Situation - I've taken the air pump off my '87 XJ-S, which means that I need an idler pulley of something else to take up the slack in the belt.

I don't really need or want to fit an alternator just to serve this purpose. I have a rebuilt Bosch alternator in the car now, and all seems well with it.

I've also removed the engine driven fan and am putting electrics in, which means that I have the shaft and idler pulley from that assembly to work with.

I've taken a 3/4-inch thick piece of aircraft grade aluminum, and have put it between the air pump mounting plate and the air pump bracket. I then mounted the idler pulley and arm onto the air pump bracket. I had to use the bottom hole of the arm since using the "center" hole won't work, there's no room to put the tension arm. I would then drill a hole in the aluminum plate to run the tension arm through, and using a shorter length belt I'd be able to tension the belt (I've not yet drilled the hole in the picture...it might not look like there is room for it but there is).

Just fitting all the pieces together loosely indicated that the belt alignment should be very close if not right on. Everything seems to have sufficient clearance.

What I really like about this set up is that I don't have to buy much. I'll have to get some longer bolts and other minor hardware, but that's about it. I had the aluminum sitting around from another project, and the rest of the parts came from the car. Anyone who has priced out the cost of using Jaguar parts to make this assembly will understand...

Thus my question...is this a bad idea from some reason I can't see?

Thanks,

John
1968 XJ-S V12, 62,000 miles