Isuzu SUV Forum banner

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

14820 Views 59 Replies 3 Participants Last post by  Enemigo
I couldn't find a write up on how to do this install. I think it's way past time to do so. I'll do all the work and take the photos with help from people on here. I'll change the thread up as I go in order to have all the steps be in the correct order. I'm going to start the how-to with the transfer case already removed from the transmission and on a work bench. I got stuck pretty quick, so I'll post what I have for now and see if I can get some help from members here when I need.

Let's go!

With the transfer case out and drained, make sure you clean up the outside to prevent stuff from falling in once you open it. I used various brass wire brushes and a pick here and there to dig rocks and dirt out of hard to reach places. I kept my vacuum near by to keep the dirt pile to a low roar as I went along and found stuff I had missed on prior passes. I'll post the Indy4x instructions in italics.

Starting at step 5 of the install instructions provided by Independent4x, remove the four 12mm bolts on the low shift unit and remove. I tried to separate the case first, and had difficulty removing this as the case was preventing the ball from coming out. After taping the case with a soft hammer it vibrated out. Shouldn't be a problem if you do this step before pulling the case apart.

Next remove the 9 bolts and the 2 stud bolts from the house. NOTE! Mark the location where the 2 stud bolts were removed for later assembly. I used grease paint. If you forget, they are at the bottom, on either side of the drain plug. It starts to separate a bit on it's own and you can get a small pry tool in to help it along.

Remove the high-low speed ball detent unit. (This is a 3/4" hex fitting (19mm) that is located on the outside of the housing inline with the shift rail shaft. Remove the hex fitting, spring and ball. DO NOT leave the ball in the hole, as it will fall into the rail shaft hole when the shaft is removed. The yellow arrow indicates the correct detent. I removed both and the bolts, springs, and balls are identical.

Use a magnet to remove the spring and the ball. Any magnet (or a pick) will work for the spring, but you'll need a small enough magnet to fit down the hole for the ball. Pretty sure this is just some cheap one I picked up from Harbor Freight or whatever auto parts store.

Pry the housing apart. NOTE! The 2 locating dowel pins and all the internal shafts (expect the rear wheel drive shaft) stay with the front half of the housing.

This is where I'm stuck now. The case doesn't want to come apart any further, and I'm reluctant to keep prying. I've looked at other instructions on other boards and don't see anything about removing the drive shaft flanges.

Do I need to do this? What could be holding this together? Does it just need more gentle coercing?

That's all for tonight. Let's get all hands on deck and we can make a detailed thread together.
See less See more
  • Like
Reactions: 1
1 - 20 of 60 Posts
Its been eight years since I did my 3:1's, but I seem to remember having to take the flange off. Because that shaft has to slide back through the housing, and with the flange on there is no way for that to happen.
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.
See less See more
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.
See less See more
Problem is the nut is a B to get it off now.
Gotta find a way to hold it still so you can get it off.
It would be easier to get it loose in the truck but can't do that now. And can't engage 4wd to lock the front output from spinning.
I'm tell you now, don't hold a flat head against the satellite hub because it can warp and won't slide easily.
Also you didn't have to pry up the soft nut where it was staked. When you use force to undo it, I promise it will come free and off.
I'm not sure how best to tell you to undo that nut, but you'll find a way.
Also knock the pins out the shift rails now before you go further. Once you get the nut off that is the next step.
Don't take apart the 4wd cluster when you drop it out.
I got the nut off without issue. I'll update later. Is the idler gear the center one?
Surprised. Must be newer than junk I've worked with.
Impact helps too.
Idler is the middle which you swap for the revo plus the low gear on the main shaft
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.
See less See more
Unscrewing the nut chases the threads
Makes them clean but you can bugger them up for sure
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.
See less See more
I'm sure you've all seen this link before, and I think it will get me through most of the rest of this. However, I don't see anything about replacing any shift rails. ... ?g2_page=2
You replace one shift rail; the one that came with the revo set. It is 'shaved' to clear the larger idler gear.
Here is a comparison to see the shaved edge compared to the stock one. This is required.
2015-02-02 20.01.33.jpg

You need to knock out the pins. Take the allen hex method that Brad showed me. Cut the "L" off and you now have a straight piece of metal for using as a punch.
Those are hardened steel tools and are great for using as a punch to knock the roll pins out.
I hold the allen with my pliers, here I laid them down to take the picture. The teeth on the pliers are perfect for holding the allen straight to smack the roll pin through.
You won't hurt the rails smacking the pin. Also you need to strap down the case to hold it from moving.
Jerry said you won't break a rail unless you're the hulk. They are hardened steel.
Doing an mua5 you need to knock out all the pins except one on the shifter, I can't remember which one right now.
But the ar5/auto case, since the main shaft comes free, you only need to knock out the one in my picture and the one on the double ring thing. Doing this from memory now, May need to come back to this.
2015-01-25 17.25.27.jpg

This is me getting ready to put them back.
2015-02-07 14.24.57.jpg

Also you're not doing the snap ring method the "jerry" way. :D
He said to use a zip tie through the eye holes of the snap ring.
If you don't have one small enough or strong enough. You can do this too.
When you go to set the snap ring, torch it and it will melt the zip tie or cut it. But $10 says you can't reach under the revo gear head so you'll need to torch it or find a weird shaped knife. :lol: Like maybe a fishing knife.
2015-02-02 21.19.26.jpg

You can't get any of this out or back together by just pulling the idler.
The idler is overlapped by the main shaft gear and the small end of the idler overlaps the 4wd cluster.
It has to come out together and go back together all 3 together.
You may need a helper hand putting it together or some straps to walk it in inch by inch.


See less See more
I got those two pins last night, and all 3 internal snap rings. After reviewing the other link, it became clear I'll have to pull everything out together. Almost everything is loose now. I haven't taken off the front drive flange yet, and I think that will be my next step.
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.


See less See more
If your rubber o-ring feels good, reuse it.
If your front output feels good, reuse it. But I would change it if it has any sign of brittle ness or garbage on the seal/lip edge.
over time it can eat away at the edge and it will weep. So may as well change it now.
Thanks for the part number, that's very helpful. I've got a few different O-ring kits laying around so I'll check and see if I have the right one. Would it be wrong of me to use an A/C system grade, green O-ring if that's what fits?
Think the only difference did they are nitrile?
I dunno. Just has to withstand oil I guess.
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?
See less See more
You don't need those on the new one.
It wouldn't hurt to the put the collar on the end because it shouldn't move. But the small plate gear that has one less tooth does nothing now. (count it, it indeed has one less tooth)
Jerry said that that plate gear is to quiet down the action between the low gear and the entire cluster. Neat idea but not necessary now.
Also on the new Revo idler on one end there won't be a groove for a snap ring. Nor do you need one since it is pressed in place by the rear clam of the tcase.
You're almost done truthfully.
There are some neat mods you could do to convert it to fully manual as some people would want to do at this point and do away with push button 4wd. But I recall you said you wanted to keep it.
I see that discussed on here from time to time, but don't want to clutter this thread with that mod. Are there other threads about that I could check out? At one point in time I thought I didn't want manual hubs either, and now I have them.
1 - 20 of 60 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.