Techline: Your Top 4x4 and Off-Road Tech Questions Answered HerePosted in How To: Tech Qa on September 24, 2018
GM IFS Axle BeefI wrote to you before and greatly appreciate your advice. I recently stuffed 315/70R17 tires under my ’11 Chevy 1500. My question lies with my front centersection. I’m thinking about building a custom IFS front axle based off a Ford Dana 44 TTB centersection. I’ve got everything figured out for the build, but I have concerns about my Autotrac transfer case and the frontend spinning all the time with the deletion of the axle disconnect. I would also be adding a Detroit Truetrac limited-slip differential to the mix. I do moderate wheeling and I am not a rockcrawler or hard core. Do you think this would open a giant can of worms and should I just keep the front stock with the exception of new gears and upgraded axleshafts? I’ve got some other upgrades like steering lined up as well.
The IFS GM front axles and steering have never taken a liking to larger tires and aggressive off-road use. The steering link failure is generally the biggest concern on the GM IFS 4x4s. Companies such as EMF (emfrodends.com) and JD Fabrication (jdfabrication.com) offer heavy-duty tie rods and ends that can cure that ailment.
It will certainly require some significant fabrication skills, but your TTB Dana 44 differential idea is a sound one. I wouldn’t worry too much about not having the axle disconnect. Although, you’ll likely want to use CV-style joints for smoothness, rather than U-jointed axleshafts. The Eaton (eaton.com) Detroit Truetrac is a great limited-slip differential for mild off-road use. The gear-driven design means that there are no clutches to wear out and there is no need for special additives in the oil. However, I think it could potentially cause unusual steering input on the road in some situations, such as when cornering, even in two-wheel drive. You might be better off with an open differential, ARB (arbusa.com) Air Locker, or some other selectable locker with an open differential setting.
Ultimately, this kind of modification requires a lot of planning, measuring, time, and money. If you’re not currently blowing up the IFS axle and CV axleshafts, maybe stick with what you have. JD Fabrication offers 930-style CV axleshafts with adapters and RCV (rcvperformance.com) offers extra heavy-duty axleshaft replacements if the ’shafts are an issue in your application. With JD Fabrication or RCV axleshafts and heavy-duty steering links, you have covered the biggest issues with the GM IFS front ends. Maybe hold off on the TTB Dana 44 project until you start cracking the GM aluminum IFS axlehousing.
Flexing M1008How do I get more suspension flex on my M1008 CUCV? It currently has a 4-inch lift with new leaf springs in the front, lift blocks in the back, 35-inch tires, and Bilstein shocks. I need to use it for trailering and hauling too.
Via Instagram @cappaworks
When it comes to suspensions, there are two things that generally don’t go together: suspension flex and high load capacity. It’s nearly impossible to get both without some compromise. Up front, any number of aftermarket suspension lift companies offer leaf springs that will flex well, although there are some tips and tricks to improve it. If the rear suspension is unmolested, aside from the lift blocks, there are some flex gains to be had that will diminish load capacity.
First and foremost, make sure you have the proper length shocks. They should not be topping or bottoming out prematurely. The factory front and rear CUCV shock mounts allow for admirable length shocks. Up front, the factory short spring shackles can limit the leaf-spring movement. Consider upgrading to longer Offroad Design (offroaddesign.com) greaseable shackles. It’s a simple bolt-on upgrade that will keep the leaf springs from colliding into the frame and increase suspension travel. This modification will not alter load-carrying capacity. Consider removing the front sway bar. It greatly limits suspension articulation.
Out back, you may want to swap out the lift blocks for the 2.5-inch shackle flip kit from Offroad Design. The flipped shackles will help the rear springs move more freely during compression and droop. This modification will negate the use of the factory load leafs on top of the leaf springs, which is fine if you are only looking at around 500 pounds of trailer tongue weight or bed cargo. If you plan to regularly load up with more than 500 pounds of cargo, you’ll likely want to retain the lift blocks and load leafs and simply accept that the truck can’t do everything well.
5160 Bilstein RebuildWhat parts are needed to convert the direct-fit Bilstein 5160 shocks into custom valved shocks using 7100 parts?
Via Instagram @cappaworks
Technically, the Bilstein (bilstein.com) 5160 shocks are not at-home serviceable. They are sealed shocks with high-pressure nitrogen inside. Improperly disassembling the pressurized shocks could result in injury. However, the 5160 and 7100 are very similar, and pretty much all the internal components are interchangeable. You can ship your 5160 shocks back to Bilstein and the company will revalve the shocks to your specs and convert them to be take-apart shocks using 7100 rod guides and 7100 reservoir end caps. When the shocks are returned to you, they can be taken apart and revalved or rebuilt just like any 7100 series shock. All of the rebuild components from a 7100 can then be used in the 5160. The conversion could be done at home, but Bilstein would only recommend it be done by someone with in-depth shock knowledge.
Entry-Level WelderI want to learn to weld. What type of budget welder would you buy for things like welding on leaf-spring perches or fabricating basic rock sliders? Will a simple old-school stick welder work?
