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7,178 Posts
Discussion Starter · #1 ·
I haven't written one of these in a while and it was requested, so here it is. This will help you split your O2J transmission case and remove all the components, either for cleaning, replacement, or if you want to install an LSD =)

Let me know if you have any questions and I'll try to answer.

Start by removing the transmission by using previously written DIYs and drain the transmission fluid.

***If you are having problems getting this far, this DIY may not be right for you because you could cause serious damage to your transmission if not reassembled properly.

- 11mm socket
- 13mm socket
- ratchet
- T45 Torx bit
- T60 Torx bit
- 8mm triple square bit
- 6mm allen bit
- Propane torch
- 3 arm gear puller
- 2 arm gear puller
- Bench grinder (to grind down 3 arm puller arms)

NOTE: Bag EVERY part you remove from the tranny. Some bolts are very specific in size and length.

Removing the 5th gear selector

- Remove the five 11 mm bolts holding the outer transmission cover.

- Loosen but do not remove the 5th gear selector adjuster bolt with a T45 Torx bit.

- Notice there are 2 parts; the bolt itself and the selector adjuster. When you fully remove the bolt, make sure you don't drop either piece into the case.

- Remove the 5th gear selector fork retaining bolts with an 8mm triple square bit.

- Remove the 5th gear selector fork. It should come out as one piece, but the pivots are loosely attached, so do not loose them.

- Pull outward on the 5th gear selector. Pull out very slowly, as there are 3 spring loaded selector bits that will come out as well. Do not loose these or drop them in the case.

- Remove the 5th gear selector, and set it to the side.

- Carefully remove the 5th gear selector bits, and bag them along with the 5th gear selector. Notice how they are installed.

- Remove the T60 torx bit that is holding the 5th gear on. I could not budge these with a breaker bar, so I ended up just impacting them off.

- Notice there is a washer under each bolt.

- Lastly, remove the spring that is sitting inside the 5th gear syncro hub. It should come out easily with a blade screwdriver. (no picture included, it is the small silver clip)

Removing the 5th gear
CAUTION: You MAY damage your syncro or your idler gear in this process. Make SURE you have heated up the gear to loosen it. I take no responsiblity if you damage your transmission.

- Notice the gap between 5th gear synchro hub and the brass synchro. This is where you will need to get your pullers in. NOTE: I have found that you can also fit the pullers under the syncro hub if you grind them down a bit more. This is MUCH safer and won't damage the syncro.

- I had to grind down the lower side of my gear pullers in order to fit them under the syncro hub.

- Once you feel that you can get the pullers in, then heat up the synchro hub with a propane torch. Go around the outer ring of the gear. I heated mine for a good minute or two to make sure it was hot.

- Reinstall the gear pullers, and loosely install the T60 bolt in the shaft. This will give something for the puller to press against as you extract the syncro hub. Then pull out the 5th gear syncro hub. It may take a lot of cursing and re-orienting the puller arms on the syncro hub, but eventually it will come out. Don't forget to unscrew the bolt periodically as you are extracting the hub.

- 5th gear syncro hub removed. You have a good view of the brass syncro here.

- Brass syncro removed.

- 5th gear rides on the shaft over a needle bearing roller, so it should come right out.

- Using a 2 jaw puller, repeat the removal process for the 5th gear idler. I could not fit my 3 arm puller between the case so I had to use a 2 arm, and grind down the arms a little bit. (More cursing ensues)
Note: The second time I did this, I ground down the 3 arm puller some more and was able to fit it under. This is a safer method since it distributes more of the force around the gear.

- Remove 5th gear idler.

- This is a perfect opportunity to upgrade to a TDI 5th gear. This will drop highway RPMs by 200-300 RPM.

- If not already removed, remove both output flanges by unscrewing the Allen bolt inside the flange with a 6mm allen socket.

