1985 AMC Eagle wagon build

[The Dark Side of Will]

These old eagles are way cool.

They are pretty funky. It would be nice if there were a 4:1 gearset available for the NP229... that's the only thing this driveline is missing.

[Honest Don]

Atlas?

[ericjon262]

Atlas?

$$$$$$$$$$$$$$$$$$$

[The Dark Side of Will]

I think an Atlas would double what I have in the car, even including the expected Eaton E-Lockers front and rear.

*MAYBE* that will work out in the van.

[The Dark Side of Will]

I ordered a 19817-010 from Summit. This is an Eaton E-Locker 4 for Dana 30 with 3.54 and numerically lower ratios with 27 spline axles.
I only later learned that it's an E-Locker 4, which means that it has 4 spider gears.
I bet it doesn't work with the Eagle 2.35 gears...

So NAAAAAAAAATURALY this unit has the wrong flange offset for my Eagle 3.54 gears.

I *THINK* AMC moved the pinion over in the housing by the difference in flange offset between the high and low ratio carriers. This lets them use the 2.73, 3.06 and 3.54 gears they already had, but with the 3.73+ carrier. The 3.54- carrier then is only used with the 2.35 gears they used in the later 258 powered cars. Feh.

So I'm going to snag a 19818-020 and see if that fits.

Anyone want a 19817-010 for your Wrangler? Brand new, never been installed.

[The Dark Side of Will]

Per some wisdom in the Eagle community, the AMC 2.35 gears use the 3.54- carrier, while AMC's carrier for the 2.73, 3.06 & 3.54's is a unique piece that has the flange HIGHER than the standard 3.73+ carrier. Sigh. At least the 18918 e-Locker will be closer... maybe close enough that I can have a ring gear spacer made. I'd have one made for the 18917, but it would require even more case mods, plus making the spacer "hub centric" on the carrier. Maybe the flange on the 18918 would be close enough for a "simple" spacer to work. Of course Eaton *could have* left the ring gear pilot long enough that any gearset would work with a thick enough spacer, but they weren't that cool... even though it would not have cost them anything.

Quick mafs tells me that the pitch RADIUS of the 2.35 pinion is ~0.500 bigger than the 3.54 pinion, calculated at the ring gear's ~7.2" diameter. That bears significantly on how far AMC had to move the pinion and may preclude moving it over only by the difference in flange offset between the high and low ratio carriers... IOW, may have had to move it over further and go with the unique carrier just because of the huge size of the 2.35 pinion. Thanks, EPA.

[The Dark Side of Will]

18918 locker arrived at my dad's place today; I'll get to play with it this weekend.

[The Dark Side of Will]

Played with the 19818 locker over the weekend.
I pulled the ring gear off the AMC-Unique carrier. The ID chamfer on the ring gear pilot bore is ~0.100 deep, which make things a little more difficult.

I took the three units into the QC lab to measure the flange offset using a height gauge.
3.54-: 1.820 (Spec from RockAuto is 1.810)
3.73+: 1.938 (+0.118 from 3.54-; spec is 1.943)
AMC: 2.149 (+0.211 from 3.73+; don't have a spec)

On both Eatons, the ring gear locating journal looks 0.320 long.

Soooooo... 0.320" (journal length) - 0.211" (difference in flange offset) = 0.109 (overlap of ring gear on locating journal)

0.109 overlap initially sounds good, EXCEPT that the ID chamfer on the ring gear is 0.100 deep. So maybe there's 0.010 overlap, maybe there isn't because +/-0.010 is about the best confidence I have in some of those measurements, as I was eyeballing edges next to the calipers.

HOWEVER, the AMC carrier was installed with 0.030 & 0.007 (0.037 total) shims on the gear side and 0.028, 2x 0.010 & 0.005 (0.053 total) on the far side. If I drop the far side shims down by 0.040 to 0.013 or so and increase the gear side shims by the same amount, that will move the ring gear flange 0.040 closer to the ring gear, which increases the overlap from 0.010 +/-0.010 to 0.050+/-0.010... which is workable.

That means that I can make a 0.170-0.180 ring gear spacer, which can be ground from a 3/16" laser cutting.

ETA: Because I'm adding a ring gear spacer and the stock ring gear bolts are 7/8" long, I can put the assembly back together with 1" ring gear bolts, which are hella easier to find than 7/8" bolts.

[The Dark Side of Will]

Also thinking seriously about modifying the 3.54- ring gear pilot journal by turning down the case and then using shim stock to build it back up to a greater length. That would let me use the unit I've already modified, and sell or return the unit I have not modified... so I end up a little better off for $$$. I'll need a 0.339 ring gear spacer if I go that way. I'll take some measurements and try to talk to the machinist this weekend.

Basically, that would mean turning down the ring gear pilot journal until is was at least 0.450" long and enough smaller than the 4.500 original dimension that I can use a readily available shim thickness like 0.020" to build up the journal back to the original size.

