Got It Backwards
Question: In mid-engine rigs that you see in rockcrawling, what keeps them going forward when the engine is turned 180 degrees? Do they switch the transfer-case outputs or am I thinking about this way too hard?
M. McKenzie
via 4Wheeloffroad.com
Answer: Most of the time they build custom axles with the centersection turned upside down so it gives them ground clearance and turns in the correct direction. Some use a V-drive that corrects the drive direction. These are made for the marine industry, but have been used in many desert race trucks with rear-mounted engines pointing the opposite direction.
Tow Winch Tech
Question: I need some info on a winch for a '67 K20 Chevy with a 465 four-speed and a 205 transfer case. Is there a PTO hydraulic winch I can mount on my transfer case similar to a tow-truck setup? I have been looking in all the parts catalogs and can only find the one that connects to the power steering.
Bill H.
via 4wheeloffroad.com
Answer: The SM465 four-speed you have, like many older-truck manual transmissions, has a place for a PTO drive. Ramsey (918.438.2760, www.ramsey.com) and MileMarker (800.886.8647, www.mile marker.com) make a full line of hydraulic recovery winches. Most of the dealers can also supply the PTO hydraulic drive pumps, reservoirs, hoses, and control valves.
Budget Bigger
Question: I've got a '96 5.7L 4x4 Chevrolet K1500 pickup and it's hands down the best truck I've ever had. But as we all know, a good truck can always be better. And by better I mean taller, louder, and just plain bigger. Now I'm not someone who can afford to lay down $1,500 or more to achieve this goal. And so I was wondering if there is any way to get the look and the performance of a jacked-up truck without having to break the bank.
John K.
via 4wheeloffroad.com
Answer: You are on a tight budget, but don't fret. If you want your truck louder you need to modify the exhaust. We actually like a subtler exhaust note while wheeling, but going with some Cherry Bomb (www.cherrybomb.com) glasspack mufflers should help increase the rumble without breaking the bank. As for lift, that's going to be expensive with your IFS truck. My advice is to spend your money on a set of 33-inch tires-or 35s if you're willing to trim a bunch of the body to make them fit-and just go wheeling. Save up your money and swap in a solid axle when you have a few grand in the bank.
Nuts, I'm Confused
Spring Versus Sprung
Question: I own a '99 TJ, a typical red TJ on 35s. I have been doing research on custom suspensions in order to build my own. A lot of times I see reference to unsprung weight but I never find more on this. My question is how does unsprung weight affect the vehicle? Handling? On road and off? Can you please explain this to me?
Alison
via 4wheeloffroad.com
Answer: This is a great tech question and something that most off-roaders don't think about until it's too late, thus it wins this month's "Nuts, I'm Confused" tech question prize. Unsprung weight is the weight of any components not supported by the springs of your suspension. So the axles, tires, and wheels are all unsprung weight, whereas the chassis, body, engine, transmission, and transfer case are all sprung weight. Shocks, springs, and suspension links that cross between the sprung and unsprung are divided evenly between the two sides.
In 99 percent of motorsports the goal is to have as little unsprung weight as possible since this is weight that rides along the ground and is affected by the terrain. Lighter unsprung mass allows the tire to better follow the terrain over various imperfections. Lower mass objects are easier to accelerate and change directions. Hit a rock and the unsprung weight must ride up and over it, cross a pot hole and the unsprung weight must drop down in and up out of it. At the same time, in most cases, the sprung weight should be significantly higher than the unsprung weight. This enables the suspension to move rapidly below the chassis without affecting the attitude of the chassis. This means that the driver within the vehicle is isolated from the wheel movement. If the unsprung weight is the same or higher than sprung, the chassis has less ability to isolate itself from the wheel motion. Then the more sprung weight you have the more power you need to move it. It's sort of like that schoolyard game dodge ball-a small guy can move faster but when he gets hit by the ball (unsprung weight) it will knock him on the ground. A big guy is slower but the ball will hardly affect him. Imagine you are tossing an apple in the air and catching it repeatedly. Your arm will not likely move down too much as you catch it. This is because you likely weigh significantly more than a tennis ball. Perform the same toss with a big watermelon and it will likely affect the posture of your shoulders and back. This is because it is much closer to your same weight.
The wild card comes in with rockcrawling. This is the one motorsport where a lot of unsprung weight seems to work because it lowers the center of gravity (CG) and helps plant the tires, but as soon as you include speed like in the rock racers, the additional unsprung weight becomes a detriment. In fact we have seen many rockcrawling competitors fill their front tires with water or lead shot to help lower the CG.
In any case the shocks need to control the movement of the sprung and unsprung weight, and since your question is so good, Edelbrock (310-781-2222, www.edelbrock.com) will be sending you some of its Extreme IAS shocks. These have the patented Ricor IAS technology with a 46mm IAS valve for superior control. This system delivers superior control in demanding conditions by keeping the tires on the ground without sacrificing all of the comfort on the highway. The shock tubes are rolled closed, not welded, for a no-leak seal. A 5/8-inch-diameter Nitro Steel piston rod won't chip or flake, making for excellent off-road durability. Plus these IAS shocks are now zinc-plated and "clearcoated" for long life, and available for lifted trucks with OE mount locations.