What? 32RH to AW4 swap? Finally!
What? 32RH to AW4 swap? Finally!
I read everything I could find about the AW4 swap into a Wrangler TJ and every write up I could find was for a Manual trans to the AW4. Many people have asked about the 32RH to AW4 swap but I haven’t seen one write up on it, so I thought I would try to. The jeep that will be receiving the transplant is a 2002 Jeep Wrangler TJ Sport with the 4.0L with the 3-speed 32RH trans. The donor Jeep Cherokee was a 2001 4.0L 4x4 AW4. Let me appologize now for rambling on here but i just want y'all to get the full story for why i did what i did with certain things in my build.
First let me start by saying that the 32rh started out as a TF999 in like 1970 or something, it is a very old, and outdated transmission. Yes it has gone through many modification and re-engineering but bottom line it is still a 3-speed transmission
that was built and designed when the speed limit was 55 MPH on the highway. The speed limit on the highways in Austin, Texas now is 65 MPH &70 MPH and I think in some places it gets to 75-80 MPH on the highways through out Texas. So needless to say the 32RH needed to be replaced way before 2002 in my opinion.
A Jeep wrangler in its stock form with this engine and trans combo is OK and has a decent amount of power and MPG. However if you throw a lift kit on it, install bigger tires, heavy bumpers, spare tire carriers, weld in roll cage and other heavy stuff tends to rob the engine of power and kills MPG. If you re-gear the axles to make up for the lost power then the engine starts spinning at a really high rpm when cruising down the highway which, as I found out isn't good.
So here is a little bit of my jeeps story, I got my jeep about 3 ½ years ago it is a 2002 TJ sport 4.0L and 32RH bone stock with 31" tires. Now i'm not a wealthy man, I am a mechanic with 12 years experience and many certification but broke is broke and I am broke. All of my mods have been slowly done, in stages through out the last 3.5 years. I save some money do some of the mods, sell my old parts to recoup some funds and repeat. Yeah it takes a while but doing it right the first time saves a lot in the long run. I have put on it a 3.5” lift kit and a 1” body lift and 33” tires, a hack and tap type SYE and a front drive shaft from a ford explorer that I cut and rebuild and had balanced and welded to use as my rear drive shaft. I got my hands on a pristine ford 8.8 with 3.73 gears and disc brakes from a 2000 ford explorer, I then cut off the old brackets, then set up the new brackets, burned 'em in and installed. Had to get adjustable rear control arms to dial it in perfectly. ( really though, it wasn’t that easy but look for write ups on how to do it, very fun project). I then removed front drive shaft cause the gears didn’t match front to rear. This was only done as a temporary solution till I could finish all my axle swapping and re-gearing unfortunately it was about a year and half of temporary 2wd. I know a 2wd Jeep Wrangler is ridiculous (Wrangler JK).The 3.73 were a noticeable step up from the 3.07 and 33's but still wasn't where I wanted it. Slowly over time I got all the parts I need, a HP Dana 30 from a 96 Cherokee, new 4.56 gears, and master install kit, new axle seals and ball joints. I built the axle on the ground in my garage set it up perfectly and then swapped in. The front drive shaft was still left out until I could get all the parts for the rear Ford 8.8. I got Ford 8.8 4.56 gears and master install kit with all new seals and built it a couple weeks later. Man the jeep drives great with 4.56 and 33's! i had a hard time deciding on gears. i was going back and forth between 4.10 and 4.56 gears with the 3 speed auto trans i had. Alot of threads were saying said 4.10 were great with 33's and 35's but wished they went to 4.56 for the 35's. in my old ford truck i built i went 4.10 and wished i had gone to 4.56 or 4.88 after it was all said and done. So I decided on 4.56 because a lot of people online said it was perfect for 35” tires, which was in my Jeeps future and figured that it wouldn't be much different with 33's and wasn't planning to keep the 33's on long. What i didn't realize was how much highway driving i actually do here in Texas.
I live in Austin TX, and if you have ever visited you know it takes 30 minutes at a minimum to get any where, and you have to take the high way most times which is 65 mph or 70 mph. I live in south Austin and my parents live just north of Austin so after one trip up to see my parents I quickly realized that my engine was doing just over 3,000 RPM's at 60 MPH!! that is not good.
