lee82gx
Active Member
Howdy, recently I've had the pleasure of rebuilding yet another diff, this time the aluminium upgrade diff also suffered a backed out screw, so much so that it just jammed the whole drivetrain. It only costed me a days running and another chewed up pinion as the spur / center diff remained jammed against the diff mount.
I took the opportunity to swap out the diff pin ARAC8008 as suggested by elders of the community. To my surprise the pins felt thinner to the touch and prompted me to do a quick check - here is the original pin as spec'ed 2.25mm x 9.8mm. Only ~2.22mm. I have swapped out a few by now and every single one measures 2.21 to 2.22mm
Here is a replacement from a HSS rod 2.25mm sourced from the nether regions of China.
Thankfully the diff input cups DO ACCEPT a 2.25mm pin, ie its holes are larger.
Assuming equal material properties this geometry netts a ~5% higher bending stress for the thin pin. I am also pretty sure in professional engineering these days you will be hard pressed get a 2.22 drill bit when you order a 2.25mm one, because the tolerances are usually much tighter than that. It takes a special kind of cost cutting to actually save some weight or cost to even custom tool a 2.22 extrusion hole. Just wondering.
FYA, I've started using Loctite 290 on the center diff and motor mounts. Previously the blue loctite 242 keep backing out on me for some reason. I'm praying for just a 10 pack continuous run with this. The last few rounds its been just 1 pack and back to the bench, 24hrs curing of loctite really sucks.
I took the opportunity to swap out the diff pin ARAC8008 as suggested by elders of the community. To my surprise the pins felt thinner to the touch and prompted me to do a quick check - here is the original pin as spec'ed 2.25mm x 9.8mm. Only ~2.22mm. I have swapped out a few by now and every single one measures 2.21 to 2.22mm
Here is a replacement from a HSS rod 2.25mm sourced from the nether regions of China.
Thankfully the diff input cups DO ACCEPT a 2.25mm pin, ie its holes are larger.
Assuming equal material properties this geometry netts a ~5% higher bending stress for the thin pin. I am also pretty sure in professional engineering these days you will be hard pressed get a 2.22 drill bit when you order a 2.25mm one, because the tolerances are usually much tighter than that. It takes a special kind of cost cutting to actually save some weight or cost to even custom tool a 2.22 extrusion hole. Just wondering.
FYA, I've started using Loctite 290 on the center diff and motor mounts. Previously the blue loctite 242 keep backing out on me for some reason. I'm praying for just a 10 pack continuous run with this. The last few rounds its been just 1 pack and back to the bench, 24hrs curing of loctite really sucks.