The Automatic to Manual Swap Thread -

LinkBack Thread Tools
post #1 of 105 Old 04-05-2006, 01:57 PM Thread Starter
Registered User
1992 YJ Wrangler 
Join Date: Jan 2005
Posts: 866
The Automatic to Manual Swap Thread - UPDATED!!! 07/07/06

I finally finished everything. I documented everything. There are few pics right now but its pretty detailed. This is my first writeup so let me know if something needs clarification. Here goes:

I decided I was going to swap out my AW4 (Automatic) for an AX-15 (Manual). Since I could find little to no information on this, I decided to make my own write up on it as well. My advice is to get a hold of a transmission jack, a compressor, and air tools to say the least. Your life will be much easier with these tools at your side. You don’t necessarily need these tools but it makes it a lot easier.

Before you decide to undergo such a project, keep in mind a few of the factors to help you decide if you really want to get rid of the automatic transmission. Automatics are generally better off-road, while in heavy traffic, and for hauling trailers around. On the other hand, manual transmissions provide better fuel economy, give you more control, and in my own personal opinion, are way more fun to drive. This is somewhat of a permanent project so make your choice carefully. In my circumstance, I hate automatic transmissions; it takes away so much from the pleasure of driving. Plus, you need to be a better driver to use a manual transmission off-road. Whatever the case may be, find out which one suits your needs first of all.

The vehicle being used is a 1989 Jeep Cherokee XJ. The Jeep rolled out of the factory with an AW4 automatic transmission and 3.55:1 axle gear ratios. The stock gears will be a plus factor in the end. Manuals come with a higher, lower numerically, gear ratio (3.07:1) where automatics come with lower, higher numerically, gear ratios (3.55:1). NOTE: THE BOLT SIZES LISTED IN THIS WRITEUP ARE FOR JEEP CHEROKEE SPECIFIC. IF YOU ARE USING A DIFFERENT YEAR, MAKE, OR MODEL, THE SIZES LISTED MAY OR MAY NOT BE CORRECT.

The reason lower gears are a plus is because the ratios are different. By having more rotations of the engine for a given vehicle speed it allows the engine to wind up to within it's power band to produce more torque, but trading fuel efficiency due to the high number of revolutions for a given speed. Putting in lower gears will also reduce your top speed, but will trade that in for acceleration. Having larger tires will call for a need for lower gears to be able to turn the big tires, so this swap will help out my oversize tires just a bit.

The first step to any project is preparation. Make sure you have everything because it is no fun to be halfway through a project and realize you don’t have what you need. I have compiled a list of the parts and tools that will be used. Note some are not required, but make the job smoother.

Socket Set – Standard
Wrench Set – Standard
Socket Extensions and Adapters
Air Guns
Air Ratchet
Transmission Jack
Jack Stands
Bottle Jack or equivalent
Drill with Hole Saw’s
Grinder with Cutoff Wheel
Breaker/Cheater Bar
Screwdrivers – Phillips
PB Blaster
RTV High Heat Gasket Sealer

Cross member and mount for new transmission
Flywheel for your year specific
Clutch Kit
Pedal Assembly
Master Cylinder
Matching Transfer Case
Manual Models Cover Plate
Shift Boot and shift knob for Gear Stick

In the parts department there are hurdles to watch out for. First of all, before you go out and get any transmission, make sure the bolt pattern on the bell housing matches your engine. Always buy a new clutch kit from your local auto parts store while the transmission is out of the vehicle. Also it would be a great idea to get a brand new flywheel for your year specific. Ask me how I know All parts can be bought brand new, but then it gets really pricey. If you are on a budget, then the local junkyard is your new friend. The transmission, shifter, pedal assembly, master cylinder, and transfer case can all be taken out of the junkyard. Note: if you have to get a new transfer case to match, or if the new transmission is shorter/longer, then you also need the matching front and rear driveshaft.

The bell housing pattern of your particular vehicle is of great importance. You want a transmission that will bolt straight up to your engine, unless you want to fork out $300-$400 for an adapter piece. All the same, a Jeep 4.0L with an automatic transmission has the same bolt pattern as a Jeep 4.0L with a manual transmission.

After you have distinguished if your transmission will match up to your engine, then you need to decide if your transfer case will match up to your transmission. My Selec-Trac Transfer Case that came from the factory has 21 splines on the output shaft. The new transmission I acquired has 23 splines. Because of this, I need a new transfer case with 23 splines to match and possibly even the shift linkage, depending on transmission length. I ended up trading my NP242 for an NP231 because of the 23 splines. I wasn’t too happy about that, but I’m on a budget so I didn’t run out and get an adapter piece.

