Originally Posted by
MassiveMods
The GRP rod is a 29.5 mm x 4.20 mm top yoke x .0499 bottom yoke with a 5 mm Crank pin . The Go rod wont work as the top yoke on it is 3.99 mm.
and im glad you asked the question ! cos i dug out my engine Cemetary Box .. ( where all the ones that didnt make it live ) And found a GRP, and in its box i found an original new 28-0600 ROD ! in the pics below im using a CNC machine setting pole to measure its dia. The pole set i have was given to me from a huge CNC machining / engineering company here in AUS back a few years ago when i was designing and making custom rods for Drag Racing and Off road applications .. , the poles are used to calibrate their CNC machines and are extremely accurate. The 5 mm pole will fit snugly in the new 28-0600 and the new 21-0600 but not in the original 28-0600 as pictured below.
Hoep this finally puts this one to rest
Cheers MM
Good enough for me my friend
I also think some of the confusion came about because of the long history, and easy parts availablity of GO motors in this part of the world. We have worked with the older rods etc from Gen 3 (or earlier in some cases), so we do know the older generation motors, and the subtle changes that occured from phase to phase of the different generations better than most in other parts of the world. It would appear that outside of Australasia, nobody else knew that the 28-0600 rods changed (late Gen 5) before the introduction of the newer 21-0600 rods. Hence they were comparing apples with apples instead of apples with oranges and not seeing the difference in sizes we were trying to explain to others.
Anyway, all sorted now - if you have an early Gen5 or older motor and you want to replace the rod, get the new GX coated crank (21-0907T-03), coated wrist pin (P-0414-03), and new Pro rod (21-0600) - or just upgrade to a new GX motor and be done with it. You won't regret it
