Send your Gearhead questions to:
- Off-Road Adventures, Gearhead Dept.
- 610 West Walnut Street
- Compton, CA 90220
or email them to:
Spacer Cadet
I have heard many negative things about wheel spacers, but saw a well known TV hot rodder use 1-inch spacers on a mega-buck rod. I instantly became confused. I have held off using wheel spacers, but they would really be an inexpensive way for me to run 31x11.50s on my ’97 Nissan Pathfinder. I have 31x10.50s now that run very well, rubbing only during a major twist of the vehicle.
Dave Burgess, Memphis, Tennessee
Spacers are like many other things; OK if you use them wisely and properly, but disastrous when you don’t. They WILL put extra stress on the wheel bearings and change your steering geometry up front, possibly causing increased tire wear or bearing failures. Up front, spacers seem to cause the most wheel bearing trouble with rigs using unit bearing hubs (not the case with your ‘Finder). There are sometimes issues with wheel studs, nuts coming loose and so on. Sometimes the original studs are too long and protrude past the spacer. I was not able to get a clear consensus from Nissan people on spacers for your rig. A 1-inch spacer is pretty mild in most cases and no more harmful than a similar change in wheel offset. If you decide to use one, bear in mind the issues raised above. Use Loctite and a torque wrench on the bolts attaching the spacer to the hub.
Slushbox or Gearbox
Wassap! I’m going to be buying a Jeep pretty soon and I’m not sure if I should go with an auto or manual. I don’t plan any rock crawling, but I would like to be able to take on some pretty tough trails at some point.
Matt B., — Via e-mail
Ah, that age-old question again. Overall, the manual requires a higher level of driver skill than an automatic. Also, the average manual of today is not ideally geared for the trail (tall first gear ratios). Combine them with the average tall axle gear ratios... your Jeep is grunting and you’re slipping the clutch to keep from stalling. A manual trans Jeep with a larger, more powerful engine will do better in this situation. Manual trans rigs tend to be harder on the drivetrain than automatics because they transfer more shock loads. Automatics offer a great deal more flexibility in all situations and the torque converter makes it feel like the Jeep has lower gears. They turn that flexibility into heat, so important accessories for trail ready automatics are a trans temp gauge and a trans cooler. Remember that taller gears equal more heat. Automatics soak up a certain amount of power, so they are better matched with larger engines. That means no 2.5L fours with automatics, OK? A 4.0L with an automatic is a pretty good match. Overall, for most drivers and situations, the automatic is the better choice.
Holy, Shuddering Crewcabs, Batman!
I have an ’03 Chevy 1500HD Crew Cab short bed with a 6-inch ProComp lift. The truck has the stock two-piece driveshaft. On takeoff, I get a shuddering that quickly goes away. I was told this is either due to the angle of the driveshaft or because I have a two piece driveshaft. Which one is the true answer? I have shimmed the shaft down some and is has alleviated the shudder a bit. Should I put a one piece driveshaft on it?
Troy H., Somewhere, USA
Actually both are true answers. Two piece driveshafts are especially hard to dial-in on lifts. Shimming the center carrier down is how it’s done, but because you are dealing with the angularity of four u-joints and two shafts, it can be tough to get a perfect result. Ideally, you want the u-joint angle of the two joints on the rear section to be the same (at the carrier and at the pinion). Ditto for the forward shaft (t-case output/carrier). Those can be adjusted by spacers under the carrier, wedges in the spring pack to move the pinion, and lowering the transfer case a bit. You can’t eyeball it.... it must be done with a dial-type protractor! That said, I have heard of guys that spent interminable hours setting it up and still having a shudder because drive shaft angles are not a static thing. Pinion angle changes on acceleration due to torque. The custom built one piece shaft is the more expensive solution, but it gets the job done quick. Just make sure that the angle at the pinion and at the t-case output are equal, or use a CV joint and make the pinion angle equal the shaft within a couple of degrees.
Quick Air 2 Q
Yo. On page 72 of the June ’04 issue, Trent Riddle states, “Now, air is also used to fill your tires but also to operate your locking diffs.” I asked around and one parts counterman struggled with the question before he found the working pressure for the ARB is 600-700 psi. This may not be an accurate recollection of his figure, but I do recall it was much higher than the Quick Air’s 105psi max pressure. I’m thinking about putting Air Lockers in my 2002 Ford F-250 PSD, and since I already have a Firestone air suspension system and storage tank, I’m wondering about using my existing setup with Air Lockers.
Tom Pogoler, Chatsworth, California
Yo yoself. Whoaaa, 6-700 psi? Either you’re suffering from early Alzheimer’s or the counterman was smokin’ whacky-weed in the back room before looking it up. Seriously, ARB Air lockers are designed to operate within an 85 to 105 psi range. They may not engage well at the low end and too much pressure can cause leakage and early seal wear. Your air suspension setup should be just fine, and if the pressure is too high, it’s easy to install a regulator to drop it a skosh. Good news, huh? This will save you the expense of buying the compressor. I recommend using the ARB solenoids and if you don’t use the ARB wiring harness, at least use their nifty switches and fab a wiring harness to match their diagram (except for the compressor circuit).