"When in doubt... Floor it"
1989 XJ 4.0L I6 - AX-15 Swap - NP231 - 4" RC - 33x13.50 MT Claws

2005 WK 4.7L 3.5" RK, 255/75R17 on Rubi Wheels
1992 YJ 4.0L 5" ProComp on 35x12.50 Trxus MT

Last edited by Jeepin_XJ_101; 07-07-2006 at 07:39 PM.
Jeepin_XJ_101 is offline  
Sponsored Links
post #2 of 105 Old 04-05-2006, 01:59 PM Thread Starter
Registered User
1992 YJ Wrangler 
Join Date: Jan 2005
Posts: 866
Interior Console and Shifter

Now that you are prepped and ready to go, you have all the tools, and you know this is what you want to do, its time to dive in. There are a couple different routes you can take to achieve the ultimate goal, but I will document my own route for accuracy purposes. I started off with the easiest thing I could think of. The console is easy and takes about five total minutes to take off, provided you have a console of course. It is held down by a few screws so grab your Phillips head screwdriver. Once the screws are removed, grab the handle of your automatic shifter. Press in the button and pull up swiftly and firmly. Also, if you have four-wheel drive, which in my case I do, pull the lever to the center, or neutral position. This just makes taking the console off easier. If you have power mirrors mounted by your emergency brake, then this is the time to unplug them at the connector. Do the same for the light switch connectors underneath the shifter plate. The shifter plate can be popped off with a screwdriver so just pry it out and unplug the connector. Pull the console out and set it somewhere out of the way. Remember to always keep your parts and tools organized so you know what goes where when its time to reassemble.

At this point you need to fold back your carpet, if you have carpet. You can get a grip on it underneath the dash where your feet go. Just pull it out of there to where you can reach the transmission hump. Since I am planning on spraying truck bed liner on my interior floor, I just cut the carpet out and threw it away. There are around eleven 5/32” head screws holding the cover plate down and four more holding the four-wheel drive shifter plate down. Just grab a ratchet and 5/32” socket and have at it. There are two cables attached to the shifter, you need to pop them off with a screwdriver in order to remove the shifter itself. After this is accomplished you just pull the shifter and cover plate off and you have on big gaping hole in the middle of your vehicle.

Master Cylinder Install and Pedal Assembly

Next I decided I wanted to get the master cylinder installed and out of the way. Go grab your drill, its time to do some cutting. This step can be saved until the end if you prefer, but I wanted it done by the first days passing. You need a hole saw that is roughly ¾” in diameter. Open your hood and take a look at the firewall on the farthest driver’s side point. There are two punch marks if you look closely. By word of mouth I was told that there was one punch mark and that was where you needed to center your main hole. Wrong! The two punch marks are the location for your two bolt holes. Both 9/16” bolts. The center of the main hole is exactly 1” lower than the top punch mark and 1” higher than the bottom punch mark. I would recommend marking the firewall before drilling. Because I drilled the top punch mark with my ¾” drill, I had to make a 1” drop bracket and re-drill my holes in order for the pushrod to actuate. The pushrod is the rod coming out the back of the master cylinder that connects with your clutch pedal. Here is the pic of the final assembly for the master cylinder with my drop bracket:

The new pedal installation sounds easy on paper, but is actually a lot of trouble for us bigger fellows. I inverted upside down in my drivers seat in order to see what I was doing. There is a bolt going through the brake pedal holding on the brake light switch and the brake pushrod. Unbolt that and the brake should swing freely. Up at the top where it is swinging there is a bolt going all the way through. I believe they are 11/16” you need to get a wrench on both sides. After some grunt work you should be able to slide the long bolt out. Ditch the brake pedal; it’s too big to work with the clutch pedal. Grab your ‘new’ brake pedal and clutch pedal. The bolt going through them should be twice as long (or close). The great thing about this is the brackets are already there. Slide the bolt through the new brake pedal just as you had taken it out, then push the clutch pedal up there and also slide the bolt through. Tighten the bolt and bolt back up the brake light switch to the brake. Now that your pedals are installed you can see a bar going straight to the master cylinder pushrod. The pushrod conveniently slides right on, and there is a small hole in the bar for you to put in a cotter pin to ensure the pushrod doesn’t fall off during use. Get in the upright position and test the clutch pedal to see if it actuates nicely enough. There won’t be much pressure on it yet because it is not hooked up and bled properly yet, but make sure it pumps in and out just fine. Pedals are now done, time to move on.

