I bought a FD alternator modified for installation on earlier cars with a double pulley to replace the stock serpentine pulley. Someone on the forum was selling them years ago. I had it on my old RX-4 for several years. It worked great, but the belts broke regularly. For a while I figured it was because finding two matching belts was nearly impossible. I finally realized that was not the problem. The pulley that came with it did not align the belts properly. Instead of a ~1/4 inch space between the two belts, this pulley has virtually no spacing between them. This puts the front belt at an angle and wears it out. The space between the two grooves meets in a knife edge. I actually cut my finger when I ran it across the edge.

I am trying to find a replacement pulley, but I've had no luck so far. The FD alternator has a 17mm shaft while the old school, SA, FB and FC alternators have a 15mm shaft. Any ideas where I might find a double pulley with appropriately spaced grooves that will fit a 17mm shaft?

 

Respeed has one for around $17

 

Only one I see on their site is for a 15mm shaft which fits 79-91. I need to one fit a 17mm shaft to for 93-95. I figured I could ask Billy to ream one larger if I can't find one.

 

not sure if this will help or not. i was looking for one myself last year..except for an FB alternator...but it may help you:

https://www.rx7club.com/1st-generation-specific-1979-1985-18/who-selling-those-dual-slotted-alternator-pulleys-here-667263/

 

Thanks Dave. I need a pulley that fits the larger 17mm shaft on a 3rd gen alternator. 1st and 2nd gens have 15mm shaft. '87 Turbo ll made me look at RESpeeds site again and I noticed that Billy will ream the FB/FC pulleys to 17mm. I contacted him and he is going to do that for me when he gets them back in stock at the end of the month. Thanks for the help.

 

I took my REPU double pulley to a speed shop and they put it on a lathe to get the correct shaft size. $10 later it was perfect.

 

The problem is more complicated than I realized. Here are the FD alternator (top) and the GSLSE FB alternator (bottom).



Rear of the FB alternator showing the connections.



The connections are on top of the FD alternator.



The pulleys. Custom FD double pulley on top. FB on the bottom.

 

could just be me, but that FD alt..look's like an s5 rx7 alt.

:AA:

 

This is the removeable bushing/spacer on the FB shaft that I didn't know about.





This is the FD shaft. No spacer. I can only assume there is a similar spacer on the stock FD configuration. Can anyone confirm that?



The custom FD pulley has the spacer built in. You can see it in the third picture. Here is the knife edge between the grooves that I was talking about.

 

So... I need a 1st gen pulley with the center hole reamed to 17mm and a stock FD spacer (if there is one ) or a FB spacer with a hole reamed to 17mm also. I just realized as I'm typing that maybe the OS alternators have a 17mm spacer also. I believe I misspoke at the beginning of the thread when I said OS alternators were 15mm. They have 17mm shafts like KansasCityREPU mentioned. Right? I have several of those that don't charge any longer. I'll check one of them.

 

The spacer is built into the rear of the stock FD pulley. There are 2 thickness spacers throughout the years. Been a while so I am not sure the year breakdowns but there are thick or thin spacers to go behind the pulleys.

-billy

 

I removed the pulley off one of my non-working RX-4 alternators. The shaft is 17MM ID but it has two flat sides. The bushing has no flat sections and is 1/4" longer then the 15 mm ID bushing from the 1st gen. I have cut the bushing and installed a reamed two piece 1st gen pulley on the 3rd gen alternator. I'm hoping the double pulley will fit as well. The FD shaft is shorter, so not much room for error.