Revolution Gear 3:1 install ('99 Trooper manual)

A surprise phone call from Lorenzo got me back on track, at least for the moment.

The electric motor on the back of the T-case, next to the rear driveshaft flange, needs to be removed before the case will separate. There are two bolts, and one stud bolt. In the picture I'm holding the long bolt where it goes to remind me for reassembly, but all the holes are different so it shouldn't be difficult.



I had the case pulled apart as far as I could, and I couldn't get this motor off. By pushing the case back together, it was able to unhook from the tooth and fell off with no trouble.


Here is a kind of overview of the area with me holding the motor. I'm sorry for the poor pictures. We all know this site has terrible photo hosting, so I keep having to crop the photos to fit the max width limit and it hides a lot of info.


Here is the case separated. This is the front, that retains both dowel pins and all of the gears but one.


And here is the back of the case with the one gear that connects to the rear drive shaft.

Next step per Indy4x instructions, Remove the snap ring on the input shaft. I'm indicating this snap ring in the photo.


Here is the snap ring and the bearing.


Using snap ring pliers and a small screw driver you can remove the snap ring and set aside.


Next, Remove the #6305 ball bearing from the input shaft.


I used a three-jaw gear puller to remove the bearing. Place the jaws on the back of the bearing, screw in the bolt until it holds itself in place, then use a ratchet to tighten the puller and pull the bearing off. The shaft turns as it pulls the bearing off, but it came off smoothly.


Bearing removed and still in puller.


Use a 3/16" wide x 3/32" thick tool to pry the hammered in portion of the nut at the key slot. Remove the nut. A small screw driver fits in this slot perfectly.


DO NOT DO THIS. I used a hammer to gently tap the screw driver into the slot as a wedge to open the dimple up. The screw driver was a bit too narrow for this, so I found a second screw driver and continued to tap on the top screw driver. DO NOT DO THIS. This was unnecessary and damages the threads.


Now it should be opened up enough to get the nut off.

The nut is 41mm or 1 5/8". In this photo I'm indicating the shift fork.


Simply slide it back, and it does two things. 1) it creates clearance to fit a wrench onto the nut (since I don't have a 41mm socket), and 2) it locks all the gears together for the next step.


Next I chalked the case up in my vise and clamped down on the front drive shaft flange.


It turns out that 2:1 gearing is still enough to turn the driveshaft flange in the vise when you put the wrench on the nut, so I slid a rod through a flange hole and up against a cooling fin. Try to get that shaft up into the base of the fin so you don't break it off.


I happened to have this 1 5/8" monster wrench hanging around. If you can have a second person to stand around and support the t-case, it'll alleviate a lot of fears about busting it loose out of the vise and dropping it onto the floor. I didn't have any help, but managed to get the nut loose.


I had a heck of a time focusing properly here, but you can make out that when I hammered that screw driver into the nut peen, it laid the threads over and broke some of them off. This also made it less than smooth when the nut came off, but fortunately the rest of the intact threads kept everything clean.


All the remnants of those damaged threads.

Now I'm stuck again. The next instruction from Indy4x is Release the snap ring that is under the gear on the idler shaft. This is the snap ring that holds the idler shaft to the housing. (This snap ring will remain loose around the idler shaft but will allow the idler shaft to move outward).

I've done that here. I first removed the outer snap ring (not sure if I needed to or not).


The snap ring under the gear they are talking about is this one in the photo. Ignore the gear puller in the upper part of the photo, as the way it is installed is just pulling on itself.


I used the Jerry method of running a wire through the holes of the snap ring to hold it open. The solid wire pictured broke twice, so I switch to a braided wire with a sheath, which also broke. However, in trying to get the snap ring to stay closed, I somehow got it out of position like I was supposed to.


Now I'm to the point where the idler gear has enough play that I was able to maneuver one of the shift rails out of place, but everything is interfering with each other and I can't figure out what piece needs to be removed first, nor how to remove anything.

Here you can see the shift rail out of place.


The flat, round piece fits in the slot immediately to the right, and the shaft fits into the hole toward the top of the photo. After you remove (partially) the interior snap ring, it allows the idler gear to move forward enough for this piece to come out.


