Auto to manual transmission swap (TF-727 to AX-15) in a 1991 Grand Wagoneer

**MtnYJ** · 04-26-2012, 04:35 PM

The Work

If you're still with me, or have scrolled this far I guess you'd like to read some tech.

We did this in phases to reduce the down-time of the Waggy. We started with everything related to the firewall area, both inside and outside the Jeep. First was the clutch/brake pedal assembly.

Our Waggy had a manual transmission brake pedal with a plate riveted to it to make it wider for the automatic transmission application; I've heard this is common practice. In any case, all we had to do was grind the rivets and pound them out to make ourselves a manual transmission brake pedal.

When it was time to reinstall the brake pedal, we used the pivot rod from the manual transmission J truck which has an extension to hang the clutch pedal.

Clutch pedal

Brake pedal

Once the pivot rod and brake pedal are installed, the clutch pedal slides on the left side and is held in place with a circle clip. We had to trim a fair amount of metal off the J truck clutch pedal, as there was serious interference with the wiring under the dash of the Waggy.

A tip for hanging the pedals; pull out your gauge cluster. With it removed, you can see the bar that the pedals hang on, and it makes alignment and final installation much easier.

**MtnYJ** · 04-26-2012, 04:36 PM

Once we had the clutch and brake pedal mounted, we measured the distance between the surfaces or the pedals where the master cylinder rods would connect. We used this measurement to design a template for drilling the firewall for the clutch master cylinder.

The template indexes with the firewall mounting holes for the brake master cylinder. Since the brake master pedal rod is in the center of the large hole, it's easy to measure the distance to where the clutch master hole will be. This is probably easier explained with a picture.

Basically, it came out with the clutch pedal rod and the brake master rod being at the same height on the firewall. Drill the large center hole for the clutch master first! Once that is drilled, knock the studs out of the clutch master, insert it in the hole, and mark the holes on the firewall for the studs using the stud holes in the master cylinder. If you mess this part up, you'll end up with much larger holes in your firewall than you need! Ask me how I know! :rant:

Once we had the pedals installed and the clutch master mounted, it was time to figure out where to mount the clutch rod on the pedal. This was a highly scientific process consisting of looking at it real close and messing with it.

We ended up using vice grips to clamp a bolt to the pedal in different locations. Once we had the bolt clamped on we reinstalled the pedal, and attached the clutch rod to the bolt. From there, we were able to push the pedal down to check master cylinder travel and floor clearance. Once we found the right spot, we marked the pedal and drilled and tapped a hole in it.

We ended up with the pedal stopping just shy of hitting the floor, so we'll still have room for the vinyl floor mat and insulation.

This was a good pausing point for the first stage. As the Waggy sits at this point, it is still entirely driveable, as long as you remember the clutch pedal doesn't actually do anything yet, and the brake pedal is skinny! We needed to get the Waggy inspected (for state annual safety requirement), so we actually did drive it like this.

**MtnYJ** · 04-26-2012, 04:38 PM

When we returned from the inspection I thought to myself, we should really tie the plastic clutch line up out of the way so it doesn?t touch the hot exhaust. Well, I thought about it too late, and now we have two plastic clutch lines with nicely melted-shut ends!! I did some research online, and talked to a co-worker who had just swapped a hydraulic clutch in place of a mechanical clutch. The gist of all the info I could find online says that once you open the hydraulic system on one of these plastic clutch slave and master systems, you have to buy a new one. Folks say you can't bleed them, and that the hose and master/slave are one unit. Well, those folks are wrong. My co-worker pointed me towards this guy: http://www.jdaent.com/oemreclli.html

I was able to purchase adapter fittings for the master and slave cylinder, and a custom made length of stainless steel braided hose that works great!

The bleeding procedure was a little different, but entirely do-able. We did it in three parts. First the slave cylinder, then the master & hose, and then the system as a whole. The trick for the slave cylinder is to compress the cylinder, and then let it out slowly as a helper pours brake fluid into the hole where the hose would connect. This expels all the air and replaces it with fluid. For the master cylinder, we installed it in the Waggy, connected the hose and let it dangle over a drain pan. We poured fluid slowly into the master until it ran out the end of the hose. Once there was fluid at the end of the hose, we connected the slave cylinder. The last step is to tighten all the fittings and cycle the clutch pedal several times slowly, while keeping an eye on the fluid level. The system is somewhat self bleeding, you will be able to see a steadily decreasing amount of bubbles appear in the master cylinder as the pedal is cycled.

