Level 1 · Street
Frame connectors and torque boxes
- Pair of CNC-cut frame connectors
- Front and rear torque boxes (set of 4)
- The foundation: ties the rails together and reinforces the suspension mounts
Chassis stiffening · A, B & E Body
Mopar chassis stiffening kits, Level 1 to Level 3.
Your Mopar was built without a full-length frame. The front and rear rails stop short, so the floor pan carries the load between them, and the body twists under hard launches and cornering. Our chassis stiffening kits tie it together with CNC-cut frame connectors, torque boxes and bracing, in three levels for A, B and E-body cars.
Level 1 from $762.64
Free shipping anywhere in the US
30+ years building Mopars
3 levelsfrom frame connectors to mini tubs
28 kitsmatched to A, B and E-body years
CNC-cutstiff without heavy, thick plate
$0shipping anywhere in the US
Why stiffen a Mopar unibody
Let the suspension do the work, not the body
Springs, sway bars and shocks only work as well as the structure they mount to. When the body flexes, it soaks up load the suspension should control. Stiffen the chassis and the car launches straighter, turns in sharper and feels solid on the road.
Frame connectors
Often called subframe connectors. A CNC-cut pair bridges the gap between the front and rear frame rails so the floor pan stops carrying the load.
Torque boxes
Four boxes reinforce the points where the suspension feeds force into the unibody. The factory added them to some of its highest-performance cars for the same reason.
Front-end bracing
Inner fender braces and a lower core support brace stop the nose from flexing, so steering input goes straight to the tires.
Room for real tires
Rear spring relocation moves the leaf springs inboard, and the mini tub kit opens the wheelhouses for much wider rear tires.
Compare the levels
Level 1, 2 or 3: pick the one that matches how you drive
Each level includes everything in the level before it. Prices below are for A and B-body kits; E-body Level 3 is $2,238.72.
Level 2 · Autocross and canyon
Level 1 plus front-end bracing
- Frame connectors and 4 torque boxes
- Inner fender braces (set of 2)
- Front lower core support frame brace
Level 3 · Big tires, big power
Level 2 plus spring relocation and mini tubs
- Frame connectors, 4 torque boxes, fender and core support braces
- Rear spring relocation kit, both sides
- Mini tub kit for much wider rear tires
Find your kit
Chassis stiffening kits by body and year
Choose your car, then the level. Each button opens the kit page with full fitment, parts list and photos. Not sure? Call or text 516-384-6438 before you order.
A-body chassis stiffening
All A-body kits →1967-75 Dodge and Plymouth A-body
Dart, Dart Sport, Demon, Valiant, Duster, 1967-69 Barracuda1963-66 Dodge A-body
Dart1963-66 Plymouth A-body
Valiant, 1964-66 BarracudaB-body chassis stiffening
All B-body kits →1966-70 Dodge B-body
Charger, Coronet, Super Bee1966-70 Plymouth B-body
Road Runner, GTX, Belvedere, Satellite1971-72 Dodge and Plymouth B-body
Charger, Road Runner, GTX, Satellite1963-64 Dodge B-body
330, 440 and Polara1962 and 1965 Dodge B-body
1962 Dart and Polara, 1965 Coronet1962-65 Plymouth B-body
Savoy, Belvedere, Fury, Satellite. Level 3 fits 1963-65.E-body chassis stiffening
All E-body kits →1970-74 Dodge Challenger
E-body1970-74 Plymouth Barracuda and 'Cuda
E-bodyInstallation: these parts weld in
We recommend an experienced shop, with the car supported at ride height so the chassis is not twisted while welding. Remove undercoating and seam sealer at each weld area first. Level 3 also means cutting and rebuilding the rear wheelhouses.
Free shipping anywhere in the US
Every Level 1, 2 and 3 kit ships free to all 50 states and DC. The kit ships separately, direct to you. US territories, APO/FPO and international orders are quoted at checkout.
Then finish the job up front
A stiff chassis lets the suspension work. Pair it with our Mopar front suspension kit and the 14:1 steering box upgrade.
Questions
Chassis stiffening FAQ
Which level do I need?
Level 1 is the foundation for any street car: frame connectors tie the front and rear rails together and torque boxes reinforce the suspension mounts. Level 2 adds front-end bracing for cars that see autocross, road courses or hard back-road driving. Level 3 adds rear spring relocation and a mini tub kit for owners going to much wider rear tires.
Are frame connectors the same as subframe connectors?
Yes. On a unibody Mopar the two names mean the same part: a connector that bridges the front and rear frame rails. Every kit on this page includes a CNC-cut pair.
Do the kits bolt in?
No. The parts weld in. Some pieces fit factory locations and others reinforce known weak spots, so plan on an experienced shop with the car at ride height while welding.
What tire size will fit with Level 3?
That depends on your wheel offset and how far the springs move inboard. Pick your wheel and tire package before installation, so the tubs and springs end up where you need them. Call us with your sizes and we will talk it through.
Is shipping really free?
Yes, to any address in the 50 states and DC. The kit ships separately, direct to you, and anything else in your cart is quoted at checkout as usual.
Which kit fits my car?
Use the list above by body and year, or call or text Peter at 516-384-6438 with your year, model and plans. He has spent 30+ years building muscle and pro-touring cars and still drives his Dart GT on the street and on road courses.
Tell us about your car. We'll match the level.
Year, body, tire plans and how you drive it. Peter will point you to the right kit.