Via Instagram @cappaworks
You could make a basic arc (stick) welder work for these applications. You’ll likely want to start with E6013 rods but use E7018 rods for your structural welding projects. However, I think you’ll be much happier with your finished projects if you spend a little more up front and at least step into an entry-level MIG welder. Take a look at the Hobart (hobartwelders.com) Handler 140 or Miller (millerwelds.com) Millermatic 141. Both of these welders can lay down weld beads on 3/16- to 1/4-inch-thick steel. Most 4x4 metal projects won’t make use of materials that are thicker than this. If you prefer to plan for the long term, can swing the added cost, and have access to 220V power in your shop or garage, I think you’ll be better off with an entry-level 220V welder like the Hobart Handler 190 or the Miller Millermatic 211. These bigger machines will have better duty cycles (won’t overheat as easily), and they will give you some room to grow into as your 4x4 metal projects become more complicated.
Samurai to the RubiconI’m planning on taking my Suzuki Samurai to the Rubicon this summer. Any advice on spare parts to bring?
Via Instagram @cappaworks
The Suzuki Samurai is a robust little 4x4. The steel ladder frame, leaf-spring suspension, and solid axles are dirt simple and incredibly durable. The biggest concern will be ground clearance. I’ve personally seen a talented driver bump and bang a completely stock Suzuki Samurai over the Rubicon trail, receiving only a few scrapes and dings in the paint. The underside had to have been pretty banged up though. If you don’t have a lift, larger-than-stock tires, and plenty of ground clearance, you should consider a good gas tank skidplate and some rocker guards. As always in the big rocks, the steering linkages are vulnerable to bending. Maybe pack some spare tie rod and drag link parts. Other than that, bring the regular spare parts and tools along with a spare tire or a plug kit and an air compressor.
Five-Speed SwapI have a ’84 GMC K25 with a mild big-block. When swapping out my SM465 four-speed transmission for an NV4500 five-speed, should I keep the original mechanical clutch linkage or should I upgrade to a cable or hydraulic setup? I use this truck for towing too. I’m looking for reliability and easy-to-source parts if something fails on the road.
Via Instagram @cappaworks
The NV4500 will be a huge asset for top speed and fuel economy, especially on the highway with a torquey big-block V-8 engine. There are two different GM NV4500 transmissions available: the ’93-’95 version and the ’96-up version. A different bellhousing is needed for each. Advance Adapters (advanceadapters.com) offers adapter bellhousings for both. The bellhousings require the use of a traditional GM clutch fork for simplicity. I think it will benefit you to make the switch to a hydraulic clutch. The hydraulic clutch linkage is less likely to be affected by chassis flex off-road. Advance Adapters offers a GM hydraulic clutch linkage bracket (part number 715535) for use with the NV4500 bellhousings. The bracket is designed for an ’85-’91 GM slave cylinder (Napa part number 73117). You need to couple this with a firewall-mounted hydraulic clutch pedal. You can either source a factory GM clutch-pedal assembly, or make use of an aftermarket pedal. These are available from companies such CNC (cncbrakes.com), Tilton (tiltonracing.com), and Wilwood (wilwood.com).
GI Gyp SpecsI need the specs on the Four Wheeler GI Gyp CUCV project. I’m in process of building a ’82 GMC.
The GI Gyp started as a stock ’85 M1008. The front suspension was upgraded using 6-inch Tuff Country (tuffcountry.com) leaf springs with Offroad Design (offroaddesign.com) shackles. The steering was upgraded and reinforced with an Offroad Design crossover steering kit and steering box brace, PSC Motorsports (pscmotorsports.com) power steering pump, remote reservoir, steering box, and 1.75-inch-bore ram-assist.
The rear suspension retained the stock leaf springs sans load leafs. The shackles were flipped via an Offroad Design 4-inch-lift shackle flip. RuffStuff Specialties (ruffstuffspecialties.com) U-bolts and spring plates were used to perform a U-bolt flip for increased ground clearance.
For whatever reason, this M1008 came with 3.73 gears and open differentials front and rear. Most M1008 CUCV trucks came with 4.56 gears and a rear Eaton (eaton.com) Detroit Locker. The front Dana 60 remained unchanged, the rear 14-bolt received an Eaton Detroit Locker, and the pathetic 3.73 axle gears remained in place. The truck rolled on 39.5x18/15 Interco (intercotire.com) Super Swamper Bogger tires mounted on 15x12 Eaton (ntwonline.com) beadlock wheels with 1.5 inches of backspacing.
The dented factory truck bed was tossed in favor of the bed from an M101A2 military trailer, which turned out to be a completely bolt-on upgrade.
The original bench seat was replaced with a suspension seat and mini bench seat from PRP (prpseats.com). The column shifter was removed. A custom-made shift tower and Winters (wintersperformance.com) Sidewinder gate shifter took its place.
To see all of the modifications made to the GI Gyp M1008 CUCV, go to fourwheeler.com and search “GI Gyp.”