Question: I have a '72 GMC 3/4-ton 4x4. I recently put in a locked-up 4.56:1 GM 14-bolt rearend, but my stock Dana 44 front is a 4.09:1. This seems to work fine off-road but not on the street. I am getting two new tires, Q/78-16s. There is about a 1-inch difference in height between the new and old tires. Should I put the new tires on the front or back to cut down on the bind?
Answer: Change out the gearing to match! You're going to break all sorts of parts, if you haven't already. Different tire size is not the answer. What if you get a flat on the trail? Are you going to carry two different-size spares? Also, you should not be using four-wheel drive on the highway. Use it only on a loose surface.
Even with the matching gears, there is some variation in tire size and axle speed while turning, and even going down the highway, in a straight line. When turning the vehicle, the front axle will turn at a different rate than the rear due to the radius of the front circle that the tires turn on is different than that of the rear. Some slippage must take place to compensate for this. In a loose surface, this can take place, but on the highway it's a different story. The tires must skid a bit, which wears them out quite fast, and in fact with this much gear ratio difference, they have to skid a lot. Besides that, it puts a great amount of strain on all drivetrain components.
Question: I have a '71 Chevy K-5 Blazer and I heard about a problem that they have with the steering, i.e., that when you would turn the wheel, it would somehow bend the frame. Is this true, and if it is, where or what can I do to fix this?
Answer: This generation of Chevy trucks, be it a Blazer or a pickup, have a tendency to crack the frame around the steering-box mounting holes and eventually, in a worst-case scenario, actually tear out a piece of the frame at this mounting point. It's not real common with stock vehicles unless they have been used really hard, but it sometimes shows up. When larger tires and a lift kit are installed, it becomes much more prevalent.
The majority of the problem is caused when a poorly designed or low-cost suspension lift kit is installed. When the vehicle's ride height is changed, what happens is that the axle and related drag-link mounting point are now at a greater distance, height-wise, from the steering box than they were originally. Unless some method of compensation-like a modification to the pitman arm, drag link, or raised steering knuckle-is used, you end up with the steering-box gear off-center. This limits the steering box's turning sweep to the right. In a sharp right-hand turn, there is still more angle for the steering knuckles to turn than there is movement in the steering box. This puts more pressure onto the steering box, and its mounting location, than it was ever designed for and eventually damage occurs.
There are quite a few different companies that make reinforcement kits. RJR Off Road (800/632-9192, www.rjroffroad.com) offers a weld-in brace that will not only repair any damage but strengthen the frame in this area. Off Road Design (970/945-7777, www.offroaddesign.com) tackles the problem in a bit different way with not only a repair plate but brackets that triangulate the mounting area to stiffen it up before it breaks. Rough Country Suspension (800/222-7023, www.roughcountry.com) makes a new steering arm with the proper geometry.
Question: I just got an '87 Toyota 4x4, four-banger, Thorley header, recent rebuild on motor, Weber carb, aluminum intake, and 33x12.50 BFG muds. Is there anything else to help with power, or is it just gears left? The truck will only be driven 30 miles at a time on the highway.
Answer: Sounds to me like you have a really good start on building a nice four-wheeler. I noticed that you didn't mention anything about changing the camshaft out for a "competition grind" of any kind. I think that this was a wise choice. Too many people think that a camshaft change is the way to more power. Yes, it can do wonders to wake up an engine. However, the power gain is in the upper rpm bracket, and you generally end up losing both torque and horsepower at the bottom end of the rpm range. With your small engine, you need all the torque you can get it to put out.
Yes, I know that lower gearing will up the operational rpm, but also more rpm means more wear on the motor. Let's talk about lower gearing. My choice would be to first change out the axle gearing to something in the 4.88:1 range. Yes, I am aware of the fact that they make gearing in the 5.29:1 and 5.71:1 range, but I think that is way too low as it makes for a much-too-small pinion gear. This small size lacks the necessary strength for serious use, with always worrying if it is going to break-or should I say, when it is going to break.
Yeah, I know you said that you only plan on driving it 30 miles on the highway. Well, plans have a way of changing over time. This way you're not going to be working the clutch too hard (you did or are planning to go to a stronger aftermarket clutch, right?) and you will be able to use Fifth gear on the highway if so needed.
My next step would be either one of the various "doubler" transfer-case combinations that are available, or a lower gearset for your present transfer case. I wouldn't get too carried away with super-low gearing unless your thing is to get out and walk beside your vehicle. How low for overall gearing? Sorry, I don't have an answer, as everyone's driving style is a bit different, and vehicle use is a bit different. That's why I suggested you start out with just the lower axle gears, then check with the locals that you run with as to what their gearing is and how it works out for them.