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M12

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WesternRed View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote WesternRed Quote  Post ReplyReply Direct Link To This Post Posted: Feb/04/2020 at 6:25am
I just posted in the other thread regarding parts for the M12.

If it is mostly a cruiser, maybe the occasional trip to the strip, then the M12 will be fine and rebuilding it is by far the easiest and cheapest option.

If you want to go drag racing on a regular basis then do the 727 since you can actually buy all sorts of performance parts for it. The 727 will take a lot of abuse in stock form (assuming good condition), but depending on how serious you are about racing, you may find it needs upgrades as well.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote WesternRed Quote  Post ReplyReply Direct Link To This Post Posted: Feb/04/2020 at 6:29am
M12 (well 11B actually) here:



Lasted 74 low 13 second passes between rebuilds, I now have a dedicated drag car with a 727, so the BW trans will not be abused anywhere near as much this time around.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ADAM12MATADOR Quote  Post ReplyReply Direct Link To This Post Posted: Feb/04/2020 at 7:22am
Back in the early 1980's i bought a modified valve body for my M11 from JW Transmissions in Florida.  I did i quick search and they are still in business. Contact them, maybe they can help.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rsrguy3 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/04/2020 at 1:52pm
At this point I need a pump for it, it always shifted firm so I wont be messing with the valve body.. The car was eating flex plates 25 years ago, after a lot of reflection I'm pretty sure the cracked bell housing may have been the cause, it had been welded, but I won't be risking it so I'll be looking for an undamaged bell for the rebuild as well. I'm not dragging the car so it will easily be durable enough for my use, as the car had almost 200k miles before it had issues. Those are issues I attribute to a 19-25 year old kid.... me, not understanding the alignment issues that probably caused the flex plate issues is likely why the trans didn't go longer.... In addition adding a billet flex plate without addressing alignment issues has almost certainly permanently ruined my pump... Live and learn. 28 years later, better now than never. 

Edited by rsrguy3 - Feb/04/2020 at 2:07pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ADAM12MATADOR Quote  Post ReplyReply Direct Link To This Post Posted: Feb/04/2020 at 3:55pm
M11 and M12 trannys use the same bellhousings so you should be able to locate one. Fatsco Transmission Parts in New Jersey might have your pump or other rebuild parts. JW might have the parts too. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rsrguy3 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/04/2020 at 7:37pm
Sending an email now! 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rsrguy3 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/11/2020 at 11:16pm
Well.... Had some downer news today. The trans rotating assembly came apart, cleaned up and went back together fine today.  Valve body... not so much, turns out the clown that rebuilt it for me in the mid 90's didn't o/h the valve body, but he did get it wet. Upon disassembly Gary and Chuck found 4 busted springs and corrosion, one piston(valve shaft?) had pitting so bad it was immediately appearant that it wasn't serviceable anymore, the bore wasn't any better... Looks like the scavenger hunt for a serviceable VB is on. I guess I know now why it felt like I wasn't making power on a new rebuild. Pretty serious downer for me everything was looking very promising. I suppose a little more patience is in order, it's not like a few more days is going to matter since it hasn't been driven regularly in 25 years. 

Edited by rsrguy3 - Feb/11/2020 at 11:18pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote amx007 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/12/2020 at 8:21am
For comparison sake pull a m11 vb  check it out I have m11 I’d put up for look see
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rsrguy3 Quote  Post ReplyReply Direct Link To This Post Posted: Feb/12/2020 at 7:55pm
Well my guy ordered one from fatsco... I just hope it’s out of a 12 and has the factory shift kit that mine use to have... Fingers crossed.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote amcenthusiast Quote  Post ReplyReply Direct Link To This Post Posted: Feb/13/2020 at 6:53am
[QUOTE=rsrguy3]So.... The resolution is to get the 71 Z-code on the road this year! I have a 727 from a 73amx and the original m12. Both need to be rebuilt, the 727 needs to have the crank machined. I think the TF weighs less but what else should I consider? 
1. Which is tougher
2. Is there a way for me to find the parts and rebuild it myself? Any vids? 
3. Are there any substantial reasons to go with the TF over the m12? 
4. Should I use the billet steel flywheel/flexplate and bell spacer I have or try to find an originalflex plate. 
[/QUOTE

Perhaps I've got it backwards but I thought we just discussed this on the other BW12 modifications thread.

