Hey all,
First off, thanks to @Fake_Snake for letting me have access to some of his CAD files, they were a big help and his work was an inspiration for this project.
We've been road racing this car since 2022. It's gone through many iterations but the one constant was always the triangulated 4-link. Even with heim joins the car was still unpredictable and, for lack of a better term, squishy. It was dodgy under braking and the snap oversteer from the binding was a real nuisance. More than a nuisance, really - it cost me about two weeks worth of repairs after one of these episodes put me in the tire wall at AMP and destroyed the right side. After our last race of 2024 in December @GTLizard and I decided to rip out the 4-link and design our own 3-link. As mentioned before, @Fake_Snake had started a thread on this and had started building one for his autocross car - we took his post as inspiration and built our own. My better half was nice enough to pick me up a Crealty Scan Otter for Christmas (thanks Shannon!) so I was able to scan the rearend and tunnel at ride height, remove the rearend, scan the tunnel again and then merge the scans for good data to use as a starting point. From there, I designed the 3rd-link mounting point on the rearend itself. Since this is a racecar and has a lot of the emissions garbage removed, we didn't have to worry much about clearance above the rearend. This part was pretty straightforward - there are 0.500 pucks that locate on the stock 8.8 bushing holes and then everything either bolts or welds onto the top of the center section. Everything is made from 3/16 HRS and 1.250 OD, 0.120 wall steel tubing. The down bars that go to the anti-vibration bracket are 14ga wall, 1" square. It is fully removable in case we ever want to go back to the 4-link.
The more difficult part was the 3rd-link mount in the car itself. Our tubing bender will not do 180° bends, so I used a Competition Engineering driveshaft loop kit from Summit and cut/adapted it to fit the car. The tubing, though only 0.095 wall, is very sturdy and good quality - it welded well. I braced and triangulated everything I could just to keep things from moving, then as some extra insurance we bolted the top mounting bracket into the car's tunnel. In a street car this would require removing the carpet and rear seat but it didn't bother us here #becauseracecar. It is welded to the tunnel as well but the material there is paper thin and I paranoia crept in - hence the bolting of the top bracket. The 3rd-link itself is 1.250 wall, 0.120 wall tubing with Allstar Chassis Tube Ends and Competition Engineering rod ends. All hardware is 5/8 Grade 8.
Of all the things we've done to this car, this made the single biggest difference. All four of our drivers took 1-2 seconds off their best lap times and we won our class this past Sunday at CMP with Lucky Dog Racing League.
I've posted some pictures of the CAD, the build and the final result. Feel free to reach out with questions or comments. Thanks for looking!
First off, thanks to @Fake_Snake for letting me have access to some of his CAD files, they were a big help and his work was an inspiration for this project.
We've been road racing this car since 2022. It's gone through many iterations but the one constant was always the triangulated 4-link. Even with heim joins the car was still unpredictable and, for lack of a better term, squishy. It was dodgy under braking and the snap oversteer from the binding was a real nuisance. More than a nuisance, really - it cost me about two weeks worth of repairs after one of these episodes put me in the tire wall at AMP and destroyed the right side. After our last race of 2024 in December @GTLizard and I decided to rip out the 4-link and design our own 3-link. As mentioned before, @Fake_Snake had started a thread on this and had started building one for his autocross car - we took his post as inspiration and built our own. My better half was nice enough to pick me up a Crealty Scan Otter for Christmas (thanks Shannon!) so I was able to scan the rearend and tunnel at ride height, remove the rearend, scan the tunnel again and then merge the scans for good data to use as a starting point. From there, I designed the 3rd-link mounting point on the rearend itself. Since this is a racecar and has a lot of the emissions garbage removed, we didn't have to worry much about clearance above the rearend. This part was pretty straightforward - there are 0.500 pucks that locate on the stock 8.8 bushing holes and then everything either bolts or welds onto the top of the center section. Everything is made from 3/16 HRS and 1.250 OD, 0.120 wall steel tubing. The down bars that go to the anti-vibration bracket are 14ga wall, 1" square. It is fully removable in case we ever want to go back to the 4-link.
The more difficult part was the 3rd-link mount in the car itself. Our tubing bender will not do 180° bends, so I used a Competition Engineering driveshaft loop kit from Summit and cut/adapted it to fit the car. The tubing, though only 0.095 wall, is very sturdy and good quality - it welded well. I braced and triangulated everything I could just to keep things from moving, then as some extra insurance we bolted the top mounting bracket into the car's tunnel. In a street car this would require removing the carpet and rear seat but it didn't bother us here #becauseracecar. It is welded to the tunnel as well but the material there is paper thin and I paranoia crept in - hence the bolting of the top bracket. The 3rd-link itself is 1.250 wall, 0.120 wall tubing with Allstar Chassis Tube Ends and Competition Engineering rod ends. All hardware is 5/8 Grade 8.
Of all the things we've done to this car, this made the single biggest difference. All four of our drivers took 1-2 seconds off their best lap times and we won our class this past Sunday at CMP with Lucky Dog Racing League.
I've posted some pictures of the CAD, the build and the final result. Feel free to reach out with questions or comments. Thanks for looking!
