CJs, many J-trucks and other hefty applications, is actually the rear axle design for the IRS Humvee—and that says a lot, given the Hummer's weight and loads.

 

The 2.35 axle ratio is odd for 4x4s but not for the Humvee, as that vehicle uses reduction boxes at the wheel hubs to take a tall (numerically lower) center member ratio and drop the gearing at the wheels.  The Jeep CJ's tallest axle ratio in the '80s was 2.73, and you likely could find a complete CJ-5 or CJ-7/8 rear axle with that ratio.  This would be a Model 20 axle and quite a bit stronger than your current axle.  You would need to match up the front axle ratio in what I presume is a Dana 30 center section?  Please let us know the front axle design.  A Jeep CJ with the 2.73 rear axle would have a Dana 30 with 2.73 ratio at the front.

 

You may even be able to find Humvee gearing in the 2.35 range and use that ring-and-pinion in a Model 20 Jeep CJ or J-truck rear axle application.  This would match your current front axle ratio...

 

First see whether the Jeep CJ or J-truck/Wagoneer AMC Model 20 rear axle will fit...Maybe 2.73 gearing would do okay at the front and rear of your Eagle?

 

Moses

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Appreciate the response Moses about the AMC 15. Unfortunately, while the front axle is a D30, its an oddball one. Eagles came with 4 different gear ratios 2.35, 2.73, 3.08, and 3.54. If I had the 2.73, 3.08 or 3.54, I could easily swap out the gears to match a rear end replacement. The 2.35 ratio axle is a different carrier and there are no gears that will fit it other that the 2.35. I'd have to find a new front axle to do any gear swapping.

 

That's why I was hoping the ring and pinion out of a AMC 15 would swap into a D35. I have found that the carrier break for D35s will support a 2.35 ( Carrier break for D35s are 2.35:1 - 3.31:1 and 3.55 - 4.88:1 ) but locating a 2.35 gear for the D35 has obviously been a problem.

 

Good tip on the AMC model 20 axle. WIll look into that deeper and see if there's any that were made with the dimensions I need. Which versions of the Hummer had the model 20? H1, H2 or H3?

 

Rich

 

P.S.: The picture is my 98,000 mile 83 AMC Eagle Wagon. Mostly stock, fun car to drive and tends to draw attention as most haven't seen one on the road in a LONG time.

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Rich, the D35 rear carrier, even if unearthed in a 2.35 ratio, would not fit your AMC 15 axle, although it would fit the D35 swap axle you originally considered.  The AMC 20 is actually an 8.875" ring gear, bigger than the name-dropper Dana 44.  This is why the 20 works nicely in the Humvee—yes, the military-design Hummer 1 model with IRS. 

 

You might find a Humvee surplus AMC carrier with 2.35 gears, it's at least worth exploring.  You'd then need a Jeep CJ or J-truck beam rear axle housing (since the H1 is IRS).  Likely the Jeep CJ would be the right width axle, and there are narrow and "wide-track" versions.  The last CJ-7/CJ-8 in '86 offered a Dana 44, not sure if you'd find the 2.35 or 2.73 axle ratio for that axle.

 

This is an interesting car, indeed.  Groundbreaking engineering, understated utility, the Eagle 4WD (AWD) served as a grand experiment that led to the launch of the most popular Jeep model in history—the 1984-2001 XJ Cherokee.  Eagle proved the worth of unit body construction in a 4WD vehicle, the XJ Cherokee took that engineering to the next level with a 4x4 SUV and beam front axle. 

 

Moses

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Footnote to your current front axle:  If a 2.73, 3.08 or 3.54 carrier will fit your front axle housing, that would provide a wide range of axle ratio options.  Instead of seeking just a ring-and-pinion gear set, the correct carrier for a D30 front axle would provide the platform for using the more common ring-and-pinion gear set ratios.

 

I would think that the 2.35 ratio is awfully tall.  Any of the other three ratios are common to Jeep rear axles and AMC as well.  You could even do a Model 20 rear axle swap with 2.73, 3.08 or 3.54 ratio with the correct D30 differential carrier and ring-and-pinion installed in your front axle.  Does that work?  Could be much less costly.

 

Moses

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Moses, 

 

A 2.73, 3.08 or 3.55 carrier will not fit my front axle. For reasons unknown to most those in the Eagle community ( check out amceaglesden.com ) the front D30 with 2.35 gears was an oddball axle. If you have a 2.35 gear, no other gear will fit. If you have the other ratio's, you have all kinds of options.

