How to install your rear bumper system
A walk through the install process of your new rear bumper system
If you've recently became the new owner of a rear bumper system, you may not know how all of the different pieces fit together to mount to your chassis. Whether it's KG, Righetti Ridolfi, Parolin, or Freeline, they all typically have similar pieces. OTK is essentially the same process, but will differ slightly with their parts.
You'll begin by installing the two mounting posts to your chassis (figure 1.1). The key to securing the two mounting posts to your chassis starts with installation outside of the chassis. In your hands, drop your smaller washer into what will become the outside of the mounting post, drop the larger washer into what will become the inside. Now drop your 10mm bolt through the two washers and mounting post before hand tightening the rubber (with threading on the inside) to your bolt. You should have one sold piece now that you''ll mount to your chassis.
To finish installing your mounting posts to your chassis, grab a 17mm wrench or socket on an impact and tighten the piece to your chassis tube (figure 1.2). Nice and tight will do, you don't have to set any world records for strength. You'll do this for both sides, left and right, before we head into the next segment.
The next piece to install is what you'll eventually mount your rear bumper to, it's the rear bumper support (figure 2.1). Supplied typically with a short 8mm bolt, washer, and nut, you'll fasten your support to your post solidly. After successfully mounting both your right and left supports solidly to your posts, we'll move on to the next segment, mounting the bumper.
You'll notice on the bumper a pair of elongated mounting holes. Line those holes up with your support holes and press the bumper to your supports. Now it's time to grab your hardware, which should typically be an 8mm bolt with washer and nut, and tighten your bumper to your supports (figure 3.1). Again, you don't need to show off your strength, but make sure it's nice and solid; you don't want the bumper to move side to side. Your entire system should be nice and tight at this point. However, it is common to see the support loose on the post. You can loosen the support by taking a couple of turns out, but still keeping the bolt within the nylon of the nut so that it doesn't vibrate out while on track. This will free up the rear end and allow it to flex more in certain conditions.