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October 2012 Nuts & Bolts Tech Questions

Posted in How To on October 1, 2012 Comment (0)
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October 2012 Nuts & Bolts Tech Questions

Prerunner Protection
Q I have an ’01 Dodge Ram 1500 Sport, and I’ve looked everywhere to find a prerunner-style bumper for it. I want to make her look as cool as the new RamRunner package that Mopar is offering. My question comes out of concern for my radiator. Is it possible to find a prerunner bumper without sacrificing the safety of your daily driver? Will they protect my truck from minor bumps from light poles or the idiot doing burnouts in the parking lot of school? (I ask because I’m 16 and you know us teenage drivers). I love my truck, as it was a summer break project with my dad (bought it after it had minor crash). We put on new fenders, headlights, radiator, and a whole new front axle and hubs, so I want to keep her safe while having good looks.
Josh
Via nuts@4wheeloffroad.com

A Check out Addictive Desert Designs (ADD), addictivedesertdesigns.com. The company has a prerunner bumper for your truck. I feel a prerunner front bumper will protect your truck just as well if not better than a factory bumper. Most factory bumpers are not really that heavy-duty, and a prerunner bumper like the ADD one is frame-mounted and built of tubing and a stout skidplate. I think it will be fine for daily use and off road abuse. Of course, any major collision can damage any type of bumper, so this must be taken within reason, but I see no reason why it won’t help protect your truck and make it look better.

Sway Bumps?
Q I am building a ’91 YJ. It has 42-inch Irocks and 1-ton axles. It is four-linked front and back with 14-inch Fox air shocks in the rear and 14-inch Radflo air shocks up front. What would be better: air bumps front and rear, or a sway bar like Currie’s Antirock? I see some with just air bumps and some with just the sway bar. I’m still in the mockup stage of the build and don’t know which one to go with. It will be strictly off-road. Any input would be greatly appreciated.
Brian
Via nuts@4wheeloffroad.com

A Air bumps (also known as nitrogen-charged bumpstops) and sway bars do very different things. This is like asking if you should add a winch or a trailer hitch; both are useful, but they don’t do the same thing at all.

A sway bar is a torsion bar spring that is linked to the axles and the frame. Its sole purpose is to stabilize the vehicle against sway or body roll. As your suspension cycles up and down the sway bar moves freely, but as your suspension articulates (one tire moves up and the one on the other side of the axle moves down) the sway bar twists. This is a spring-loaded twist, and it will try and resist this articulation. The sway bar works throughout the suspension travel, constantly trying to keep the vehicle level over the axles for a more stable driving experience and even tire-to-ground pressure.

Some suspension designs are less prone to body roll than others, and some may not even need a sway bar. This is hard to determine without seeing your suspension work. It may be best to finish the vehicle without a sway bar, but leave room for it should you wish to add one later if you have significant body roll. The Currie Antirock Sway Bar is great for both on- and off-road use, and Currie has an informative video on its website about how they work: www.currieenterprises.com/cestore/antirock.asp.

Air bumps are designed to help control the compression damping of your suspension. They are often 2 or 4 inches long, and as the suspension compresses they hit the axle and slow down the last few inches of suspension travel. Inside the air bump is a small amount of oil and a nitrogen charge. As the suspension compresses and the axle begins to compress the air bump, the resistance ramps up very quickly to slow and stop the suspension movement. Consider air bumps a worst-case-scenario rescue that protects other components from crashing together if you take a big hit and compress the suspension fully.

Your air shocks are very similar to air bumps. In air shocks the nitrogen charge and large-diameter shock shaft work together and act like the shock and spring. It can also ramp up resistance in the last few inches of travel and acts similar to an air bump.

In your case with air shocks I would recommend the sway bar over the air bumps. Your air shocks can be tuned to act similar to air bumps in the final inches of compression. However, they are less likely to fight body roll or sway. If you were running a coil or coilover-shock type of suspension the air bumps would be more helpful, but you may still need a sway bar. I think in your case a sway bar is the smarter upgrade at this point.

Nuts, I’m Confused
Shocking Measurements
Q I am working on a cheap Jeep project and need advice. I have a ’74 CJ-5 with a 4-inch suspension lift and 35-inch tires. I added F-250 shock mounts on the front to raise the shock mount bolt up and stop cutting my tires. I now need longer shocks, and this is the problem. My source said to jack up one corner under the axle and measure a compressed length, then jack up the same corner under the frame and get an extended measurement at full droop. The measurements are 20 and 24 inches, respectively. I called to order shocks and was told that was incorrect. I also told them the specs on the lift kit and mounts, and the measurement from upper to lower mount with the Jeep sitting on the ground, but they still could not help me. How do I need to measure this to get the correct shocks?
Ted H.
Via nuts@4wheeloffroad.com

A The best way to measure for shocks on a leaf-sprung vehicle is to remove all the springs from the spring pack except the main leaf. Then reinstall just the main leaf. You’ll need a simple steel block to take up the space of the missing leaves, and this all needs to be bolted back to the axle with the U-bolts. Now you can compress the suspension and get an accurate measurement from shock mounting point to mounting point for a compressed length (see photo).