After a week of driving, and gong to my parents house twice doing 60 almost the whole way I started getting noise from the bottom end of my engine. Started out only on accel under a good load and after a week became louder and more noticeable. Long story short I had to tear the bottom end out and replace and rebuild everything. Got it back together and have been driving it ever since but I refuse to go over 55 mph for fear of it happening again. I started to do some research on getting my RPM's down so I can at least go the speed limit. I found two options that were reasonable and that could be done fairly cheap. I could re-gear everything, again, to 4.10 and get 35's and be wishing I had the 4.56 gears or I could do a trans swap to a manual trans or to the AW4 4 speed. I liked the auto trans, both of my previous cars were manual trans and I hate shifting in and out of gear in this crazy Austin rush hour traffic. So AW4 it was. Stu Olson's site has a couple good write ups on the AX15 manual transmission to AW4 swap. I read through every thing like 20 times and took notes on what parts I would need and printed out all the wiring stuff he had posted on how to wire up the trans TCU to the Wrangler PCM. Stu's write up for the manual to AW4 swaps are very detailed and he has many good pictures, most of the stuff in his write up is the same for this swap minus the differences in the original transmission set ups. I’m basically telling you that it is possible to do the 32RH to AW4 swap, and I am telling I have done it and these are parts I needed and the parts that were reusable. This swap is probably not for a novice but really wasn’t that hard. If you have ever taken out a 4x4 transmissions before then you can do this swap.
Here is the parts list as it is needed for the 32RH to AW4 Swap.
1. AW4 trans from 1998-2001 (most desirable Set up to use). Make sure it comes with wiring harness, range sensor, cooler line ends, shift cable bracket, Torque converter with the bolts to bolt it to the flex plate and the kick down cable ( kick down cable is mounted in the trans and is accessible by removing the trans pan)
2. AW4 trans TCU 1998-2001 4wd or 2wd (mine came from a 1999 2wd Cherokee)
3. Cherokee main harness connectors for the TCU and the 2 other ends of the trans harness connectors. ( see Stu's site)
4. AW4 flex plate ( yes it is different than the 32RH flex-plate. the hold down bolts and spacer is reusable from the 32RH flex-plate.)
5. You will also need the AW4 Trans dust shield. It is mounted behind the flex-plate and sandwiched between the bell housing and engine block.
6. You will have to get the (CKP) Crank shaft position sensor from the Cherokee, mine came still installed in the trans bell housing. It will plug right into the original wrangler CKP connector, (the CKP wiring was the same for the 2001 Cherokee and my 2002 Wrangler)
7. You will need the AW4 Dipstick tube and hold down bolt, and you need a dip stick tube from a 4wd Cherokee as well. (The 2wd dip stick is shorter for some reason)
8. You can run to the junk yard and pop out the shift indicator panel from a Cherokee and install it in the wrangler shifter if YOU WANT TO (not necessary but lets people know that something was done to the Jeep). The only difference is the Wrangler one has 1 and then 2 and then D whereas the Cherokee one has 1-2 and then 3 and then D doesn’t really matter they will both work fine but I wanted people to know I had a different trans so I got the Cherokee indicator and installed it after cleaning it thoroughly lol.
9. You will need a stand alone t-case shifter bracket (one that is not mounted to the tub like the factory set up) Advance adapters part # 715542 I ordered mine from quadratec.
10. You will have to get 2 longer bell housing bolts for the 2 16mm bolts on each side of the bell housing ( 3 o'clock and 9 o'clock) the bell housing is about a 1/2” thicker and the original bolts will tighten up but only a couple treads and you don't want to chance stripping them out or having them rip out since there are only 4 bolts really holding the bell housing to the block. The original size is7/16”x 2.5” and you NEED a 7/16”x3” bolt. Get grade 8.
