2.5L to AX15 conversion

Skulljeep683

Skulljeep683

New member
My 2.5L is strong, been building on it for sometime, however my bottle neck is my trans without servicing and with a 133k on it, i think its time to bump up my reliability to the ax15, i figure im going to need to keep my bell housing and im tossing in an upgraded clutch, so will i need the clutch for the 2.5l or the 4.0? among other footnotes to be aware of on this conversion...
 

Can't keep your bellhousing, need one from a Dakota 2.5L 5spd as they came with the AX15.

The AX15 isn't any more reliable than the AX5, they're both equally problematic as Chrysler incorrectly used and recommended the incorrect gear oil which subsequently corroded the synchros. Using either when used is a crapshoot.

You can greatly increase the life of either transmission by using the correct gear oil, like Redline MT90 which is a pricey full synthetic that is specially formulated to be easy on the synchros, shifts like warm butter even in the coldest of weather. MT90 will often improve notchy shifting and lengthen the life of a transmission with worn synchros.
 
okay cool! i just figured that with the motor putting out more juice id have to put in a stronger trans, any recommendations? Im up to suggestions, i want something close to the same gearing so it can be streetable and have the granny gears on 1st and 2nd but have the high speed top end for highway. cause right now mine will book 90mph in 5th gear crusing, but when i build up the motor more i want something i wont grenade as far as transmissions.
 

well is there any trans that will bolt up to my my motor and transfer case that will be considered an improvement? And thanks for the info! thats not too bad seeing as i was thinking of much higher numbers.
 
Skulljeep683 said:
well is there any trans that will bolt up to my my motor and transfer case that will be considered an improvement? And thanks for the info! thats not too bad seeing as i was thinking of much higher numbers.
Click to expand...

If you value overkill verus cash quadratec has a kit to swap in an NV4500 transmission in your jeep...but if I rember the add it runs north of 3k.
 
yeah i saw that... my only thing is idk if thats worth it. if i do keep building up this 2.5 will the trans hold? thats my worry... so putting in something better was my logic on defeating the possibility of spewing trans guts when i put her in gear.
 

I really don't see a 2.5 killing any transmission. I'm curious as to why you feel you need to upgrade? What have you done to it?

Sent from my SCH-R830 using Tapatalk 2
 
Ive done full bolt ons soon head and motor build, gasket matched manifold and bored out the tb opening, bored out tb from a 4.0, tb spacer, k&n system to a hoodscoop "ram air", longtube header, high flow cat, flowmaster 40 series dual outlet which dumps 6in before the axle, jet stage 2 chip, 180* thermostat, full aluminum radiator, electric cooling fan, and a high friction clutch "sport clutch" or "stage 1"
 

Bounty__Hunter said:
Run Redline MT90 in the AX5 and it will last a long time.
Click to expand...
i just might do that, but in theory wouldnt i get more speed from a newer trans or at least the availability of a short throw shift and a dual friction clutch option? also the ax15 has interchangeable parts with the trans from the 2jz motor, so if you hybrid certain parts you could essentially have a solid gearbox. because i keep hearing how the trans in these things are junk and then when i log on everyone says mixed messages. im just trying to find out whats truth and whats fiction.
 
If you're gonna throw that kind of $ at the 2.5 Why not swap in another engine? 4.0 195 hp stock, I can't see the 2.5 making much more than that, and you'll never make as much torgue as a bigger engine. Not trying to be a Debbie Dower just trying to help.

Unless thats what makes you happy, then go for it!! :cool:
 
I don't like to be a downer but iv worked on race cars a long time with all that stuff that u put on there with no major intrenal work u probuly only got a bump of 30 to 40 over stock do go with what they say u get on the box u never know till u hit the dyno most of your power is only ganna come from your heads cam and valves all upper motor your streanth comes from your bottom end cams pistons and rods exhast is tricky to big or to much flow u can rally lose hp or turqe u need some back pressure. U know learn as u go. That 2.5 won't blow anything u put behind it maybe a cluch that's abot it. Good luck to ya and keep at it.
 

After the motor build I'm going to be boosting it with either a supercharger kit or turbo. And I found a shop near me that can performance tune my computer.
 
When I'm done with building the motor I'm going to boost it with either a supercharger or turbo kit I found. And I found a local shop willing to performance tune it. It's all about showing people you can build them and make something different. I just want to do it this way. Also if I get a bigger engine then I'm gonna super build that then costing more cash in the long run. I'm doing this for the adventure, and looking for the interestimg combo of power and durability. Hence my original trans question. Another reason is to have some better gears for city and highway, and still have off road use. I know I sound crazy, but I'm a fenatic like the rest of you, it's what I wanna do.
 
Dual friction clutch will get you more holding power, but a stock LUK clutch will do just fine behind that motor. I run a short-throw shifter and it is a large improvement over stock, gets your through the gears much quicker.

You're not going to hurt an AX15 behind a hopped up 4banger, especially if you run a quality synthetic fluid.

I fully understand wanting to hop up a 4banger, they're a simple, fun, high-revving engine. Relatively light weight and super easy to maintain. Have you checked out the forums at 4bangerJP.com - Index ?
 

Bounty__Hunter said:
Dual friction clutch will get you more holding power, but a stock LUK clutch will do just fine behind that motor. I run a short-throw shifter and it is a large improvement over stock, gets your through the gears much quicker.

You're not going to hurt an AX15 behind a hopped up 4banger, especially if you run a quality synthetic fluid.

I fully understand wanting to hop up a 4banger, they're a simple, fun, high-revving engine. Relatively light weight and super easy to maintain. Have you checked out the forums at 4bangerJP.com - Index ?
Click to expand...

I'm gonna check them out. But I appreciate the input, and I'm glad theres more out there that get it. :)
 
Allrighty, so come tax season I'm buying a new ax15 or rebuilt one, the motor is a 2.5L stroked to 2.9L forged internals gear drive timing with a stage 2 stroker cam and stronger valve springs with port and polished head and intake manifold, 65mm th and spacer plate, and tuned ecu, promotes 225 horse and 240 torque just the bare motor, turbo kit shortly after. Working with jeepersandcreepers.com and 505 performance on the motor build. So get the plate and bellhousing and dual friction clutch and run the mt90 weight and all is good correct?
 

I killed 2 AX-5s behind my TBI 86 2.5L in an '86 Comanche 4x4. I hauled too much stuff I guess.
 
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