Rear
suspension installation and tips for cars with
rear isolators. My car was starting to squat on
one side and I decided it was time for springs.
I like the car a lot and didn’t want to go the
cheap route (I don’t feel suspension or brakes
are a good place to skimp). Our Magnums were
blessed with good handling for their size & time
but over the years, time & miles do take their
toll. I went a little overboard and replace
every thing I could find new (NOS when
possible).
Parts List:
Set of 5 leaf H.D. springs (just suspension)
aftermarket
Set of 4 U-Bolts. Don’t be cheap. Get new ones
and the nuts, as they’re still available from
Mopar.
Set of 4 urethane isolator bushing (OEM was
rubber, discontinued long ago, got them from
Just Suspension)
Set of isolator clamps. Mine were beat and I was
lucky to find them new (Just Suspension). These
hold the Isolator bushings. Just Suspension
didn’t have many left.
Set of E body Polyurethane Shackles. They are
the same dimensions as the Magnum’s and are
REAL AWESOME. They allow a lot more spring
travel and are used by Mopar Action Magazines
lap of America Valiant.
New shocks. I used Monroe’s as KYBs are too firm
for the NJ roads.
Sway bar links and bushings (if you can find
them). I could not find end links and had to
drive 80 miles to get the rest of the stuff from
some dealer in NY State.
Removal:
1) Place car on safety stands so the suspension
hangs free and put a hydraulic jack under the
center of the rear, and raise axle enough to
take weight off springs. You may now disconnect
the rear shock abs at the shock plate or remove
them for replacement; this is a good time to do
so.
2) Disconnect sway bar end links (If you can’t
get new bushings for this, no reason to remove
it).
3) Lower the axle to allow springs to hang free.
Keep the jack under the center of the axle and
just touching.
4) Loosen & remove u-bolts, DO NOT TOSS THEM
YET, if they aren’t available a leaf spring
company can make them, you will need the old
ones for this. I did get them from a local
dealer.
5) Remove spring plates and isolator clamp with
bushings
6) Make sure you SUPPORT THE AXLE, It is heavy
and will hurt you!
7) Loosen the nuts from the front hanger and
remove three on each spring but leave one loose.
LUBE THEM GOOD, the hanger is not available.
Now loosen and remove the rear shackle. The rear
of the spring can be lowered. Now take out the
front bolt that is loosened and take out the
spring.
8) Remove the hanger from the spring; do not
worry about the front eye bushing, as your new
springs SHOULD have it installed already. You
will probably need an impact gun on the thru
bolt. NOTE IF YOU LET THE AXLE DROP, BYE-BYE
BRAKE LINE!!!!!!!!!
Installation:
1) Take your new spring and install the front
hanger (do not tighten it fully yet)
2) Put the front hanger thru its holes and
install nuts to 35 foot-pounds.
3) Assemble the rear shackles and install to the
manufacturers specs if using polyurethane, again
to not tighten all the way yet. Don’t forget to
lube these urethane bushings or they will creak
loudly. If you use OEM type shackles or repro
w/rubber bushings all is same but do not lube
rubber bushings.
4) Position the upper isolator bushing and the
spring/shock abs plate over the locating pin on
both sides and place the new U bolts through the
holes. If you are using the new urethane
isolators: a) not necessary to lube. b) Have
them in a 70F-80F degree environment so they
will be flexible.
5) Put the lower isolator bushing in the clamp
and put it up and thru the U-bolt studs then
install the nuts. Tighten this to 45 ft pounds.
If you use OEM bolts they are tough to turn,
this is ok as these are "staked” so they cant
back out.
6) Install new shock and sway bar end link. Do
not tighten yet.
7) Put drums and tires back on, Tighten lugs to
85 ft pounds (yes I really do this) and lower
car to ground.
8) Tighten front pivot bolt to 125 ft-pounds (do
your best, kind of tight here), shackle nuts to
45 ft pounds for stock (READ the instructions
for aftermarket), and the shock absorber nuts to
35 ft-pounds. Tighten sway bar link end now too.
9) Measure the front ride height, as it may have
changed (when the rear goes up the front goes
down). Take for a test drive. You should do a
front-end alignment
You should now be rewarded with a nice firm ride
and be able to have friends ride in the backseat
without bottoming out Enjoy!!!!
Notes:
On this job I removed the wheels and drums even
though the service manual says nothing about it
as a step. It makes it easier to maneuver the
axle with the extra weight removed. Not to
mention safer.
Try to have a helper with you, so if you get
hurt someone is there, plus this stuff is not
light and the positions are awkward.
If you use the urethane parts, they will need
patience and finessing, but it is worth it. Do
not try to draw parts together with the bolts.
It will cost you.
I highly recommend a Factory service manual.
I’ve seen them at swap meets as low as $5.00
used $40 new. Well worth it.
Note that the Isolator clamp is deeper on 5 leaf
cars than 6 leaf cars if you want to upgrade,
these clamps are hard to get. My parts sources,
and lots of tech advice from:
My local Dodge dealer. I am blessed with a local
dealer full of MOPAR nuts. they got me the U
bolts and located a lot of hard to find bushings
and sway bar brackets, My car did not come with
a rear bar, even though it has HD suspension.
Just Suspension, 1-800-872-1548 owner Bill
Kanouse. This guy has a lot of Mopar stuff at
reasonable prices. He supplied the urethane
Isolators, Isolator clamps, Heavy-duty leaf
springs, and Polyurethane shackle kit. He is
also getting me a new HUGE front sway bar that
fits same as original. He even has a few of our
torsion bars. ONE OTHER THING, this guy realizes
that cars were made after 1974 and said he is
hoping to help service these cars. He may look
into reproducing the Isolator clamps and
possibly torsion bars. He has been calling Mopar
Performance to get a status as they list them
but don’t actually have them. These bars are
just about all gone!!! One way to get other
vendors going is for them to hear there is a
market. A lot of these guys know each other.
