1985 AMC Eagle wagon build

[The Dark Side of Will]

I ordered the 61T gear from Cobra on Monday, but they don't expect it to ship until tomorrow (WTF?), so it probably won't be available until next week.

[The Dark Side of Will]

<SIGH>... of course the 25T gear I already had doesn't mesh with the 61T gear I received... The parts listings I've seen don't show which gears are paired with which. This means that there could easily be a pairing of 25 teeth with something else for a Jeep application and I have that 25T gear.

I guess the way to find out is to order the 25T Camaro V8 5th gear output, make sure it meshes with this 61T gear and compare it to the 25T gear I have. I can't use the Camaro gear because the Jeeps use a 23 spline output shaft while Camaros use something else (28?). I guess I could swap to a 28 spline output, but then I'd have to change to a GM style T-case... I don't think there are any with the same functionality as the 229 and there aren't any 28 spline input gears for the 229.

Pics of T-case mix/match:

Insides of 119 T-case. Note the single shift rail for changing between 2WD and AWD. The aluminum cylinder on the top of the stack is the VC housing.


Empty volume in 119 where low range gear set isn't


On the left, the 12 internal bosses for the 12 extension housing bolt locations. In the center, the TWO bores for the low range and 2/AWD shift rails. This is my factory-low-range 119 rear case half, but from this view, the two should look the same.


Low range gear set in 229 T-case

[Atilla the Fun]

Is it 28? I'll go check, but I believe it's 27.
The GM transfer case seems good to me. You could do the full-time AWD like the Sy/Ty, or have a 2.72:1 low with push-button. Both of these are aluminum-case. And both are left-side for the front diff. If this is of any interest, it's the NV231.

[The Dark Side of Will]

The beauty of the 229 T-case is that I can have both... It can be full time AWD with viscous coupling in high range or it can be locked 4WD in low range, with a 2.62 reduction... in the same unit. And it has fixed yoke outputs.

[Atilla the Fun]

That sucks: forced to have viscous, plus no slip-yoke output which reduces un-sprung weight.

[The Dark Side of Will]

Fixed yokes are desirable for an off-road rig. Slip yokes tend to bind and cause problems on lifted vehicles with higher than stock driveline angles.

[Atilla the Fun]

What about the viscous part? Is there anything about it that seems advantageous to you, for ANY application?
Slip yokes can be combined with double-U-joint-style CVs, front only or front and rear, but how much angle can an Eagle have?

[The Dark Side of Will]

The Eagle has fixed yokes *STOCK* and works just fine... I'm not going to put forth effort to change it.

No, an Eagle won't have much driveline angle.

[The Dark Side of Will]

What about the viscous part? Is there anything about it that seems advantageous to you, for ANY application?

Viscous coupling is good in very slippery conditions, when something like a posi or a quaife wouldn't be passing enough torque to properly load up.

There's a video of an E30 325iX Touring (wagon) doing some off-roading in the snow. It has VC's center and rear with an open front. It's pretty much unstoppable and almost never spins a tire in the video.

[Atilla the Fun]

You hit on an interesting point, or maybe 2 related points there. So don't take this as argument.
There are all styles of traction differentials, you well know. Some, like the popular Eaton and the Auburn Pro, can use extra-stiff preload springs, and as such, low-traction situations make them act like a spool until traction is found. However, the GM Gov-Lock, while somewhat fragile for performance use, is excellent in low-traction, like on ice.
When I was driving my '79 Firebird over Soldier Summit, many winters ago, I had a surprising revelation. The theory of an open diff in such a car is that the right rear will spin, but since the left rear continues rolling at the same speed of the car, the tail will follow the nose. Well, dad passed a really slow car, radioed me on our CBs that it was clear to pass, so I eased into my throttle. I had an open diff, and was in drive ( TH350 ) with a 2.73:1 axle and 4 new Firestone FR480s in a size 215/75R15. Even so, my experience didn't match theory, both tires spun, and the tail slipped right. ( I steered right, ended up across the ditch, and managed to keep momentum enough to get back on the road, the whole time on the CB giving dad a running report. Once back on the road, I let go of the button and heard lots of truckers started laughing at my fool arse ) Ever since then, I've given up the wrong belief that opens are safer than traction diffs.
My buddy Brian's 300ZX turbo had the viscous, and I still remember pushing him up a snowy driveway that my old LTD did with an open diff. So much for my belief in viscous. He had new studded snows, my new snows were NOT studded.

[The Dark Side of Will]

Maybe your buddy's VC was shot?

[Series8217]

There's a video of an E30 325iX Touring (wagon) doing some off-roading in the snow. It has VC's center and rear with an open front. It's pretty much unstoppable and almost never spins a tire in the video.

My Outback Limited is set up the same way. Viscous center and rear, open front. I've never had traction problems on any surface ever, and I do a lot of offroading. (e.g. http://www.youtube.com/watch?feature=pl ... PgxmDuvPag)

By the way, the failure mode of the Subaru center VC is that it binds when hot, becoming fully locked rather than turning into an open diff.

[The Dark Side of Will]

There's a video of an E30 325iX Touring (wagon) doing some off-roading in the snow. It has VC's center and rear with an open front. It's pretty much unstoppable and almost never spins a tire in the video.

My Outback Limited is set up the same way. Viscous center and rear, open front. I've never had traction problems on any surface ever, and I do a lot of offroading. (e.g. http://www.youtube.com/watch?feature=pl ... PgxmDuvPag)

By the way, the failure mode of the Subaru center VC is that it binds when hot, becoming fully locked rather than turning into an open diff.