**MtnYJ** · 04-26-2012, 04:39 PM

From here on out, we're committed (some may say commit-able!). It's time to remove the old components. There's not much to tell about dis-assembly, and I don't need to explain to you guys how to remove a transfer-case and auto tranny so let's just assume you have that part done. The only thing we did differently was take measurements of where the transfer-case output nut was in relation to the underside of the body.

(see measurement written on body to mark location of output nut)

There are tons of threads on different forums about the clocking, bolt pattern, and mating of transmissions and transfer-cases you can research for hours on end. I know because I did it. I didn't really write too much down, but instead just tried to keep in mind the general concepts and various ?gotchas? we might face. The TF-727 has a ?6-bolt round? pattern for the transfer-case just like the AX-15, and they share the same diameter and spline count output shaft; that part is simple to understand. The confusing and contradictory information I found was in relation to the ?stick-out? of the transmission output shaft, the input bearing/seal clearance on the transfer-case and the clocking pattern of the 6 bolt mounting pattern on both components.

I'd love to say at this point that I can confidently tell you exactly which parts fit for sure, and which ones don't but I'm not sure anyone can do that. I've heard folks say the parts that went into some Jeeps depended on what was available in the parts bin on the assembly line at the time. I'm starting to think there is some truth to that. Instead, what I can tell you is that the particular Jeeps that donated parts to this swap worked together in the following way.

Once we had the TF-727 out of the Jeep, we were able to set the transmissions side by side for a proper comparison.

Automatic (TF-727)

Manual (AX-15)

The AX-15 we used came from a 1998 Jeep XJ, and had the same clocking pattern as the TF-727 from our Waggy. That was a big help! Now that we've established the clocking pattern will work fine, it's time to check the fit of the NP-208 to the AX-15.

The NP-208 was about 3/4? shy of sliding onto the back of the AX-15

Luckily, we had a Novak clocking ring for a AX-15 to Dana 300 project sitting around. Using the Novak ring as a spacer instead of a clocking ring filled up the space between the trans and transfer-case. I actually called Novak and asked if there was another product they sold as just a spacer. The short answer is No, they don't. Normally they are very helpful, but in this case it was like pulling teeth with the guy on the phone, so I ended up just bouncing my ideas off of him. We ended up agreeing that it would be safe to use the clocking ring as a spacer by swapping out the transfer-case studs for 1? longer studs that would pass through the spacer and attach to the transmission as intended from the factory.

**MtnYJ** · 04-26-2012, 04:41 PM

Figuring out the trans and transfer-case would fit together was a big relief, but now we have to get the power from the engine to the transmission. Online forum research was a big part of the project, but like I mentioned earlier, there is a lot of contradictory information available. Everyone seems in agreement that the AMC V8s are externally balanced, and the 4.0 straight 6 engines are internally balanced. However, just like the transmission to transfer-case fitment information I was able to find, there are different schools of thought on how this balance difference can be overcome.

Some people say you have to use the AMC 360 flywheel and some people say you have to use the 4.0 flywheel. We chose to use the 4.0 flywheel since we had decided to use so many other parts from the 4.0 equipped Jeep XJ. Using the 4.0 flywheel only presents one problem; it's neutrally balanced. When removing the AMC 360 flexplate, it's easy to see that it isn't neutral, it has several weights attached to it.

You can tell from the pictures how careful I was to mark the flexplate so that I could make sure I put the flywheel back in the same orientation. I wish I would have known that they only go on one way! :loser: Anyhow, once the old flexplate was in hand, it was time to get the machine work done on our 4.0 flywheel, and so begins ?the day of phone calls? as we begrudgingly refer to it!