"When in doubt... Floor it"
1989 XJ 4.0L I6 - AX-15 Swap - NP231 - 4" RC - 33x13.50 MT Claws

2005 WK 4.7L 3.5" RK, 255/75R17 on Rubi Wheels
1992 YJ 4.0L 5" ProComp on 35x12.50 Trxus MT
Jeepin_XJ_101 is offline  
post #3 of 105 Old 04-05-2006, 02:00 PM Thread Starter
Registered User
1992 YJ Wrangler 
Join Date: Jan 2005
Posts: 866
Undercarriage - Part I

First of all, raise the vehicle and support it with jacks. If you only jack up one end, then block off the tires. To disconnect the shafts, grab an 8mm wrench and unbolt the four bolts on each end of the shafts. The rear only has bolts on one end, the other end just slides right out. For easier reach to all the bolts on the driveshaft, put the vehicle on jacks and throw the shifter into neutral. This enables you to spin the driveshaft to gain access to all the bolts easily. This is a prime time to replace the u-joints.

Undercarriage - Part II

The connections to the transmission are the next items on the list. It is imperative that you remember where everything goes. I started on the transfer case where I disconnected the speedometer gear at the cable. I moved to the reverse lights wiring, they have a connector that you can just pop off. You can also use a 7/8” wrench and unscrew it. Be wary that if it is spun too much then the wires will wrap and eventually break. Stick with the connector option, and if you must unscrew it, do it after the connector is disconnected. Moving up towards the front driver’s side of the transmission, I ran across the four-wheel drive shift linkage. I passed up the linkage to get the easy connections out of the way first. Right next to it was a wire harness that ran up and into the engine bay. The connector is located just to the side of the valve cover/heads. The last connector on that side is behind the linkage plate. You can follow the wires behind it where you will find a connector harness. Just unplug it and be on your way.

The shift linkage can be done a few different ways. For simplicities sake, I disconnected it at the plate. There is one bolt going through the link bar and the plate just above the cross member. The bolt itself is 9/16”. There is another bolt to the side of it inside the plate hole. This is one of the transfer case bolts so separate them accordingly. The third bolt is through the cover plate in the cab. These are also 9/16” bolts. You can see the bolt through the driver’s side corner of the cover plate. Then just let the linkage hang mounted to the transmission hump, unless of course you need to install new linkage to fit your transmission. In that case it slides out the transmission hump and the new one goes in the reverse of removal. Just past the linkage there is a cable with a ½” bolt attachment. This is the shifter linkage cable. Then get back into the engine bay and pop off the throttle cable. It’s located right next to your air intake/throttle body. You can ditch this because it is not necessary for the manual transmission models. Just pull it out from where it leads to the shifter. Now proceed to the passenger side of the transmission for the cooling lines. Here is a pic of the throttle cable. The blue line I have drawn is the old cable that I took out. Everything else stays:

There are two cooling lines on the passenger side of the transmission that run all the way up to the driver’s side radiator. These are 7/8” bolts and they are torqued down. To break them loose I had to push and kick the wrench with my foot. Get yourself a cheater pipe it will be easier. Once they are loose, transmission fluid will drain out so catch it in a bucket. Always store unused or old fluids in some sort of container and recycle it at your nearest auto dealer or auto parts dealer. After successfully breaking free the cooling lines, while you are waiting for the fluid to drain out all the way, follow the lines up and unscrew the various hangers. Keep following the lines to the front where the radiator is. They end up on the driver’s side, one on top, the other on the bottom. These are 9/16” bolts so grab a wrench and unscrew them. Remove the cooling lines and ditch them if you would like, because you don’t need them anymore. While you are up there grab the transmission dipstick, pull it out, and set it aside. Get back down to where the cooling lines went into the transmission and right next to it is the Neutral Safety Switch. I recommend just taking it off at the connector in the engine bay for reasons you will see ahead. Follow the wires up to the engine bay, it will lead you to the passenger side of the valve cover where there are two harnesses. The one on the left is for your NSS. All the connections should be off by this point.

Always, always double check to make sure all of the connections are loose. You don’t want anything to snag up or hang up while you are on your way down with the transmission. Once you make sure everything is loose from the transmission, its time to unbolt the transmission. Start off with the cross member and transmission mount.

"When in doubt... Floor it"
1989 XJ 4.0L I6 - AX-15 Swap - NP231 - 4" RC - 33x13.50 MT Claws

2005 WK 4.7L 3.5" RK, 255/75R17 on Rubi Wheels
1992 YJ 4.0L 5" ProComp on 35x12.50 Trxus MT
Jeepin_XJ_101 is offline  
post #4 of 105 Old 04-05-2006, 02:01 PM Thread Starter
Registered User
1992 YJ Wrangler 
Join Date: Jan 2005
Posts: 866
Undercarriage - Part III

The cross member consists of eight bolts. Four of the bolts are in the middle and two bolts are on each end of the cross member. The inner four are part of the transmission mount and are ½” heads. Unbolt the inner four and support the transmission with a jack under the pan. I picked up a transmission jack from Harbor Freight because I would be using it often. I would recommend that route because it is easier and a whole lot safer, but for $80 it is up to you if you want to spend the extra. Once the transmission is supported, you can unbolt the frame rail bolts. These are 15mm and you might need a breaker bar to loosen them up.