[Honest Don]

Also thinking seriously about modifying the 3.54- ring gear pilot journal by turning down the case and then using shim stock to build it back up to a greater length. That would let me use the unit I've already modified, and sell or return the unit I have not modified... so I end up a little better off for $$$. I'll need a 0.339 ring gear spacer if I go that way. I'll take some measurements and try to talk to the machinist this weekend.

Basically, that would mean turning down the ring gear pilot journal until is was at least 0.450" long and enough smaller than the 4.500 original dimension that I can use a readily available shim thickness like 0.020" to build up the journal back to the original size.

So something like a "speedy sleeve?" How thick is the case wall? Turning shouldn't be a problem if you indicate it in a 4-jaw or something. Instead of a separate shim, what about building it into the ring gear spacer?

[The Dark Side of Will]

In concept, yes, like a speedy sleeve. In execution it'll probably just be wrapping the journal with shim stock.

Incorporating the sleeve/shell into the ring gear spacer makes the spacer much more complicated to manufacture.
I can have a flat one laser cut and surface ground. I'd have to have one with an integral sleeve milled.

[pmbrunelle]

Could spray-welding be applicable, if it's a process that prototype machinist does?

[The Dark Side of Will]

I would *LOVE* to have access to that or 3D metal printing... The prototype guy works out of his garage by the hour; he doesn't have a spray welder.

I've worked with a plater in the area before, but they're pretty expen$ive and probably can't plate the modified area up enough to close the resultant gap. I'll put some pics up this weekend.

[Honest Don]

In concept, yes, like a speedy sleeve. In execution it'll probably just be wrapping the journal with shim stock.

Incorporating the sleeve/shell into the ring gear spacer makes the spacer much more complicated to manufacture.
I can have a flat one laser cut and surface ground. I'd have to have one with an integral sleeve milled.

I got ya. I was still stuck on lathe work for some reason.

Shim stock could work if you're patient during assembly. maybe try wrapping it around something with a smaller OD beforehand to get it in shape?

[pmbrunelle]

If the shim stock works itself out of the gap and winds up loose in the diff, that could be bad news.

Another idea is to use shim stock to center the gear on the carrier during assembly, then remove the pieces of shim (leave enough length to pull out the pieces).

Afterwards, you would be relying on the friction joint to keep things in place. Dunno if that's enough.

[The Dark Side of Will]

I probably could be done on a lathe as well... either way, getting the shell thin enough to be workable would be difficult.

[The Dark Side of Will]

Sooo... Some A$$hole at Eaton made the surface between the ring gear pilot journal and the "intermediate step" concave, so it's a PITA to measure. There's another curve from the intermediate step down to the main OD of the case.

The ring gear pilot OD is 4.500
The intermediate step OD is 4.450.
The diffence in ring gear offset is 0.339. The Eatons are 0.005 larger between the bearing seats than the AMC, so subtract 0.003 from the left shim and the ring gear spacer to get a spacer thickness of 0.336 to use with the 3.54- Eaton.
To the 0.336 ring gear spacer, add the 0.100 height of the ring gear ID chamfer.
The freshly turned portion of the case would need to be at least 0.436 tall.
The intermediate step is ~0.800 from the flange, so extending the reduced OD out to the intermediate step will be exactly the right thing to do.

Then I wrap the diff in 0.025 shim stock to install the spacer and ring gear.

It also looks like turning down to 4.460 would extend the new surface far enough to locate the gear on top of the 0.336 spacer, and only require 0.020 shim stock.

The circumference of a 4.450" circle is just under 14".
McMaster has 0.020 & 0.025 shim stock in 8"x12" sheets for <$20 in 18-8 SS or brass. Since I'd have to cut it, brass might be easier to keep the cut edge flat.
McMaster also has 3/4" and 1" wide shim tape at 0.004" thick, consisting of 0.002" 18-8 SS and 0.002" adhesive. Four to five turns of that would get to the right diameter. It comes 9 feet to the roll for $10-$12 depending on width. The nice thing about the tape is that I don't have to worry about it working its way out and I don't have to deal with burrs from cutting it on every edge. I'm not sure how precisely four turns of it would stack up, though.

[Honest Don]

I'd do the thicker brass over the tape. The tape has a pretty good chance of scrunching up as you draw the ring gear on. If slipping out is a concern, maybe use wider shim than what you need and hit it with silver solder to the case in a few places after assembly. Give the shim a good shoulder to sit against and maybe a hose clamp for good measure as you draw the gear up onto the shim.

[The Dark Side of Will]

I haven't test fitted the ring gear on either Eaton unit yet... I guess I need to do that. If I take 0.025 off the radius and put 0.024 back, that might be ok if it's a press fit..

[Honest Don]

How good is your welding? The more I think about it, the more I lean towards running a bead around it and turning that down to size. Go a little bit at a time on alternating sides and take breaks to minimize heat into the part.