 

Which is why I was wondering about if there were similarities between the AMC 15 and the D35. Some of the reading I've done state the AMC 15 and D35 are the same ( check out wikipedia that says "The Dana/Spicer Model 35 is an automotive axle manufactured by Dana Corp since 1985 when American Motors (AMC) sold its axle tooling equipment to Dana.The axle was originally named an AMC-15 when it was first made in 1962"). One of many acticles I've found to state that.

 

The reasoning I wanted to stay with a 2.35 gear in the rear is I didn't want to swap out the front axle and that the XJ D35 rear axle is close to a bolt in swap for the Eagle rear axle of which I can fit rear disk brakes to my Eagle. With the AMC 20 models, I've not found one used in a vehicle that has the 4.5" bolt pattern.

 

Based on your information, It doesn't look like I have a choice. With the Ring and Pinions not being compatible between the AMC-15 and the D35 and none of the many places that sell new gears show a 2.35 for D35, I might have to bite the bullet and search for a front axle with from a car with the other ratios. 4 cyclinder cars had 3.54 gears, 2.73 were an option and 3.08 gear was part of the trailering package.

 

Apprecate your responses and wisdom. Have followed your writings for years as I've been a long time Jeep fan (have owned a 67 J-2000, 71 and 81 Wagoneers, 93, 98 and 01 Grand Cherokees) and a fan of yours since I can remember (I have your Jeep Owners Bible in my home library too)

 

Rich

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Ah, that's very interesting...I've rebuilt D35s and found them unlike the AMC Model 20, maybe the 15 does not follow the design features of the Model 20?  A quick way to determine this might be a ring-and-pinion or carrier comparison or parts interchange search.  I do not have a schematic drawing of the AMC Model 15 axle, only the 20.

 

See if you can find an AMC Model 15 parts illustration, perhaps from an AMC factory workshop manual.  Do you have the Eagle OE shop manual?  Copy a parts or service illustration to a .jpg and share, please. 

 

This is intriguing, indeed.  I'm always interested in new findings, and this is news to me.  One thing you mentioned is the 7.5" ring gear.  The D35 is slightly larger, though that may be a technicality and not significant.  The concerns are carrier design, ring gear bolt pattern and diameter, the shim and housing bore locations, bearing sizes (another way to cross reference, incidentally*), the axle shaft splines and count, and the depth/length and diameter of the pinion shaft.  A ring-and-pinion aftermarket gear source may be able to cross reference the AMC 15 versus the D35.

 

Note: For a quick parts interchange approach, head down to your local NAPA store or bearing supply and have them look up the differential carrier and pinion bearings for both the AMC 15 and the D35.  See what's really going on here.  This is a quick and simple way to determine bearing and shaft sizes, carrier bearing saddle O.D. and so forth—essentially "reverse engineering".

 

Finding a 2.73, 3.08 or 3.54 front axle from an Eagle would be sensible if not too costly or hard to find.  That brings into account more popular D35 rear axle options, especially the 3.08 and 3.55 (which works with a Dana 30 3.54 front).

 

AMC 20 axles have a distinctly different bearing and shim layout than any Dana axle...Let's dig deeper, Rich!

 

Moses

 

P.S.:  Thanks for your comments on my Jeep Owner's Bible, Rich, had a feeling you knew the "Jeep Thing", too!

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I have access to factory manuals so will post this evening. A lot of places say the AMC 15 is 7.5" ring gear (they are rounding off the size), but its actually 7 9/16".

 

Great idea on the carrier and pinion bearing suggestion! Will look into that this evening too.

 

There are a few Eagles out there being parted out so finding an axle one is doable, just finding one in Virginia is another matter. Seems all the parts cars are out west. Most likely will be from a SX-4 as more of them came with 4 cylinder engines and the 3.54 gear. For my needs a 3.08 would be better as my Eagle doesn't see off-road use.

 

The AMC I acquired (oddly enough through a raffle) gives me best of both worlds, AMC style, Jeep(ish) drivetrain. Would rather have a Full size 70's or early 80's wagoneer though :)

 

Rich

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Moses,

 

Compared rear end parts with NAPA and was surprised by the results. The pinion seal was a different part number and the wheel bearings were too (can understand the wheel bearings as the D35 has a thicker axle). For what I could find for the 83 Eagle same part numbers were used for a D35 out of a 89 Cherokee. Looking at a bunch of different places tonight that sell D35 ring gears, the are 7.562" in diameter. The AMC 15 Ring Gear is 7 9/16" in Diameter (which converted to decimal is 7.562 also). I'm still trying to locate pinion shaft size at the moment.

