Yup, it’s time for an informative blog post. Below is an illustrated account of my replacement of the center bearing on the drive shaft of my 1988 Chevy C1500 extended cab, extended bed, pickup, two wheel drive with the 5.7L V-8. For those of you who don’t know, the center bearing, seen below, is used to support a really long drive shaft on really long vehicles.
I was fixing a leaky radiator hose when I noticed that the center bearing on my truck looked a little worn. The rubber that holds it in place and dampens vibrations was pretty much gone, and I could shake the whole drive shaft with my hand. Now I knew why I got speed wobbles on the interstate and what that loud rattling was.
I hate spending money, especially to pay someone to do something I can do myself (Yes I know that the law of comparative advantages says that this is not always to my economic advantage. I also just like feeling manly and using tools.), so I went online and bought a new center bearing. Based solely on the price and what the picture on the website looked like, I chose a Timken Center Bearing for $21.55 plus $10.65 shipping and handling from partstrain.com. A few days later my part arrived.
I had done some research on center bearing replacement from these fines sources: Yahoo! Answers, eHow, and Automotive Helper. I even had the Chilton’s manual for my truck. It all seemed pretty straight forward and easy. I was a little confused about using a press to remove something, but I figured I was a smart, resourceful guy and I’d figure that out in time, more on that later.
First of all, I recommend you have a vehicle that sits high enough off the ground that you don’t need to jack it up, preferably, get one that you can sit up underneath. It’s way easier on your back. This is in contrast to my wife’s Ford Focus. A new born couldn’t sit up underneath it. Not only that, but I’d have to disassemble half the car to get to the part that needs replacement. Though little Ford Focuses don’t need center bearings, so I guess it’s a moot point. On a serious note, you should block off the wheels of your truck (see picture on right), and if need be, jack it up.
Chalk on drive shaft(left) and transmission(right)
Next you’ll want to use some chalk to mark where the drive shaft intersects the transmission, differential, and where the two halves of the drive shaft intersect. This way you can be sure to put the drive shaft back together exactly the way you found it.
Drive shaft (right) going into differential(left)
Most likely your drive shaft has been balanced to rotate with out vibrations, and if you put it back in differently than the way it was when it was balanced, you’ll have a rough ride. Also, the drive shaft has splines which help ensure you put it back on properly.
Removing the center bearing from the truck's frame.
Now you’ll want to loosen the bolts that hold the center bearing in place, thus allowing the center bearing to move freely. This’ll make disconnecting the drive shaft a lot easier. On my truck a 15mm nut and bolt were used to secure the center bearing to a cross member of the frame. Thankfully the nut and bolt were such that I could loosen the bolt with out having to hold the nut in place. I used some WD-40 to loosen the bolt and nut. I don’t think they had ever been touched in the 23 years of the truck’s life, so they were pretty hard to loosen.
Two bolts holding the metal retainer to the rear differential yoke, securing the universal joint bearings
Finally things get interesting. To remove the drive shaft you’ll want to disconnect the drive shaft from the universal joint bearings at the rear differential. There are two universal joint bearings, each held in place by a metal retainer which is secure with two bolts. Carefully remove these two bolts and then pull off the metal retainers. On my truck the drive shaft was under enough pressure to hold it in place even with the retainers totally off. I had to use the claw of a harmer to pull the universal joint away from the differential’s yoke. The image at right shows two bolts on one side of the universal joint securing the U shaped metal retainer to the rear differential yoke. Between the rear differential yoke and the metal retainers are the universal joint bearings.
Pins hanging onto universal joint after bearing fell off
In all the instructions I read they said to use tape to hold the universal joint bearings in place. When I used my hammer to nudge the drive shaft away from the differential’s yoke one of the bearings fell open, see picture on left. At first I was terrified, but the bearing is a pretty simple pin bearing and I used a small flat head screw driver to push all the pins back into place and then pushed the bearing back onto the universal joint. See picture on right.
Push universal joint bearing back onto universal joint
I was super careful to not touch any of the internals of the bearing and to not allow dirt to enter the bearings. After this I used duct tape to hold the two bearings on the universal joint. Why we can’t engineer a better way to secure a bearing in this age of technological advancement is beyond me.
Half of the drive shaft with the old center bearing still stuck on it at right.
Now that the drive shaft is free of the rear differential you should be able to pull the drive shaft out of the transmission. You should also be able to pull the two halves of the drive shaft apart. Be super careful to keep these open ends clean. In the picture on the left you can see the half of the drive shaft that connected to the transmission with the old center bearing still stuck on it at right.
Here’s where things got complicated for me. So it turns out that the center bearing is just held onto the drive shaft by friction, but not just a little friction, a lot of friction. At first I thought I could just use a hammer and knock the bearing lose, eHow said I could, but I was worried about damaging the drive shaft and causing it to lose its balance. Everything I read said to use a press to remove the old bearing. I thought a press was a machine that pressed things together, so I was really confused as to how you would use something like this to remove something that had been force in place in the first place. And I still don’t know. I assume you’d have to use a press in reverse to pull the bearing off the drive shaft. My tapping with a hammer didn’t work, so I got professional help.
All that was left of old bearing
I walked over to Courtesy Auto Services, and the guy there grabbed the biggest hammer he had and smashed the old bearing to pieces. I mean he just beat the heck out of it. This gentleman was not as concerned with knocking the drive shaft out of round as I was.
And in the end he was right. The banging did nothing to the solid steel drive shaft. Even after all of this, the inner bearing race was still firmly stuck onto the drive shaft. After trying to cut that off his coworker walked up with an air hammer and popped the bearing race right off. Then they used the air hammer to force the new bearing on. Maybe it was because my truck was so old, but that bearing wasn’t going to come off with just a hammer, so I’m not sure how eHow thinks if you don’t have a press you can just use a hammer and punch.
Splines on male end of drive shaft
After that I cleaned off everything, put more grease in the open ends of the drive shaft, checked the position of the splines and reversed the disassembly. I put the drive shaft back into the transmission using the chalk and the splines to guide me.
Splines on female end of drive shaft
Once the the splines were properly aligned it slide right in. Then I did the same thing with the two halves of the drive shaft at the center bearing. Finally put the drive shaft universal joint back into the rear differential’s yoke and bolted the metal retainers back in place.
That’s it. After that I took the truck for a little drive around the neighborhood and all was well. No rattles or vibrations. All told I spent $32.20 on my new bearing and getting it to me. I paid the guys at Courtesy Auto $10 for their time. Not half bad.