The stock MK4i ground clearance is 1.75" from 2x1 to the bottom of the drive wheel. My team’s lift kit raises that clearance to 2.25". The goal is to allow a not to pass under the 2x1. We accomplished this by increasing the length of the intermediate shaft and wheel mounts by 0.5". The intermediate shaft that SDS uses is an Aluminum 6061 rod machined down. Our kit is a 7075 Aluminum 3/8" hex shaft with two E-clips and a 3D printed spacer.
Here’s a side by side comparison of the stock SDS MK4i (right) and the MK4i with the lift kit (left). Google Drive link with .STEP file and .PDF drawing for manual machining the intermediate shaft.
I think the main idea with this configuration is to make the chassis and bumper clearances more forgiving for an under-the-bumper intake because, in standard mk4i configuration, the note’s thickness is greater than the height of the chassis tubing from the ground. Please correct me if missing something.
Mk4is can be mounted below the frame bars instead of above by flipping the mount plate. This picture shows each SDS module and its configurations. The frame bar is sketched in pink. The second one from the left gives you the entire wheel diameter of ground clearance without making custom parts.
Yes, you’re right. I had seen the same idea from @wgorgen in the mk4i frame height thread. When you use the configuration on the second-left picture, the clearance goes up to 4 inches. I thought that this design’s purpose was to lift the frame just the right amount to keep the cg of the bot lower. I am not sure if it will be worth it given that you have to replace to intermediate shaft, but this could be a nice option for a team with a shop.
Yup this is pretty much it. We try to be cg conscious as well, so we decided the tradeoff of making the whole robot 1.75 inches lower (vs the clearance config) for the marginally lower cg and easier under the bumper at the cost of a couple days of machining time was worth it for us.
It also means we don’t have do worry about protecting the motors which stick up, or having to mount our bumpers lower than the bottom of our frame.
I was thinking that doing something like this would be good to be able to fit a larger wheel under the module if the game called for it. You could pretty easily extend the wheel further down and put a 6” wheel in there. Only thing is you have to be careful about if the wheel is going out of frame perimeter at certain angles.
This is actually what we were inspired by to make this, in preseason we were planning what we would do if we had a terrain game, and our emergency backup plan was lifting them to fit a 6" wheel with a larger bevel.