 

I've attached the drawing for the AMC 15 axle from the FSM.

 

Rich

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Thanks for posting the illustration, Rich...There are distinct similarities between the AMC Model 20 and your AMC 15 rear axle.  They obviously were the basic AMC axle design, common to each other yet sized differently—like a Dana, Corporate or Ford axle.

 

The D35 and these AMC axles differ in that the Dana axle places the carrier shim packs between the carrier bearing cones and the flanges on the differential case.  This requires the nuisance bearing removal to stack shims properly, or the use of bearing cone proxies for trial fitment, like I talk about in my Jeep books and at the magazine.  

 

The Model 15 and Model 20 have the shim/spacers placed between the axle housing seats and the backside of the carrier bearing cups.  This makes the carrier bearing preload and ring gear backlash adjustment considerably easier since the new bearing cones seat against the differential case flanges.  An AMC differential carrier can be installed and removed with the carrier bearings in place.  (You remove the bearing caps and carefully pry the carrier out; tilt bearing cups carefully during installation as you set the correct bearing preload.)  The AMC axles are much easier to set up than a Dana.

 

I'd go the extra step and compare the bearing sizes for both the pinion and carrier cups and cones...Then compare the lengths of the pinion shafts and their spline arrangements.  From drawings, the AMC axles (beyond just their axle shaft outer bearing and hub design differences) have distinctions from a Dana design.  Let's confirm whether parts interchange.

 

Moses

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From NAPA, the pinion and carrier cups and cones (including the bearing kits that include Bearings, Seals, Gaskets, Accessory Components and ring gear bolts ) are the same part number for both axles. Good suggestion to compare parts like that. I'm still trying to locate specs on the pinion itself, but based on the bearing numbers matching, diameter at least is the same. Still the pinion seal is different, but thinking maybe that can be attributed upgrades to the D35. Have learned some great lessons from you here. It's appearing the differential are alike, but I would sure love to find someone that's pulled a ring and pinion from an AMC 15 and put it in a D35.

 

Rich

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I'd like to see the parts from each unit side-by-side.  Also like to see if the AMC 15 differential carrier will actually fit a D35 axle housing.  This would include not only the bearing sizes but also the bores for the axle shafts and the ring gear bolt pattern.  We need to also take into account the ring gear inside flange diameter and the overall width of the carrier flanges. 

 

The space between the carrier bearing positions would have to be the same, too.  We know already that the shim locations for the carrier bearing preload and ring gear backlash are different...The pinion flange and U-joint type/size also need consideration.  A driveline length issue or U-joint differences may require a new driveline build.

 

The bearing size similarities are intriguing but not yet conclusive for parts interchangeability.  We'll dig deeper, Rich.

 

Moses

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As a footnote to all of this, Rich, why do you want to replace the 7.5" AMC Model 15 rear axle with a 7.562" D35 axle?  Is it the axle shaft/hub design?  Or the popularity of the D35 in modern Jeep vehicles?  What is the gain—if any? 

 

The stamina of the AMC 15 should be comparable to a D35.  Model 15 axles, as you share, have a reliable track record in AMC cars back to the early 1960s (likely post-dates the closed torque tube axles found in earlier AMC cars).

 

If the issue is the axle shaft/hub configuration, I have some helpful pointers on how to keep the hubs in place and not have issues here...

 

Moses

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Moses,

 

Two reasons, one you touched on with the axle shaft hub design, and two, eventually I want to upgrade the rear to disk brakes. There are numerous articles out there that show how to use the disk brakes off the rear of the ZJ and adapt them to the XJ (which never came with disk brakes).

 

Would love to hear your pointers on keeping the hubs in place.

 

Rich

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Rich, I moved the topic on Model 20 AMC rear axle hub installation to the 1972-86 Jeep CJ forum...You'll find my lengthy reply and a PDF there.  The Jeep owners will benefit, too.

 

Here's a direct link to that post: http://forums.4wdmechanix.com/topic/277-rear-wheel-hub-installation-on-amcjeep-cj-with-the-model-20-rear-axle/

 

Trust this is helpful to you and other AMC rear axle/hub techs!

 

Moses

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