Now would be a perfect time to tackle the exhaust. You need to unbolt it at the Y-pipe which is the easy portion, and unbolt it at the connector in front of the catalytic converter. There are two 9/16” bolts, but you need a deep socket to reach up there to get a grip. The bolts in front of the catalytic converter are also 9/16” and there are four of them in a square shape. These are the tough ones. I broke two of the bolts and bent one of my 9/16” wrenches trying to loosen them. Do yourself a favor and get some PB Blaster. After you manage to get those pieces unbolted, grab a ½” socket and unbolt your exhaust hangers. Try not to break them; you will need them for reassembly. After the exhaust is loose and the hangers are off just finagle them over the axles and pull them out of there.

The next item on the agenda is the transmission mount. There are two 18mm bolts torqued down so grab your breaker bar and be prepared to do some grunt work. Of course if you have air tools like I did, they will spin right off. I did the first bolt by breaker bar and told myself there had to be an easier way, then lo and behold there were my air tools sitting in the garage untouched. Then, there is a ½” bolt holding on the exhaust mount that you need to remove.

After you get the transmission mount off you have two choices. You can leave the transfer case on when you pull out the transmission, or you can take it off prior to removing the transmission. Because of balance issues on my jack, I decided I would remove the transfer case first. There are six 9/16” bolt in a hexagonal pattern holding it on. A couple of them should already be removed from when you were taking the four-wheel drive linkage off. Make sure they are all unbolted all the way around and the transfer case should slide right off. If there is a sealer on it, a rubber mallet should do the trick. The transfer case is kind of heavy so I would recommend a jack. I just slid it off and lowered to my chest slowly. I then rolled myself out because I was on the crawler and set it down. Once again I would recommend a jack because it is much safer and won’t put your rib cage in danger, or get a buddy to help you lower it. If you tilt it, then fluid will spill out. I know, I got it all over my pants and had to trash them because it wouldn’t come out.

The last thing you need to do in order for that transmission to come out is unbolt the bell housing. There are about ten bolts, all of varying sizes, and the top two on my model, were ‘torx’ head bolts (E14). Torx head bolts are extremely common on Jeep’s, so it would be in your best interest to get a set. You might find that raising and lowering the transmission on the jack will provide easier access to the upper bolts. On the eleven o’clock position of the bell housing there is a sensor called a Crankshaft Positioning Sensor (CPS). I had to replace mine because it went bad a couple days before I began the swap. You might want to replace it for peace of mind though. It is held on by two 11mm bolts. The two bolts on the 3 o’clock and 9 o’clock positions are 5/8” bolts. The two on the bottom portion in the 7 o’clock and 5 o’clock position are 18mm bolts. Lastly, the one on the very bottom 6 o’clock position is ½”. Support the engine under the oil pan with a jack stand before removing the transmission. The last thing you need to do is also the hardest thing you need to do. Pulling transmissions as well as putting them back on is no walk in the park. I suggest getting a friend or two to help you out with this step. If it is the first time your transmission has been removed it will seem as though it is stuck. There will be some time put in pulling, grunting, shaking, and screaming before it comes off. There are few exceptions, of course. Once it is off, lower it and roll it out from underneath the vehicle.

Clutch and Flywheel

Get back underneath; you need to unbolt the torque converter. There are a couple bolts all the way around it, they are ½” bolts. Work in a crisscross pattern. Slide the torque converter off and set it aside right side up because there is transmission fluid inside of it. Next there are six bolts in a hexagonal pattern that are ¾” in size. If you need, take a screwdriver and jam it in the gear teeth to prevent it from moving. The flywheel is fairly heavy so make sure you have a nice grip on it to support it. Once the flywheel is off you can see a hole in the engine block that was in the center of where the flywheel was. This is where you need to stick your through out bearing. The through out bearing comes with the clutch kit. Grease it up like crazy and also the inside of the hole where your bearing will go. This might need a little encouragement to go in so what you can do is grab a socket that fits the circumference of the bearing and hit the socket with a hammer. This will slowly slide it into place. Once you make sure it is all the way in and in place, grab your new flywheel. If you are using a transmission from another engine, then you will need a flywheel for that year specific. Since I was using 87’ parts on my 89’, they had the same engine, and same style (Renix Engine), so I was able to buy a new flywheel that came from years 87'-89’ (I chose 89 because of my XJ being an 89, but same engine/tranny = same flywheel). Torque on the ¾” bolts that hold up the flywheel and get a hold of your clutch, pressure plate, and alignment tool that all comes in the clutch kit. The purpose of the alignment tool is to make sure you don’t slide the clutch around while bolting it on. When bolting the clutch back on, you can use the same bolts that were holding the torque converter on. Once again, bolt it back on in a crisscross pattern and tighten them up really well. Your clutch and flywheel are now installed.

