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Advice please 86 MJ transmission died


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Hi fellow Jeepsters,

I did search and apologize because I know this has been hashed over and over.

 

I have been a member of the Ol'Yahoo Comanche group and now need advice.

 

I own a 1986 MJ with the 2.8 carburated. It has a 3 sp automatic 904 TF that has finally died.

My Transfer case is Select track. The motor had a rebuilt longblock about 2 years ago but I never replaced the trans. The trans for years has made noise, shuddered. I knew it was living on borrowed time.

 

What is the easiest fix? Do I just find a rebuilt 904TF noncomputerized?

or do I go with a Ax5? If so what year and do I have to get anything special to make a AX5 standard work on my truck that came with a 3speed automatic.

 

I assume going with a standard I will need new pedals? Cut a hole in my tunnel.

Any other swaps that will work.

Thanks in advance for your input.

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You won't need to cut a hole in the tunnel. The hole should be there, just with a plate over it.

 

You can get an AX-4 or AX-5 from any year XJ/MJ/YJ/TJ. You'll probably want to find a newer one already mated to a NP231 T-case. The only problem you should have is finding a flywheel for your motor.

 

Another issue you may have is driveshaft lengths. I don't know how long the TF 904 is. You may need to research that and see what the difference is between that and an AX-4/5.

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I think your best option is to find a good tranny shop, pull the tranny your self and deliver it to the shop for a re-built.

 

Swapping over to an manual with the 2.8 is going to be a tough find for the bell housing alone.

 

Plus theres more to it than just swapping out the pedals and cutting a hole, like Geonovast noted, the drive shaft needs to be changed,

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Swapping over to an manual with the 2.8 is going to be a tough find for the bell housing alone.

 

2.5 and 2.8 use the same bellhousing.

 

A flywheel would be the hard-to-come-by aspect of it. I know the 2.5 and 2.8 don't use the same flywheel, but I don't know what other vehicles with a 2.8 he could yank a flywheel from.

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Thanks to all of you for the replys:

Geonovast, If I do go with an AX5 do I suppose I would need to get the clutch pedal

assymbly off the donor jeep. Is the clutch cable going to come through the floor?

 

As far as finding a trustworthy trans shop, I really think that is going to be the hard part. I would really like a standard if possible provide I can find a flywheel that mates the 2.8 with the AX5. I am assuming the flex plate is what we are talking about as it is externally balanced in the 904TF and I guess internally balanced in the AX5. Or is this another can of worms.

 

I am located in Cental Texas, Salado 76542.

 

I will know more about what I am dealing with when I pull the old trans out and get a look at the shaft length. The torque converter on the 904 for this 86 is a German Sachs and rare and expensive and I think kaput.

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If I do go with an AX5 do I suppose I would need to get the clutch pedal

assymbly off the donor jeep. Is the clutch cable going to come through the floor?

 

Yes you will need the manual pedal setup.

 

There is no cable, It's all hydraulic. You may have to drill the hole in the firewall for the master cylinder.

 

I would really like a standard if possible provide I can find a flywheel that mates the 2.8 with the AX5. I am assuming the flex plate is what we are talking about as it is externally balanced in the 904TF and I guess internally balanced in the AX5.

 

Flex plates and flywheels are not the same thing.. but they go in the same place.

Flex plates are for automatics, Flywheels are for standards.

 

Best option is to have a donor vehicle. Grab everything related to the transmission, including the T-case mated to it, and the front driveshaft. You'll have to have yours either cut down or re-tubed if you can't find one.

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If you want to stay with the auto, search online for rebuit trans for your application. I did this on a friends toyota, it came with three year unlimited miles warranty, new torque converter, and all. Its been almost 4 years now and he has yet to have a problem. They even arranged the pickup of the core. If you are willing or able to do the swap yourself this may be a good option for you. I'm sorry I can't remember the name of the company that we got it from, but it was a national chain. This may be the easiest swap option for you if you don't think you can set up the stuff for the manual trans. By reading your posts it does look like your are getting confused by all the options, but what you do should depend on your abilities and if you are able or willing to do some modifications. We are here to help!

 

And the 2.8 is externally balanced no matter what trans you have. The 2.8 flywheel I have was mated to an AX5 and would keep your engine externally balanced. PM me if you need the flywheel and Ill work on getting a shipping price.

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Once again thanks to all.

I think I am going to go with a remanufactured 904TF. Not that I love this tranny but since it is the original one and lasted 200k miles I can not complain.

 

This will make life easier (I hope). I will send the remanufacture company all the numbers off my unit and spline count on my Tcase etc to hopefully get the right one sent to me. I have way to much into this truck to let it go.

I will hopefully post a positive update when I am back on the road. Right now I am on a motorcycle and get no coffee on the ride to work in the morning. :shake:

Anyone ever hear of these folks http://www.colemantaylor.com/

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Coleman Taylor IS the place I got that toyota trans. I remember the name now that I see it. They seem to have done a good job on the rebuild I got and My buddy is still driving that car. Its been about 4 years ago I replaced it. It was shipped by truck, and picked up the same way, you just have to let them know when you are ready to return the core. I would reccomend them, but I'm just one person. I wish you luck!

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