About a year ago I blew out the third gear synchro on my original transmission, I drove around on it just rev matching perfectly to get into gear, but after a week or two that got old. Luckily I was able to pick up. A perfect condition replacement transmission for $350 shipped. So now I have the spare transmission sitting in my garage and I’ve been contemplating cracking it open to replace that synchro.
I’ve never done transmission repairs, so I started this tread to keep all my pictures and notes from taking it apart and fixing it, just I case anyone down the road needs to do this as well.
I was suggested to do a full synchro replacement for all the gears, but I learned from building my engine that one thing at a time is best. My tranny was really healthy, I didn’t go big turbo until 55k so it only has like 20k of big turbo and hard shifting abuse, everything should be fine with the exception of the 3rd gear synchro and the gear itself.
Progress starts tomorrow and I’ll be posting up anything I find and any tools I need to build to dismantle it.
If any of you guys have experience please feel free to chime in.
Some of these tools you might be able to rent at a local store, like the blind hole puller or the bearing splitter.
Roller ball bearing puller - $89
Blind hole bearing puller - $75
250mm 2 Arm puller - $160
Ebay search for “Universal 2 arms puller” looks like this
Might be in a blue box too, same thing. You also don’t need the three arm puller, but you can get it if you like.
Shop Press. with arbor plates - $200
Custom tool that I made - $40, if you need advice on how to make this shoot me a PM.
Bearing splitter - $30
8" 3 arm puller - $15
Transmission Disassembly DIY
This DIY assumes you’ve pulled the transmission, drained the fluid, and you have the transmission laying face down(bellhousing) on a piece of cardboard.
Step 1 - Remove the Center Differential housing.
Get a 3/8ths socket wrench, a 12" extension and a T45 bit. Remove 6 torx bolts that hold the center diff housing to the transmission cover.
Pull the housing off slowly, as soon as you can get your hand in there and hold the center diff from falling out. There is a spring inside the center diff make sure it doesn’t fall out. Put the diff and housing away.
Step 2 - Remove the Transmission Mount
Using a 13mm socket, remove the three bolts from mount and set the hardware and mount aside.
Step 3 - Remove the Transmission End Cover.
Using the T45 used in Step 1 and an additional extension, remove 12 T45 bolts surrounding the housing. Gently tap the housing from the bottom up, to get the sealant to break free and allow the cover to come off. This might be tight, just give it a nice tap with a rubber mallet and a screwdriver or prybar and it will loosen up easily. Set the cover aside and you will see this.
Step 4 - Examine and remove the plastic oil collector
Grab the black, plastic oil collector and pull it off gently, no tools are needed. Examine the magnet for shavings. I had a 3rd gear synchronizer failure, you can see that I have some aggressive shavings in there. Yours should look better if you didn’t have any serious damage.
Step 5 - Lock the transmission shafts.
Before we can remove any gears, we must lock the shafts so that they won’t spin. Find the electrical connector on the passenger side of the transmission, Its held in by 3 - T45 bolts, Remove them. Pry it off gently, being weary of the o-ring.
Now use a 1 and 1/16ths socket to remove the two detents above the cover.
You should see something like this.
Use a flathead screwdriver to pry out the dowel pin.
Then push the selector shaft from the drivers side out through the opening you just made.
Selector shaft out of the tranny
Now press the two first gears forward. You have now locked the shafts together. Well done.
Step 6 - Remove the output shaft hulk bolt (hulk because you’re going to need to find a hulk to break it loose.)
Use an m12 triple square, an extension, a 3/8" to 1/2" adapter and a 1/2" breaker bar.
Once you realize that this will never happen, go ahead and drop the transmission on the ground, and devise a way to keep the transmission from turning. For me this is what worked.
What you see here is a thule ski rack bar (with ski rack attached, for extra weight to create leverage ;)) attached to the breaker bar with m12, the transmission is held on the other end by a $50 harbor freight engine stand. I had a 170lb assistant hold the engine stand. This is one tough cookie.
