Oh, and one more thing, I used the well known JK gearing chart and looked up the engine RPM for the two Jeeps I mentioned in my first post. A 3.8 auto JK with 35s and 5.38 gears is turning 2495 RPM at 70 mph.
Well, ya got me there. I've only run 5.13's in my 3.8L JKU with an auto and running 35's but even at that, I recall running up closer to 3000 RPM at 70 MPH. I have a really hard time believing you were only seeing 2495 RPM at 70 unless you never recalibrated your speedo and your shift points were off or something.
A 3.6 auto JK with 35s and 4.56 gears is turning 2544 RPM at 70 mph. So I wasn't too far off with my seat of the pants remembering what each Jeep felt like at highway speed.
That sounds a bit more on target but I couldn't say for sure being that I've never run 4.56 gears with 35's.
I am currently running 37" tires on my 2012 JK with a 3.6L motor and 5.38 gears. At 70 MPH, I'm turning about 3200 RPM and it SUCKS!! I used to run 5.13's with the same tires and was doing closer to 2800 RPM and to me, that was more acceptable but still on the high end. No big deal because I like the extra power it offers but the only way you're going to see your RPM's down in the 2500 range on a 3.6L motor and at 70 is with 4.88's. I suppose with 35's and 4.56, it could have similar results.
Except I had it wrong, the 3.6 with 4.56 gears is actually geared lower than a 3.8 with 5.38s. The difference is in the driveshaft RPM, which is way way way higher on the 3.8 with 5.38 gears. That is why they can be so hard to eliminate vibration from.
WTF are you talking about?? The type of motor you have will have NO BEARING on how fast your drive shaft spins! You literally can drive your Jeep at 80 MPH, cut the motor and I guarantee you that if you have driveline vibrations, THEY WILL STILL BE THERE even with the motor off. MOST driveline vibrations come from the FRONT shaft as caster needs to take precedence. The higher the gear ratio, the faster your shaft will turn with every rotation of your TIRES. In other words, for every rotation of your FRONT TIRES make with something like 5.38 gears, your FRONT drive shaft will rotate 5.38 times and that is crazy fast! ANY balance imperfection will be amplified at this speed and that's why you have vibrations - NOT because of what motor you run. :naw:
So, ... after all of this, my original point was that when choosing between a PR 44 and PR 60, I would recommend the PR 60, at least in part because of the locking hubs.
Really?? That's a TON of money to be spending just to have locking hubs.