I picked up an unorthodox racing under drive pulley. The installation requires the main front bolt to be removed. I realize I need to keep pressure on the clutch / flywheel to prevent the front stack from falling. However, will the stack need to be re-shimmed?

 

Are you sure you need to take off the main front bolt? Usually the pulley just comes off with the 10mm bolts.

 

Yeah I am sure, this unit replaces the whole piece. (not sure of the actual name) but the steel piece the trigger wheel and stock pulleys bolt to.

 

Unles you have the engine out of the car, I would sell it and buy the later style pulley (which was a simple bolt on.) The consequences of getting this wrong are nasty.

 

Engine is not out of the car but I have the trans out so I cav get some good forward pressure on the flywheel to hold everything in place.

 

You mean backwards pressure

 

Re-shimmed? No. Mazdatrix has some suggestions:

http://www.mazdatrix.com/faq/pulley.htm

I'm surprised they still sell that version of the pulley. I assumed they had discontinued that one since they do have pulleys which don't replace the entire assembly any more.

 

Edit: forwad is correct I was mistaken

 

It is an older pulley, it came with a lot of parts I picked up. Is the gain worth the risk of having to remove the front cover?

 

No

 

Not familiar with the old design, but if there's a risk of having to remove the front cover I'd forget it. What a PITA. And for what? You won't see any real gain in power and underdriven pulleys for a streeted car come with other potential issues as well......
https://www.rx7club.com/forum/showthread.php?t=810990