This was submitted to the mailing list by our resident pro, Carl Beck.

see http://www.zhome.com/ZCMnL/tech/MacPhersonStrut.htm

Aircraft type landing gear - aka "struts" - were redesigned and
applied to automotive use by an Engineer working for Ford of England
in the early 50's - Mr. Earl F. MacPherson.

In that sense of the term - an Automotive "MacPherson Strut" or
"strut" is actually comprised of a shock absorber with a coil spring
mounted above it. The "strut" is attached to the auto structure at
the top of the coil spring and the wheel hub is attached at the
bottom - the bottom of the assembly is located by a lateral link and
anti-roll bar (al la TR-7) - or by a lower Transverse Link and
Tension Compression Rod (al la Z).


On our Z's the MacPherson "strut" is comprised of: (without regard to
how the Japanese translated it in their Part Manuals;-)

1. Strut Tube: - the "shock absorber tube" with a spring perch or
seat welded on the outside of the tube near the top.. the spring sits
on this perch/seat. The front axle is located at the bottom. The
combined Strut Tube and Shock Absorber are referred to as the "Strut
Assembly".

2. Shock Absorber: -the "shock absorber" built into the inside the
strut tube (normally replace by a cartridge insert). The shock
absorber "piston rod" moves in and out of the tube/cartridge and is
damped in it's movements via oil flowing through very small valves
attached to the lower part or bottom of the piston rod.

3. Coil Spring: - the "coil spring" mounted near the top the strut
tube, sitting on the spring perch - the perch is welded to the
outside of the strut tube.

4. Spring Seat: - that holds a slightly compressed spring, at the
top end of the shock absorber piston rod. The top end of the shock
absorber piston rod is threaded - so a nut/washer holds the spring
seat in place there. The "bump stops" sit on the top of the shock
absorber tube - held in place because they surround the shock
absorber piston rod. Under full compression of the coil spring -
they stop the spring seat - from bumping the top of the shock
absorber tube.

5. Mounting Insulator: - the mounting insulator is bolted to the car
with three bolts at the top.

6. Strut Bearing: - The mounting insulator rides on the "strut
bearing" thus allowing the Strut Assembly to turn right/left.

If you shorten the springs, shorten the travel or length of the shock
absorber piston rod (as happens with all to many cartridge type
replacements), overload the car - - you increase the possibility that
the suspension will "bottom out" - - - - - meaning it hits and
compresses the bump stops. For this reason you almost always want to
replace the bump stops when you change shocks.. cheap insurance....

A farther modification of the design of the Automotive Strut was done
by Colin Chapman of Lotus to adapt it to the rear suspension.... Mr.
Chapman located the strut via the use to two links at the bottom to
restrict lateral and longitudinal movement.

Thus our Z's use MacPherson Struts on the front suspension and
Chapman Struts on the rear.

So What Does Nissan Call The Parts in the Front Strut?
1. Strut Assembly = Assy. Strut Front Suspension (assy includes the
tube, the axle & shock)
2. Shock Absorber = Assy. Shock Absorber
3. Coil Spring = Spring Front
4. Spring Seat= , Assy. Bumper Bound
5. Mounting Insulator: = Assy. Insulator Strut Mounting
6. Strut Bearing = Bearing - Strut Mounting


So .. you can't find "Bump Stops" - in the Parts Manual because they
are part of the "Assy. Bumper Bound - but you can buy them in the
after-market.

BTW - Later year Z's used a dust cover over the shock absorber piston
- to help keep dust/dirt off the piston and out of the seals that
surround it... thus lengthing the life of the shocks... not a bad
addition to the older Z's while your at it...


More than you wanted to know....
FWIW,
Carl

Carl Beck
Clearwater, FL USA
IZCC #260