Last year around this time I wrote, that I found my 25 year old Clod Buster in my basement and did an overhaul to the whole car. One part of this overhaul was, that I wasn’t satisfied with the steering of the standard 4-wheel steering of the car and I described some changes I made. However, it turned out that, when driving on grippier underground etc. the steering still did not do what I wanted. Another downside was, that, due to the fact that the car now was much faster, the steering needed some adaption to that as well. This couldn’t be achieved with the old linkage and just one steering servo!
After some research I found these parts on Thingiverse. This servo mount replaces the front and rear bumper and can hold an individual steering servo per axle. This replaces the standard central servo and the whole linkage including the servo savers.
First thing was, to remove the old servo, the linkage, the servo savers and the bumpers. After mounting the new 3D printed parts and holding the servos into place I noticed that, in my case, they were much too high! They nearly touched the upper part of the chassis and did not leave any space for the range of the springs. Also, with the quite bulky 3D printed front part and the servo on top, it looked not so nice. The servo should hide between the 3D parts! I tool a small aluminium tube and cut 16mm parts out of it to mount the servo 16mm lower into the mounting. This nearly hides it completely and gives range for the springs!
Then some other difficulties appeared. One was, that you can only use a servo horn with one arm. Meaning, that I could not link both wheels to it – I had to stick with the link between the wheels. Another was, that the servo will only fit with the horn on the right side sine the differential will not leave enough space on the left. So I decided to rotate the links to the steering between left and right. Look at the pictures on what I exactly did. The link from servo to wheels moved from the right to the left side, the higher balljoint went to the underside.
I used two Blue Bird BMS-35A Servos. With their titanium gears they are robust enough to run without servo savers (at least they are more robust than the links) and they are strong enough to turn the heavy and grippy wheels of the Clod Buster while stationary. They are not very quick and they are not so cheap – but they are perfect for the job.
After the update, the steering finally works as expected! It is exact, works while stationary and, the most important part: it is adjustable! I now use all four channels of my Futaba 4PX receiver and mixed the ECUs and servos with the programs for dual-ecu and 4-wheel steering, which are included in the remote control! Unfortunately I could not find any good guides or references to it on other sides, so I took photos of all screens:
First thing to do is, to switch on the Dual ESC and 4WS mixing in the mixing menu of the remote control. You have to select the secondary steering and ESC Channel. Make sure no other mixing rules apply to these channels. Then just activate a switch and dial for these two settings on the 4PX and you are able to switch the drive and steering on the fly while driving and adapt to the conditions and to how fast you want to drive.
The result of all this, including the previous overhaul was far more than I expected and truly got my Clod into the 21st century! He now looks good, is very fast and steers well! Great to have some fun in the snow! 🙂