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Z31 Suspension
Tech Article: Z31 Suspension
By: Chuck Strong
Originally published in the Z Club of Texas Newsletter
Z31's are some of the more commonly seen Z cars on the road, but most have not seen much, if any,
maintenance. It is a shame to see such nice cars bouncing over every bump, and swaying around
every corner. Z31's are actually very dependable, but like everything, need to have a few things
replaced to keep them in top form. One person can replace all the items mentioned here on a weekend.
Whether you bought yours new, used, or are looking to buy, most every one I have seen needs the
same suspension work: shocks and suspension bushings. Shocks are obvious, but many owners overlook
the suspension bushings. Ever notice how your Z31 clunks with almost every shift? It's not the
differential mount. It's the rear crossmember bushings. The play in the steering? Usually ball
joints and tension rod bushings. The rubber bushings in the cars just dry up and shrink, allowing
for a great deal of excessive movement.
The front suspension bushings are fairly easy to replace. The bushings needed here are for the
tension rod (2 for each side) and sway bars bushings, including endlinks. The tension rods can be
removed by unbolting the two nuts on the front control arm and one nut on the tension rod bracket.
Be sure to note the orientation of the bushings and their size because they are different and if
installed incorrectly they can affect the alignment. The sway bar bushings are attached by two
bolts, and are easy to replace. I recommend replacing the endlinks with new bolts and polyurethane
bushings for added performance. Unfortunately, very few Z31 bushings are available in polyurethane.
While the front suspension is being worked on, it is a good time to check the ball joints on the
control arm. The easiest way to check this is push on the top of the tire and rock the car side
to side. If there is play in the wheel, or you hear a popping sound, it is usually the ball joint.
Nissan does not sell just a replacement joint, just the control arm as a unit. There are aftermarket
joints available, but Nissan does not recommend them because of possible damage or weakening of the
control arm during replacement. The easiest way to fix this problem is to buy control arms with
good ball joints from a wrecking yard that has a Z that has met an untimely demise. The control
arm comes off with three bolts after removing the tension rod and sway bar. If the control arm
has never been off before, it must be separated from the strut housing. Age makes them stick.
Just use a large hammer and a chisel where they meet.
The rear suspension needs fewer parts, but takes more time. The sway bar and endlink bushings are
replaced the same as the front, but the crossmember bushings will require air tools and a press.
There are two ways to remove the crossmember bushings: with the crossmember on the car, or off.
If you do not have air tools, the crossmember must be removed and then taken to a shop to have the
old bushings pressed out and the new pressed in.
To remove the crossmember, you will need to remove the bolts that attach the trailing arms
(2 each side), emergency brake cable that is routed through the crossmember, the four bolts
that attach the differential, and the three bolts that hold each bushing in place.
To remove the bushings while it is on the car, remove the three bolts that hold in the bushing.
The bushing itself has a metal outer sleeve and it must be cut in half on one side. The best way
to do this is with an air chisel. After it is cut, it can be easily pried out. The new one must
be pressed into place, but I have been able to use an air hammer. It does not fit in perfect, but
seems to work fine.
After replacing all these parts, the difference in ride quality is GREATLY improved. Everything
will feel much smoother, and more accurate. Driving a Z is pure joy, but not if your suspension
is in bad shape. So, go fix your Z, and get back to having fun again.
© 2007 Triad Z Club
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