Roll Center

Posted by Richard Robbins on

Quick tip from a weekend racer. Recently I went from a club race at CTRC in Menifee California to a Club Race at Thunder Alley in Beaumont and then back to an annual race at CTRC. At CTRC my truggy was working perfectly and other than driver error it was perfect, rotating in and out of corners off then on power with no slide or hooking. When I got to thunder alley the next weekend which is a much larger and faster track I had issues. 

 I got my kid on the track and  I only got a couple packs to practice with my ET48.3. Right away I noticed on the dry high speed track the truggy was noticeably loose entering corners. What can I do to fix this in 30 minutes or less before qualifying?  For bigger races and people with more time they might change an entire setup between drastically different tracks. But some of us weekend warriors and club racers don’t always have the time or resources for that kind of a setup change. My go to was to change the roll center on the rear of the truck via camber links. Five minutes later and one simple adjustment brought me from the back of a pack of open class racers to mid and top 3 in my heats. 

How do you adjust roll center via camber links and why? Camber links are quick, diffs, shocks, etc not all that quick, although tekno’s 2.0 cars are a lot faster with the awesome new quick access diffs. There are also other roll center adjustments, but they need more explanation so I wont get into other roll center adjustments in this post, but will in the future. So the weekend racer explanation from someone with degrees in nothing related to physics or engineering  is that the lower the links are on the rear tower the higher your roll center is, that is the higher up on the truck or buggies center of gravity will initiate a roll with direction change, such as  into a corner. The higher the links are on the tower the lower  the truck or buggy will want to  roll with direction change,it feels stiffer side to side, more “square”. A  simple experiment, hold your arm out with a hand against a wall and have a friend push you towards the wall. How hard are you to move? Now lower your hand a few inches and have them push again? Which was harder to move? With your hand lower your body wanted to roll above your arm (high roll center), with your hand higher on the wall your body wanted to roll lower but was harder to move because you had a lower roll center.    

The simple adjustment of moving one hole up  on the tower can mean the difference between consistent corner entrances, or a car that wants to spin out. The weekend after Thunder Alley I went to Martin’s cup, an annual race at CTRC which is a much smaller, tighter track. I left my camber links the same as thunder alley on my first pack, I noticed I could not get the rotation I wanted entering the tight, not really ⅛ scale truggy friendly corners. I went back to the pits, dropped my rear camber links to a lower hole (higher roll center spot on the rear tower) , checked my camber and I was back in business  hitting the inside of the tight corners. Why the rear camber links ? Simply because they change the feel of the car more drastically then the front, yes the front does work similarly, but it isn’t as drastic and doesn’t change rotation as much as it does steering.  Questions, Comments, All Caps disagreements post them below.


Leave a comment

Please note, comments must be approved before they are published

Net Orders Checkout

Item Price Qty Total
Subtotal $0.00

Shipping Address

Shipping Methods