SUSPENSION

The goals for the truggy's suspension included providing a stable, affordable and strong system that would allow for considerable flex and articulation. I couldn't affort to spend thousands of dollars for a coil-over suspension, but at the same time, I did not want to be limited to to the articulation allowed by traditional leaf spring suspensions.

FRONT SUSPENSION

The front suspension consists of a more-or-less traditional spring-over axle suspension combined with a shackle reversal. There are, however, several minor twists that will provide increased flex and articulation. The first of these twists are the springs themselves. They are the rear springs from an FJ60 wagon. The spring packs contain 7 leaves and the individual leaves are tapered and include anti-friction pads at each end. They were nearly flat when removed from the heavy wagon. The advantage they have over stock FJ45 (or 40) springs is in their length -- 45.7" compared to the stock FJ40/45 length of 42". For comparison, FJ55 springs are 45.5 " in length.(For consistency, the lengths quoted here are taken from Rob Mullen's Land Cruiser FAQ [http://www.off-road.com/tlc/faq/frame.html#HD_NM_3]) The longer spring, when used in conjuction with a long shackle allows for more drop and hence better articulation. Another advantage is that the 60-series springs used the larger spring eyes and bushings than those on the 40/45. Use of the large spring eye with rubber bushings allows for more twist in the spring relative to the spring pin, and hence more articulation. The rubber bushings will wear out quicker than poly bushings, but who cares on a trail rig like this .

The FJ60 series springs are like those used on the 40 series (but unlike the FJ55s) in that the spring pin is off center. In the original application, the short side of the spring pack is always oriented toward the transfer case so as to reduce the effects of axle wrap and minimize the amount of pinion rotation as the spring pack travels thru it's range of motion. I have always believed in this philosophy and have never "flipped spring packs" in order to increase the wheelbase. For the front axle, this means that the short side of the spring should be at the rear toward the transfer case. Since the springs originally came from the rear, I had to flip the spring pack front to back in order to put the short side of the spring pack to the rear when installed as the front springs. This also required that I re-drill and flip the #2 leaf in order to put the military wrap at the front of the spring pack. This arrangement places the springs with the short end of the pack toward the transfer case and the military wrap at the front spring hanger.

In order to place the axle in its original frame position with the longer springs, I had to lengthen the front frame horns by 3". Furthermore, the longer springs combined with the angle that the frame tilts downward in the area where the shackles would be mounted necessitated that the front spring hanger be lowered 1.5" in order to keep the spring pack approximately level at the final ride configuration. In order to accomplish all of this, I made my own front spring hangers. I roughly copied the design used by Toyota so that I could use the stock FJ60 spring pins. I started with 4x6" rectangular box tube with a .250" wall thickness. I then narrowed the box and milled it to the desired shape.

The mounting of the shackle at the rear of the springs employs a "through the frame" approach. This approach is required owing to the slope of the frame at the shackle mounting location. A mount welded onto the bottom of the frame will tilt the spring back and hence the front pinion too far downward. Mounting the upper shackle pin through the frame also allows for use of a longer shackle which provides more movement for the spring. The location for the hole to be drilled through the frame is determined by mounting in the front spring hanger only the primary leaf from the pack. With sufficient weight on the frame, a floor jack can be placed under this single leaf and when the jack is raised the leaf compresses. I place a piece of .250" thick flat bar between the rear spring eye and the bottom of the frame. As the leaf compresses the rear spring eye pushes up against the flat bar and frame and then moves aft along the frame as the leaf flattens. The maximum amount of movement (extension) is achieved when the leaf is perfectly flat. Further compression causes the spring to invert and the spring eye to begin moving forward. The location of the center of the spring eye just before inversion is marked by the yellow line on the frame. Given this point on the frame and the desired length of the shackle, the location of the hole through the frame is easily determined. I cut a 1.25" diameter hole through the frame and weld in a 1" o.d. tube with a 3/16" wall thickness. Alignment is achieved by fitting a long 5/8" diameter rod through both driver's and passenger's side holes and set perpendicular to the frame. 5/8" bolts are used for the shackles.

Here is a view of the shackle with the weight of the drivetrain and frame on the springs.Currently the shackles are 5.5" in length between centers. The additional weight of the body will result in further compression and an angle on the shackle of very near to 45 degrees -- the optimal value for a leaf spring suspension. I may need to lengthen the shackles, perhaps to 6.5", but want to try out the existing ones first. Shocks are Rancho 9012 adjustable units. Final placement of the shocks and towers will need to wait until I can cycle the front suspension in order to determine the optimal amount of up-travel for the suspension.

