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Do-It-Yourself Chevrolet / GMC 4x4 Van Conversion Kit

    There are a few basic things that need to be decided before you start building a GM van. The design of the GM van didn’t change much from the mid 70’s to the mid 90’s, so we don’t have allot of limitations. Find a van that has a good body and interior. Unlike Ford vans, when a GM van gets rusty, you can’t swap another body onto the frame. GM vans are of unibody construction, and the frame horns are part of the body. The Chevy G10 & 20 and the GMC 1500 & 2500 van are the equivalent to the 1/2 ton GM trucks and Blazers / Jimmies. The Chev G30 and GMC 3500 are equivalent to the GM 1 ton truck.

Front Axles for Chevrolet G10/20 & GMC 1500/2500

    If you want to use 1/2, 6 lug axle and wheel ends from 1/2 truck or Blazer, you will need to drill the rear axle shafts and brake drums to match the new 6 lug wheel pattern. It won’t do any good to use the rear axle from the donor truck. For one thing, it’s not wide enough and the pinion yoke is centered. If you look under your van you will see that the pinion is offset to the right . The vans engine is offset to the right side of the van to create more room for the drivers side controls. Keeping the GM 10 or 12 bolt rear axle may not be a good idea anyway. The axle is fine for stock 15 in tires, but the shafts and axle wheel bearings will take a horrific beating if you install 33 to 35 inch tall tires.
To change your GM 1/2 or 3/4 van to something heavier, you could use the eight lug K20 4x4 front axle and wheel ends with the rear axle from a 2wd GM 1 ton van. There are two axle to choose from. The older GM 14 bolt 10-1/2 and the GM 14 bolt 9-1/2.
 

    The Dana 44 front axle is the most popular axle used in a GM 4x4 van conversion. Early 1/2 ton Dana 44 axles had closed steering knuckles with drum brakes, you don’t want to use one of these. For a couple of years, open knuckles with drum brakes were use, you don’t want one of these either.The early open knuckle disc brake Dana 44’s also had wheel bearings of a smaller size. The inner wheel bearing is not much bigger than the outer wheel bearing.

    There are also different types of steering knuckles, some are designed to have the tie rod ball joint drop in from the top (with the castle nut underneath) and some were designed with the opposite taper. Make sure that you find a set of knuckle that match with the same taper size.
The top reamed knuckles are frequently found with their tapered egged out. The tie sits low in the taper anyway, so it you have to ream the damaged knuckle to clean it up, the ball joint will sit much lower and there wont be room for a tie rod end dust boot. So only use them if they look perfect. The top reamed knuckle also present another problem. When used with leaf springs, a straight and level tie rod will interfere with the leaf springs. A custom tie rod with a one inch offset will be required to create more clearance between the tie rod and leaf springs.

Front Axle: Chevrolet G30 and GMC 3500

    Eight lug Dana 44 axles from a Chev/GMC 3/4  ton 4x4 trucks come in a couple of different configurations. The mid 70’s trucks use the Spicer “Big Hub” style wheel ends with a large externally mounted locking hub. In 1978-79 the hub style changed to the more common internally splined locking hub found in the 1980’s.
The big hub style wheel ends have spare parts availability problems. The spindles, outer shafts and wheel hubs are no longer manufactured. They are also prone to having the inner wheel bearing race spin inside the wheel hub. If possible try to find the 1987-79 type wheel ends. Parts availability is still good and you will have fewer problems.

    The eight lug Dana 60 is a good choice for those who want a heavier axle. But you are not limited to axles from the 1970’s. Dana 60 axles are common in the 1980’s. Wheel hubs have been a pain in the butt to find over the last few years. Dual wheel Dana 60 axle can easily be converted to single wheel by changing the hub and rotor with parts from a single wheel axle. Be cautious when buying a Dana 60 front axle. Many of these axles come from trucks that have had hard lives. Service trucks, oil field and mining vehicles have been beat to crap and get parted out. Look for the following signs of abuse.
  
*Oil leaks between the axle tube and center section.
*Crushed  spring pad on left side axle tube. There is a good chance the axle tube is bent from     that point out to the wheel end.
*Spring pad solid but the front and rear edge of pad is no longer flat and smashed down.
*Evidence of welding where axle tube meets center section.
*Pinion shaft loose in pinion bearing (possible spun bearing race)

Axle Gear Ratios

    All front and rear GM and Dana axles can be matched except for the 3.42 ratio. If you need to use a 3.42 ratio in your front axle, you will need to use a 1980 -up GM 10 bolt front axle. You will still need to use the 1978-79 GM Dana 44 wheel ends. The axle u-joint and ball joints are the same. The GM 10 bolt axles stock wheel ends have a different style knuckle. The knuckle is not flat on top and a Pathfinder steering arm cannot be mounted to the top of it.

 Transmissions and Transfer Cases

    The benefit of converting your van with parts from a donor pickup is, you won’t have to buy a special extension housing and coupler shaft. The disadvantage of using  pickup parts with a right hand offset is the shifter will be closer to the passenger side front seat. Most early pickups have a Turbo 350 trans and a New Process 205 transfercase. Later, in the 1980’s used a New Process 208. Unless you are in love with full-time 4wd, avoid the New Process 203. Whatever you decide to use, try to buy all your parts from the same donor truck. Get everything you can, buying all the little “missing” parts can eat your bank account alive.
If you buy your parts at a salvage yard, pull the parts yourself! Junkyard guys are cutting torch happy and love to whack the ends off a transmission crossmember, letting the transfer case drop to the ground, which puts a nice crack in the tranny tail housing or adapter housing. You may need that tranny crossmember anyway and you will have control over what little parts don’t get left behind.
 

