So I was at the track the other day talking to a fellow racer that was having a heck of a time with their car eating shock piston e-clips. For the life of him/her he couldn’t figure out why after a few runs the clips kept popping off the shaft. He brought the car over to me and asked if I’d ever seen such a thing. Having been in the hobby for a while I had seen this more than once. Let’s go over what’s causing it and how to fix it along with other shock adjustment/fixes.
Now in this case the buggy was running on a medium grip track where the car needs to roll. The track can also get bumpy and has some decent sized jumps. So the driver had lengthened the shocks by unscrewing the shock eyes a few turns. Now that he/she didn’t realize is that by doing so this can allow the shock piston to travel further up into the shock body and cap. In his/her instance it was travelling so far up that the piston was contacting the cap and popping the e-clip off the shock shaft after a few hard hits(remember the big jumps). To fix this a few EXTERNAL shock limiters that sit above the lower spring cup corrected the issue. Personally when using external limiters I try to use at least one old o-ring to soften the likely contact of two hard parts together, being the limiter to the lower shock cap/body.
Now shock limiters can be used for a lot of things. Uptravel is often overlooked on cars. It can cause all sorts of issues on the car. An example is certain 2wd SC trucks if you have too much up travel the rear cvd bones will contact the rear differential outdrives. If this is allowed to continue you will not only likely bend one, but snap one of the cvd bones ending your run and maybe your day. You will see what is known as “witeness” marks where the two parts will rub together often polishing or marring the finish. In the case of the diff/cvd bone contact, you will see shiny silver on the bones, rather than the black oxide finish. Again this is where a few shock up travel limiters can help. Remember the limiter goes between the shock body and the top of the spring cup. Yes you can put them below the cup but this will change your ride height, raise your CG(a little) and can cause the spring cup to come off the shock shaft.
Shock limiters can and often do go into the shocks to limit their down travel, also known as droop. Droop can help keep the car flat in the turns almost acting like a sway bar. The difference is that the internal limiters will act independently compared to a sway bar that ties the two sides of the suspension together. More limiters means less down travel and less suspension throw. Less down travel in the front can help with on power steering preventing the cars weight to transfer to the rear under acceleration. More limiters in the rear can help keep the car flat in the corners giving you more corner speed.
Another trick I learned was to always put a small single limiter under shock piston even if the kit doesn’t call for one. The reason for this is that it prevents the piston from hydro locking at the bottom of the shock body. Some shocks are better than others but nearly all of the shocks I’ve built have this phenomenon in some way. In 1/10 shocks a small .030 or .5 mm limiter will prevent this from happening. On the track you will find your car/truck lands a bit softer off of jumps when the suspension is coming off of full extension.
So there you go, some brief info on what shock limiters can do for you.