This gearing thing has got me wondering and I suppose this is as good of a place as any to ask. Hope I didn't miss this in the faq. A few questions:
Exactly why do you regear?
When you do regear.. what are the changes?
Is it mainly for highway driving or do you notice a difference while idling or in a low gear as well?
I plan on upgrading to a 2 - 3.5 inch lift suspension and 31-33 inch tires. Am I going to want to regear to 4.88? (I think that is the limit for the stock axles if i've read right) I don't plan on swapping axles anytime soon if at all.
and
Another question if anyone cares to answer...
I'm running 30s right now. I've never driven my jeep with the stock tires. I've heard of people regearing with only 30-31 inch tires. Is there that big of a performance difference running 30s with stock gearing as opposed to running stock tire size with stock gearing? (I wouldn't know seeing how I've never driven with true stock tire size)
Thanks for reading
The reason for regearing is to get the engine working in it's powerband. When you go with larger tires it changes the RPM's for any given speed. The difference is in relation to the hight increase. As the tire size goes up the RPM's drop. This is a problem because the engine is designed to work in 2500-3600rpm range. So if you're running in 5th at 3600rpm at say 65mph and change tires to something larger, your RPM's may drop to 2600rpm's in 5th. Add in hills and wind and you can loose 500-600rpm's easily which will drop you out of the powerband.
So to correct this, we regear the axles.
What's changed? The Ring & Pinion, Pinion bearings, Carrier bearings. Sometimes this will require a carrier change to allow for the lower gears. Since the D30 and D35 stop at 4.88:1, you will need new axles to go lower.
Check out these threads;
http://www.4bangerjp.com/forums/viewtopic.php?t=731http://www.4bangerjp.com/forums/viewtopic.php?t=467http://www.4bangerjp.com/forums/viewtopic.php?t=173Oh and would I regear for 30's? No. Nor would I regear for 31's. It's not that big of a power hit to warrant spending a good chunk of change on gears. This is especially true if you're going to go larger later. Once you settle on the largest tire size you will ever want to go with, then regear.
