[PorkChop]

Originally Posted by robo

http://forum.miata.net/vb/showthread.php?t=349293


http://t0.gstatic.com/images?q=tbn:A...pnBhU7U06neswg

There is a mod. worth reading. A frame that bolts the diff to the gearbox. What I dont understand is that if mazda fitted this as standard on some cars called a ppf <and they break> how come they have they have been omitted in the roadster builds.

Bob

Bob

The PPF frame is standard to all mark 1/2/2.5 MX-5s (not 100% sure about the mark 3, but I would be surprised if it's different).

It's essentially an ali C section beam (about 5mm material thickness) that is hard mounted to the diff nose via 2 x 8" bolts. The beam runs alongside the prop (and covers the O/S side of the prop) and is hard mounted to the gearbox tail, again with 2 x 8" bolts. It's worth noting that the PPF is the only mounting on the front of the diff. The only compressible mountings (AFAIK) are the diff ear rubbers and the engine mounts on the front subframe. Therefore, any rotational movement about the driveshaft axis will be affected by the moment of the engine/gearbox.

As an aside, I read on miata.net that Mazda say that if the rear upper top hat washers are removed, they render the PPF scrap.

It might also be worth seeing what sort of upgrades Flyin Miata or Performance 5 do for the rear diff area (FM have built a 800+bhp Miata and offer lots of tuning bits).