You would think that in a city as big as Raleigh, it wouldn't be a problem to find a machine shop to match-balance a flywheel to a flexplate. Well, it is! I looked on some local forums and asked around, and everyone recommended the same place; T-Hoff Machine. I spoke with the shop and they said they would take a look at it. I dropped it off with the counter guy who said he thought they could probably do it, but that his flywheel guy could tell us for sure. About 10 minutes after I left, they called and said they couldn't do it. They gave me the name of another shop to call, and even said if the other shop could do it they would deliver it to the other shop for me! Talk about great customer service! Around the time the other shop said they couldn't do it, I let the wife know it was getting difficult to find a shop. Between the two of us, we spoke with 11 machine shops! It was quite interesting really, they all work together really well, most of the calls we made were shops recommended by the previously called shop! Late in the day, the wife called and said she had a winner. Not only did they say they could do it, but they were significantly cheaper than the ONE other shop in Raleigh that said they could do the work. I left work early and carried the flywheel and flexplate to NAPA on Six Forks Rd and talked to Frank in the machine shop. I introduced myself and said he had spoken to my wife. When I asked him if he was familiar with what I needed done, not only did he not look at me like I had three heads, he said ?sure, you got a flywheel that's balanced, and you want it thrown out of balance just like the flexplate?... Ding ding ding, we have a winner!! :applause:

Frank called me two days later and I went and picked up the flywheel and flexplate. The work was top notch, finished on time, with no surprises on the final bill. I went ahead and had him also resurface it, as it's cheap insurance.

You can see from the pictures that the balance work required three rather large divets be drilled in the back of the flywheel, and one smaller one in the front side.

**MtnYJ** · 04-26-2012, 04:42 PM

It's assembly time!

For the most part, assembly isn't any different than if you had just pulled everything apart for a new clutch. Just as you would do anyway, we put in a new pilot bushing, in this case it's one for a 1973 CJ-5 with a 304 V8. There was nothing to remove from the crank related to the automatic, there was just a hole to receive the pilot bushing.

I installed the ?new? flywheel, using part of the handle from my floor jack to block the flywheel against a leaf spring so it couldn't turn as I torqued the bolts.

Once the flywheel was torqued down, I cleaned it thoroughly with brake cleaner. Now, the can of brake cleaner says to use it in a well ventilated area. I initially thought that under the Waggy with the floor all taken apart was well ventilated; I was wrong. Before I got too high, I grabbed my charcoal mask, but not soon enough to not be inspired to take a self portrait. I guess you could say it's what the flywheel would see if it could see...

Well, I sobered up and got back to installing stuff. Using my Haynes manual, I was able to figure out which two wires that were originally plugged into the automatic controlled the reverse lights and which one operated the neutral safety switch. The neutral safety switch was easy, I simply followed it back up to the starter relay, cut it off, and ground it to the inner fender.

The reverse light switch was also pretty easy. I had cut off the reverse light pigtail from the XJ in the junkyard, so all I had to do was splice the two Waggy reverse light wires to the pigtail. It doesn't matter which one goes where, as all it does is close a circuit when you put it in reverse.

Clutch installation was really boring, which in a conversion as involved as this one, I consider to be a pretty good thing!

**MtnYJ** · 04-26-2012, 04:43 PM

At this point in the swap, it was time to call in a few favors. The AX-15 isn't heavy, but it can be awkward for one person. We had two people helping with the install of the tranny; so there were three of us under the Jeep and Sarah working above to help guide things.

This made it really easy, so easy in fact, that when I forgot to install the throwout bearing and clutch fork no one really minded pulling it all back out! In addition to having to pull the tranny back out for the internals, we also forgot to install the cover that keeps gunk out of the bell housing. This is still not in place, but it looks like it would be nearly impossible to install it in it's current configuration anyway. The plan for the future is to cut it off so it doesn't have to go between the block and bell housing anymore, but will instead just cover the opening of the bell housing.

With the tranny installed it was time to install the bell housing-to-block bolts. I should mention that the bell housing flange on the AX-15 is thinner than the TF-727 flange so we had to cut off some longer bolts to fit. No big deal; if there are going to be problems, these are good ones to have.

**MtnYJ** · 04-26-2012, 04:44 PM

The transmission mount was next on the list to install. In order to determine where it would sit, we needed to install the crossmember and transfer-case. We weren't ready for final installation of the transfer-case so we left out the spacer and had a dry test fit.