Next, reassemble your spring pack and put the frame up on jackstands so the suspension is at full droop. You’ll want the tires and wheels on so it drops out completely. Then measure for the extended length of the shock by measuring from center of spring mount to center of spring mount.

Finally, set the Jeep on the ground with the weight on the complete spring pack, and you can measure the distance again. This will tell you how much up and down travel the suspension has.

Another less precise way to measure is to find the distance from the axle to the bumpstop at ride height. Then add about three-quarters of the height of the bumpstop, as they can compress a fair bit. Take this result and subtract it from the distance from shock mount to shock mount at ride height, and you’ll get pretty close to the compressed length of shock you need. However, you want to be sure the axle can move up to that bumpstop and that the tires won’t crash into the body. Otherwise you may need to extend the bumpstop. Then repeat the step from above for measuring droop length.

Your question is really good, and one of those things that a lot of folks don’t do properly. As such, I’m giving you this month’s Nuts, I’m Confused prize. Rancho has agreed to send you a set of shocks from the new Rancho RS9000XL series. These shock absorbers are designed for off-road use as well as towing and hauling with larger tire and wheel combinations. The new RS9000XL shocks have adjustable damping with either a 2.75- or 2.38-inch-diameter reserve tube. Their massive shock body allows them to run cooler and more consistently even under the most demanding conditions, enhancing performance and durability. They are constructed with a larger-than-typical 18mm diameter nitro-carburized rod. To learn more about Rancho shocks, visit www.gorancho.com.

Wandering Willys
Q I have a ’49 Willys pickup with stock running gear, Timken and Dana 27 axles, a ’56 Studebaker 289 V-8 (that was installed in the ’60s), a Warn overdrive, and an 8274 Warn winch. It’s a really beat-up farm truck but has a ton of character. My goal is to slowly restore as I use it. I want to keep it old-school except for the suspension and steering.

I’d really like a suspension that handles well on the street but can haul a lot of weight and doesn’t beat the tar out of you off-road. Would nice custom-made leaf springs (with shackle reversal) with beefy sway bars (with disconnects) work well, or would more of a Cherokee-style coil front setup be better? Are there junkyard parts that could be made to work? I’m looking for a simple, strong, long-lasting suspension that’s durable. I don’t need an ultra flexy suspension. I want to use this truck as a truck, not really a trail machine. It will see snow and mild trails. 

For the steering, is there a nice manual setup that would work well for this thing? I’m a machinist and an engineering student, so fabricating and welding wouldn’t be a problem for me. I’d prefer something I could do myself.
John K.
Via nuts@4wheeloffroad.com

A I did a similar build a few years back with my Dumpster Project, a Dodge M-37 with new running gear (Mar., June, Sept. ’10 and May ’11). As much as I like the leaf-spring rear suspension with coil-sprung front suspension I think you should go with leaf springs front and rear. My advice would be to find a leaf-spring suspension for something like a Jeep YJ wrangler, or better yet a Toyota Land Cruiser 60 series, and make that work under your truck.

My first thought is ARB (www.arbusa.com), which offers springs and shocks for both of these vehicles along with various-rate springs for heavy loads. This way you’ll have the hauling capacity you’re looking for. For example, you could get a set of ARB’s Old Man Emu 2-inch-lift springs for an ’86 Land Cruiser for a medium or heavy load capacity and you’ll be getting a strong, simple suspension without a ton of lift, and it should ride much better.

Of course, a softer load and a set of air bags may also allow you to adjust the ride quality if you’re not running a full load. You’ll likely have to make you own spring hangers and shackles, as the OME springs may be a different length and width compared to your factory springs, but that shouldn’t be a problem. Shock mounts may also need to be adjusted.

I think a Saginaw manual steering box with a crossover steering setup would be possible, but I’d say that adding a power steering pump to the engine and a power steering box to the frame would be much nicer for driving. Advance Adapters has many power steering conversion kits (www.advanceadapters.com).

Submission Information
Confused? Email your questions about trucks, 4x4s, and off-roading tech using “Nuts, I’m confused” as the subject and include a picture (if it’s applicable). Digital photos must measure no less than 1600 x 1200 pixels (or two megapixels) and be saved as a TIFF, an EPS, or a maximum-quality JPEG file. Also, I’ll be checking the forums on our website (www.4wheeloffroad.com), and if I see a question that I think more of you might want to have answered, I’ll print that as well. Otherwise drop it old-school style with the envelope addressed to the address below. Letters published in this magazine reflect the opinions of the writers, and we reserve the right to edit letters for clarity, brevity, or other purposes. Write to: Nuts & Bolts, 4-Wheel & Off-Road, 831 S. Douglas St., El Segundo, CA 90245 fax to: 310.531.9368 Email to: nuts@4wheeloffroad.com

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