Jeepin Al wrote:
Looks Good Joe!
Good Luck with it.
My original test mule (must have over 100K on it now), ran with 295R75's AT's on the road, and 285R75's MTR's on the trail. It has 4.10 gears and a true trac up front and the lock-rite in the rear. My front dif had a custom machined alum collar welded to the dif, and I had plates welded to the area that normally cracked. I did some wild things with the KJ, and it held up. Just try to keep you foot off the skinny pedal, limit wheel spin on hard surfaces (rock), so that when the wheel catches it will not shock the system. This impact shock breaks things.
Nice seeing you again Joe, and good luck!
Al
I am no kind of engineer, but I will say again that I think that the TrueTrac might actually make the D30a live longer as, when the free wheel is spinning, it is already re-routing power to the wheel on the ground.
I think "conventional wisdom" on gear ratios may not be correct all of the time. Many vehicles were made with less HP than a KJ yet axle ratios in the 2.70-range. Most of the mid-80's & up Grand Wagoneers had 2.71's in the axles. You just have to accept the downside, such as running in a lower gear to cruise on the highway. Most tranny's from that area had a 1:1 top gear instead of .75 or whatever. Running in 3rd would still probably get you around 1:1.
Lower gears on the tiny D30a ring gear would just seem to make them weaker.
Also, remember that your tranny enters into it. I'll bet that either the 5-spd or especially the 6-spd would be able to live with 32-33" tires and 3.73-4.10 gears easier than the auto.
In my Cherokee, I run 285/75/r16 tires with 3.54 gears and it actually made the jeep more usable over-all. It cruises on the road in fourth better and the crawl ratio is still right at 48:1. My first gear is 6.32, though, but it really helped the 1:1 4th gear ratio out on the road. In many cases, you gotta give some to get some, and accepting some downsides might just be what is needed for most of the lifted KJ's. For many, the equipment & mods they post are for bragging rights, not what is actually needed. Look how many post about the $$$ spent on electronics, chrome goodies, high-end lights, and things of that sort with no mention of traction adders but the still talk about the goal being off-road performance. I'll take an ugly POS that kicks butt off-road anyday because, at least around here, off-roading means trail-rash or at least pinstripes. Chrome don't get ya home. If you did both, great. I honestly envy you.
Most of us worry about mods based more on what we read than what we need, without considering that what TJKJ does with his jeep and what I will do with mine are not in the same ball park, no matter how badly I want it to be. In many cases, spending your money on a true-trac, a detroit, 4.10s and a readily available lift with 235/85's or 245/75's would get us further along most trails then spending even more coin on a bigger lift to get 1/2" more real-world tire height out of a 285/75 on a KJ.
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