REAR SUSPENSION

The rear suspension is a 4 link, 1/4 elliptical design. It is the product of collaboration with Jason Conover, co-owner of S&N Fab in Stanwood, WA. Although a 1/4 elliptical suspension is is conceptually straightforward, the performance of the suspension is critically dependent on the design and geometry of the control arms or "links". Variation in the position, angles and lengths of the links can result in undesirable features such as excessive rear steer (a condition in which the rear axle "turns" when articulated) or excessive anti-squat (a condition where the rear of the rig lifts upon power and the axle wants to walk under the rig when climbing). S&N has been building custom 1/4 elliiptical suspensions for several years and their design has proven to be effective in several competition rock buggies. I contacted Jason in 2001 to inquire if he would be willing to build parts required for me to make a custom suspension. He agreed and on a trip through Eugene to a rock crawling competition last fall he dropped off the parts, including the links, hangers, heim joints and shackles. Unfortunately the system Jason originally designed would not work on the truggy. The doubler positions the NP205 right where the link hanger on the passenger's side needs to go. The only options would be to A) increase the wheelbase by 6" or B) move the hangers back and shorten the control arms by 6". Neither option was acceptable, since there was no way I wanted to end up with a 112" wheelbase and in Jason's experience the shorter links would create unacceptable rear steer. So Jason came down to my shop in August of 2002 and together we built a custom 1/4 eliptical suspension specifically for the truggy.

In a normal leaf spring suspension, the leaf spring pack serves to both locate the axle (attach it to the frame) and support the sprung weight of the vehicle. A 1/4 elliptical spring consists of a regular spring that has been cut in half and mounted upside down. One end of the half spring is firmly attached to the frame while the other is attached to the axle housing with a shackle. With this configuration the springs have no ability to "locate" the axle. Control arms, or links, are thus necessary to locate the axle fore and aft, prevent the axle from moving from side to side and the pinion from rotating up or down. The geometry of the links determines how much the axle can move and articulate. Link suspensions vary in both number and geometry of the links. Some consist of 3 or 4 nearly parallel links and a panhard bar to prevent side-to-side movement. The panhard bar can be eliminated if two or more of the links are triangulated rather than parallel.

The truggy suspension consists of four triangulated links. The links were fabricated from schedule 80 pipe and include large (1" diameter shaft) agriculture heim joints on each end. They can be described as consisting of 1) a lower pair of links that are triangulated from the centerline of the frame to the outer front portion of the axle housing and 2) an upper pair of links that are slightly triangulated from the inside of the frame rails to the outermost edge of the differential. These upper arms mount above the axle housing on 7" tall brackets. The links are adjustable in their length and can be used, for example to move the axle fore and aft or to rotate the pinion up or down. The upper and lower links are of approximately equal lengths at 43" measured from the centers of the Heim joints.

The links are attached to the frame by a crossmember welded to the bottom of the frame and gusseted to the side of the frame. The crossmember is made from 2x4 rectangular box steel with a .250 wall thickness. Extending two inches below the frame, the crossmember is the lowest point under the drivetrain, and will also serve as the rear support for the skid plate. The image to the right gives a good view of the crossmember, the front ends of the links and the heim joints used to join them.

These two images illustrate the range of motion allowed by the link system. Owing to the geometry of the inks, at some point of artuculation the upper and lower links will collide with each other. The images here show the axle housing at the point of link convergence. At the inside of the frame, the vertical travel allowed is almost 15 inches. Of course it is greater at the end of the axle. At the maximum amount of movement, the rear steer is only 1/2 ". Also evident in the image to the right is the fact that as the axle articulates it also swings a bit from side-to-side. This is a useful feature since it moves the wheel being compressed away from the frame, thus allowing more compression before the tire might rub on the frame or body. Obviously, I don't want the links to actually collide with each other. A combination of bumpstops and limiting straps will be used to limit the suspension movement so as to prevent link damage. If I decide that more movement is desirable, I will make a new set of upper links with a slight bend in them that will allow for more articulation before the links interfere with each other.

The fixed end of the springs attach to the frame at the point where the frame begins to angle up to clear the axles. In order to provide a flat surface and to tuck the springs up high away from obstacles, I cut a notch in the frame as shown in the image to the left. The notch includes a flat 3/16" plate welded into the center of the frame with a hole in it cut for the centering pin of the spring pack. A 3/16" thick scab plate was welded onto the inside of the frame to strengthen this area.

