Project E36 M3 - Guibos and Driveshaft Bearings October 29 2013, 0 Comments

I remember watching a show called the Forza Motorsport Challenge, where several competitors raced in a series of challenges and winners got credits for mods to be used in subsequent challenges. It was a pretty cool concept of bringing the Forza Motorsport video game into reality. I remember watching the final race. The battle was heated, and everyone was in contention for the top step of the podium. One of the muscle cars was powering down the straight when the sound of a thousand Riverdancers on bath salts erupted and instantly the inside of the car was filled with a violent swirl of debris. I was sure the engine had exploded. When the car finally came to a rest on the side of the track and the cloud of debris subsided, it was revealed that the drive shaft had snapped. In the process it had thrashed around so violently that it ripped out a huge portion of the floor pan. The car was done for the day.

That's what I think of when I think of drive shaft failures, so when I saw a small crack in the drive shaft coupling (aka guibo) of our E36 M3, I didn't waste much time attending to it. The job took several hours performing it solo and documenting every step, but there wasn't anything too difficult.

The first thing that needs to happen is for the exhaust to come off so that we can have access to the drive shaft. Working from the back of the exhaust to the front, we unbolt the muffler support brackets. Shown is an aftermarket Borla catback exhaust, but the OEM exhaust mounts very similarly. Before the muffler is detached, support the exhaust with a jack or jack stand so that it doesn't hang exclusively from the front mounting point and bend of weaken the piping. 

Moving forward, detach the rubber hangers just aft of the cats. You can either unbolt the brackets that hold the upper halves of the hanger, or you can slip the lower portion of the hanger off of the cross support. One of ours was broken, and we have two new ones on order. The nice thing about getting under your car periodically is seeing things and catching them before they turn into bigger problems.

Next, remove the oxygen sensors and move them out of the way.

Last, remove the nuts holding the exhaust onto the headers. You'll need some socket extensions. Our X-brace got in the way a little, but we were able to leave it on and remove the exhaust with it in place. It helps to have a second set of hands so that someone in the front can lower and maneuver the front section of exhaust while the other person simultaneously lowers the aft section. With a single person, it is possible to lower the aft section enough so that the muffler has some room to maneuver and then go wrestle with the front end.

 

The drive shaft is almost nekkid now. Unbolt the heat shield, and now you have full access to the drive shaft.

Before we yank out the drive shaft, it is important to note the alignment of the drive shaft with the transmission output flange. The drive shaft is balanced, and it must be re-installed in the exact same orientation or it will likely wobble and create vibration issues. We used white paint to make a couple of marks on the drive shaft and the transmission output flange.

We did the same at the aft end of the drive shaft. The splined portion is the aft section of drive shaft.

With everything marked, we can start loosening bolts. On the forward end, you'll need a backing wrench to hold the nut while you loosen the bolts off the guibo. To access all the bolts, you'll need to release the parking brake and put the transmission in neutral, turn the drive shaft to where you need it to be, and then reengage the parking brake when you want to lock the drive shaft in position. We had to use a breaker bar to get ours loose, since there was some light corrosion on the fasteners. A penetrating oil like PB Blaster can help.

Now to disconnect the aft end of the drive shaft. There is a nut that tightens the forward drive shaft down on the splines of the aft drive shaft. Loosen it, and the drive shaft should be able to slide aft further onto the splined shaft. Undo the two bolts holding the drive shaft center support bearing (CSB) to the chassis. When the CSB is free, the drive shaft will drop, and the front end will be freed from the transmission. Tip of the day: don't smash your face. Also, support the aft drive shaft so that it doesn't just hang.

Use a pair of large snap ring pliers to remove the snap ring that holds the bearing on. Then it is off with the old and on with the new.  We put a bearing puller on the CSB. All it did was stretch out the rubber portion, and the bearing didn't budge.

Plan B: we cut out the outer portion with a knife and threw it aside. This allowed the bearing puller to grab the bearing itself.

Here is the bearing puller in action. Note the floor jack holding the aft drive shaft up.

Here is a the new CSB and the old parts you will need from the old assembly. If we were to go back in time, we would have ordered the smaller parts too when we ordered the CSB, but we cleaned them up and they are perfectly functional.

We're halfway there! When you put the bearing and the backing plate back on, make sure it is facing the right way. It is not a symmetrical part. Do not push on the outer race of the bearing during installation, or you can damage. it. We used a section of piping and a mallet to drive the new bearing onto the driveshaft. Reinstall the dust cover and the snap ring.

Everything goes back together the same way it came apart. There are just 3 things to note:

1) There are arrows on the guibo. The arrows point to which flange each bolt should be bolting to. Is the arrow pointing forward towards the transmission? Use that hole to bolt it to the transmission flange. Is the arrow pointing aft? Use that hole to bolt to the drive shaft.

2. Apply some forward pressure to the center support bearing while tightening the two mounting nuts. The idea is to take any slack out of the aft drive shaft section.

3. Tighten the nut that locks the forward drive shaft onto the splined shaft after tightening everything else on the drive shaft. As you are tightening the guibo, it is going to pull the drive shaft forward, and the drive shaft is going to need to be able to slide forward and aft.

Everything else goes right back in how you would expect it to go back in. Bolt everything back together and you're done. 

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