Slave Cylinder

The slave cylinder also comes with the clutch kit. The only drawback is that you need the fittings from the old slave cylinder. Hopefully the old slave cylinder is still on the transmission if you pulled it from the junkyard or somebody else’s vehicle. Take the fittings and transfer them over to the new slave cylinder. You are provided with new retainer clips in your clutch kit. If those are not on properly, it will leak. There is also a retention bar that needs to be tapped in and fitted with a locking washer that is all provided with the kit. It is very small so avoid dropping it or damaging it. Maneuver the fittings through the side exit on the bell housing. This takes care of the slave cylinder for now.

"When in doubt... Floor it"
1989 XJ 4.0L I6 - AX-15 Swap - NP231 - 4" RC - 33x13.50 MT Claws

2005 WK 4.7L 3.5" RK, 255/75R17 on Rubi Wheels
1992 YJ 4.0L 5" ProComp on 35x12.50 Trxus MT

Last edited by Jeepin_XJ_101; 06-06-2006 at 12:34 AM.
Jeepin_XJ_101 is offline  
post #5 of 105 Old 04-05-2006, 02:02 PM Thread Starter
Registered User
1992 YJ Wrangler 
Join Date: Jan 2005
Posts: 866
Mounting the New Transmission

When mounting the transmission back up, alignment is the key. If the splines don’t match up, then no dice. You must make sure you are going in straight, as well as having the splines lined up before it will go on. This may take a couple tries, and make sure you do not damage the teeth on the clutch in the process.

Mounting the New Transmission – The Drawback

While we attempted finagling the transmission into place, we realized that it just was not going to make it on. We thought about what could be stopping it from reaching all the way. We were just over an inch away. I called up a buddy of mine who has a lot of experience in the automotive department and explained my predicament. I figured there was some trick to getting it to slide on. He explained that the input shaft on the new transmission was longer and needed to be cut down. I measured the difference on the AW4 as compared to my AX-15. Sure enough it was much longer. We grabbed a tape measurer and found out the difference in length. We grabbed a grinder and cut off enough of it to match, I think it was around 1 ¼”. It is also important to bevel the edges of the shaft after you cut it. Basically all that is, is rounding off the edge of the new cut. Here’s a pic of my cut and beveled input shaft:

Once you make sure it is flat and beveled, raise it back up and try it again. If it fits, usually you will feel it fall into place. To make sure that the splines did match up, put the transmission in gear, grab a socket of ¾” and head to the front of the engine. Have a buddy sit behind the transmission and watch the shaft. At the front of the engine, on the bottom of the block below the drive belts and pulleys, there is a bolt. This is the crankshaft bolt. Hook up your socket and turn the crankshaft. If your buddy says it is turning the shaft, then it is meshed and aligned properly. Proceed now with bolting the bell housing back up. When bolting up the CPS make sure the wires are clear of the exhaust. Torque back on all the bolts to the bell housing and you are finished with mounting the transmission back onto the engine.

Re-assembly – Part I

Re-assembly will be super easy if you remember how everything came off and what size sockets/wrenches you used. For detailed purposes I will walk you through re-assembly as well. The first thing on is the Transfer Case. There are six bolts that hold it up that are all 9/16”. You can lift up the transfer case and slide it on. There should be no trouble with it, unless of course you find out your splines don’t match. In this case I had to swap over to a Command-Trac in order for it to fit. If you would like, you can put some rubber gasket sealer on before you put it back up. Take note of which bolts you will use to mount your linkage.

The transmission mount and the exhaust mount are next. The exhaust mount has one ½” bolt and the transmission mount has two 18mm bolts. Remember they were torqued on when you took them off; you need to torque them down when putting them back on. Grab the breaker bar and tighten them really well.

Exhaust is easier put together than taken apart. Hopefully you did not bust any bolts like I did. The hardest part is getting the exhaust back into place on account of it being so long. Once you finagle it around the axles or however you would like, bolt it up to the exhaust mount and y-pipe, and then get the hangers bolted back on. The bolts for the exhaust are all 9/16”.

The last thing you need before you can take the jack off the transmission is the cross member. Remember there are eight bolts total, two on each end and four in the center. Since the transmission is supported, you can start either in the middle or on the ends. It is easier to line everything up if you start with the center four. The center four are ½” heads and the outer four are 15mm. Make sure you torque the outer ones on to make sure it is supported. You may remove the jack from underneath the transmission.

Re-Assembly – Part II

A nice place to start for the connections is the shift linkage. It takes three bolts, two of which are already in the transfer case. What you need to do is line up the plate and find the two bolts that bolt on the transfer case. Unbolt them and set them aside. Go back inside your cab and on the drivers side of the transmission hump there are four bolts holding the linkage bracket on. They are 10mm. Unbolt them and the bracket should just fall off. Anyways take it into your work bench you will need to drill a new hole (at least for my application).

