Send your Gearhead questions to:
- Off-Road Adventures, Gearhead Dept.
- 610 West Walnut Street
- Compton, CA 90220
or email them to:
Wheeling Soccer Mom
I have a 2002 Chevy Avalanche with a three-inch body lift and 35x12.50 Trxus tires. I’d like to put a six-inch lift and bigger tires on it, but I’m worried about the gears and the axles because it’s only a half-ton. I’m not sure how big I can go and am not sure if I believe what all these guys have been telling me. I also have all the rest of the doodads, including the “Her Toy” hitch cover and personalized “Silyboys” plates.
- Dana — Via e-mail
- Buffalo, New York
For once, Dana, the males are correct. Most half-ton axles, regardless of make, are safe with 35s, but not with much bigger than that.
A Saucy Wench...I mean Winch!
My project is almost complete. It’s a 1955 CJ-5 with an LS-1 Chevy V-8. Now it’s time for attention to the winch. What size do I need? Will I need to upscale my battery/electrical? How do I mount it? What kind of fairlead?
Curtis — Via e-mail
Winches should be sized according to GVW. The rule of thumb minimum is GVW plus 15 percent. Even better GVW plus 50 percent. It doesn’t hurt to have extra capacity, but your CJ-5 should be just fine with an 8,000-pound winch. As for electrical: dual batteries, with one being a deep cycle dedicated to the winch, are ideal. Barring that, use a marine-type battery. They can tolerate repeated discharge and charging, where a normal starting battery cannot (for long). Ideally, use an industrial-type (100-percent duty cycle) alternator with the highest capacity applicable (about 120 amp minimum). You’ll need a five-rib serpentine or dual belts for alternators above about 140 amps. Use single- or double-ought battery cables and high-amp terminals. As for fairleads, use the roller type with wire rope and the hawse type for poly rope. The mount should be stout first and foremost, pretty as a secondary issue. You can find both in one mount, but if you have to choose one or the other, go for strong.
Learn more about truck winches and winch accessories.
Rambler Rambles: Low Buck, Big Power CJ Engine Swap
I have a 1984 Jeep CJ-7 with the original 258-6 and five-speed tranny. I have done all the cosmetic/suspension stuff — but a fully emissioned six-cylinder just doesn’t seem appropriate. I don’t want to go Jeeping with the dime-a-dozen small-block Chevys or 302 Fords. The 304 AMC never did much for me, either. I do, however, have a 1974 Wagoneer with a 401ci V-8/TH-400/Quadratrac. I’m not a fan of the Q/T, but I’d like to swap the 401 and auto tranny into my CJ and keep it all Jeep. Advance Adapters said it could be done with about $500 in parts. I can turn a wrench, but I am by no means some fab tech born to weld. I can’t afford a huge money shop job and don’t want to turn my Jeep into a rolling basket-case of ill-conceived engineering.
D. — Via e-mail
Your idea does everything you want. It’s pretty much a bolt-in, not outrageously expensive, and results in 215 horses and 320 pound-feet (as per 1974 Jeep specs). The driveshafts will probably have to be modified for length (front longer, rear shorter), and I’d recommend upgrading to larger u-joints and yokes to handle the 401’s extra torque. You also may have to modify the t-case mounting location by redrilling mounting holes. As for the swap, you need to change the right engine-mount bracket and the engine mounts themselves to CJ V-8 pieces. You mentioned (and I edited) that you already have the biggest CJ radiator. That might, or might not, be enough. It should be a four-core radiator with the V-8 HD cooling fan and shroud. Advance Adapters makes the adapter to couple the TH-400 trans to the Dana 300. There is the usual plethora of small things to do, but, as swaps go, it’s an easy one that pays off big-time in the power department.
Rambler Rambles 2: 304 to 401 or 304 Enhanced
I have a 1976 CJ-5 with a 304 and a three-speed manual. I am planning a slow-build of the Jeep. Would it be better to build the 304 or swap in a 401? Is the 401 a bolt-in? I only plan on running 33s, so can I get by with a 2.5 or do I need a four-inch lift? Are my stock axles up to 33s? It will be a daily driver, but I’d like it to be an all-around capable vehicle. I am hoping to end up with a 225-horsepower engine with good torque.
- Dan Szarkowski
- Bismark, ND
To start, all the later AMC V-8s will directly exchange (304, 360, 401). You need to address the cooling system with a bigger engine as noted above. In addition, the flywheels are externally balanced to each engine type. If you were to retain your T-150 three-speed, you’d have to have the 304 flywheel balanced for the new engine. The 401s are getting scarce and expensive. It’d be easier to find a 360 from a Grand Wagoneer, which was built through 1991. The extra cubic inches will make it easier to get near the 225 horses you want, but you could get there with the 304, too, with headers, dual exhaust, a mild cam upgrade, and an aftermarket four-barrel intake with a 500cfm carb or a throttle-body injection system. I’ve seen Edelbrock’s AMC Power Package (cam intake and carb) in action, and it really wakes up those old Rambler motors. As for your axles, I’d recommend a one-piece alloy axle swap for the rear AMC-20 and perhaps an upgrade to 4340 shafts for the front Dana 30, with the big u-joints.
The Gearhead Speaks
With fuel costs reaching never-before-seen highs, we’ve had a lot of questions relating to fuel economy. Many of them have involved gearing and big tires. Several readers have written in mentioning that either a tire, or gear change or a combo of both would affect speedo readings. They pointed out that if you used an inaccurate speedometer to check mileage, you will get inaccurate results. That’s very true. For the record, my answers on this topic in the past, for the present and in the future are based on the assumption that you have an accurate speedometer. I have covered this topic in several past issues, including the June ’04 Four-Wheel Finesse on MPG and the June ’03 Four-Wheel Finesse, “Doing the Math.”