We wanted to keep the install as simple as possible, using off the shelf parts where ever possible, just to make replacements easier to get when we are wheeling in the middle of nowhere. Keeping with this theme we didn't want to do anything too custom with the tranny mount.

I bought a metal YJ mount from the junkyard, and mated it to a stock Waggy auto tranny isolator. It was actually really easy, I only had to drill two new holes in the metal YJ mount and enlarge two oval holes in the stock Waggy cross member.

This part of the swap, I'm not willing to call finished yet - after we installed the rubber isolator it settled; or so I thought. Upon closer inspection I realized that it was broken! I don't think we put 10 miles on it. It was from AutoZone if anyone is interested. We replaced that one with one that cost twice as much from Advance Auto. So we're up to a $10 transmission mount now! This one has settled a little, but isn't broken so we're going to let it ride for now. If this one fails, the plan is to go to a polyurethane mount. My only hold up with that is that I'll feel obligated to switch to polyurethane motor mounts as well. At that, I'm worried about extra vibrations and harshness; yes, I know it's a Jeep!

Update: After a few wheeling trips the transmission mount needed to be replaced again. We purchased the polyurethane mounts for the transmission and motor mounts. The motor mounts were pretty destroyed, so it's a good thing we were replacing them.

These poly mounts are holding up pretty well so far (after 2-3 wheeling trips).

**MtnYJ** · 04-26-2012, 04:45 PM

Speaking of cross member, there's another gotcha... It sounds simple enough in all the threads I could find about this swap; everyone agrees, all you have to do is move it to use the rear set of stock holes on the frame rails. They are right about that part, it'll bolt right into the second set of holes on the frame, they're even sleeved like the front set so you don't have to worry about that!

The problem comes when it's time to reattach the exhaust and emergency brake cables.

With the YJ transmission mount and the Waggy isolator, the drivetrain rides a little lower in the chassis, this includes the exhaust mount that attaches to the trans mount. What happens is the mount places the exhaust in the same location the cross member needs to be.

This issue was easily (temporarily) solved with the sawzall, The cut-off exhaust was set aside for now.

We bolted YJ transmission mount, Waggy isolator, and transmission together by enlarging the holes in the crossmember that are used to bolt to the isolator. To help with the theme of a clean install, we also created a bracket for the torque arm and welded it to the crossmember.

The e-brake cables should be a bolt in affair. The front cable connects from the pedal through the transmission crossmember to the mid cable. When the transmission crossmember was moved, this needed to be accounted for in the cables. The front cable is longer than a stock Waggy cable, to account for the distance the crossmember was moved back. The mid cable is shorter than a stock Waggy cable, again because the crossmember was moved rearward. Except on this side, the connections the cable needed to make are closer than before.

The problem we ran into was that because the drivetrain sat lower, and thus closer to the transmission crossmember there wasn't room for the e-brake cables to come through in their normal spot.

Update:
So we messed up the placement of the drivetrain on that crossmember, which means the exhaust and emergency brake cables would have fit just fine. Apparently we lowered the drivetrain by about 1 1/4 inches during the swap. So we added a spacer between the crossmember and the transmission mount and are currently testing this.

The exhaust is fine. The emergency brake cables are fine.

So far no strange vibrations in the drivetrain. The rubber isolator was broken almost immediately, so we replaced it with a more expensive one, which broke after a few trips, so we went with polyurethane. We also changed the engine mounts to polyurethane, which was good because the rubber was destroyed, so we won't have any mismatch of vibration issues. The next step will be to build a custom transmission mount to replace the steel YJ mount. Without measuring, it looks like a flat plate bolted to the bottom of the AX-15 would also be able to catch the top of the polyurethane isolator.

**MtnYJ** · 04-26-2012, 04:46 PM

For final install of the transfercase, we used the Novak clocking ring part #153 as a spacer between the transmission and transfer-case. This solved the interference problem between transmission output shaft and transfer-case input shaft. In order to do this, we installed 1 inch longer studs on the transfer-case prior to it's installation.

Blue RTV was used to seal the spacer to the transfer-case

and the same to seal the spacer to the transmission and bolted them together.

