Service instructions start on page 9B-40 of the 1976 BUICK SERVICE MANUAL. However, I had found a web site that showed a step-by-step approach to this repair on a Jag with the same GM A6 compressor. I followed that guy's steps and never even cracked open the Factory Shop Manual (FSM) til I was writing this. A very easy task with the right tools and a little care. I'm glad I found the page linked below or I might never have attempted the clutch replacement.
http://www.bernardembden.com/xjs/comclutch/index.htm
Since web pages have a habit of moving and disappearing, I'm going to use a few of Bernard's pictures here for quick reference. Please do refer to the original page if the link still works as you are reading this.
As he points out, don't even think about trying this without a proper puller and installer. I bought a Mastercool (MSC91000A) Deluxe Clutch Hub Puller/Installer Kit from Amazon for about $55. I am sold on this brand as I have found the previous tool sets I've gotten from them are outstanding.The kit has several different pullers and installers for various brands/types of compressors. You can probably just buy the ones you need for *this* compressor for a lot less.
So, I removed the center nut from the compressor shaft using a thinwall, deep 9/16" socket. I found I could jam the tip of a screwdriver into one of the three "slots" on the face of the clutch and wedge the shaft against the socket that was over the nut and it would keep the clutch from turning with the socket as I backed the nut off. The nut was not on very tight and it mostly seems to be there as a safety backup. Trust me, that clutch is not coming off even if the nut isn't there.
The clutch removal tool threads into the clutch and the center bolt pushes against the shaft. Fairly simple. I had no trouble at all getting this part off.
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| Photo by Bernard Embden |
With the clutch off, you can see the snap ring that secures the pulley. As the reference web site says, snap rings have a habit of flying off the pliers and disappearing forever. He put a towel down but I was just very, very careful. And yes, I nearly had mine fly off! Large snap ring pliers are required. I bought K-D Convertible Internal & External Snap Ring Pliers - Large from Amazon, at around $20.
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| Photo by Bernard Embden |
The pulley is not pressed on but is a "zero clearance" fit. If you're lucky it will slide off by pulling on it, but I was not lucky. As Bernard's web site described, I had to use a small puller to remove the pulley. The compressor shaft must not be used to pull or push this pulley or any other component not on the compressor shaft itself. As advised on the web page, I used a 1-1/8-inch socket which fit over the center shaft and rested on the compressor nose. I used a bit of flat metal stock on the socket for the puller to push against.
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| Photo by Bernard Embden |
The coil that came with my rebuilt clutch looked awful! I decided since there were no apparent problem with the electric/magnetic portion of the clutch, I would leave the original coil in place and keep the rebuilt spare on hand in case I ever needed it. I am also decided to save the old pulley as a spare because while the face was a bit scored, I found out later from the FSM that this is normal and not a reason to replace it.
Installing the new pulley required a socket that would contact the edge of the pulley's bearing but slip over the compressor nose where the snap ring seats. I tapped gently until I could clearly see there was room enough for the snap ring. Then I popped the snap ring back on, making sure it was well seated.
The clutch shaft square drive key had stayed in the old clutch so I tapped it out with a screwdriver and placed it carefully in the new clutch keyway. Be sure to line up the slot carefully before you go bearing down on the installer tool! [According to the FSM, you should allow the key to project approximately 3/16" out of the clutch keyway. Oops! I did not check this.] The tip of the installation tool screws onto the compressor shaft threads, then the outer nut presses the bearing against the clutch face with one side of the bearing rotating with the nut to reduce friction as it forces the clutch onto the shaft. Super simple.
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| Photo by Bernard Embden |
Per the web page, you want a clearance of .010 to .015 between the clutch face and the pulley face, measured with a standard set of feeler gauges. If you set the gap too close, put the puller back on to increase the gap. No surprise, my clutch was not perfectly flat so I got different readings at various locations around the circumference of the clutch. But I was able to keep the gap between .010 and .015 as Bernard's web page suggested. [The FSM indicates there should be approximately 3/32" space between the frictional faces of the clutch drive plate and pulley.] Then I put the nut back on the end of the shaft using the screwdriver wedge as before. [Again, the FSM contradicts this and says to tighten the nut to 14-26 lb. ft. torque. Then it goes on to say the air gap between the frictional faces should now be .022" to .057" and refers us to Figure '9B-70. Oh well. ]
Belts back on and everything tightened up, I now have a vibration free and perfectly functioning compressor clutch with a minimum of time and money invested. And, I did not need to open the system or do any recharging. Many thanks to Bernard for his excellent web page and instructions.
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