Clutch installation

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This technique requires you to have a dial point indicator (DPI). It is a device used to measure runout and is accurate to 0.001".
Start by taking the glow plug out of the engine. If you keep the glow plug in it will effect the reading from the DPI. Next setup the DPI to measure the side of the clutch. The DPI I use can be clamped to the engine mount but depending on your DPI you may have to setup a board that the engine and your DPI can be mounted to. Set the measuring tip of the DPI against the side of the clutch as shown in the picture on the right. The clutch should be bolted down at this point. Next rotate the clutch so that DPI tip is against the side with the bolt. You do not measure directly on the shoe part of the clutch as this will set itself once it is expanded against the clutch bell. Rotate the face of the DPI so that zero is aligned with mark on the face. Now turn the clutch 180 degrees so you can take a reading from the other side. This measurement should be less then 0.002" from the zero mark. If it is not then you have three more positions to try the clutch in. Take the two bolts out and hold the fan while you rotate the clutch 90 degrees to the next set of bolt holes. Tighten the two bolts and again measure the difference. If it is more then 0.002" then rotate the clutch 90 degrees and try again. If none of the four positions is 0.002" or less then you may have a bent crankshaft or the fan hub is not centered. I would take the fan off and test the crankshaft. If the crankshaft is fine then you may want to try another fan.

NOTE: So what if the fan runout is fine (0.003" or less) but none of the positions for the clutch will give a good runout. Aside from getting another fan you maybe able to grind away some of the inside of the hub so it will let the clutch move in that direction. Now for the clutch, insert the clutch in the fan hub but do not bolt it in. We need to find out if the inside of the fan hub was manufactured right and will use the clutch to do this. You could angle the DPI to get the point on the inside surface but that puts it at an angle and you do not get the currect measurements so to counteract that we are going to use the clutch to measure this. Rotate the clutch so the point of the DPI is beside the bolt hole. Now hold the clutch in place with a little pressure pushing it toward the DPI. Now rotate the fan a full turn. If you get more then 0.003" runout then I would fix it. What I do is mark the side that is pushing the clutch more toward the DPI. In other words as you rotate the fan you will see the needle move clockwise (this usually means the point is being pushed toward the indicator). At the point where the needle has rotated to the maximum clockwise position, hold the fan still and mark the side opposite of the point with a felt pen. Now take the clutch off and use a grinding bit on a Dremel to grind a few thousandths off that half of the fan hub.
Now that you have opened up the hub we need to find the best bolt holes to attach the clutch. There are 2 sets which gives 4 possible positions. Pick one and bolt the clutch in place. Place the DPI point on the middle of the outside of the clutch. Take note of the DPI reading at the bolt area then rotate the clutch 180 degrees and check the other bolt hole area. If it is off then loosen the two bolts and push the clutch opposite the direction that it is off and tighten the bolts again. There is not much play in the bolt hole area to work with so if you cannot get close to zero runout then rotate the clutch 90 degrees to the next bolt hole position and try again.