Superb suggestion. Now where are those damn mods when you need one?
I was preparing to PM you. lol. I assume you can take it from here?
Superb suggestion. Now where are those damn mods when you need one?
Jim...Have you used or seen any cranks that were pinned ? Which way is the best in your opinion . I have pinned crank and fingers crossed ! Thanks
Joe
Which way you going Sam ?
After looking at pics of where the factory key sits, I am absolutely going to pin my crank. I plan to really crank up this 4.0L (like 30lbs) and find it's limit, so the balancer and snout are a big concern of mine.
If I could go back in time before I assembled my motor, I would have double keyed the crank, and definitely would have machined the crank for an M14 size (factory is M12) ARP2000 stud, and run a fine thread nut instead of a bolt for even more clamping force.
Here is a great thread on that topic:
Crank Tech
Now, for 99% of everyone out there, this sort of modification isn't necessary. But I feel I'm in that 1% who will be pushing this 4.0L to its limit, and I really don't want to be hindered by a crank failure. So if I can make this a lot stronger than it needs to be, then I will. I'm okay with replacing a clutch, or replacing a broken axle. But I definitely do not want to have to replace a broken crank. It's very costly and time consuming.
Here is a pic of a factory balancer that clearly shows the small press fit area, and that the factory single key only reaches 75% of the keyway, utilizing only the thinnest part of the balancer hub.
I am going to be at 24/25 lbs with my kb 3.6. Is there anything extra you guys think I should do?
You're double keyed already, so just make sure you run a good ARP bolt torqued to a ridiculous amount, and you should be good.
By going to a stud, anchored behind the journal diameter changes, but down into the main or counterweight of the #1 main, you place everything on the snout in compression and remove the tensile load from the crank snout. The 9/16" stud solution provides more than double the preload (~24,000 pounds) of the stock 12MM bolt - with no tensile load applied to the snout.
Sam - some simply awesome tech provided in that thread. What sticks with me...
...that briefly explains why Ford went to the longer bolt and counter bored crank.