Manual Transmission Rebuild

Diagnosis

This project car is going strong at over 350,000 km. Unfortunately, after accidentally rolling through one of the largest puddles I had ever encountered, the alternator was pooched (an official diagnosis). Seeing the battery light come on in the dashboard and smelling the strong odor of burning wiring, I knew this repair couldn't be procrastinated.

Step 1: Verify the problem

Before diving into a repair it's always a good idea to verify the diagnosis. I used a multimeter to check the voltage at the battery terminals with the engine off. No problems here, the battery was holding a steady 12.05V. But when I started the engine, the voltage dropped to 11.79V. Much lower than the 13.5V to 14.5V the alternator should be producing. This confirms that the alternator was struggling to power the car and charge the battery properly.

Step 2: Taking out the alternator

Analyzing the alternator gave me a quick understanding of which bolts and connections to remove from the old one currently in the car. The alternator is held in place by the belt pulley, a mounting (pivot) bolt, a tensioner bolt, the primary electrical output connection and a smaller ground connection. I started by removing the belt pulley, then the tensioner bolt, then the mounting bolt, and finally the electrical connections.

Problem: Once it was removed, it became very clear that I had underestimated the difficulty of this repair. The alternator was too large to fit through any gap in the engine bay which left me with 2 options. Either I take out my entire air intake system which includes disconnecting the carborator (yikes) to bring it up out of the engine bay, or I remove the front passenger side CV axle to create a gap large enough to remove the alternator from below. I chose the latter.

Step 3: Passenger Side CV Axle Removal

Since it's an older car I decided I might as well replace both CV axles entirely. This was a really smart move because the passenger side axle fell apart with almost no effort. The bearings were free and grease was everywhere. Partly my fault for not being careful enough.

Step 4: Driver Side CV Axle Removal

The driver side CV axle was a different story. Instead of being an easy slide out, I had to remove the ENTIRE suspension assembly.

Step 5.1: Transmission Removal

At this point, the transmission was half way from being ready to be removed. Both axles were out and all the fluid was on the driveway. I was having issues shifting easily between gears, so I decided this would be the best opprotunity to take the transmission out and rebuild it.

Problem: The transmission was extremely heavy and I didn't have a transmission jack. I ended up having to use a floor jack with a piece of wood on top to support the transmission. It was a sketchy process, but I managed to get it out without dropping it.

However, the day my bud came to help with this process it rained, because of course it did. I didn't have access to the garage at the time, so we had to improvise on the driveway.

Step 5.2: Transmission Removal

Trying to remove the transmission in the rain was a complete disaster and didn't really go anywhere. Don't do this.

To remove the transmission, I had to also remove the starter so although I dont have the photos for that, I decided to replace it too.

After a lot of struggle and many missed connections we finally got it free.

Step 6: Transmission Teardown Part 1

30 years of grease and dirt build up. The initial teardown process required many hours of just scrapping clumps of grease from the main case and bell housing. This included disassembling the speedometer gear housing, shifter lever, shfit detent balls, throwout bearing, the case bolts, etc.

Step 7: Transmission Teardown Part 2

The next step was to remove 5th gear. For whatever reason, the 5th gear lives in its own little housing on the outside of the transmission case. Because of this, anyone with this transmission should be aware that any minor transmission leaks can become a very serious problem and will likely starve 5th gear of oil. However in the case of repairing, this is very convenient, so it was a simple matter of removing a few bolts and sliding the gear out.

Problem: The 5th gear was chipped from previous grinding when shifting. This was a really fun surprise...

Solution: Do nothing. It is a minor chip and not worth the effort to replace this hard to find part.

Step 8: Splitting the Bell Housing from the Main Case

This was surprisingly difficult and I struggled to get it out. I tried carefully prying it with a flat head screw driver but this started to dent the maluable aluminum case. I then tried yanking it out with rope but in hindsight this was terrible idea and almost broke my back. I was desperate enough to try and use floss/string to pry it out. I tried for days with varying methods but was unsuccessful and eventually opted to take it to a shop. However, no shops around would even take it in and I was forced to take it to a powertrain shop who usually doesn't work with transmissions in general. They are truly my heros and had it cracked in half an hour.

Step 9: Transmission Teardown Part 3

Heres a quick montage of the teardown of 4th to 1st gear including the linkages and reverse gear.

Step 10: Rebuilding the Transmission

Rebuilding the transmission was a LOT harder than tearing it down. On multiple occasions I had put the synchros in the wrong orientation or messed up the fragile linkages. By the end of it I had dismantled and reassembled the transmission 3 times, testing the shifting by hand to make sure everything worked properly. I wont show the images here, it just looks the same as dissassembly in reverse, but with gallons of brake cleaner.

I replaced as much as I could but some of the bearings were really trapped in there and since they were still in great condition I opted to leave them alone and avoid damaging the aluminum case.

The last thing to do was clean the mating surface between the main case and bell housing with soft sandpaper to remove the old crusty gasket pieces (this was done during disassembling). Then install the new gasket with a thin layer of Black RTV to ensure a good seal.

Step 11: To be continued...