I took the springs out of a 2002 Ford F350 pickup.The original springs were cut, using a chop saw, 3" from the center. The short side ws scrapped and the long side used for the 1/4 ellipticals. The springs are mounted upside down and held to the frame with Grade 8 square u-bolts. The Ford springs are fitted with large rubber bushings in the spring eye and those werehHey will compress further when the body and box are added.

The springs use a shackle to attach to the axle housing. The shackle was made by welding a section of channel iron to the end of a spherical rod end. The rod end (Heim joint) is the same as is used on the four links, and the tabs welded onto the axle housing are also the same. On a quarter elliptical suspension, the ride height is adjusted by moving the mounting tabs forward or aft on the circumference of the axle tube. If the tab is moved forward, the rod end moves forward and down relative to the eye of the spring. This moves the top of the axle closer to the spring eye and thus decreases the height of the rear end. Right now I have the tabs placed nearly on top of the axle tube. The springs are so flexy that I anticipate the weight of the cab and box will place the ride height about right.

Here are two more pictures of the rear suspension.

Below are some pictures that illustrate the suspension in action. As you can see the Truggy articulates nicely. I still need to play with different combinations of bump stops and limiting straps so that the drop is controlled properly and the tires do not rub on the box or hit the front fenders.

Suspension Upgrade

Although the suspension worked pretty good for three years, my front suspension had some problems:

1) When the axle would drop (say at the top of a ledge without pulling the front down with the winch) and the spring pack would open up, all of the unsprung weight was placed on the primary leaf. Bent and broken primary leafs were a common feature.

22) When the axle would drop the pinion rotates downward and moves away from the transfer case. In my case, the pinion would rotate so much that the 1410 series u-joint would bind and the driveshaft would pull apart (even with a 12" slip joint). Also, as shown in the picture below, the rotated pinion would often hit rocks . I ruined the driveshaft yoke by grinding it on rocks when the pinion was rotated down.

I chose to address these issues by replacing the front leaf springs with coil-over shocks working through a 4-link suspension system.

Front 4-Link Suspension

Front four-link suspensions need to fit into a limited amount of space, and this poses some problems. When I originally installed the engine, I used the common Walker "crossover" exhaust pipe. In addition to being butt-ugly, this crossover exhaust takes up an incredible amount of space. I made a new exhaust system using a collection of 45, 60 and 90 degree mandrel-bent, 2" exhaust tube. The goal was to tuck the exhaust as close as possible to the oil pan, keep it as high as possible and free up space on either side of the inner frame rails. This created considerably more room on the passenger's side of the engine bay( pic on right).I was able to keep the exhaust high and tucked up next to the pan.

A lot of the space on the left rear side of the engine is occupied by the traditional oil filter assembly.This assembly mounts the filter vertically and requires the large-sized filter. Some late-model GM engines used a much smaller oil filter assembly (GM part # 12562833). In this assembly the filter is mounted horizontally. In addition, the assembly accepts the much smaller ( NAPA 21040) filter. As you can see below, the entire oil filter is positioned above the frame rail, completely out of the way of the link assembly.

The new exhaust and oil filter give considerably more room for the links and mounts.

In the hope of providing some useful informationI thought I would share three tricks that I found especially useful for this project. This project was made much easier by making use of three "devices" designed to either move or locate the axle or the four links. Since I did this project alone in my shop and I only have two hands, reliance on devices like these really helped.

1. Over the entire course of this project I probably have moved the front axle in and out from underneath the frame about 20 times The project is much easier if you have the axle at the appropriate ride height on a moveable dollie. Here is a simple dollie I made from 1.5" x .25" angle iron and two small jack stands. It allows the axle to be easily moved by one person. It also allowed me to determine the desired caster setting once and then keep that fixed with a simple tube supporting the pinion.

2. Because the axle was moved in and out so many times, it was very helpful to be able to quickly and precisely re-locate the axle in the desired final position. I did this by welding some 1.5" square tube onto the side of the frame rails. I determined the desired positioning of the axle and tack- welded these tubes to the frame before I cut off the leaf springs. To the extent that the frame was straight before I cut off the leaf springs, the axle should be located square. I moved the front axle forward by 4 inches -- giving me a new wheelbase of 110". The tubes locate the axle both fore and aft and laterally (by aligning the edge of the centersection against the tube). With the axle on its dollie, I could quickly and easily position the axle right where I wanted it to be -- and keep it there during the construction.