Cracking the case.
Note: If you are ONLY replacing 5th gear for the TDI upgrade, skip to reinstallation. If you are installing an LSD, keep going!
- Remove the deep bolt near the bottom of the casing with a T45 Torx bit. This holds the reverse shaft support bracket in place.

- Remove the outside bolt holding the other side of the reverse shaft support bracket with a T45 Torx bit.

- Place the selector shaft in the neutral position. If the shaft can move in and out, then it is in neutral. Then, remove the two bolts holding the selector shaft in place with a 13mm socket.

- Gently tap the selector shaft with a rubber mallet to seperate it from the casing.

- Remove the two bolts holding the selector shaft guide in place.

- Look down the selector shaft hole, and place a long extension into the hole. The goal is to push the selector shaft guide out from the other side.

- Remove the four bolts for the pivot pins with a T45 torx bit. Then work the pivot pins from out of the casing. Don't loose the O-rings on the pivot pins.

- Now, start on the outer case. On the 5th gear side, remove the 10 long bolt with a 13mm socket; they are all the same length. I found it easiest to loosen each bolt by hand and then take them out with an electric impact.

- On the other side of the case, remove the throwout bearing support by unscrewing the three 8mm triple square bolts.

- Then, remove the eight 13mm bolts on the clutch side of the transmission case.

Splitting the case
- Now, you are ready to split the case. You can see the seam of the transmission in the next picture. Whack the case with a rubber mallet, and eventually you will see the seam start to seperate.

- When you pull the top case off, it should look like this.

- Remove the selectors from the input and output shaft. The long tab goes towards the top.

- Remove the single bolt from the reverse gear selector shaft. It is either a T45 or a triple square, my notes were not clear on this.

- Then, remove the reverse gear support from the selector shaft.

- From here, you should be able to work out the reverse gear selector and the reverse gear shaft.

- Next, remove the four nuts holding the output shaft onto the case.

- You should be able to wiggle out the input shaft out of the casing.

- Next, lift out on the output shaft. It should come right out of the casing.

- Lastly, pull straight out on the differential. It should come right out of the casing.

To Be Continued...

7,178 Posts
Discussion Starter · #2 · (Edited)
LSD Installation

This is not designed to be a DIY but I had some pictures from the install, so put together this "familiarization guide". I don't have torque specs or details, but here is a general overview of what it takes to install an LSD.

- Remove the ring gear from the old differential. This one is fun. You need to drill out the heads of the old rivets, and then use a drift to push them out of the holes. No pictures here, but the instructions from Peloquins' website are here:

1) Ensure differential is square to drill bit.
2) Use a center punch and a hammer, place a small indentation in the center of each rivet so the drill bit doesn't wander.
3) Start with a 21/64" drill bit, drill the large face of the rivet ~3/4 deep from the face of the rivet. This puts a channel into the rivet to allow the head to be removed.
4) Use a 1/2" drill bit and drill the large face of the rivet. You should see the rivet head spin away from the shaft once you have drilled deep enough.
5) Use a 5/16" drift and tap out the rest of the rivet.

- Use a couple of 2x4's as cribbing, gently tap out the ring gear from the differential. I used a plastic mallet and tapped evenly around the differential until the ring gear came off.
- I marked which side of the ring gear was which with a sharpie so I wouldn't screw up the reinstallation process.

Now for some pictures. These were taken of the Peloquins LSD I installed, but follow the directions included with your LSD.
- Use some oil and lubricate the outer lip of the differential where the ring gear will sit.

- Set the ring gear on top of the differential, using the marks you made before. It won't go all the way on, but you want to align the gear so the bolts can go through the holes.

- Install the 4 alignment bolts finger-tight, skipping a rivet hole in each.

- Clamp the differential in a vise using the flats on the lower shaft. Since the bearing isn't installed yet, you should be able to access these flats. Tighten the four bolts equally to seat the ring gear flush with the cover.

- When the ring gear is flush with the differential, remove the four alignment bolts and throw them away.

- Place the four locking plates as shown in the picture below.

