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Stock transmission crossmember questions...


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Now that I have the 4.0L and AW4 transmission in my '86 MJ (previously 2.5L and ax-5, 2wd,) I've noticed a major concern with the stock transmission crossmember.

 

The question is basically this:

 

Were there different crossmembers for different engine/transmission combinations? Or, is it the mounting locations on the uni-rails that are the difference?

 

Right now the location that the crossmember bolts to is about 2 1/2" too far forward against the location of where the transmission mounts to it. Any insight would me most appreciated...

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The front 2 holes are for a 2wd and the rear 2 holes are for 4wd.

 

Move the crossmember back to the rear 2 holes and it will line up.

???

 

The holes also vary depending on what engine, transmission, and transfer case combination you have. The difference in location is 4 inches, not 2-1/2 inches, so that's not the complete answer.

 

Each tranny and transfer case combination used a different tranny mount, even though the cross members were all the same. If you're not using the correct mount for the tranny and transfer case that you now have in the truck ... that's the problem.

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The front 2 holes are for a 2wd and the rear 2 holes are for 4wd.

 

Move the crossmember back to the rear 2 holes and it will line up.

???

 

The holes also vary depending on what engine, transmission, and transfer case combination you have. The difference in location is 4 inches, not 2-1/2 inches, so that's not the complete answer.

 

Each tranny and transfer case combination used a different tranny mount, even though the cross members were all the same. If you're not using the correct mount for the tranny and transfer case that you now have in the truck ... that's the problem.

 

I am using the crossmember, and mount from the AW-4 that will be residing in the MJ. It does not line up. I was under the assumption that there were 4 bolts per side, not two for 2wd and two for 4wd. Can anyone clarify this???

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Yes, there are 4 bolts on each side of the transmission cross member.

 

One bolt and one stud on the frame, and two bolts on the bracket inside the frame.

 

You have and are using the correct transmission mount, there is a difference from the BA10 and the AW4 / AX15 mount.

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for a bit of info...the holes DO NOT vary based on 4wd or 2wd. at least not with an ax5 transmission. they vary between transmissions, that is it.

 

did you swap your rear axle? or, did you match your front axle to 4.10's?

 

cause 4 cylinder 5 speed will be 4.10 gears for the rear axle, MAYBE 3.73's though.

 

hopefully ya did...or it isn't gonna work. that is, if you did a 4wd swap at the same time.

 

either way, double check those gears.

 

and...what did you do with the old motor and trans? I need a crankshaft, connecting rod(s), and I could use the guts of the tranny.

 

-Pat

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What do axles have to do with this? I'm running an HP30 with 4:56 gears and a Ford 8.8 rear w/ 4:56 gears when the time comes. Thanks for the offtopic.

 

Oh, and that motor and tranny went through the shredder before my eyes. I tried to get rid of it for months, but could definately understand why nobody would want it.

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What do axles have to do with this? I'm running an HP30 with 4:56 gears and a Ford 8.8 rear w/ 4:56 gears when the time comes. Thanks for the offtopic.

 

Oh, and that motor and tranny went through the shredder before my eyes. I tried to get rid of it for months, but could definately understand why nobody would want it.

 

damn. wish i'd have known bout them

 

and the axles, I was just heads-uppin ya in case you didn't know. some people get mislead enough to run 3.55 with 4.10, and wonder why the case breaks.

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Believe me when I say I've played w/ my share of axles. I've also watched my share of weeeee-todds run a variety of ratios at one time. The result is always KABOOM.

 

Anyways, If this is that big of a clusterfawk of confusion, I'm just going to make myself a Clayton Off-Road style 3-piece crossmember, since I'm making longarms anyways. I really just wanted something to stick on there so I can start my new '99 driveline up and play w/ the Snap On scanner to rid myself of codes!

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  • 1 month later...

The holes are not there. I guess this is another issue with '86 only Comanches. Here is a picture of where the 4.0L and AW-4 sit in comparison to the bolt locations on the transmission mount and the uni-rail:

 

 

I'm not overly concerned, as I'll need a custom skid/crossmember for my custom fab. front long arms anyways. Just consider this a heads up. An '86 MJ 2wd has only two holes per side.

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Had the same problem myself not long ago. And belive me, i tried everything to get the aw4 boltet onto the old 5speed's bolt holes. What a waste of time! Its just not possible.

 

My solution was to jack up the transmission with the crossmeber attached to it, make shure it is properly centered and alligned...and start drilling new holes!

 

 

 

DSC00405.jpg

This is on the passenger side, and here you see it from inside the cab

DSC00406.jpg

Bolt 1 goes just trough the bracket inside the frame rail, nr. 2 is under that cover you see in the last picture, there was a hole in the floor there already. And nr. 3 goes all the way trough the frame rail, both 2 and 3 are welded stuck.

 

Maybe not the best way around this problem but it seems strong enough for me. Have done some pretty hard wheeling lately and i there is no signs of stress og things falling apart.

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Now that I have the 4.0L and AW4 transmission in my '86 MJ (previously 2.5L and ax-5, 2wd,) I've noticed a major concern with the stock transmission crossmember.

 

The question is basically this:

 

Were there different crossmembers for different engine/transmission combinations? Or, is it the mounting locations on the uni-rails that are the difference?

 

Right now the location that the crossmember bolts to is about 2 1/2" too far forward against the location of where the transmission mounts to it. Any insight would me most appreciated...

 

 

The mounting location on the unibody rails are in different positions depending on the tranny. Measure the mounting location on a Cherokee with a 4.0L/AW4 and you notice the difference. The AW4 is longer than the AX-5 and thus the mounting location is further back. I ran into the same problem when I did my conversion, I ended up modifying the cross member:

 

xmember.jpg

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  • 13 years later...

Been a long time since anyones been here but I have my solution. I was supposed to cut socket sized holes for the middle but I Ended up cutting the top like an idiot and had to patch it, and cut the bottom. So it’s a lot uglier than it already was but successfully holds my trans. I’m hoping it’s a temporary solution till I can pay someone to make me a really solid one.

71FD418C-0D5D-4118-B3E6-D55265C50977.jpeg

B9E96DB5-7151-48DD-89D0-75C74324B925.jpeg

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