This shows the new idler gear, and shows that it's a large gear toward the bottom, and a smaller gear at the top, all one piece. That larger gear is prevented from being removed by each of the two gears on either side, and each of the shift forks attached to the rails.


I'm indicating what I'm calling a shift fork, and you can see one on either side of the idler gear, preventing the idler from coming out.


Here is everything again just as an overview. You can see that the large gears on either side of the idler gear hold the idler in place. It's clear that I need to remove the shift forks and rails, but it's not clear how to go about this. There are several pins in the wrist of the shift rails, but I tried moving a few of them with a drift punch and they didn't seem to want to move, so I'm not sure if they are directional or not. I hope not, because I don't know how I'm going to access them from the other side with any amount of force.


Finally, here are the rest of the Indy4x directions, which I'm sure will make perfect sense once I'm done, but at this stage, they aren't that helpful. There is a diagram included with the Indy4x instructions, but none of the parts they mention are labeled in the diagram.
Using a long eared pulley puller, pull off the low speed clutch drive assembly. (The drive assembly includes the low speed gear, shift ring, spined shaft drive part, shift yoke and shift rail). NOTE! The idler shaft may have to be pulled up slightly to clear the yoke's removal. If the roller bearing and the inner assembly, make sure that you do not lose the inner bearing sleeve's drive ball that is located in the input shaft. Remove the idler shaft. Pull up by hand. Remove the snap ring on the idler shaft.

I found the part number to the front output oil seal.
NATIONAL 710768 I verified this across a few different years on the front output all have the same National part number because the case output is the same for rodeos and troopers, doesn't matter mua5, ar5 or auto case. Same junk.
or search for isuzu parts 8970467020 or 8970467010 or 8970467030 or 8970467031 Looks like the part number changed over the years.
You can try SKF 18015 but the pic don't look right from what i found. If you find one in store, make sure it looks like this:


You'll need the o-ring that goes on the front output. I haven't been able to find it but jerry can get some.
You can also take the o-ring to the part store and try to match it up. Most important is to not get it too thick or too thin.
Must be same diameter obviously.
Also trick I mentioned on the phone. When you go to stake the nut, before you screw it back on the output flange, put a dab of blue rtv sealant on the stake mark.
Jerry said they can weep there under pressure and I've actually seen it weep there too.

EDIT: I was able to punch the wrist pins out of the shift rails as shown in the pictures from Lorenzo. It was nothing special, just a punch and hammer and they pound right out.

All three shafts and gear sets need to come out together. In order for that to happen, you need to remove the front driveshaft flange. This is a 36mm socket and you can use the same method of sliding a rod through one of the driveshaft bolt holes, up against the case, between cooling fins, to stop everything from turning to loosen the nut. There is no snap ring here, the ones in the photo are from other areas. Once the nut is all the way off, use a soft dowel (wood, plastic, etc) to tap the shaft loose.


The idler shaft needs to be tapped out as well, but there is no access from the back like the other two shafts. I threw my 3-jaw gear puller back on as pictured, held a steel rod between two of the pullers (with my thumb off to the side) and tapped the whole assembly out with a hammer. Of course make sure you've loosened the internal snap ring under the large gear first.


Here is everything out of the case.


I had already partially pried the small bearing off of the idler gear, but the best way is to use a bearing puller and chalk it up into your press as pictured.



Press each bearing off the same way. Make sure you have a helper catch the idler gear as it drops. Or if you like excitement like I do, squat down to catch the idler with your off hand as you pump the press with your dominant hand, all while placing your face right where all the action is taking place. Wear safety glasses.


Now I have some questions. Here is how the factory idler gear is set-up.


There is a thin gear, a shim, and a collar on the bottom/back of the idler, as well as the internal snap ring. Do all of these components transfer over to the new idler gear?


Obviously the thin gear will do nothing with the new, larger idler gear, but it seems like it acts as another shim and with everything in place, it is the correct height to support the bearing. The Indy4x instructions only say to put the bearings onto the new idler gear, but don't mention any of the shims or the collar. What's the consensus?