- I used some red locktite on the differential bolts, and then installed the eight differential bolts finger tight in the holes. Hopefully the LSD you bought was quality and came with ARP bolts.

- Remove the differential from the vice and press on the bearing. I had a press so I used it. Make sure the bearing goes straight on and is not cocked or misaligned.

- Obtain a brass punch and a hammer.

- Use the brass punch and knock out the bearing race from the case. Work your way around the race until it comes out. Be careful not to damage the lip of the case.

- When the race comes out, there will be a small shim between the case and the bearing race. You are supposed to adjust this shim based off play in the differential, but since this was a brand new differential I used the same shim as came installed from the factory.
- Lubricate the lip of the case for the bearing race installation. I used a little bit of installation lube but oil should work fine.

- Set the bearing race in the case hole and press it into place. Again, make sure it goes straight on and is not cocked.

After all parts are removed and you have replaced / repaired everything needed, make sure ALL your parts are clean. I did this by using a plastic bristle brush and dipping it in kerosene and then scrubbing the part. After the part is clean, pour a little oil on the part to prevent rust. Tranny oil is preferrable, but it really doesn't matter as long as it is synthetic.

- Ensure the tranny magnet is installed properly and clean.

- Install the differential back into the case. It should spin very freely.

- Make sure the o-rings are in place at the base of the studs for the output shaft, and then set the output shaft on top of the case. It should spin freely with the differential; ie they should move together.

- Set the input shaft on top of the case. All three should spin together freely.

- Install the four output shaft nuts on the other side of the case. I made these tight, but not too tight because I didn't want to crack a stud. I've seen it done.

- Install the reverse gear selector assembly in the case. Since it is spring loaded, it will give you some resistance but it shouldn't be too bad.

- Install the reverse gear selector bolt. Again, I made these tight but not too tight.

- Place the reverse gear selector support on the selector shaft. It should just sit there.

- This one is tricky. Slide the selector forks on the output shaft selector hubs. The fingers should slide into the slots, but they won't want to stay there very easily. This becomes a problem when you try to maneuver the top part of the case into place. Before you RTV the seams, try fitting them together a couple of times to make sure you have it right.

- When you are satisfied with the alignment, apply a THIN coat of RTV across the mating surfaces. I will assume you cleaned off the old sealant as part of cleaning the case. Then set the case halves together.

- Install the housing bolts on each side of the transmission. (no picture here, refer to the removal section)

- Install the side bolt for the reverse gear selector support. Use your finger to align the hole.

- Install the top bolt for the reverse gear selector support.

- If you installed the selector forks correctly, you will see a the holes for the pivot pins. These won't line up perfectly, so GENTLY work them in place with a screwdriver before installing the pivot pins. It sucks when you just try to force them in and the selector forks fall off the hubs...after you have already sealed up the case.

- Install the selector shaft guide at the bottom of the transmission. (no picture here, refer to the removal section)

- Look down the selector shaft hole. If you did your job right then all the holes will line up and you will be see this.

- Slide the selector shaft down in the hole. The cup aligns only in one direction, so get it aligned prior to installation. Then install the two bolts for the selector shaft.

- Install the 5th gear idler. Place it on the splines, and then use the bolt and washer combo to press it onto the shaft.

- Install 5th gear. It should slide right into place. Make sure the needle bearing is installed.

- Make sure the synchro ring is in the proper slot; it should be in the big slot on the splined selector hub, not the small slot.

- Make sure the lower spring is still in its proper place.

- Install the 5th gear selector hub by using the bolt and washer combo to press it onto the shaft.

- Using the information at the very front of the DIY guide, install the upper spring and the selector bits. You will have to press them in and hold them in place while you slide the 5th gear selector on top of them. Note that the bits need to be aligned with the cut grooves in the 5th gear selector.

- Loosely install the 5th gear selector adjuster and bolt. Do NOT drop them into the transmission!

- Install the 5th gear selector, the pinions, and the bolts.

