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Author Topic: Weight Reduction: Putting Your M-Body On A Diet  (Read 17900 times)

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Weight Reduction: Putting Your M-Body On A Diet
« on: January 21, 2008, 22:44:05 »

Putting Your M-Body On A Diet  - Where is the Weight?

Below, excerpted from old posts, are suggestions for reducing the weight of your M-body.

Engine Compartment/Drivetrain:

  • Carburetor and intake manifold swap. A cast-iron 4-barrel intake and carburetor weighs about 73 lbs. The 2-barrel intake and carburetor probably weighs a bit less. An Edelbrock aluminum intake and a 4-barrel carburetor weighs about 31 lbs. Weight savings: 40 lbs.
  • Remove Air Injection System. Removing the air pump and assorted plumbing. Weight savings: 12-15 lbs.
  • Remove the Lean-Burn Ignition and replace it with the Mopar Performance Electronic Ignition kit. Even weight swap on the components, but it will allow you to toss maybe 5 lbs of wiring and vacuum lines/valves/paraphernalia and make the engine much easier to work on. Weight savings: 5lbs.
  • Swap out the stock clutch fan assembly and shroud with a simple aluminum shroud and cheap electric fan. Weight Savings 10-15 lbs. (This is only recommended for drag racing.)
  • Edelbrock aluminum cylinder heads. Edelbrock aluminum small block heads weigh only 30lbs a piece vs. about 50lbs each for cast iron small block heads. Weight savings: 40 lbs.
  • Exhaust headers.  Headers will save about 40-50 lbs over the cast iron manifolds and pre-cats. Weight savings: 40-50 lbs
  • Exhaust Y-pipe. Switch to a non-cat Canadian Y-pipe. The stock Y pipe with 3 cats weighs about 35lbs. The  non-cat Canadian Y-pipe weighs around 9lbs according to Autozone. Weight savings: 26 lbs.
  • Remove the A/C system. The A/C system, including the compressor, lines, and condenser has to be worth 40lbs or more. The trade-off is uncomfortable hot weather driving. Weight savings: 40 lbs.
  • Denso alternators are lighter than stock factory alternators. Weight savings: 10lbs.
  • Underhood insulating pad. Weight saving: less than 5 lbs.
  • Use a mini-starter.  If your M-body did not come with one, (1987-earlier models), you can use a mini starter for a 1989 Diplomat or any 90s Dodge ram truck. Weight saving: 5 to 10 lbs.
  • Manual Steering box. Replace your power steering system with a manual steering box. Weight saving: 40 to 50 pounds.
  • Transmission - Remove the factory dampener.  This is a piece of solid iron that bolts to the tailshaft to reduce drivetrain harmonics.  It is very heavy and you can do without it. Weight saving: 15 to 20 pounds.
  • Battery. This won't save any weight, but moving the battery to the trunk improves weight transfer.


  • Clean out the trash. Do not haul unneeded tools and junk around in the trunk.
  • Use a temporary (donut-style) spare if you can find one that fits. Weight saving: 20 lbs.
  • Rubber floor mat and sound deadening. If you have a cop car with a rubber floor mat and sound deadening,  the mat, underpadding & insulation will weigh close to 90 lbs. You can replace it with 8 lbs of carpet and 18 lbs of lightweight heat reflective insulation. (Dynomat Extreme deadener-  $120 for 36 sq. ft. and light) Your car will still be whisper quiet and you will save more than 60 lbs. Weight savings: 60 lbs.
  • You can also replace your sound deadening pad with Cascade VB-1X(1G) Sprayable Damping Compound
  • Swap out your power split-bench seats for some manual ones. The non-power passenger front seat is almost 60lb.  The power drivers seat is about 80lbs. Weight saving: 30 to 40 lbs
  • Another option if you have power seats is to grab a set of manual seat rails from a junkyard M-body, remove your seats from the power rails and swap them to the manual rails. Should shave a few pounds...
  • Another good bet are Diplomat/LeBaron & late Aspen/Volare coupe seats.  Most are manual and they are considerably smaller than the ones in a Mirada or such and they are almost always power.
  • Omni seats have the exact same mounting and you could get them bucket version and in the same colors as Fifth Avenue interiors. A lot of stuff from an omni will interchange, including the
    floor shifter console which *should* be the same as the ultra rare diplomat floor shifter.
  • Switch from power to manual windows. you could save ~40lbs switching from power to manual
    windows. Weight savings: 40 lbs
  • If you have a big stereo system, ditching the subs/box would be 30 lbs... there's not a whole lot of opportunity to save weight without affecting appearance and comfort.
  • Cabin sound deadener.  There is a thick sound deadening pad that goes behind the upper back seat cushion that probably weighs 10 to 15 lbs. You can replace it with 5lbs of lightweight heat reflective insulation.  Weight savings: 5-10  lbs.
  • Steering wheel. Use an aftermarket steering wheel. Weight savings: 5 lbs
  • If you don't care about having heat in the car you could remove the heater box, that thing does weigh a few pounds..


  • Fiberglass fenders.  Some fiberglass companies used to sell fiberglass fenders for 1980 Aspens & Volares.  They have been discontinued now, but if you can find these fenders used, they will bolt up to your M-Body.
  • Fiberglass bumpers.  Some fiberglass companies also sold fiberglass bumpers for 1980 Aspens & Volares.  They have also been discontinued, but if you can find these used, they will bolt up to your M-Body.
  • Bumper shocks. These items weigh a ton. You can cut the brackets off the shocks and weld them to the exhaust tubing with the same diameter. The shocks are supposed to be filled with hydraulic fluid, so it needs to be removed before you apply any heat to them or they could explode. You can also make up some mounts out of 16 gage steel. The downside of doing anything to the bumper shocks is that your frame could be heavily damaged if you have an accident. Weight savings: approximately 75 lbs for all four shocks.
  • Bumper core.  The inner structure of the bumpers has a lot of excess metal.  Cut whatever you don't need, as they only really need to be a medium between the bumper "shock" and the bumper "skin"  Member CudaZappa lost 50lbs out of his Chrysler 300 using this method. Weight savings: 50 lbs.
  • Swap to aluminum bumpers. M-Body chrome bumpers weigh about 43 lbs without the bumper shocks. Bumpers from 78-83 Fairmonts or 74-77 Non-Z28 Camaros were made of aluminum to save weight and meet CAFE standards. They can be adapted to M-bodies. Fairmont bumpers are 73.62" wide and 74-77 Non-Z28 Camaro bumpers are 74.4" wide. For reference, M-body front bumpers are about 74.2" wide.
  • Drop from a dual exhaust to a big single. single 3.5" flows as good or better than dual 2.5",but has 30% less volume of metal.


  • Cop Car wheels.  Cop car wheels weigh about about 4-5 lbs more than than civilian M-body wheels.  Replacing them with civilian wheels will save about 20 lbs. Weight savings: 20 lbs.
  • Alloy wheels. Alloy wheels weigh at least 4-5 lbs less than than civilian wheels and probably 10 lbs less than cop car wheels. Weight savings: 20 to 40 lbs depending on your original wheel.
  • Dog dish hubcaps. Dog dishes are much lighter than either the full flat wheel covers or the spoke-style ones.


« Last Edit: April 24, 2008, 13:04:38 by Reggie »
"There is only one success - to be able to spend your life in your own way." - Christopher Morley 1890-1957, American author and editor

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