Since my transmission is roughly 1" longer I need to drill a new hole accordingly. Consequently there are two holes on either side of the main hole with two screws in them, 1" from the main hole. I just drilled out the left hole bigger to allow the linkage to fit in it nicely. The bracket in the pic is upside down.

Here is a shot of it reinstalled and the linkage moved back 1"

Nice and straight... Much better!!!

Remember the hose from the master cylinder that you set aside. You now need to take that and hook that to the valve lines from the slave cylinder. One of them is a feed line and the other is a bleeder line. You want to connect it to the feed line, it just screws on. At this point you can bleed it if you would like, but I chose to wait until the end to bleed it. You also need to connect the speedometer cable to the transfer case, and wire a pigtail for your reverse lights to work. Wiring a pigtail means to use a piece of wire with plugs on each end to mate the existing reverse light wiring to the new transmission. I waited until the end to wire this up so instructions will come later. There are minimal to no connections involved with the manual transmission so this is a plus for re-assembly.

Now that everything is connected, you can mosey on over to the driveshaft portion. The front driveshaft is connected by four bolts on each end. They are in a circular pattern at the transfer case. Tighten them nice and tight and make sure it doesn’t bind. The four on the other end are holding on two clips. Bolt them up nice and tight and make sure the entire driveshaft doesn’t shake or rattle. On the rear driveshaft, the best way to do it is slide it into the transfer case and then lift the other end up into place. The axle end is the exact same as the front axle end. Tighten them nice and tight and make sure there is no play in the driveshaft.

Re-assembly – Part III

You are almost done, get back inside the cab and plug the light bulb into the four-wheel drive lever and bolt up the four-wheel drive cover plate into the transmission hump. You will notice that there is a big hole in the floor still. Because the cover plate you had before is so small, you will not have room to shift gears. You need to get the cover plate from the manual model of your vehicle. There are around eleven 5/32” screws that hold that assembly down. If you want the new cover plate you will need to drill new holes for it to fit. I just left mine off, its not too big of a hole. If you had carpet and wanted to keep it, now is the time to fold it back into place. Take your gear shifter and place it into the hole in the transmission. There is a specific slot to put the gear stick into, so just play around with it until you get it to go. Make sure you can move around in neutral at this point. From there you can get a shifter boot at an auto store to go around your gear stick and plug up the hole.

If you had a console you can fit that back on now. Screw in the main console piece with your Phillips screwdriver and plug your power mirrors back in if you had them. There are two other pieces to the console that you need to screw back on at this point.

"When in doubt... Floor it"
1989 XJ 4.0L I6 - AX-15 Swap - NP231 - 4" RC - 33x13.50 MT Claws

2005 WK 4.7L 3.5" RK, 255/75R17 on Rubi Wheels
1992 YJ 4.0L 5" ProComp on 35x12.50 Trxus MT

Last edited by Jeepin_XJ_101; 07-07-2006 at 07:36 PM.
Jeepin_XJ_101 is offline  
post #6 of 105 Old 04-05-2006, 02:04 PM Thread Starter
Registered User
1992 YJ Wrangler 
Join Date: Jan 2005
Posts: 866
Bleeding the Master Cylinder

Bleeding the master cylinder is a two man operation. One needs to be in the cab and the other needs to be underneath at the bleeder valve on the transmission. While the one of you fills up the master cylinder with standard brake fluid and pumps the pedal, the other needs to open up the bleeder valve once pressure is built up. Have the other person pump the clutch pedal and make sure that the master cylinder does not suck in any air. When it gets low, put more brake fluid into the reservoir. After about 10 pumps, hold the clutch pedal down. The person on the bottom will open up the bleeder valve while the clutch pedal is being held down. Once the bleeder is tightened again, give the pedal another 10 pumps. Repeat. The point of this process is to get any air bubbles out of the system. When the bleeder valve sprays out fluid with no air bubbles coming out, then it has been bled properly. Remember to never let the master cylinder suck in any air. Top it off at the end and you are finished. Close up the bleeder valve and test the pedal. There should be a good amount of resistance, but not too much. Run through the gears and make sure it is actuating.