Ok so never mind that... Comparing 727 to M12:

1) Which is tougher?

Now, the 727 is 'tougher' than the M12. Why? Because the 727 uses larger diameter size for the clutches. This feature gives the clutches more leverage against the rotating assembly. It's like putting a longer handle on a hammer.

I'm saying 'now' for a reason though, because back then, around '71, the 727 was only recently cured from a durability problem; prior to '70, the 727 had an input shaft endplay issue where the same question 'which is tougher' could be answered the other way, saying the M12 is tougher because it had no input shaft issue... which is important, I think, to defend the reputation of the AMC car.

2) Is there a way for me to find the parts and rebuild it myself? Any vids?

Just because one can find parts (for either transmission) does not mean they can rebuild it, by their self.

This is because the automatic transmission is not a simple mechanical thing; it's not like making pizza.

The AM iron case automatic is easier to rebuild DIY, primarily because it has a separable bell housing which makes it much 'nicer' to handle on a workbench. Because the 727 has an integral bell housing, it's bulky and awkward to move around on a workbench. Other than that, they are both a 'two clutch, two band' type automatic transmission -both similar in their basic construction, and neither unit is 'easy' to assemble ...where the word 'easy' is subjective, in relation to the person's own mechanical ability.

Yes, there are 'parts galore' for both units, and the cost for parts is about the same -not much difference there between the two.

I take my time when I rebuild an automatic transmission. I devote a full week to it. Most of the time is absorbed into cleaning parts and maintaining a clean workspace. To make a video would be even more tedious and boring IMO. Make a video? I don't think it would be entertaining.

Can you do it yourself? If you consider yourself as having natural mechanical ability yes, the best way to acquire the skills is to get 'hands on experience'. Of course, DIY with no transmission rebuild manual would only be another handicap; lacking guidance, alongside lacking experience.

3) Are there any substantial reasons to go with the TF over the m12?

The most 'substantial' reason to rebuild the original unit for your car is to keep it all original, because a '71 Javelin with 401 is among the greatest muscle car combinations ever made. And, this is amplified because Javelin won Trans Am in 1971.

This makes it a 'true collector car', and plausibly ignorant to 'molest', by arbitrarily treating the car like a meaningless smorgasbord of parts. It's not a meaningless pile of parts; it is a true collector car that is worth more in original condition -where unmolested specimens are highly sought after.

To turn this question inside out, the AM iron case Shift Command unit features lower parasitic loss, and will send about 12 more hp to the drive wheels than if the car came with a 727. -So, even though the 727 evolved and became more durable, the M12 still offers a small power making advantage. -Not substantial, but very real and 'actual'.

4) Should I use the billet steel flywheel/flexplate and bell spacer I have or try to find an original flex plate?

On any true collector car like '71 401 Javelin, authenticity is key to higher appraised/market value.

Therefore the stock type flywheel, stock bellhousing etc. is the smarter choice.

All '66-'91 AMV8s are externally balanced.

To do the car 'right', the engine should be re-balanced with an original type flexplate.

Having the engine 'built right' is a 'substantial' reason that will affect the car's market value.

The main problem here in all these questions is related to awareness of the car's actual rarity and collectability.

It's a super rare highly collectable muscle car and should be treated as such.

How many stock condition '71 401 Javelins are left 'out there'?

Probably under 50 cars left? -generous estimate?

Some cars deserve restoration, some don't.

A 'high option' '71 401 Javelin that originally came with 'Machine wheels'?

Definitely 'yes' -this is a car that deserves an authentic restoration, plain and simple.




Edited by amcenthusiast - Feb/13/2020 at 10:24am
Link to XRV8 Race Parts website: www.amcramblermarlin.1colony.com
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