If you have ever driven a classic A-body and thought, “This is awesome… but it also feels like the front end is negotiating the corner separately from the rear,” welcome. You are among friends.
Ridetech’s Momentum Chassis kits are the nuclear option in the best way. Instead of trying to modernize a 1960s/70s chassis one bracket at a time, you start with a purpose-built performance foundation and build your suspension, steering, brakes, and driveline around it.
Quick disclaimer (the grown-up stuff): A full chassis swap is serious work. Use proper safety equipment, support the vehicle correctly, and know your limits. If you are not 100% comfortable lifting the body, routing brake/fuel lines, and dialing in alignment, have a qualified shop handle the install. Also, modifications can affect warranty coverage on certain components, and you should always drive responsibly on public roads.
What a “complete chassis kit” really means
With a complete chassis kit, you are not just buying “better control arms.” You are buying an engineered system where the suspension pickup points, steering layout, and packaging were designed together. Ridetech’s Momentum chassis approach is built to move beyond factory geometry constraints and give you modern handling goals from the ground up.
On the 1968–1972 GM A-body Momentum chassis, the base kit starts with the chassis itself and core hardware (think front sway bar, control arms, rear link bars, and a Ford 9-inch housing), then you choose major options like spindle style, rear width, shocks (coilovers vs air), third member, rack-and-pinion, brakes, and air management.
Why go full chassis instead of bolt-ons
To be clear: bolt-ons can work great. But full chassis kits make sense when you want multiple goals at once, without stacking compromises:
- Modern geometry baked in: You are not limited by factory pickup points.
- More tire and wheel clearance: Bigger footprint without playing “clearance whack-a-mole” on the inside of the frame.
- Rack-and-pinion steering: More direct feel than an old, worn recirculating ball setup.
- Packaging for real power: Headers, exhaust routing, driveline strength, and brake options are part of the plan.
In other words, you are buying fewer “maybe this will work” moments. And fewer “why does it rub only when I turn left over a manhole cover” mysteries.
The options that matter (and why)
1) Pin spindle vs hub spindle
Ridetech lets you choose between their tall AFX pin spindle or a Corvette brake/hub spindle option. Your spindle choice affects brake and hub compatibility, so this is one of the first decisions to lock in.
2) Stock width vs narrowed rear
For the A-body Momentum chassis, Ridetech offers a stock-width rear (60.25 inches) or a narrowed rear (57.25 inches) Ford 9-inch housing and axle package. The narrowed option is usually about wheel/tire packaging and your end goal (street, track, or “I want the widest tire that still lets me turn”).
3) Coilovers vs air (ShockWaves)
You can spec the chassis with Ridetech coilovers or ShockWave air suspension, with shock options in HQ (rebound adjustable) or TQ (triple adjustable). If you want set-it-and-forget-it simplicity, coilovers are the usual play. If you want ride height control (and your car’s stance to have multiple moods), air starts making a lot of sense.
4) The Ford 9-inch third member
Ridetech’s third member options for this chassis include a Yukon nodular iron case, aluminum Daytona pinion support, a 1350 yoke, Timken bearings, and an Eaton Truetrac style limited slip. Gear ratio choices typically include 3.50, 3.70, 3.89, and 4.11, which gives you room to match your tire diameter and transmission choice.
5) Steering: rack-and-pinion (yes, please)
One of the big “feel” upgrades here is steering. The Momentum chassis design incorporates a commonly available 1999–2004 Ford Mustang steering rack, with Ridetech calling out a PSC quick ratio option in their documentation for a more modern response.
6) Brakes and air management
Brake packages and air management (like a RidePRO e5 system for air suspension builds) are the final big building blocks that turn the chassis into a complete, drivable system.
Fitment and “does it fit my A-body”
The 1968–1972 GM A-body Momentum chassis is intended for classic A-bodies like Chevelle, GTO/LeMans/Tempest, Cutlass/442/F85, and Skylark/GS, and Ridetech notes it fits convertibles. They also list exclusions (wagons, 4-doors, certain related platforms like Grand Prix, Monte Carlo, and El Camino/GMC Sprint), so double-check your exact model before you commit.
Also worth noting: Ridetech highlights that their best wheel/tire combo testing included 275/40R18 tires on 18x9 (6-inch backspacing) or 18x10 (6.5-inch backspacing) with no lock-to-lock steering issues on factory inner fender liners. That is a helpful sanity check when you’re planning wheel and tire sizing.
Install reality check: tools, safety, and sanity
If you are doing a full chassis swap at home, treat it like a serious shop job. Because it is.
Safety equipment you should have:
- Eye protection and mechanics gloves
- Hearing protection (you will use power tools, even if you swear you won’t)
- Jack stands rated for the vehicle weight (plural, not “the sketchy pair”)
- Wheel chocks
- Fire extinguisher (fuel systems and grinding sparks do not negotiate)
Common tools that usually come into play:
- Floor jack, tall jack stands, and/or a vehicle lift
- Engine hoist and/or body lift setup (depending on your method)
- Torque wrench, impact, and a full socket/wrench selection
- Ball joint tools and steering linkage tools
- Brake tools (flare tool, line wrenches, bleeder setup)
- Angle finder, tape measure, plumb bob/laser (for sanity checks)
- Cutoff wheel/grinder and a good set of drill bits
Post-install non-negotiables:
- Professional alignment (and a real test drive plan)
- Re-torque after initial shakedown miles
- Verify brake performance in a safe area before normal driving
Yes, this is more work than swapping springs. On the upside, it is also dramatically more likely to end with a car that feels modern, confident, and predictable.
Featured Ridetech Momentum chassis kits
Here are two complete Momentum chassis kit options we have in our Ridetech collection. Both are for 1968–1972 GM A-body and are the “with pin spindle” variants:
- Ridetech 1968–1972 A-Body Momentum Chassis (Pin Spindle, Stock Width) - SKU: ART-11243799
- Ridetech 1968–1972 A-Body Momentum Chassis (Pin Spindle, Narrowed Width) - SKU: ART-11243798
Freight heads-up: A chassis kit is not a “toss it on the porch” shipment. Plan for truck freight delivery and the logistics that come with it.
Shop supporting parts by category
Building a complete chassis setup usually means you’ll also be shopping around these sections (because the project always grows legs):
- Shop all Ridetech parts and kits
- Suspension kits
- Shocks and shock hardware
- Control arms, sway bars, bushings, mounts
- Steering
- Brakes kits and parts
- Drivetrain
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Tell us about your build
What are you building: Chevelle, GTO, Cutlass, Skylark? And what wheel/tire size are you trying to fit without turning your inner fenders into modern art? Drop your plan (and your pain points) in the comments below.