- To adjust the 5th gear selector, manually engage 5th gear by pushing down on the selector. While the gear is engaged, push down on the selector adjuster and tighten the selector adjuster bolt.

Testing the gears
Obviously, you want to make sure the transmission works in each of the gears prior to reinstallation. You do not need to fill it up with oil to do this since you are only making low speed rotations. The goal is to spin the input shaft and watch the response of the output shaft. To do this, you will need to use a ratchet with the appropriate bit to turn the input shaft. I found it easy to slide the tranny output flange into the differential and watch it turn as I moved the input shaft.

- The at rest position as shown is for 2nd and 4th gear. I put a pair of nuts on the shaft so I could turn the shaft. Clockwise and counterclockwise will latch the gear.

- Push in on the shaft slightly, and this is the position for 1st and 3rd gear. Clockwise and counterclockwise will latch the gear.

- Push in on the shaft all the way. This is the reverse gear position.

- Pull out on the shaft slight, and this is the position for 5th gear.

- Reinstall the 5th gear cover with a new gasket.

- Reinstall the throwout bearing guide tube.

1,381 Posts
:eek: i have it out now and no idea how to put it back. Can you do the reinstall asap!!!!:(

Just kidding :p. Nice diy though, thank you! i just might buy an lsd now

19,049 Posts
nice write up, getting a fully built tranny next week

1,260 Posts
holy sh!t i wouldnt recommend most the people on here to diy anything to do with their trannies... but kudos on the work
i agree with him theres ppl on here that are mechanically inclined tht "think" they can do this when its not an entirely as easy as it looks, trust me i rebuilt my trans not an easy task haha got it done tho not entirely finished yet. good thing i had a extra o2j sitting around already built:thumbup:

but overall great DIY write up :beer:

15,993 Posts
great post....but again i wouldnt dive into this if you arent experienced with trans

the steps look easy but there are many things that can go wrong and thats where an experienced person can help

but i will say taking it apart is the easy part....reassembly and making it all work correctly is another thing :laugh:

110 Posts
Thanks for finishing the second half Mike! Really thorough DIY. Everything went smoothly taking the trans apart and putting it back together. It's really not that difficult with the right instructions.

I installed the selector fork pivot pins as soon as I mated the two case halves to ensure the selector forks would not shift off their hubs while buttoning up the case.

As an aside... the threaded pieces that sit inside the large bevel gear in the stock diff that secure the output flanges CAN fall inside the cases if they are jostled in the wrong manner. They don't really have anything securing them.

I'd recommend threading the conical bolt back in when the output flanges are removed to prevent this.

Thanks again! Good luck to anyone else attempting this :)

3,469 Posts
As an aside... the threaded pieces that sit inside the large bevel gear in the stock diff that secure the output flanges CAN fall inside the cases if they are jostled in the wrong manner. They don't really have anything securing them.
Anyway to get to the threaded pieces without having to split the case if they do fall?

110 Posts
Some metal wire, a lot of patience, and a miraculous feat of legerdemain.

This... It's tough, but it definitely can be done (I would know, haha!). I actually wrapped some metal wire around a small, strong magnet. It was MUCH easier to locate, grab and maneuver the piece with a magnet than by hooking it with plain old wire. The wire has to be pretty stiff or the magnet will just pull itself onto the differential.

As long as you can get it back in view, you can get the conical bolt back in and then it's very easy to put back in place. I coated the threaded piece with thick assembly lube and a q-tip before seating the piece to help ensure it wouldn't fall down again when I had to put the flange back on.

935 Posts
first off. amazing write up!

my question is this, i am going to buy a .72 5th gear kit from autotec and I am wondering if replacing just the 5th gear can be done without removing the transmission? Maybe just taking off the wheel and the fender liner.

935 Posts
You can replace the 5th gear and idler pulley without removinng the transmission. It really helps to have a lift, but I have done it in my garage.
thats what I wanted to know thanks for the fast reply :beer: I will be doing this in my garage.
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