November 2011 Nuts & Bolts - Tech QuestionsPosted in How To on November 1, 2011 Comment (0)
Steered Strong But Wrong
Q I have a Chevy K10 that has a 14-bolt rear, a Dana 60 front, and 38x12.5x15 TSLs and uses Off Road Design’s crossover steering kit. Last year I was wheeling and broke a 10-bolt stub shaft in a twisty bog. Just before it broke I noticed I had absolutely no left-hand steering. Much reading led me to believe crossover steering would help by correcting the poor geometry of the stock GM steering system. After getting the 1-ton upgrade done, my power steering pump quickly gave up the ghost, screaming and puking fluid everywhere, which wasn’t too surprising to me; it had a hell of a hard life. I changed that out for a new one, and now it seems the truck has a left turn issue even sitting still! The truck needs to be rolling a little to steer left. I never had this issue with the 10-bolt/stock draglink configuration. All the steering components have been changed—2WD steering box, pitman arm, draglink, steering arm, axle—and I’m hoping I don’t need to go hydro-assist. I was really hoping the crossover steering setup would eliminate the loss of directional steering in trail twist situations, as well as be more mechanically advantageous against the big tires. There does seem to be a slight popping sound when steering, even when not rolling. Could bad kingpin bushings be causing the steering to bind in one direction or the other? Any suggestions you can throw my way would be greatly appreciated.
A I ran your problem by the crew at Offroad Design (www.offroaddesign.com) and got the following answer from S. Watson:
“Crossover steering typically does all he’s asking for. I’d start by putting it on jackstands and cycling everything to make sure it moves where it’s supposed to and everything is centered when it’s supposed to be. If it’s not steering when all that checks out on stands, it’s a power problem.
“One thing that could be rearing its head here is the fact that we trade a little bit of power for turning radius with our crossover system. When the truck is sitting on stands, it will likely overtravel the steering stops by a small amount each way. When it’s sitting on the ground though, that extra throw helps compensate for the springs moving side-to-side and lets you hit the steering stops most of the time. The downside to this range of motion is that you lose some power compared to a system that won’t hit the stops all the time.
“Not turning left is weird and makes me wonder if things are adjusted right, but that should be taken care of in step 1 above.
“38s on a fullsize in tight terrain definitely falls into the category of ‘needs hydro assist’ for us, and that seems to solve all the power problems. Things like wheel backspacing can add steering drag too. For example, a skinny 38/wheel combo can steer much easier than a fat 38 on a small backspace wheel.
“Bad kingpin bushings/springs can be making a popping noise but probably won’t add any extra drag. Another place to look for the popping noise is in the frame crossmembers. Once the rivets get a little loose they let stuff move around. At that point it’s time to start bolting on better crossmembers and bracing and welding up some of the factory stuff to stiffen it up.”
Q I have a ’95 Chevy K2500 with a 14-bolt rear, skidplates, a Warn winch, and an NV4500. I’m trying to build the truck on a budget and would like to do a mild lift to fit tires in the 33-inch range. I have looked and looked for leveling kits and 2- to 3-inch suspension kits, but all I can come up with are lifts for half-tons. I have seen the 4- to 6-inch suspension lifts, but they are out of my budget. Is there a 2- to 3-inch suspension lift available for my truck? What are some different methods to lifting ifs on a budget?
A Torsion bar keys (PN KG09107) from Daystar (www.daystarweb.com) will help raise your truck enough for 32-inch tires. However, your truck is also a prime candidate for a Performance Accessories (www.performanceaccessories.com) 2-inch body lift, as it will help you clear 32-inch-tall tires without modifying your suspension at all and at a reasonable price. I usually recommend a suspension lift over a body lift, but if money is a concern then a body lift may be your best option. Of course, if you combine the two you should have little problem clearing 33s with minor bumper trimming
Three Hubs, No Tire Chirp
Q I have heard of people using manual locking hubs on the rear axle in case they break something in the axle. That way they can still drive in front-wheel drive. I have been reading 4-Wheel & Off-Road for over 25 years and have never heard of my idea, but it sounds doable: Put in manual hubs and spool the diff or weld the spider gears, and leave one hub locked and one open for everyday driving. Then when you hit the trail, lock three hubs instead of two. Think it would work?
A Hmm, not a bad idea. Most folks I know run front and rear selectable hubs to allow easier flat towing. I wonder, though, if you wouldn’t have some funny steering depending on which hub you lock. Going around a turn, the inner wheel wants to turn slower than the outer. Could it be that the truck will require more or less throttle through a turn depending on which hub is locked? I have a spooled full-floater going in the rear axle in my flatfender project. I’ll try it and let you know what happens.
