Homebrew Coilover setups
Pretty much everyone. Me included. Look at the shock towers. There's nothing to them- a large, cantilevered arm that is reinforced only by the sheetmetal of the inner fender. With the torsion bar suspension pretty much all of the suspension forces are carried in the lower control arm, K frame, and torsion bar crossmember. The spindle, UCA, and shock are basically "along for the ride". They obviously transmit forces, but only a small percentage compared to what is carried by the LCA's and crossmembers.
All you have to do is put a jack under the K member and lift the front wheels off the pavement on an unreinforced car to see how these cars are not intended to carry much load in the vertical plane, just look what happens to the door and body gaps when the front of the car is jacked up. There's a ton of flex there. On my car I added frame connectors, torque boxes, and "J" bars that run from the firewall to the front of the frame and tie into the tops of the shock towers, as well as boxing the shock towers themselves. The difference in chassis stiffness is amazing, and I'm still running torsion bars.
If you run coilovers into the stock shock towers, you're placing ALL of the suspension loads directly onto the shock towers. They were simply NOT designed for that. Honestly, I think they're barely adequate for carrying the forces transmitted through the stock shocks, let alone all of the suspension forces. Which is part of the reason I boxed and reinforced them when I upgraded my torsion bars and tires, which increased the loads carried by the chassis. While I like Denny's solution to reinforcing the shock towers because it's easy for most folks to install, I would personally weld those reinforcements in, and would still consider adding J bars on the top side, or at least using the US Cartool reinforcements that are being made now as well.
You can see the J bars I added to my car as well as the tie in to the shock towers in this picture. I drilled through the landing plates and top of the shock tower and plug welded everything together. I also boxed the shock towers. You can also see most of why I felt it was necessary to add that kind of reinforcements...
I reinforced the torsion bar sockets on my Duster before I went to the 1.12" bars. The sockets fail often enough on A-bodies with the stock bars, the 1.12" bars have a 300 lb/in wheel rate so I wasn't going to leave that to chance. I run 1.12" bars on my Challenger with unreinforced sockets and have so for over 50k miles now, but the E-body's seem to have received better torsion bar socket welds than most of the A's I've seen, mine included.
The only other real "issues" are fairly minor, I mentioned that they hit my Doug's headers because of their increased diameter, so I had to dimple the headers a bit. And of course installing the torsion bar boots was a royal pain. I would also highly recommend Bilsteins or better for shocks when running bars that large, damping them is a whole new ballgame. I run the Hotchkis non-adjustable Fox shocks on my Duster, which were an improvement over the Bilsteins I was running initially.
Here's a picture of the 1/8" plate I reinforced the torsion bar sockets with. I tied it into the 1/8" landing plates for my frame connectors as well. Had I really been thinking, I would have just made a single reinforcing plate/landing plate. Next time!
Pretty much everyone. Me included. Look at the shock towers. There's nothing to them- a large, cantilevered arm that is reinforced only by the sheetmetal of the inner fender. With the torsion bar suspension pretty much all of the suspension forces are carried in the lower control arm, K frame, and torsion bar crossmember. The spindle, UCA, and shock are basically "along for the ride". They obviously transmit forces, but only a small percentage compared to what is carried by the LCA's and crossmembers.
All you have to do is put a jack under the K member and lift the front wheels off the pavement on an unreinforced car to see how these cars are not intended to carry much load in the vertical plane, just look what happens to the door and body gaps when the front of the car is jacked up. There's a ton of flex there. On my car I added frame connectors, torque boxes, and "J" bars that run from the firewall to the front of the frame and tie into the tops of the shock towers, as well as boxing the shock towers themselves. The difference in chassis stiffness is amazing, and I'm still running torsion bars.
If you run coilovers into the stock shock towers, you're placing ALL of the suspension loads directly onto the shock towers. They were simply NOT designed for that. Honestly, I think they're barely adequate for carrying the forces transmitted through the stock shocks, let alone all of the suspension forces. Which is part of the reason I boxed and reinforced them when I upgraded my torsion bars and tires, which increased the loads carried by the chassis. While I like Denny's solution to reinforcing the shock towers because it's easy for most folks to install, I would personally weld those reinforcements in, and would still consider adding J bars on the top side, or at least using the US Cartool reinforcements that are being made now as well.
You can see the J bars I added to my car as well as the tie in to the shock towers in this picture. I drilled through the landing plates and top of the shock tower and plug welded everything together. I also boxed the shock towers. You can also see most of why I felt it was necessary to add that kind of reinforcements...
I reinforced the torsion bar sockets on my Duster before I went to the 1.12" bars. The sockets fail often enough on A-bodies with the stock bars, the 1.12" bars have a 300 lb/in wheel rate so I wasn't going to leave that to chance. I run 1.12" bars on my Challenger with unreinforced sockets and have so for over 50k miles now, but the E-body's seem to have received better torsion bar socket welds than most of the A's I've seen, mine included.
The only other real "issues" are fairly minor, I mentioned that they hit my Doug's headers because of their increased diameter, so I had to dimple the headers a bit. And of course installing the torsion bar boots was a royal pain. I would also highly recommend Bilsteins or better for shocks when running bars that large, damping them is a whole new ballgame. I run the Hotchkis non-adjustable Fox shocks on my Duster, which were an improvement over the Bilsteins I was running initially.
Here's a picture of the 1/8" plate I reinforced the torsion bar sockets with. I tied it into the 1/8" landing plates for my frame connectors as well. Had I really been thinking, I would have just made a single reinforcing plate/landing plate. Next time!
