M8 vs ¼ UNC Identification

The photo below will help you identify the two different reverse screws used. 

The UNC 1/4" screws used in the inital build have been uprated to the heavier M8 unit post mid 2008.

The M8 unit has one or two rings machined in to the head of the screw so it can be identified when mounted. 

Obviously drilling and tapping the existing 1/4 UNC hole would be required before fitting the upgraded M8 screw. M8 is an M8 x 1.25 coarse pitch - so a 100% thread would require drilling 8.00 - 1.25 = 6.75 mm as per the metric standard.

We recommend boring a slightly oversized 7.00  hole which makes tapping so much easier, has no strength impact and provides space for the Loctite™ to be retained around the thread.

In all cases the reverse rollers are compatible with both types - only the thread varies.

NB:  Both screws require the same  3/16"  Hex Allen Key - we continued with the original imperial hex recess to maintain commonality across all Reverse Screws.

We torque both these to 24 ft lbs. as per industry standards.