11. You will need 3/8” bulk transmission cooler hose.
12. 3/8” compression fittings for cooler hose
13. You MUST have a Super Short or Mega Short SYE to do this swap about 300.00 bucks for a good one from JB conversions, or a Rugged Ridge Mega short one.. After everything was installed I realized the 32RH was about 22 3/4” long and the AW4 was about 25 1/2” long so that is an added length of about 3 1/4”. the measured length from the center of the U-joint on my Ford 8.8 pinion flange to the center on the SYE flange was about 14” that is way too short of a drive shaft to get any articulation out of it. So I will soon be installing a super short SYE and should be able to use my drive shaft I had with the regular SYE with modifying the drive shaft. The super short SYE from JB conversions is 3 1/8” shorter than the regular SYE, which basically takes care of the 3 1/4” length gained from the new trans. We will see and I post up my results in a couple weeks when I can afford it.
14. A couple rolls of wire for making your new trans harness( see Stu's site for wiring details and pin-outs)
15. Conduit to cover the new harness and protect it from the elements
16. Solder and a good soldering gun or torch
17. 1/4” flat stock steel to make an adapter for the original trans mount. ( also see Stu's write up about how he did his) Note: remove the little 1” mount spacer that is bolted to the top of the trans mount and has the exhaust hanger bushing in it, it raises the new trans too much and is useless. Bolt the stock trans mount to the ¼ plate that was made to adapt the trans to the factory 32RH mount. I used the stock trans mount but the Short after market trans mount will work too.
18. You will need to lengthen the front drive shaft or you might be able to get one from a Cherokee I believe they are longer but i will have to take some measurements and research it. Mine is about maxed out and pulled back about 3”, it works for now but I am only driving my jeep short distances, like 10 miles and not over 55mph cause it is in front wheel drive till I get the super short SYE. Thank god for the old Ford F-150 with the 4.9L beater truck I have for when my jeep is under surgery. haha
18. You need a 10 ohm 10watt resistor from radio shack, was about 2.50 for 2 of them, you only need one. this will have to be pushed into the original jeep wrangler TC lockup connector and taped in place. This will help keep the check engine light off until a new or reprogrammed PCM can be installed. It will not stay off forever but so far driving about 100 miles with it installed the Check engine light hasn't come back on. Found this little trick out after doing a ton of research on the swap. I think the guy that figured out this little trick was named Yuri? Google is my new best friend. Eventually I will get my ECM flashed for a manual trans or just get another ECM from a Jeep TJ with a manual trans so I wont ever have to worry about the CEL coming on.(but so far with above little fix it is not necessary to replace the ECM!)
19. get a little code reader so when the Check engine light comes on you can scan it and erase it!
20. Good idea to get an external trans cooler its cheap insurance for your new transmission. ( i didnt do this yet but plan to when i get the Short SYE done)
32RH parts that are reused on the Aw4
1. Flex-plate bolts and spacer (not the flex-plate its self)
3. trans mount (with little modification)
4. 3-speed shifter and shift cable
5. transfer case ( will have to be re-clocked and the input to the t-case will need to be shortened and the inner splines need to be ground to an angle like the original, see Stu's site)
6. Factory wrangler cooler lines can be reused, I cut mine with a mini line cutter where the line was about on top of the trans on the drivers side before it makes its way forward around the bell housing and installed the compression fittings there and on the line ends that go into the trans on the passenger side ( had to bend them a little so it wouldn't be too close to the exhaust) and run the 3/8” new cooler hose to connector the two compression fittings together.
7. Trans skid plate
I Wanted to give thanks to Stu Olson, although we have never talked, I really do appreciate all the hard work he does for his site and the time it takes to write up every modification he has done, or that others have done. If he reads this and wants to add this to his site please contact me.
I only have front wheel drive right now but I have only been driving it around where I live and drove it to work a couple times and down town Austin so I have put about 100 miles on it. I looked it over the few times I drove it to work and everything looks great and runs and shifts great. Once business picks up hopefully in a couple weeks I will get my super short SYE kit and install it and put my rear drive shaft back in and then figure out what to do with my front drive shaft ( as I mentioned earlier I have a HP30 front axle and the drive shaft is about maxed out but still works with the new transmission but will need to be replaced before any off-roading because if it flex’s the front too much it will more than likely separate the slip yoke in the drive shaft).
The Aw4 transmission shifts so smoothly into and out of gear and when driving. I went to 65 MPH today just to see my final RPM's and found that at 65 MPH my RPM's are right at 2200 that's almost 1000 RPM's less than the 32RH, and man having 4.56 gears is awesome with 33's and this transmission!