I originaly designed the jeep buggy to be road legal, which meant having to keep a standard steering box and mechanical connection to the wheels. So my front suspension was set as a 3-link with panhard. Due to the steering relationship between the panhard and draglink, I didn’t have much room to put a tierod up front. I also thought it would be better to get the tie rod and hydro assist cylinder behind the axle and out of the way. I did some quick mockups and determined that a tierod could indeed fit in between my upper suspension link and the pinion on my D60.
I did some CAD design work to figure out how long and at what angle to make the steering arms. I designed these for correct ackerman for my wheelbase, remember I was expecting this to be streetable. The length was determined by figure out my max steering angle and the 8″ throw of my hydro assist cylinder. If the arms are too long then the ram won’t have enough travel, if they are too short, then the ram has too much travel. You really want everything to max out at the exact same time. I did the same for designing the draglink arm.
Here is a point I’d like to stress. A vehicle is a complex collection of different mechanism working together to create a driveable vehicle. Not thinking about how one alteration affects the other systems will often lead to issues using the vehicle and a less than stellar driving experience and potentialy a few long nights on the trail. The way the steering box interacts with the steering arms, knuckles, tie rod, assist cyl, rim offset and tires, and panhard all effect how the vehicle behaves on and off road. You can’t simply focus on one part.
I went to work and machined some 1″ plate to form the base of my steering arms. The sides were milled and the kingpin cap bolt pattern was drilled into them. I decided to upgrade the kingpin cap bolts to 9/16″ from 1/2″ for a bit more strength. The cap was also cut for the kingpin bearing thrust washer and shims. I also decided to do away with the upper kingpin bearing spring. The spring deflecting at full steering lock is a known issue that causes broken u-joints and knuckles.
1/4″ cold roll plate was used top and bottom to form the actual pockets the rod ends would attach too. All the pieces were beveled substantially before welding, welded then ground smooth. Some 3/16″ plate was then wrapped around the outsides to help tie everything together.
3/4 x 3/4 rod ends were used for the tie rod, while 7/8 x 3/4 rod ends with misalignment spacers were used for the draglink. I made my own 303 stainless steel cone washers and used grade 8 bolts throughout. I know everyone’s going to tell me I should use studs and nuts to hold the arms to the knuckle and that studs are stronger. Show me proof! Show me some actual engineering that similar size and grade, stud and nuts are stronger than bolts, and not internet hearsay. In my experience studs are commonly used for ease of assembly or in situations that will require frequent disassembly.
So far the only real downside I have found to these steering arms has been the inability to remove the front calipers with the arms installed. Everything, including the hydro assist ram is tucked up neatly and out of the way.
Future revisions will hopefully include a 9deg angle correction for the kingpin inclination, as well as externally adjustable preload for the upper kingpin bearing and a dedicated hydro assist mount.
For now they’re working out great!