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I want to remove the alternator pulley to drill and tap it for the CDS magnetic RPM sensor. I tried to break the alternator nut loose by holding the alternator shaft with a 1/2" wrench on 10mm star bit braced against the frame rail and a 15/16" box end wrench on the alternator nut. All that accomplished was snapping the 1/2" wrench and launching it across the garage. Exciting, but useless. (Safety glasses, always wear safety glasses!) Unfortunately, the fuel filler assembly is in the way of getting an impact wrench on the alternator nut so I can either remove the alternator or remove the fuel filler assembly.

Removing the fuel filler assembly would be tedious, but straightforward, with little chance of ancillary damage. Removing the alternator would be frustrating with the potential for causing damage to any number of things as I try to get a wrench or socket on that damn lower alternator bolt. Of course, I could remove the fuel filler assembly and still not be able to break the alternator shaft bolt. Then I'd still need to remove the alternator so that I could take it to a shop with a "real" impact wrench and air system.

Which would you do?

ED - All I have ever done is use an impact wrench on the nut and they came off without much problem. Our install must be a little different because I didn't have any clearance issues with the fuel system.

Thanks Bill. The sheet metal that supports the fuel filler is blocking a straight shot at the nut. Rotating the alternator all the way forward won't clear it. My fuel filler bracket installation looks almost exactly like this:

http://www.specracer.com/SRFInfo/Gen3/E ... deView.htm

It's good to know that the nut will probably come-off with an impact wrench.

Ed - Sorry, memory is short. I must have been thinking of the Gen2 or maybe I did remove the filler, but I do remember that the impact driver spun the nut off without much problem where as just a socket wrench wouldn't work. I may have used an angle adapter to remove it ???

Ed: I am in the process of assembling mine...taking off the fuel filler is not a big deal, except it is a bitch to get a new hose on the filler piece - a used one is probably nothing. I'd pull that off and use an impact.

Thanks Steve. I started on the fuel filler late yesterday, but then I noticed the water pump pulley. It sure looks like a better "target" for the rpm sensor. I can get to the pulley bolts easily. There wont be any issues drilling the pulley because it's open on the back and the belt doesn't run in a groove. I could probably do it without even removing the pulley. (I was a little concerned about drilling the alternator pulley between the base of the belt grove and the transition to the thin inner part of the casting.) I'd be measuring the rotation of what I'm concerned about: the water pump. Admittedly, it's hard to envision a scenario where the alternator keeps turning but the water pump doesn't: I don't think frozen water pump bearings aren't very common. I'm going to start going down that road today and report back.

I did end-up putting the RPM sensor on the water pump pulley. I think it's a better way to go than the alternator pulley. I did drill and tap a hole on the opposite side of the pulley from where I put the magnet. I put an 8-32 screw with an extra nut and washer on it to balance the pulley. I doubt that the rpm sensor magnet would have thrown the balance off to any meaningful degree, but I didn't see any reason not to balance it out. I would have done the same on the alternator pulley had I used it.