The factory literature on the NVG 149 I want to use for project Bad Idea says the same thing... when the VC warms up, the expansion of the silicone fluid actually pushes the plates together and it acts like a clutch instead of a VC. They treat this like a feature rather than a bug, but do qualify it by saying that "excessive" time in this operating mode can cause the coupling to fail.

The book on the NVG 149 also calls out a procedure for testing the VC, and a special tool. With the front end of the vehicle raised, the parking brake set and the transmission in neutral, remove the front driveshaft and use a special tool to turn the front output of the T-case with a torque wrench. If it takes less than 10 seconds to turn the output 90 degrees with 100 in-lbs of torque, then the VC is bad.

[The Dark Side of Will]

<SIGH>... of course the 25T gear I already had doesn't mesh with the 61T gear I received... The parts listings I've seen don't show which gears are paired with which. This means that there could easily be a pairing of 25 teeth with something else for a Jeep application and I have that 25T gear.

I guess the way to find out is to order the 25T Camaro V8 5th gear output, make sure it meshes with this 61T gear and compare it to the 25T gear I have. I can't use the Camaro gear because the Jeeps use a 23 spline output shaft while Camaros use something else (28?). I guess I could swap to a 28 spline output, but then I'd have to change to a GM style T-case... I don't think there are any with the same functionality as the 229 and there aren't any 28 spline input gears for the 229.

Further research finds that the 25T Camaro gear and the 25T Jeep gear do in fact have different pitches. I already knew that obviously, but found the explanation. The 25T Jeep gear is made to mesh with a 51T gear; thus is had a greater pitch than the 25T Camaro gear which is made to mesh with a 61T gear.

I'm going to consult with my dad's machinist friends... maybe it's possible to bore the splines out of the Camaro gear, turn the teeth off the Jeep gear and press (weld? collar?) the two modified parts together to make a narrow pitch 25T gear for the 23 spline shaft.

[The Dark Side of Will]

Winter is coming, so the Eagle is gradually starting to intrude back into my consciousness.

Atilla suggested an NV3500 for my dad's Datsun. After looking up some info on the transmission, I find that it's used in Jeeps as the NV3550 with removable bellhousing.
The NV3550 is MUCH stronger than the T5, with a 300 ftlbs torque rating and has essentially the same gearing. Both Wikipedia and Novak say it has a 4.0x first gear. Wiki thinks it has a 0.73 fifth, while Novak thinks it's 0.78. I'm inclined to think that Novak knows better than Wiki...
It has the 23 spline output and *probably* bolts right up to my modded NP229 T-case.

The T-5 is *extremely* short. I'll have to physically measure a 3550 before I can determine if I can use it in place of the T-5. Fortunately, http://www.car-parts.com says that a local yard has a unit...
Novak claims it's 23.1", but I'm going to verify that myself before I move forward.

http://www.novak-adapt.com/knowledge/nv3550.htm

http://en.wikipedia.org/wiki/New_Ventur ... ansmission

[The Dark Side of Will]

NV3550: 23_7/8"
T5: 21_3/4"

The automatics with T-case adapter are an intermediate length.

This guy swapped an AX-15 into an Eagle: http://forums.amceaglenest.com/index.ph ... #msg216720
The AX-15 and NV3550 are externally interchangeable, so an NV3550 shouldn't be a problem in my Eagle. I'll need to modify the trans crossmember and clutch hydraulic connection to mate up, but neither of those are a big deal. The output shaft is flush with the T-case mounting flange, which is the same as with a T-5, so the T-case adaptation should go smoothly. I'll need the 4.0 flywheel and clutch, but that's what I want since I'll be going to a 4.0 anyway...

So sometime soon I need to blast & paint the front diff, as well as getting the new shock mounts welded to the rear axle.

[The Dark Side of Will]

NV3550 on the way from TN.

Edit 10/1: Transmission arrived.

[The Dark Side of Will]

So I'm an engine, flywheel and clutch away from assembling the powertrain.

I've been trying to snag one each of the 258 and 4.0 flywheels.
There are two 258 flywheels... for 1987 or 88, Chrysler changed the location of the ring gear on the flywheel, moving it significantly closer to the bellhousing mounting face.
The 4.0 was introduced in 1990 (I think) and retained the same starter ring gear location.
However, the 4.0 flywheel was thinner than the 258 flywheel, but weighed the same.

I'd like to get a late 258 flywheel and, if there's enough extra material, face it down to 4.0 thickness. I don't feel like the car needs a 27# flywheel, and I really don't like driving heavy flywheels.
I'm figuring I'll get a basic stock replacement clutch for a 2000 Wrangler.

Also will need a bit of exhaust work for the 4.0 manifold outlet location to clear the Eagle front diff.

I'm expecting that I'll get the latest 4.0 I can get. Either the earliest HO or latest engines are the best, from what I've read on www.jeepstrokers.com The head went through a couple of revisions with the ports changing each time. The latest ports and latest manifold are the best, with the early HO ports being second. The middle versions of the head have a slight tendency to crack, as do the early castings of the latest head.
Initially I will run it with the 258's mechanical distributor and <gasp> a carb. I will later convert it to EFI using a frankenstributor with parts from a TBI GM "blue flame" six, a 7730 and $8D set for 6 cylinders.

[The Dark Side of Will]

Looks like what I thought about the flywheel was wrong and the ring gear change coincided with the 258->4.0 change. Meaning the flywheel I was thinking of modifying doesn't exist.
Solution: Just buy the stock flywheel and move forward.

[The Dark Side of Will]

Flywheel and clutch ordered from RockAuto for about $190 including shipping