Step 7 - Pull the 6th gear on the input shaft (smaller gear)
This step is easy, go to sears and buy these.
And then you will pull the ring off and it will look like this
Use a 3 arm puller from Autozone to remove it, I removed the third arm to have a two arm puller, made it much easier.
Don’t mind the missing gear on the output shaft, I’ll get to that in the next step, I did this out of order a bit.
Make sure to shim to puller where it contacts the input shaft so that it doesn’t score the tip.
Step 8 - Remove the 6th gear on the output shaft.
Get a bolt and washer that will be this width. make sure the bolt is short, the threads should not be longer than a half thumb. Doesn’t have to be exact, but there is no need for more length.
Use the two arm puller to remove the gear. You will see a gear, a shim, two halves of a roller bearing, and a spacer tube come out.
Step 9 - Remove the 5th and 4th gear on the output shaft.
Remove the locking dowel pin on the 5/6 shift collar rod.
Pull out the 6th gear synchronizer ring, the shift collar, and the outer portion of the synchronizer hub.
Get your puller and attach it below the 5th gear to remove the 5th gear and inner portion of the synchronizer hub.
You will pull out the inner portion of the synchronizer hub, 5th gear, a shim, two halves of a roller bearing, and a spacer tube.
With those out of the way you can now use the gear puller on gear 4.
Again you will pull out a gear, synchronizer ring, shim, and a spacer tube.
You should have all of these things by now, and hopefully catalogued nicely
10. Removing 4th and 5th gears from the Input shaft.
With the 4th and 5th gears pulled from the output shaft, we can now pull the same gears from the input shaft.
You can remove both together using this tool
However I decided to pull each off at a time using the 250mm 2 arm puller(3" ID cone filter to show comparable size)
So pull off the spacer with the 5th gear.
Then remove the 4th wheel using the custom puller tool.
11. Removing the 3/4 synchro hub and 3rd gear on the input shaft.
remove the dowel pin from the 3/4 selector fork like we did to the 5/6 selector fork. Spin the Gold colored fork around and pull it out of the way. You can now pull the outer portion of the synchronizer hub as well. The inner part of the synchronizer hub will be pulled out with 3rd gear as well. Use the custom puller tool to do this, slide it over the back end of the gear and slowly pull both pieces out. With it you will also pull out A washer, a synchro, a synchro spring, and a roller bearing.
12. Removing the 3rd gear on the input shaft and the reverse gear.
Remove the circlip that is above 3rd gear using the red circlip pliers.
Use the 250mm 2 arm puller to remove the gear.
Now remove the three t45 silver bolts shown at the bottom of this picture
Now comes the fun part! Flip the tranny so you have access to the bellhousing. Remove the throw out bearing and the clutch fork. Remove these three t45 bolts.
Remove the metal piece that is held in by those bolts, then use the circlip pliers to remove the small circlip inside.
Also remove this spring washer. Make note of the orientation.
Now remove the the roller ball bearing that is behind the circlip. You are going to want this TE 9632 ball bearing extractor using the 9mm ball bearing tips.
This will not be easy.
Don’t worry those are OSHA approved flip flops.
Ok, one more circlip behind that roller ball bearing, and now you can carefully pull the bellhousing from the bearing housing. Now you should have something that looks like this.
Note that in this picture, that triangular metal piece that you pulled three silver t45 bolts from is pushed out. To do this you will need to buy a harbor freight blind hole bearing puller. Insert the second smallest bearing puller into the hole from the rear, attach the slide hammer (silver piece on the end of that shaft in the picture). Then simply slide the hammer toward the transmission with speed and it will press out the metal piece on the other end. Pull this out of the way. Now you can reach in and pull out Two roller bearings and the tiny reverse gear.
Ok while we are here, go ahead and use a rubber mallet to gently tap or simply use your hand to push the 5/6 and 3/4 selector rods out of the transmission. tap them from the back so they come out the bellhousing side. Then wiggle and pull out the input shaft gently and you can sneak it out.