Q Unlike other 14-year-old kids, I am obsessed with off-roading. I dream of the day my magazine comes in the mail, and when it does I run into the house and read it for hours. But I have a problem. I don’t know what I want. Should I get a 4Runner, a Bronco, an Xterra, a Ranger, a Durango, a Grand Cherokee, or something else? Your magazine is my therapy, but I literally spend hours contemplating what I want. What should I do?
A As a 14-year-old trapped in a grownup’s body, I can tell you that four-wheeling is a great hobby. But first, some advice. Don’t worry so much about what your first vehicle is going to be. Rather, start saving up dollars and cents to afford that first ride. When I was your age I had a jar with a picture of a Jeep on it, and in that jar went my pennies and quarters. Then that jar went into the bank in the form of a savings account. Eventually that money turned into an old Jeep. I know some kids just ask Mom and Dad for a set of wheels, but I appreciated my first 4x4 a lot more by earning it.
As for which one to get, I can tell you all those 4x4s you listed can be great trail rigs. It really just depends on what type of wheeling you want to do and where you want to go. The smaller ones will definitely fit better in tight trails. The larger, more powerful ones make for fun desert rompers. Mud can be challenged in any of them, depending on the depth and texture of the slop you encounter. In the end, I’ve found there is no perfect 4x4 for every trail, but all 4x4s will allow you to get out there and enjoy many trails.
Another word of advice: If you’re on a budget and looking at a 4x4 to purchase and build, do research on what all is available for that truck before you buy it. I get numerous letters from readers with trucks that have little to no aftermarket support. For example, open-top Jeeps have a ton of parts available, while Durangos do not.
Thanks for reading, Brandon. Now get a job and a savings account, and when you’re first 4x4 is ready to wheel, let us know and maybe we’ll see you on the trail.
Adding or Blocking
Q I’m looking to lift my truck, a ’97 F-150 regular cab Flareside. I have found a lift that I want, but I can only find add-a-leaf for the rear or blocks, and I don’t want blocks. Should I just get the add-a-leaf and then purchase a shock for the rear. I want to use this truck for mud and some trails, but I’m lost.
A Either a block or an add-a-leaf is a fine way to lift your vehicle, but I agree that an add-a-leaf probably has better performance since it is less likely to add to axlewrap. Because the block pushes the axle away from the leaf spring pack, it allows more axle leverage on the pack. The add-a-leaf may require a new centerpin and longer U-bolts, but I agree it’s a better way to go.
Why Tall Wheels?
Q I’ve fallen victim to a bit of confusion regarding wheel and tire sizes, and I hope you can shed some light on this for me. In the past it has been deemed important to have a lot of sidewall, whether for mud or rocks. However, wheel sizes continue to get larger and larger, so a 35-inch tire on 16-inch wheel won’t have the same sidewall height as a 35-inch tire on a 20-inch wheel. Truck manufacturers seem to be moving toward larger and larger wheel sizes. I would have thought that it would have been just fine to stick with a 16-inch wheel, allowing for taller sidewalls on off-road tires.
I’m currently looking to put tires on my ’03 F-250. If I decide to use something other than the stock wheel, I’ll have to decide whether to stick with the OEM 16-inch wheels or move to a bigger wheel. But then I’ll lose sidewall height.
Can you please explain any benefits to the larger wheel sizes? Thanks.
A Larger wheel sizes are due to public demand, larger brakes being installed, and high-speed stability on the road. My personal preference is a 17-inch wheel. These seem to clear most brake packages and are the current standard amongst most OEM truck companies. Some 4x4s come standard with 18- to 20-inch wheels, so these may have even larger brakes that a 17 won’t clear. But if you have 16s and are looking to upgrade, I say get 17s. There are also a huge number of tires available for a 17-inch rim.
As for sidewall, the larger the sidewall the more flexible the tires, and in many ways the better they work off-road. But there is an extreme in both large and small sidewall that can hinder performance. An extremely tall sidewall may flex well but can feel wobbly, such as a 40-inch tire on a 15-inch wheel. An extremely short sidewall (say, a 30-inch tire on a 20-inch wheel) can give stable corning control, but also ride rough and allow wheel damage off-road. I usually vote for a wheel no more than half the tire diameter, but in most cases I’d go with a 17-inch wheel first.
It Ain’t So
Q I own an ’89 Toyota DLX Extended Cab 4x4 with 272,399 miles. The truck came out of Minnesota, so you can imagine all the rust. I want to get better mileage out of it, and I need advice on a great lift that will clear 33x9.50.15 BFGoodrich tires. I want to replace a lot of the old parts due to wear and tear. However, the engine, transmission, cooling system, and charging system are new. I also want to put a header system on it and upgrade the exhaust. I need the truck to perform well off-road but I want better mileage. Can you suggest a lift for it?
