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MJ 86 w/2.5 adn 4 speed - need 5 speed


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I have a 86MJ with the 2.5 and a 4sp. I have already put lower gears front and back went from the 3.55 to 3.73 - this was easy to find. But I drove someone else MJ with the 4.0 and a 5 speed. First gear was a real low granny gear. Thats is what I need. So does a 2.5 MJ come with a 5 speed and get that low granny first gear

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The 2.5L was available with a 5-speed, the AX5. Your 4-speed is the AX4. They are identical except that the 5-speed adds a fifth, overdrive, gear. 3.73 isn't enough gear for a 5-speed 2.5L. The factory used 4.10s, and for primarily off-road 4.56 or 4.88 would be better.

 

Changing to an AX5 will not get you a granny first gear. The first four gears are all the same ratio you have now.

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The 4.0 never came with any sort of "granny gear" in any trans. Do you know which trans they have? What size tires do they run? Gears in their axles? All of these thing together give you the final drive ratio. Also the 4.0 has way more torque than the 2.5.

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darn - i figured this was not going to work. So to solve my lower gear problem my best solution is to regear down to a 4.88

 

or

 

replace the 2.5 and stuff with a 4.0 or would I still have to gear lower for the 4.0

 

Also I more then likely need to replace my 30x950 tires with 33

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For the 3.73 I found a 8.8 rearend with a limited slip and then put a newer 30 in the front - got them at a junk yard for $75 a piece - that was my cheapest solution to do my first upgrade. Couldn't find anything lower like a 4.10 or 4.88

 

The 2.5 off-road and pulling just is gutless.

 

I know I can get a 4.0 with transmission and transfer case for around $500 and then lots of personal labor

 

or

 

take the truck in and have a shop put new gears in which I would bet the bill would be around $800

 

or

 

which is the way I'm starting to look for is a Cherokee with the 4.0 and at least a 4.10

 

Again to many choices - lucky this is only a hobby and I'm not dependent on it at all

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Done a tuneup on the 2.5 yet? Maybe it's not putting out its full potential. You might try a rebuilt fuel injector. Other guys have found improvement there. Is your cat OK? fuel filter? You can dump the mechanical fan for an electric one to free up a few ponies.

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Off road you should be in low range. I can't imagine even a 2.5 being gutless in low range. 4.10 axles can be found under 2.5, 5 speed Cherokees and Comanches, and quite a few exploders. But with anything larger than stock tires you want to go deeper.

 

Swapping a 4.0 into an 86 might hit a few snags on the firewall, but nothing that can't be overcome with a BFH

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