There were only a few inches between the end of the transfer-case and the fuel tank.

This drivetrain is longer than our previous drivetrain, but it still fits. We re-installed the crossmember and transmission mount to finish this installation.

**MtnYJ** · 04-26-2012, 04:47 PM

I know folks have questions about the transfercase shift linkage. We used parts from the 727 shift linkage and modified it a bunch.

Sorry I don't have more detail on this, we weren't exactly respectful of the auto shift linkage as we removed it! :hmm:

Now that we have the transmission installed, we still need a way to shift it. We traced the top of transmission onto the bottom side of the tunnel cover

then used a hole saw to cut the hole in the tunnel cover. *** Note, the square-shaped hole was cut during a previous project to fit the transfer-case shift lever.***

Next on this list was fluid. I know you guys know how to pour fluid from a jug, but this is special fluid. I think part of the bad rap the AX-15 gets is due to the use of improper fluid. I know I've personally killed a couple by using the wrong fluid. We filled the transmission with Penzoil Synchromesh Manual Transmission Fluid and the transfer-case with good old ATF.

Using the brand new hole in the floor, we installed the shift lever for the AX-15. It didn't take long to realize it was too short, so we decided to weld in a 3? extension to the transmission shift lever to fit our driving comfort.

The shift boot from the Ford Ranger was installed with self tapping sheet metal screws. The shift boots were overlapped to use the same holes in the tunnel cover that we were already using.

**MtnYJ** · 04-26-2012, 04:48 PM

Alrighty, we've got a transmission, transfer-case all mounted, shift-able and filled with the proper goo. Gotta get the power to the axles! The rear driveshaft we had done professionally, because it needs to be balanced. Remember I said we already had the NP208; that install required a pseudo custom driveshaft. We mixed and matched sections of rear driveshaft from various FSJs until we got one that fit perfectly, no welding, grinding, balancing required. It was this Franken-shaft that I took to the driveshaft shop with our measurements from the AX-15 drivetrain. They shortened and balanced it.

The front driveshaft is much less fancy. We used the stock front shaft from an XJ, with a 1? section cut out and butt-welded back together.

I know that butt-welding a driveshaft is wrong, but it's working for now. I know I know, it should have a slug in it and be rosette welded and balanced and what-not. We're running manual hubs in the front, so between that and the NP208 this shaft doesn't see highway speeds. If we end up using this Waggy on the road during snow storms, then I'll have a proper front driveshaft built.

**MtnYJ** · 04-26-2012, 04:49 PM

If you're keeping score, we're currently the owners of an AX-15 equipped drive-able Waggy, with an exhaust that stops just shy of the transmission crossmember. The responsible, grown -up thing to do would be to trailer it to the exhaust shop before any test drives as not to disturb the peace. Well, call me what you will, but I can never resist the sound of an open exhaust, especially a good ole American V8! This thing sounds great! The first test drives went great, the only thing of note is a slight to moderate clutch chatter.

Movie with sound:

So, if you'll think this through it ends up being pretty funny. We're driving around in an open exhaust V8 with a clutch that chatters. There's no graceful way to move this thing forward at a red light, you have to use some throttle. Just picture the looks I get in the rear view mirror from the soccer moms in front of me! As an added bonus, it's also so loud that I can't hear any of the clunks or rattles we all know so well! The high-school kids who paid to have their truck's exhaust sound like ours, really thought we were cool.

Because the wife is worried about the neighbors and noise ordinances and what-not, we took the Waggy and exhaust to the exhaust shop. They fixed it up for around $80; all they had to do was add a slight bend in a new section to go up and over the transmission crossmember, and added another hanger to make the exhaust more sturdy.

**MtnYJ** · 04-26-2012, 04:49 PM

Since this is a Jeep, this project will never be finished. But we are glad we did the swap, it meets our needs and wants. It's working out great so far. We tried to cover everything that we thought was important in this write-up. If you have any questions or comments, please let us know. We took more pictures than you see here, so if you need another view, we probably have it. Just ask.

Auto to manual transmission swap (TF-727 to AX-15) in a 1991 Grand Wagoneer

Auto to manual transmission swap (TF-727 to AX-15) in a 1991 Grand Wagoneer

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