Fort Sill, OK
A There is no lift kit that will increase fuel economy, sorry. By raising your truck—or any truck, for that matter—you are giving it a larger front area to push through the wind. This and the rolling resistance of larger tires will hinder fuel economy, no way around it. Your best bet is to keep your truck stock and lightweight, with the tires aired up properly and the engine and drivetrain in proper running order, and drive gently.
Dessert Shafts Before Dinner
Q I have a ’78 Chevy Blazer, and I plan to upgrade the engine and the drivetrain. They tell me I have to measure the truck in order to order new driveshafts, but to do so, I would have to order the engine, trans, transfer case, axle assemblies, and lift kit and have them all installed on my truck, then do the measuring and order new driveshafts. The problem is I live outside the U.S., but I plan to order all these through suppliers in the U.S. I think there should be a more intelligent way to do the measuring and order all parts at once.
A Putting your drivetrain in your Blazer before you order your driveshafts is the best option. You could post your plan on the Internet on Blazer owners forums, or call Blazer specialists like the guys at Offroad Design (www.offroaddesign.com), and there is a possibility that somewhere out there you’ll find someone with the exact same setup as yours who can measure his driveshafts and you can order duplicates, but what if the measurements are wrong? Then you’ll have to do it all again and still wait. It’s possible that there is a slight difference between your truck and someone else’s, such as the springs don’t sit as high or the axle yoke is slightly different.
Take my advice: Sometimes you just have to build the truck to know what you need to build the truck. That’s why so many of us either build more than one 4x4 (we learned a lot from the first project) or never build another one (we got really frustrated from the first project). I understand that ordering all your parts at once would be great, but some items just need to be ordered after the drivetrain and suspension are installed.
Nuts, I’m Confused
Q I’ve been a reader for over four years and have learned an amazing amount out of this magazine. I have a question about shock valving. What is it, and how does it work? I’m really lost when it comes to talking technical about shocks.
A Shock valving is the science of adjusting valves within a shock to better control the suspension. Shocks can have various types of valves, but most performance shocks have a valve or shim stack that controls how quickly or slowly the shock compresses and rebounds by controlling the oil flow through the piston of the shock. The piston is attached to the shock shaft, and the oil is encased in the shock body the piston moves though.
This all comes into play when you are driving over rough terrain. If you are driving at speed and hit a big berm and the suspension compresses too quickly, you can bottom out the suspension and cause parts to break. If the suspension compresses too slowly, the truck can buck and jump. The same goes for rebound, or the movement of the suspension away from the chassis. At slow speeds you may want the suspension to drop out quickly to keep your tires on the ground, or you may want it to droop out slowly so as not to push the vehicle off an obstacle during four-wheeling. The same applies for high-speed wheeling, where you want the tires to stay on the ground but not kick or buck over obstacles.
For the majority of applications, shock valving can be set at a happy medium and left alone for various terrains, but for extreme performance, such as competitive rockcrawling and high-speed desert off-roading, the valving can be very different. For example, the new trend of desert racing and rockcrawling combined has resulted in a challenge for shock tuners to get a middle-of-the-road valving that works well in both (though it’s rarely the best in either).
Adjusting your shock valving is a science that is tricky and requires a clean workspace to tear down and rebuild your shocks and lots of testing to get the vehicle to work just right. Many off-road race teams do “tuning sessions” in which they work with shock manufacturers to dial in their shocks for optimal performance. This involves hours of watching the vehicle work, removing, disassembling, and adjusting the shocks and retesting to see how the new tune improves the performance. Newbie shock tuners spend a lot of “let’s try this” engineering adjusting rebound and damping, but can achieve the same performance over time.
There isn’t an exact answer for what your shock tuning should be. Most manufacturers set the tuning based on what you tell them you are doing with the 4x4, and you can adjust from there.
Since your questions is an important one to many off-roaders, especially those who have invested in high-end rebuildable shocks, I’m giving you this month’s Nuts, I’m Confused prize, a set of Fox Racing Shox 2.0 Performance Series IFP monotube shocks. These aluminum-body shocks are valved for a specific application with a well-rounded valve tune, but can be disassembled and revalved if you’d like. These are direct replacement bolt-in shocks and are available for Chevy, Ford, Hummer, Land Rover, Jeep, Nissan, and Toyota vehicles. The 6061-T6 billet aluminum body caps and eyelets use polyurethane mount bushings and are black and clear anodized. Within the 2-inch body is an internal floating piston that separates the air charge from the oil to reduce frothing and shock fade at speed off-road. Fox Racing Shox has a full line of shocks for everything from mountain bikes to rockcrawlers and trophy trucks. Find out more at www.foxracingshox.com or by calling 800.FOX.SHOX.
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