Bypassing the Neutral Safety Switch (NSS)

Bypassing the NSS has possibly been the hardest part of this whole swap, just because I could find no information regarding how to re-wire it. The Neutral Safety Switch is what keeps you from firing up your vehicle in any other gear than Park or Neutral. It is located on the passenger side of the transmission. This wire you unplugged in your engine bay during the disassembly portion. It’s to the passenger side of the block/valve cover in case you don’t remember. It is a harness with pins sticking out that make contact to your NSS harness. In my engine bay, right next to it was a second harness. The difference was black and white, literally. The NSS connector is black and the other connector is white. Take a look at the connector on the NSS side of the harness, and note the lettering for each terminal. You need to wire up the NSS to simulate it being in Park/Neutral. For this you need to snip a couple wires and solder them together. This holds the continuity in the wires, so the switch “thinks” that it is in Park/Neutral. The wire harness from your NSS is labeled at each terminal. There should be letters A-H. Here is the table for my Jeep in specific:

Connector Terminals
B + C have continuity in Park + Neutral
A + E have continuity in Reverse
A + G have continuity in 3rd
A + H have continuity in 1st and 2nd

Using this table we see that we need to bridge Terminal B and Terminal C so the continuity continues, thusly faking the sensor into thinking it is in Park/Neutral. Leave all the other wires alone. There are a couple ways you can do this. The first way is to get a spade terminal or even just a piece of metal wire (solder) and connect, or wrap around, the two pins in the harness (Terminals B + C). The second way is to snip the wires coming out of terminals B + C and to bridge the wires. Using this method you need to strip away some of the rubber outing of the wires so bare wire is shown. Twist the wires to make them straight again. Take some Solder wire and melt it onto the wire by way of a soldering iron. When the Solder is all through the wires, take away the iron and it will cool. Wrap a lot of electrical tape around the bare wires and you are finished. The same needs to be done for your reverse lights, but a switch needs to be connected in order for this to work. Here is a pic of my bypassed NSS the spade terminal method:


Take your new manual out for a test drive and make sure everything is engaging and working like it is supposed to.

Test Drive

I took my Jeep out for a spin with the new manual transmission. It was a little rough getting it into gear in the beginning. This is because the clutch is brand new. It took exactly 10 miles for it to shift smoothly and function properly. I was told this is normal, and I remember my dad having to do this when he replaced the clutch in his 94’ F-150. It accelerates nicely, I actually noticed a little bit of power gain from the “lower gears” under a manual transmission. All in all this project was completely worth it and my Jeep is even more of a blast to drive. I guess the next test is abusing it off-road. Total cost of the swap was around $300 for me.

"When in doubt... Floor it"
1989 XJ 4.0L I6 - AX-15 Swap - NP231 - 4" RC - 33x13.50 MT Claws

2005 WK 4.7L 3.5" RK, 255/75R17 on Rubi Wheels
1992 YJ 4.0L 5" ProComp on 35x12.50 Trxus MT
Jeepin_XJ_101 is offline  
post #7 of 105 Old 04-05-2006, 05:13 PM
Registered User
Join Date: Jun 2005
Location: NoVA
Posts: 656

88 Jeep Cherokee - 4.0 - AX15 - 231 - d30 disconnect with welded spiders - d35+aussie
1998 Suzuki TL-1000R
600dollarXJ is offline  
post #8 of 105 Old 04-05-2006, 05:27 PM
Registered User
1989 XJ Cherokee 
Join Date: Jan 2006
Location: West Milford, NJ
Posts: 1,609
Originally Posted by 600dollarXJ
RussoGuitar is offline  
post #9 of 105 Old 04-05-2006, 05:53 PM
Blue XJ
Registered User
Blue XJ's Avatar
1988 MJ Comanche 
Join Date: Feb 2004
Location: Sterling Heights, MI
Posts: 1,775
excellent write up, it is now bookmarked.

I will be doing this swap if (when) my auto takes a dump

'88 MJ
Blue Jeep Club Member #72
| 4.6L Stroker | AW4 | 6.5" RK Long Arm Kit | 35" TruXus MT's | HP30, 4.56, ARB, Alloys, Lockouts | C8.25, 4.56, ARB, Alloy Shafts, Disk Brakes | Warn XD9000i | Interior Cage |
Blue XJ is offline  
post #10 of 105 Old 04-06-2006, 04:12 PM
Registered User
Join Date: Mar 2006
Location: Utah
Posts: 50
Verry nice! How did you get everything for $300 tho? Aren't transmissions like $800? Sorry i'm new to this stuff.. but i'm thinkin of buying this '98 with a bad transmission and would like to swap it like this so just wondering where you got everything for $300!
CDDOG2122 is offline  
post #11 of 105 Old 04-06-2006, 04:15 PM
Registered User
olds442's Avatar
1999 XJ Cherokee 
Join Date: Sep 2005
Location: Williamsburg,VA
Posts: 4,114
nice writeup, but wow i cant believe you typed all that, i would have fell asleep

