Old School
I've been an off-and-on Jeep owner for the past 23 years and I finally found another sweet one ... a '53 M38A1, clean to the max. I'm not a rockcrawler, but living in the high desert of So Cal, we have some killer four-wheeling country, and we do crawl around. This Jeep is pretty much in stock form, except for a nice paint job (yeah! it's going to have some oak-bush scratches before it's over) and some 33-inch tires. Needless to say, my ratio between First and Second gear leaves a lot to be desired with those tires. It has 5:38s in the diffs and a three-speed tranny. Do you think going to a four-speed tranny would do the trick to make up for the lag between First and Second? What kind of tranny, adapter, and so on will I need? Eventually, not exactly in the near future, I would like to convert to a V-6. I want to thank you ahead of time for any help you might be able to give me.J.C.Via e-mail
The 5.38s will be a good match for the 33-inch tires when you go to a V-6. I'd suggest a Buick 225 with the 50-pound flywheel if you can find one. Otherwise, a later Buick 231 odd-or even-fire will fit extremely well and will give you good performance for what you use your Jeep for. A Chevy 4.3L is also a common swap and will almost certainly be easier to find.
Unfortunately, most durable four-speed swaps, like a T-18, T-98, SM420, SM465, or NP435 will leave you with the same large gap in between gears as your T-90 three-speed. If I were you, I'd think about installing a Saturn Overdrive from Advance Adapters (800/350-2223, www.advanceadapters.com) or rebuilt Warn Overdrive from ATV Manufacturing (360/256-3843, www.hermtheoverdriveguy.com) on the back of your Spicer 18 T-case. The overdrive will not only decrease your freeway rpm but will allow you to split gears to better compensate for the T-90's wide gear ratio. It takes some finessing to get the rhythm of splitting gears down with the manually shifted overdrive, but once you do, you'll have a much easier time pulling grades.
When you do get around to swapping in the V-6, I'd suggest finding an SM420 to mate to the Spicer 18. The SM420 has an excellent 7.05:1 First gear for crawling and is nearly indestructible. If you use a Chevy or Buick V-6, you can use a factory bellhousing, so the only adapter you'd need to buy would be the tranny-to-T-case. The T-case adapter can be sourced through Advance Adapters, ATV Manufacturing, or Novak Adapters. I've run an SM420/Spicer 18/Warn Overdrive combo for years with my V-6 flatfender and think it's a combination that's hard to beat.
XJ Dreamin'
Just want to start by saying I used to be an import racing fan. But since moving to the hills of New Hampshire from the Boston area, I have come to admire 4x4s and trail riding. After reading your magazine I know I want to be in the mud more than at work. My four-year-old son loves to look at the Jeep pics y'all have in there. I recently got a '99 Cherokee and know nothing about getting it ready to trail ride. It will be used as a daily driver also. My question is what size lift to use that will also be good on pavement? Will I need a slip-yoke eliminator kit and new driveshafts also? I want to run at least 32-34-inch tires. What about axles, are they going to need beefing up? Help an old city boy out, and maybe I'll see you in Moab. Thanks, keep up the great work.BartNew Hampshire
Unfortunately, XJs have relatively small wheelwell openings. Unless you're willing to cut a lot of fender sheetmetal, there's no economical way to run the size tire you're looking to run. Being from New England originally, I remember the effect road salt has on cut sheetmetal, so I'll run down two options for you.
First, I'd suggest going with a 3-inch lift and running a set of mild 31-inch mud terrains, like a BFG. This size tire will allow you to keep the factory 3.55 gears in your axles and still use overdrive on the highway. As for the lift, Rough Country offers a very economical 3-inch lift that consists of new front coils, rear add-a-leafs, and shocks. Optional T-case crossmember drop brackets and longer brake lines are recommended. This will allow you to keep your stock steering and T-case slip yoke output. There are also other more complete kits on the market, but the Rough Country is the least expensive that I know of.
Second, if you're serious about running 32-34s with no sheetmetal cutting, you're going to need a 6-inch lift. This will require front track bar drop brackets, a new pitman arm, longer brake lines, new rear spring packs, a T-case slip-yoke eliminator, new rear driveshaft, and will almost certainly result in some front driveshaft vibration on the highway. Also, running the larger tires will require an axle regear to get your performance back. Stepping up to 33s, you'll want 4.10 or, more realistically, 4.56 gears. Depending on your driving style, the stock axleshafts may or may not be adequate for 34-35-inch tires. I'd guess that if you added lockers, the axles would be right at their limits with 33s. Upgrading your rear 811/44-inch axleshafts to a set of Dutchman alloy units would also probably be a good idea at this point, and the front axle would benefit from a set of alloy shafts like those offered from Warn, Superior, Yukon, or any of the other axle manufacturers.
I'm not saying you can't run the larger tires cheaply. You could put on the less-expensive 3-inch lift and cut the fenders, but you'll still need to address the gearing and axle strength issues.
Got a tech question you're just itching to get answered? Send it on in to Jp Magazine, Your Jeep, 6420 Wilshire Blvd., Los Angeles, CA 90048, or e-mail christian.hazel@primedia.com.