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Project AMC-V8 / 5spd / AMC-20 MJ . . .


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I should be snatching up my AMC-290 V8 engine with a manual trans fly wheel assembly this Aug !

 

Now i was thinking of running the T-5 5spd everybody think's i would be better off as well as more in the Theme: "AMC-MJ" with going an AX-15 5spd instead ?

 

Summer time commuter, may tow some stuff nothing heavier then a small riding lawn mower or ATV . . .

 

That D35 ? i'm guessing ain't going to hold up ? or if it dose won't last long ? . . . So I would like to Find the MJ AMC-20 rear end in keeping with the "AMC-MJ" theme of this build :yes:

 

Not interested in the D44 or CryCo 8.?? :thumbsup:

even if it means i gotta pay more to have less i would like the AMC-20 :cheers:

 

Mike

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I believe you are looking for an AMC Model 23, the one-piece axle unit with the better tubes. It was used under FSJ's and, IIRC, was the option under the early MJ. The Model 20 was the two-piece axle, thin tubed CJ version that I would hope they left out of the MJ. Center section stuff is the same for both.

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I was listed as an "AMC-20" for the 1986 MJ "Metric ton" package . . . Either way it can be turned into a 1 piece unit if its not ;)

 

I found a kit from Moser i was debating weather or not to get it for my AMX, maybe they'd do a deal if i got 2 sets ? jamminz.gif . . .

 

 

Mike

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I believe you are looking for an AMC Model 23, the one-piece axle unit with the better tubes. It was used under FSJ's and, IIRC, was the option under the early MJ. The Model 20 was the two-piece axle, thin tubed CJ version that I would hope they left out of the MJ. Center section stuff is the same for both.

The AMC 20 was an OEM part they put on the MJ , to find one sprung under is the way to go if your looking at a direct bolt in , However so was the 44 , They have put both axles in Jeeps as far as I can remember .

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Ya this is true, I would rather run the AMC-20 just cause . . .

 

I'm not harshing the D44 at all its fine axle, I just have a theme build stuck in my head i wanted to go with and i am a stubborn SOB no arguments there ;) . . .

 

:cheers: AMC-290 + AMC-20 = AMC-MJ :cheers:

 

Mike

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The MJ M20 only came with 4.10's (& in 1986 only).

 

Good gears,

but if you run an AX-15, or an NV3550 behind the 290, first will be really low for a small tire street truck (4:1ish x 4.10), and probably pretty useless most of the time.

 

I guess it depends on what you're building it for,

the AX-15/NV3550's wide gear spacing would be OK for a workhorse, but if you want it to be quick, you'd be better off with a closer ratio car based T-5 (= NOT one of the Jeep application T-5's), especially with the 4.10's.

 

 

So, my opinion (for a street based V8 MJ)

 

Mustang T-5 + 4.10 geared AMC M20,

or

Jeep AX-15/NV3550 + 3.15 to 3.55 geared whatever axle.

 

That way you'd have a more reasonable first gear, and a tall highway cruizing gear.

 

All that assuming 30", or shorter tire, 2wd daily driver type street truck.

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I was going more for the truckish type feel.

4.10s & 235/75R15s with a wide 5 speed steep first tho not used much comes in handy for hilly starts and when loaded a bit heavier then planned . . .

 

The 290 is setup to pull 1500rpm-4500rpm so its set up as a "truck" engine more then a race car . . .

 

Driving wise truck sees 25-45mph 80% 55-75 20%

 

Mike

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Well if you're going for more of a 'Truck Build', than a 'Street Machine Build',

get the NV3550.

 

That way you'll get the more 'truckish' 4:1 low first,

and as a bonus it'll even sound like a 2.5 ton dump truck.

:yes:

 

If you go with the Model 20, try to pick up a 1971 & older 'Twin Grip' differential.

 

Those are the stronger Spicer Power Lok LSD's (2-piece carrier + 4 pinion gears).

~1972 they started using Trac-Lok's instead (1 piece case, 2 pinion gears & less bias).

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I believe you are looking for an AMC Model 23, the one-piece axle unit with the better tubes. It was used under FSJ's and, IIRC, was the option under the early MJ. The Model 20 was the two-piece axle, thin tubed CJ version that I would hope they left out of the MJ. Center section stuff is the same for both.

AMC 20 in the MJ's were all a 1 piece shaft from the factory.

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I believe you are looking for an AMC Model 23, the one-piece axle unit with the better tubes. It was used under FSJ's and, IIRC, was the option under the early MJ. The Model 20 was the two-piece axle, thin tubed CJ version that I would hope they left out of the MJ. Center section stuff is the same for both.

AMC 20 in the MJ's were all a 1 piece shaft from the factory.