3. The link tabs were positioned and tack-welded into place using "construction links" made from 1.5" square tube. By using the square-tube-links I was able to A) keep the link tabs at the desired spacing of 1.5", B) keep the link tabs parallel with each other, and C) keep the tabs on the two ends of the link parallel. By keeping the tabs on the different ends of the links parallel with each other, the heim joints have no misalignment in the rest position.

Here are the frame link mounts. These are one-piece units fabricated with a 13x5x1/4 scab plate, a 7x4x2x1/4 piece of rectangular tube with the open ends boxed, and 4 pieces of 2 1/2 x 3/8 flat bar for the link tabs. The rectangular section serves as a platform to weld the tabs onto.

Passenger side on the left and driver's side on the right. For positioning reference above the hanger you can see the bellhousing (black) and the front of the SM465 (red). The fit is still so tight on the driver's side that I had to weld in the hanger with the upper Heim joint bolted in. If and when that rod end fails, I will have to cut out the exhaust to replace it.

The links themselves are 1.5" o.d. DOM tube with a .375" wall. Before you think I am crazy for using such small tube for the links, let me add that the tubes are 4340 Cr-Mo alloy, and that they have been heat treated to a hardness of RC 40. My calculations indicate that the yield strength of these links should exceed that of a 2" DOM tube with a 0.5" wall.Eye-to-eye length for the lower links is 34" and the upper links are 31" in length. I tried to make them longer, but I simply did not have the room. Rod ends are F-K Heims with a shank that is .875" in diameter and a bore of .750". These Heims have a static load rating of 55,000 lbs.

Here is a view of the lower frame link tab. I originally tried to come up with a 4-link design that would locate all of the link hangers above the bottom of the frame. Such a design would have the lower link hanger positioned on the outer side of the frame (like the Proffitt Cruisers). After much thought, measuring and consternation, I concluded that the outside-of-the-frame geometry for the lower links will only work with full-width axles. With a front axle that is narrowed, any large tire will hit the link when the steering is at full. Soooo, I compromised again and placed the link mount inboard and beneath the frame. I tried to keep it as high as possible and reasonably sturdy.

Axle Truss

I chose to use the simple and successful tube-style axle truss.The truss consists of 1.75" DOM with a .188" wall thickness. Neither of my two friends with tube benders (one a JD2 and the other a Pro Tools) who usually bend for me were able to bend the .188 wall tube, so I had it done by the local company that makes the Tubeshark (http://www.tubeshark.com/) If anyone is really serious about bending tube, and has a lot of $$ to invest, this is one sweet bender.

The truss is supported by a vertical tube on the driver's side and a short tab that ties into the original D60 spring mount. I have zero confidence in my ability to effectively weld on the Dana center section, and hence avoided that experience.

The upper axle link tabs are again made of 2.5" x .375" flat bar. After notching the tabs for placement at the proper angle, I weld each tab on each side to the tube truss and than add the "cap" for additional support. The front of the truss also has a .75" thick tab for the winch mount and the rear of the truss has a tab for the brake line junction. More pics of the axle are given below.

Here are two views of the bump-stop platforms.

Here is the nearly completed front axle. The hydraulic ram is a PSC unit -- 2.5" piston diameter, 8" stroke and .250 wall cyllinder. Aligning a double-ended ram is a PITA with only two hands.

I got lazy and had the mounting brackets for the ram made from 1" thick mild steel -- cut with a CNC water jet. It was very cool to watch that machine work.

I also needed to fabricate new hoops for the coilover shocks as well as bump stop cans and tabs for the limiting straps. Note the large gussets on the frame. I also made a tube connecting the two shock hoops above the engine.

Coilovers are 16 inch travel, 2.5" diameter Sway-A-Way units. Springs are Eibach and include 1) a 16" primary with a spring rate of 350 lbs/in. 2) a secondary coil with a spring rate of 150 lbs/in. and 3) a 6" long tender spring that provides just enough push to keep the primary spring seated in the bottom cup on full extension.

By ditching the leaf springs I was able to remove 7" from the front frame rails but still keep a small bumper and my stinger and bib hoop. My approach angle is going to be greatly approved -- no more of the bulldozing for me. I also chose to set the winch down between the frame rails and put the fairlead in the middle of the bumper instead of on top.