My 84 5th Ave was ordered with the "heavy duty suspension" option. The car is equipped with 5 leaf rear springs, but it also has the 7 1/4 rear axle with 10 inch drums. Police models also got a heavier-duty suspension than civilian models, but they got 8 1/4 rear axles and 11 inch drums.

Was the civilian "heavy duty suspension" equivalent to the police suspension? In other words, are the civilian heavy duty leaf springs, front sway bar, and torsion bars, equal in spring rate to the cop versions? Can I just add a cop car rear sway bar and have a cop suspension or do I need to change out the front suspension and rear springs too?

The factory service manual says,

"Heavy duty rear springs are offered as part of the heavy duty suspension option and have a higher spring rate for greater stability under loaded conditions. They are part of a complete, engineered option which includes heavy-duty torsion bars, and heavy-duty shock absorbers."

The rear suspension section differentiates the rear springs only by number of leaves, and it says standard duty springs are 4 leaf, but heavy duty, taxi, and police springs have five leafs. Are alll five leaf springsets equal? Does heavy-duty suspension include a thicker front sway bar?

Thanks.

_________________
Casually looking for a Clifford hyperpak intake for cheap.

The '84 FPC shows two pairs of torsion bars, one of which is noted "POLICE ONLY". Two torsion bar to lower control arm bushing packages, one of which is noted "POLICE & TAXI ONLY", two sets of front shock absorbers (standard, heavy-duty), two front sway bars/bushings/straps (one for standard & heavy-duty, another for extra-duty and firm-feel), three sets of rear leaf springs (standard, heavy-duty, and police), three sets of rear shock absorbers (standard, heavy-duty 1", and heavy-duty 1-3/8"), a rear spring shackle upper pin bushing insert used only w/extra-duty, and only one rear sway bar for any/all vehicles so equipped.

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

Thanks Dan. So it sounds like civilian "heavy duty" suspension packages got mid-range stiffness, but only cop cars and Taxis got the really stiff stuff. Interesting. The service manual makes it sound like only two complete package levels, not three.

_________________
Casually looking for a Clifford hyperpak intake for cheap.

Okay, here's some new ones for you:

How much does an M-body 8 1/4 rear axle weigh?
How much do m-body cop car rear leaf springs weigh?
How much does a cop car rear sway bar weigh?

Thanks!

_________________
Casually looking for a Clifford hyperpak intake for cheap.