 

He's brought up in several threads that M20's are referred to as M23's when they came with 1 piece shafts (like in FSJ's).

 

I've heard that tossed around before, but can't remember if I ever saw it in any of the factory books.

 

It's possible,

like the way 'all' Jeep T170 transmissions are usually called "T176's", even though the last number changed depending on what the gear ratio's were (L6's got the low first gear, V8's were taller, and a different T17x number).

 

Either way,

I still call all T17X Jeep transmissions T176's, and those round pith helmet diffs will always be Model 20's to me as well. :dunno:

:cheers:

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I would love the lower first gear, at least a lower first then this AX-4 !

 

So this NV???? Is trans I should get ?

 

Mike

 

AX-15 / NV3350 , Super low first still usable with 31"s and 410's . I love the low crawl speed .

 

I don't know about cheap though , the AX-15 is kind of sought after in the Jeep community .

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Ya I kind of figured it would get spendy some place.

But I think it'll be worth while in the long run.

 

Small V8, lo 1st gear, 4.10s and 235/75R15s should make for a nice pulling truck.

 

Mike

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Ya I kind of figured it would get spendy some place.

But I think it'll be worth while in the long run.

 

Small V8, lo 1st gear, 4.10s and 235/75R15s should make for a nice pulling truck.

 

Mike

 

 

Sometimes it can be cheaper to find rolled XJ's for a couple hundred bucks , then you could have a few more parts for spare or sale .

Just gotta find the right one ... :thumbsup:

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4:1ish first has been around in 4 & 6 cylinder Jeeps for a while,

 

it was the only thing that made 1980's CJ's drivable with the 2.73:1 gears. :ack:

 

 

They would spec a taller 3.5ish first gear in V8 Jeeps,

the taller first gave the trans a higher torque capacity, and the V8 didn't need as low of a first anyway.

 

T-18's were the exception tho,

they used the 6.32:1 first (a real granny gear) in V8's & L6's.

Some year T-18's got the 4.02 first (non-syncro), but it had more to do with the model & year than what engine it had.

(my 73 J4000's T-18 had the 6.32:1 first).

 

 

 

AX-15 vs NV3550:

get which ever one you find first,

NV3550's have a reputation for noise, and there was a syncro issue that 'seems' to mostly be with the 2000 model year (2001 got different syncro's).

 

XJ NV3550's are kinda tough to find, since they were only made for two model years. (2000 & 2001, earlier 5spds were AX-15's, then Peugot's before that).

 

 

Most people can get by with a TJ trans in an XJ/MJ (deal with the longer shifter, and reclock the t-case),

but since you need a 2wd, that means getting an XJ, or maybe a 2wd 4cyl Dakota 5spd.

(big ? on the last one, 4cyl Dakota's used NV3550's, with their own special bellhousing, I just don't know if they made 2wd 5spd 4cyl Dakota's :dunno: ).

 

V8 Dakota's used NV3500's, same trans, but with a different bell pattern, and a NON-Removable bellhousing.

I believe V6 Dak's also used the NV3500.

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Will both the Nv and AX mate to the AMC V8 bolt pattern ?

 

Mike

 

 

Yes,

with the 4.0L bellhousing. (same bellhousing fits the NV3550, and the AX-15)

 

2.5L Dakota's also had their own bellhousing, to fit these transmissions,

the transmission would still work, but the bellhousing has the GM metric patturn (to fit the AMC/Jeep 150),

and not the AMC V8/1972+ L6 pattern that you want.

 

There was also a manual 6-speed trans used behind 4.0L's in the last few years of TJ's that would bolt right up to an AMC V8,

but that's 4x4 only AFAIK (and it's said to be weaker than the AX, or NV's).

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Alrighty so as long as I use the AX-15 or NV3550 it'll mate right up ?

 

Very cool ! Thanks for the transmission help guys, next is finding the 5spd and MJ AMC-20 . . .

 

 

Mike

 

 

This guy, in PA, has a 71' Javelin Model 20 for $15:

http://amccars.net/cgi/yabb2/YaBB.pl?num=1277333191

open rear from '71 Javelin, $15.00 each delivered to Cecil AMC day, or donation if picked up here at my house. Scrap truck leaves 6-29-2010 so pm me soon.

 

 

Same width as an XJ/MJ rear, w/10x2.5" drums (if they're included),

and it's SUA, but the perches are in the wrong location (at XJ width).

 

It does have horrible 2-piece axleshafts, just like a CJ (but with our 5 on 4.5" patturn),

but for $15, it would be worth buying aftermarket axleshafts. :dunno:

 

He doesn't specify gear ratio (71' Javelin M20 should be either 2.87, 3.15, 3.54, or 3.91, depending on engine/trans combo)

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