So as I have some “in between” evening time I continue with the gravity racer build. I am having a lot of fun building the car and I think it is because I don’t feel as though I needed to come up with a game plan or need to stick to one. I am totally building on the fly and using whatever resources I have in the shop.
I need to get it to rolling chassis stage. I decided to hack my way through the steering set up. I wanted to run a conventional automotive style steering which includes a couple of steering knuckles. I know some gravity racers run a solid axle supported by a center pivot however for this car I want to give it some responsive steering. I plasma cut out a couple of rough looking knuckles from a chunk of 2.5 x 1.5 rectangular tubing. I cut them out in such a way that they would each have a steering arm attached. I wasn’t sure how strong they would be so I beefed them up with some .250” plates. The 5/8 “ axle bolts got welded in, I then gave the units a quick blasting in the sandblast cabinet and the spindles were set.
Now what to use for a front axle. I had some chunks of old ¾” gas pipe lying around. My instincts told me to machine up some king pin bushings so that I could bearing mount the spindles however I am trying very hard to stay focused on time. I have no time for this build so…the front axle comprises of the gas pipe with a couple of holes drilled perpendicular in each end. Yes the holes are going to see some wear however this car is not going to get steered an excessive amount, wear will be minimal. I chose to run .500” bolts as king pins and intentional stacked up washer to take up the play. The idea behind using multiple washers is that I will be able to apply lube in between all the washers to help turn them into a poor mans bearing.
So with the knuckles fabricated and the axle dealt with I needed to get the assembly mounted to the frame. I using a couple of 1.5” muffler clamps and welded some angle iron brackets to the frame. Not only are the muffler clamps cheap and easy but they would also allow me to build some caster into the front end to help with the straight line stability. I haven’t actually measured the caster but I suspect I dialled it in around 10 degrees.
So now I need to come up with some way to steer the wheels. But before I could calculate steering wheel placement I needed to fab a seat in order to test fit the driver’s position. I needed something cheap, light, strong, and comfortable for a seat. I had access to a whole bunch of seat belts so I cut the belts off and proceeded to weave a seat out of them. I ended up using a large head 3/16” aluminum rivet to hold each weave together. With the basic seat constructed I was able to set it into rough position in the car and get a bead on steering wheel position.
The steering wheel is going to be race car bow tie style. I bent some 3/8” CR round bar in the Hossfeld clone bender. With a support plate plasma cut out I welded on the steering wheel handles. The steering column is made from ½” CR round bar. With a 5/8” coupler nut welded on I was able to bolt my bow tie wheel on. Once the car is aligned I will weld the bolt, steering wheel, and column together to ensure nothing come loose. The upper column got supported using a purchased flange bearing. The lower column is supported by a fabricated steel plate welded to the front axle housing.
It was onto the tie rods and the “rack and pinion”. The outer tie rods are purchased 5/16” ball rod ends while the inner tie rod ends are adjustable yokes. I wanted to build some slop in the inner rod ends to ensure no binding of the steering. The inner and outer tie rod ends are joined by a 5/16” NF threaded rod to allow for front toe adjustment as well as compensate for rear tracking. The “rack” was pure guess work. I was unsure what ratio to build it. I decided to go close to a 1:1 steering ratio. The rack comprises of nothing more then a triangle cut chunk of .125” steel with 3 holes drilled in it. The top hole was drilled to allow for the column shaft to slide through. Once the column position was determined the rack got welded onto the steering shaft.
So their you have it. Quick and dirty but yet 100% functional. The steering ratio feels good. The front caster makes for tough dry steering but I suspect the stability will be great. Next I will move onto the rear axle and the brakes. We’ll see what the garage scraps will allow me to come up with.