kj engine in a yj

yjaruba · **Posted:** Thu Aug 18, 2011 8:03 pm

I want to put a kj (03) 4x4 engine with an auto trans into a yj 4cl manual ax-5 (wrangler 93). Anyone know if the trans fits in/on my yj transfer case? (np231) Thanks

JeepinJarhead03 · **Posted:** Thu Aug 18, 2011 8:13 pm

ax15 orig trans had 23 spline , the peug and ax5 used 21

assuming no other differences youd at the least have to change to the 23

JeepinJarhead03 · **Posted:** Thu Aug 18, 2011 8:26 pm

length of the auto vs the ax5 may play a more prohibitive role, it's not just going to bolt up and be good to go, itll be front and rear drive shafts, and a bunch of converted wiring, bringing the gauge cluster from the KJ to the YJ etc, 3.7 won't crank if the ECM doesn't match the gauge cluster ODO, quirky crap like that

any particular reason why the 3.7/autos an interest? wrecked kj in the back yard or something?

if you were just talking about the transmission being transplanted I'd say sure , why not., be a good time to get some good upgraded driveshafts and stuff

but there's several much easier and cheaper overall transplants you could do

yjaruba · **Posted:** Thu Aug 18, 2011 9:05 pm

Ok thanks for the quick reply. The reason is that I had an accident with my kj and the drivetrain is still good. So I thought double the HP.... Maybe I can make the driveshaft shorter and mold it
to my ford 8.8 what I was planning to put under my yj

JeepinJarhead03 · **Posted:** Thu Aug 18, 2011 9:17 pm

not to be a brake pad or anything.. but if you're really interested in a transplant for the yj your best bet is probably to sell the drivetrain from the KJ and find a 4.3 or sbc and put a ax15 in, electronics conversion will be alot easier, and your drive train headache wont be nearly as bad

novak chevy to ax15 adapter is about 200 bucks

which is cheaper than 2 driveshafts

yjaruba · **Posted:** Thu Aug 18, 2011 9:56 pm

I really understand your point but the problem is I'm here on aruba. And its hard to sell an engine and harder to get ax-15 and to buy stuff from the us I have to pay a lot for the shipping and tax. I know someone who can cut weld and balance a driveshaft.

JeepinJarhead03 · **Posted:** Thu Aug 18, 2011 10:16 pm

ahh gotcha

well..

invest in a good set of wire crimpers and what not, my theory is anythings possible with enough creativity, ingenuity and money

theres some differences in the different era's of 231's aside from spline, i don't know if the 23 input spline on that era 231 yj transfer case is the same as the 23 spline on your kj input spline on the 231 that would be the first thing to check, if it is then its atleast a start

there's two different length 231 23 spline input gears ones about half an inch shorter than the other

2door wranglers use a long one, the KJ being 13" longer wheel base than the YJ im assuming has the long

with the teralow conversions some of the mod apps required switching to the short version so this leads me to believe the short input gear from the kj 231 will go in the yj 231 with no problems

the rest just sounds like a wiring and mounting nightmare

yjaruba · **Posted:** Thu Aug 18, 2011 10:37 pm

Well thanks for the advise. The first 2 I have but your last point (money) is the problem.

JeepinJarhead03 · **Posted:** Thu Aug 18, 2011 10:42 pm

well if you know your way around wrenches, wiring diagrams, welders etc it can happen, otherwise.. look for a kj with no drivetrain lol

tjkj2002 · **Posted:** Thu Aug 18, 2011 10:44 pm

yjaruba wrote:

Well thanks for the advise. The first 2 I have but your last point (money) is the problem.

Yeah it's not going to be a easy or cheap swap.Your going to need the entire wiring harness,PCM/TCM,and BCM mounted in the YJ to make it all work right as the 42RLE or 45RFE(could have either one in a '03 KJ) requires a TCM to run and of course the engine needs the PCM,and the BCM controls more critical functions then realized.

yjaruba · **Posted:** Thu Aug 18, 2011 10:52 pm

I'm gonna pull the drivetrain out of the kj anyway so then I let you know if it fits or not.

yjaruba · **Posted:** Thu Aug 18, 2011 10:56 pm

thanks tjkj2002
the engine was running before i start pulling the engine.
so if i let the engine think its still in the kj....
maybe i think to easy....

JeepinJarhead03 · **Posted:** Thu Aug 18, 2011 11:01 pm

sounds like he's got the entire vehicle still, it would be a "spine transplant"

i personally wouldn't want to touch it

I suppose if I was in a tight enough spot and had to , i guess there'd be a YJ 80% of a KJ bolted to it, dash and all

cut the interior harness main 6" on the inside of the firewall wire by wire and mark both sides by number and transplant as much KJ intact as possible

weld some 1" bolts to both fenders and call it Wrangerty

hope there's good beer in Aruba.

when it comes to that sorta thing i tend to not adhere to cosmetics, the little ranger i crammed spare sbf stuff in radiator and all ended up getting the front cut and extended more inches than the fenders allowed

that got patched over with steel flashing, riveted, bondoed and rattle canned

ramlebliberty · **Posted:** Thu Aug 18, 2011 11:04 pm

I had a buddy with a similar project 3.7 and trans from a comander in a yj... after 6 months of planning and talking to numerous shops, he sold the engine and tranny, and got a chevy 350 & t350. Much easier, adapters and engine mounts readily available, and CHEAPER by a ton.

JeepinJarhead03 · **Posted:** Thu Aug 18, 2011 11:07 pm

yeah i've seen several SBC yj's with TH's and a couple running novac adapters with ax15s or NVs

yjaruba · **Posted:** Thu Aug 18, 2011 11:39 pm

I like the idea of the Wrangerty.
In aruba we have Heineken and balashi. But if you like I can find a Budweiser

ramlebliberty · **Posted:** Thu Aug 18, 2011 11:49 pm

He would also need the rear diff for the speedo right? And if the KJ has ABS he'd need to accommodate that also, or tape over the ABS light. Fuel Injection system, Power accessories, there a lot going on there. It would probably be easier and cheaper to do a 5.3 swap than a 3.7 swap if you wanted EFI. Multiple vendors make plug & play wiring harnesses, adapters, better mileage and POOOWAAH!

yjaruba · **Posted:** Fri Aug 19, 2011 12:20 am

Liberty drivetrain 4 sale.

JeepinJarhead03 · **Posted:** Fri Aug 19, 2011 12:45 am

im sure it's hard to sell stuff engine wise there, but.. cross ya fingers.. at least with the 42RLE and 45RFE they're common transmissions beyond the Liberty/Nitro vehicles

at the least you should be able to sell the transmission, that could probably score you a 4.3 or SBC to start with

yjaruba · **Posted:** Fri Aug 19, 2011 9:40 am

One more question. I have my yj 5.5" lifted and 1" trans drop. With the stock setup I have no vibes (no slipyolk). Could you know what is a save angle for the rear driveshaft? With the lift and the shorted DS it may give me vibes right?

kj engine in a yj

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