Q Do you know of someone marketing heavy-duty steering parts for a GMC HD2500? My truck has 170,000 miles, and it is requiring new idler arms and tie rod ends for the fourth time. I have been useing original parts. The truck is used mainly for pulling a horse trailer, so any play in the steering is noticed, since it is primarily on the highway.
A Cognito Motorsports (866.426.4648 www.cognitomotorsports.com) has heavy-duty tie rods and idler pivot systems for your truck. Otherwise, some auto parts stores offer products with a lifetime warranty, but that doesn't solve the problem, just makes it more affordable.
Q I'm hoping that you might settle an argument between a dad and his son. This last hunting trip I chose to air down my tires. I have an '00 Jeep TJ with 35-12.50x15s. The disagreement ensued after my father told me that I need to be careful airing my tires down. I have always gotten to where I need to go with my tires fully inflated but due to lack of tread I wanted a larger footprint.
Is there a rule of thumb when airing down tires? I know that tires have different sidewall thicknesses and compositions. Is the tire size versus wheel size a consideration also? It seems to me that with a thicker sidewall and possibly a smaller sidewall area, you would be less likely to roll a tire off its bead.
A First, your dad is always right. He's your elder so he must know more.
Second, don't tell your dad we said so, but you're right. Airing down your tires is a good idea for any off-road use, as it improves traction and ride quality.
I recently spent time in Russia, and the guys who set up the trucks we were driving had aired the tires up to 40 psi for what he thought was more protection against puncture. I aired them down to 20 psi, and all of a sudden the trucks rode much better and didn't seem to skitter all over the gravel roads. I think a rule of thumb is don't air below 12-15 psi if you don't have beadlocks. Also, if you are using 161/2-inch wheels, stay above 15 psi unless you have beadlocks, as these wheels/tires have less of a safety bead inside the wheel.
A smaller sidewall does pose a problem when airing down. We like to stick to the rule of half: Your wheel should be no more than half your tire diameter for off-roading.
Airing up is great for on-road use, as it increases safety, reduces rolling resistance, increase fuel economy, reduces heat within the tire, eases steering, and helps the longevity of tires.
Q I have a '77 Ford Bronco that has a 5-inch lift on 35s that I just got roadworthy after four years of restoration. I was wondering what gears I should run to make it drive like it has stock tires. It is going to mostly see pavement, but after four years and a lot of money I don't want it trashed. I am in college, so money is a little tight at the moment to be rebuilding everything all the time. I go to the Silver Lake Sand Dunes a few times a year, so I don't really need superlow gears, just something that will make it drive like stock and turn the tires over easier than they do now. Thank you.
A Your Bronco probably came with either 3.50 or 4.10 axle gears. A good formula for gearing is the new tire size multiplied by the old axle gear ratio divided by the old tire size, and then go one ratio lower.
Say you now have 35s and 3.50 gears. Multiply those and divide by 30 for the stock tire size, and you get 4.08 (35 x 3.50 ÷ 30). That's roughly 4.10. Then, to make up for the larger mass and rolling resistance, go to the next lower (numerically higher) ratio. I'd say 4.56 is your perfect option.
If you have 4.10 gears now, then you'll likely want 4.88 gears.
Look on your front axlehousing for a small tag attached to the diff cover bolts that will list the gear ratio.