Other Weird Stuff

*Small block engines and big block engines have different bell housing patterns.

*If you plan to use the engine from a truck, be sure your vans accessories (power steering pumps etc.) will swap over.

*If you are using a vastly different motor, you may have to find a van with a similar engine to find the right accessories to make it work.

*Some van accessories are tighter fitting that a pickups. Exhaust manifolds also fit differently, they hug the block tighter.

*Turbo 350 and turbo 400 tail housings are not interchangeable, the machining and pattern are different.

*4-speed trannys can be installed if you use the rare 465 tranny top that has the shifter mounted to the rear of the shifter top. Used in the mid 80’s in 1 ton GM trucks

Rear Axle and Suspension

    Stock rear springs should work as long as they are in good condition. Lift blocks of varying heights are available to match the height of the front suspension. Add-a-leafs are also available for springs that need some help, but they will make the van ride harder.

    The lower shock mounts are welded to the axle tube, and if left in their stock position after lifting, will crush the shock when the axle housing articulates. The shock mounts can be removed with a cutting torch and relocated on the axle tube. Be very careful, too much heat can cause the tube to bend with the weight of the truck sitting on the ground. Support the axle housing just to the inside of the shock mount and also lessen the weight on the axle tube by removing the tires. A complete weld is essential or axle gear lube will leak out of pin holes left behind.

    The GM axle in a van are the same as the axles in a truck. The differences would be limited to axle width, pinion position, and brake size. Otherwise, van axles are no stronger or weaker than their pickup cousins.

Engine Crossmember

    The 2wd van engine crossmember and front suspension are assembled as one unit, remove the front suspension and you lose your engine crossmember. The Pathfinder engine crossmember is designed to be installed from below, onto the original 2wd mounting position. The engine locations seems to be slightly different from van to van. For that reason, the engine motor mount pattern is not drilled into the crossmember, so you will need to fit the crossmember into the van, mark the holes from the motor mounts onto the crossmember, remove the crossmember and drill out the holes.

    Above is a side view of the frame with the engine crossmember removed. A few lines and such will be in the way and you will need to remove or work around them. If you need to fix an oil leak on your front main or oil pan, now’s the time. Pay close attention to the engine oil filter and replace it with a shorter one if additional clearance is needed

Front Suspension Installation

    The best way to install the suspension is to pre-assemble the springs onto the axle and lift the entire assembly up into the van. Pre-assemble the springs w/ bushings, front hangers, shackles and shackle hangers, axle  u-bolts  using regular hex nuts and tighten them finger tight.  Weld the chin plate (part number #3960000) across the front frame horns and have the two piece, unwelded rear shackle offset brackets ready to install.

   The front hanger mounts will be welded flush with the front edge of the chin plate. Great care must be taken when welding the rear shackle mounts. We will provide a center to center measurement to get you close to where you need to be. We need to make sure the shackles will be in the right position for spring articulation. The ideal position is to have the the lower end of the shackle (spring eye end) an inch or so behind the upper position of the shackle (shackle hanger end)

   Lift the assembly into the frame, make your measurements, center the axle and tack weld your spring mounts. Don’t finish weld at this time! Remove the spring bolts and drop the suspension away from the hanger brackets before finish welding. If you don’t, you will melt your spring bushings.

Steering Modification

    To complete your steering, leave the OEM steering gear box, pitman arm, center link, and idler arm in place. Remove only the tie rods that were connected the old 2wd wheel ends to the centerlink. The new steering arm will be attached to the top of the right side steering knuckle. The new drag link will occupy the hole vacated by the driver side inner tie rod end.

Knuckle modification: Dana 44 and GM 10Bolt

Driveshafts

   Pathfinder can build new shafts for your conversion if a drive line shop is not available in your area. We will require a center to center measurement and yoke diamentions. The front drive shaft should be a CV or constant velocity style to improve drive shaft angles. If you plan to reuse the OEM front CV drive shaft from your doner parts vehicle, you will need to have a drive line shop modify it by changing it’s length. You will also want to rebuild the shaft before putting it into service

    If you plan to reuse the OEM Saginaw drive shaft, you will want to rebuild it first. The Saginaw CV u-joints bearing caps are held in place by nylon that was injected “hot” into the CV H-block through tiny holes. You can feel little nubs of nylon poking out of the sides of the H-block near each u-joint. To remove the u-joints, warm up the H-block with a torch to melt the nylon. Quickly drive out the u-joints while the plastic is still hot. New replacement non-nylon u-joints are available.

   If you don’t want to hassle with the Saginaw drive shaft, you can easily convert over to the Spicer style shaft. The H-block on the Spicer style CV is shorter than the Saginaw assembly. Because the Saginaw CV bolts to an elongated flange (transfer case front output) instead of a yoke. All the popular transfer cases can be changed over to Spicer style yokes.

Rear Suspension

    There are several ways to lift the rear suspension. If your springs are in good shape, install a lift block to raise the rear. If your springs are tired and weak, you can install an add-a-leaf or replace the springs with some new aftermarket units. Blocks are available in many heights and widths.

Questions on parts or need to place an order? Call Gordon @ 801-915-1402 anytime from 7:00 AM to 10:00 PM mountain time. Monday-Saturday

(Sunday is OK if you have no other time to call )