Family Wheelin...
Dad- '08 JK Rubicon- Stock, BB and 33s coming
Sister- '07 FJ Cruiser- Rear locker, BFG A/Ts
olds442 is offline  
post #12 of 105 Old 04-06-2006, 09:07 PM Thread Starter
Registered User
1992 YJ Wrangler 
Join Date: Jan 2005
Posts: 866
Originally Posted by CDDOG2122
Verry nice! How did you get everything for $300 tho? Aren't transmissions like $800? Sorry i'm new to this stuff.. but i'm thinkin of buying this '98 with a bad transmission and would like to swap it like this so just wondering where you got everything for $300!
I originally bought everything I needed minus the clutch kit and fluids from a guy on here that was parting out his XJ for $80. The tranny ended up bein bad so he was nice enough to refund me in exchange for the tranny. I took that money to the boneyard and pulled an AX15, NP231, Crossmember, Mount, and Driveshafts. I rolled into the front and told the guy I only had $80. He said the only way he could do that is if I didnt get the warranty, which was like a 2-3 week warranty or somethin like that. So I was cool with that. Then there was the clutch kit which was like $170, and the Tranny Jack that was $50 at Harbor Freight. I had all the fluids layin around the garage from previous work so I was good there. $300 give or take a couple dollars. Would have been $250 without the tranny jack but I got it because I would be putting it to a lot of use. We did my buddies BA10 - AX15 swap without a jack and it was a complete pain in the butt. Im not sure how much trannies are at other boneyards though, from what I hear about others payin a lot of money at their local boneyard, the one I go to just might be the cheapest one in the nation

Originally Posted by LuVmyJeepXJ
nice writeup, but wow i cant believe you typed all that, i would have fell asleep
I used it for credit in school as a research paper. The copy for school was probably twice as long because I had to describe what everything was as if I was teaching a total idiot.

"The clutch pedal is the pedal on the very left on the drivers side where your feet go" dumb stuff like that had to be included as well.

"When in doubt... Floor it"
1989 XJ 4.0L I6 - AX-15 Swap - NP231 - 4" RC - 33x13.50 MT Claws

2005 WK 4.7L 3.5" RK, 255/75R17 on Rubi Wheels
1992 YJ 4.0L 5" ProComp on 35x12.50 Trxus MT
Jeepin_XJ_101 is offline  
post #13 of 105 Old 04-24-2006, 08:11 AM
t bell
Registered User
Join Date: Jan 2005
Posts: 203
great writeup. Slap this one in the FAQ or something. Hey next week, how about you swap in a 6-speed?

1991 Laredo 4X4
4.0L auto
t bell is offline  
post #14 of 105 Old 04-24-2006, 08:37 AM
Resident Audio Guru
UltimatE's Avatar
1994 YJ Wrangler 
Join Date: Sep 2004
Location: Worcester, Mass
Posts: 7,104
Originally Posted by t bell
great writeup. Slap this one in the FAQ or something. Hey next week, how about you swap in a 6-speed?
why not a viper v-10 go to with that 6-speed?

(Yes I realize its a wrangler, but that too came with a I6)


White '94 YJ Sport
Black '98 ZJ Laredo - 45x60 Surco Rack - 2" Budget Boost, Addco Front Swaybar

Project (s)Low - A build log.
UltimatE is offline  
post #15 of 105 Old 06-04-2006, 07:51 PM
Senior Member
youngjeeper11's Avatar
1987 YJ Wrangler 
Join Date: Jul 2004
Location: Morgantown
Posts: 962
holy horsepower, a viper engine, thats just ridiculous. anyway thanks for the info, I am planning on doing this to a TJ, can you think of anything right away that will be different?

Jeep 1:Used to have a 93 YJ 2.5l- 3.5" Black Diamond, Chevy TBI 5.7l V8, SM 465 4 speed, 8.8 rear( 4.10, L/S), rhinoline, Mile Marker 9000, NP 231, Had to sell it due to college
Jeep 2: 89/91 YJ, 4BT Cummins, NV4500, NP 231, Old Man Emu 2.5" suspension lift, 1" body lift.....Runs and drives, but very much a project
Interned at Novak Conversions 2 summers ago

Ask me about my 4BT Cummins Motor Mounts!!
youngjeeper11 is offline  

Quick Reply

Register Now

In order to be able to post messages on the forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid e-mail address for yourself.

Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page

Similar Threads
Thread Thread Starter Jeep Forums Replies Last Post
My Auto to Manual Swap Thread xjguy98 XJ Cherokee Technical Forum 0 04-04-2008 09:20 AM
Manual to Automatic Swap bigjohn73 XJ Cherokee Technical Forum 6 10-25-2005 12:03 PM
manual vs automatic and more gecko321 XJ Cherokee Technical Forum 3 11-02-2004 01:13 PM
Manual or automatic dudejepe XJ Cherokee Technical Forum 57 04-29-2004 11:25 AM
Automatic or Manual JimmyTwoTimes XJ Cherokee Technical Forum 13 03-12-2004 10:45 AM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome