Z-Car

Datsun 240Z Clutch Replacement Hints

girl changing the oil

By Thomas Walter

A few random thoughs on changing clutches:

THINGS TO BUY:
New pressure plate
disk
throw out bearing
exhaust flange gasket (exhaust manifold to exhaust pipe) ’72 and later are different!
some grease
OPTIONAL:
Front transmission seal and gasket
Rear transmission seal
pilot bushing
pressure plate dowel pegs (3)…
Two quarts of gear fluid (90W)
DO YOU HAVE:
Clutch Alignment Tool?

I highly recommend reading the “How to Keep your Datsun/Nissan
Alive” repair book.

My ’71 4 door has 65K miles on it, with a note the clutch
was repaced at 35K miles, ten years ago! The clutch was
out of adjustment, causing the disc to slip, overheating the
pressure plate. Sad part, had it been adjusted the clutch
probably would not have needed to been replaced. 🙁

[I am not going to cover the whole job, just some tricks
to assist the next person. ].

Steam clean the underside the day before! Get the car up
on ramps, and clean the bell housing, tail shaft, and
driveline areas. More time spent now, the easier it is
when the job comes. [My clutch was slipping so badly this
was not an option this time… which in case I should
have used a can of “easy off” (yes, oven cleaner) on the
underside and a hose in the street].

JACK STANDS… use caution, you will be shaking the transmission
above your head… spend the money and buy four good jack stands.
Mine safely lift the car 18″… which is just about right.

Stock exhaust system, nicely rusted tight. My trick of
loosening the resonator clamp didn’t work. Oh, well a hacksaw
on the neat straight portion did the trick (Need to pick up
a 3″ sleeve of 1.5″ ID and a couple of muffler clamps now. :-).
Front three nuts (darn 13mm… someone was there before!) on
the manifold flange came off OK… no broken studs this time
(thankfully). [To spare me some grief, when ever I have an
exhaust replaced, I have a flange added about halfway down
-just after- the transmission. Makes removal of the exhuast
pipe much easier, and transmission mission jobs go quicker.]

Drive line bolts… need to keep the driveline from turning
while loosening a nut? Pull the brake cable! 🙂 To get the
brake cable out of your way, don’t bother loosening the
cable nuts… just pull the little clip about half way along
the floor, and move the cable out of the way.

Removal was pretty straight forward. Did the trick of using
the scissor jack on the front lip of the oil pan to tilt the
motor. Jack was on a 4″x4″ piece of wood, with a 1/2″ thick
piece of wood between it and the oil pan.

Remove the transmission cross member, with the big floor
jack supporting the tranny. I’ve learned it is easier to
get those two top bolts this way. Watch the fan when doing this,
usually if the fan blades are in a “+” position, I rotate
them 45 degrees to the “x” position, giving a little more
clearance.

With the correct angle (engine tilted up), tranny shaft down
it was simple to unbolt everything and ROLL the floor jack back.
Piece of cake (wish is was always this way).

Flywheel was nasty. Ridges, and heat cracks, in addition to being
blue. Pressure plate (p.p.) looked the same, there was still
resistance when I had pressed down on the pedal, but the plate had
no clamping force. Disc still looked good! (toss into the nearest
trash can, no way do I like reusing clutch parts). T/O bearing felt
fine, but oddly enough the p.p. finger had some serious wear to the
area contacted by the through out bearing.

[Someone pointed out old clutch disc with asbestos fibers should
be considered hazardous waste, and NOT tossed into the trash can.]

Once I had it out, it was clear I would need those dowel pegs
for the flywheel. Might as well pick up a exhaust flange gasket
and pilot bearing from the dealer (gasp, they were in stock!).
Dealer QUOTED $60.00 for ONE driveshaft U-joint (passed on that
as I paid around $20 four years ago… I have a funny feeling this
dealer has some ‘funny pricing’ on anything older than 1980).
Need to check that price with my friendly dealer in Beaverton,
Oregon (VISA, and UPS work great!)

Pressure plate, disc, and T/O being were all new, running me a little
over $100 (import place, Japanese OEM parts). T/0 was mis-labeled.
Oh, fun another parts run. 🙁

Got the correct T/O bearing. I was glad I replaced the pilot bearing…
did the grease trick. Pack the hole full of wheel bearing grease
(helps to toss it into the freezer a day before to keep it thick).
Use a 1/2″ rod to pack it it (letting the air out as you fill the
hole with grease). A 5/8″ hardwood dowel soaked in oil to swell
it is ideal tool for this, but I just pound away on my old input
shaft from a dead transmission (also a great alignment tool).
The old pilot bearing was in pieces! I have not seen that before,
but a lot of shops will just skip replacing it (hey, only 65K miles
on this one, shoot I was ready to skip replacing it).

Pulled the locating pegs off the flywheel before taking it in
to be resurfaced. Broke two of the pegs off nearly flush! &@#$!
Hmm, drilled a 3/16″ inch hole down into them, going all the way
though the dowel, but not into the flywheel. Grease again! I packed in
some grease then used a 3/16″ rod… once the cavity is filled with
grease, place the metal rod back into the hole. Hit is with a hammer,
and out it pops! Not bad. 🙂 [OK OK, I ‘bored’ the 3/16″ hole on
the milling machine… the roadster was in front of the drill press,
but you get the idea. Someone else suggested using a claw hammer, with
the dowel in the “V” section, to help lever it out.]

Got the flywheel resurfaced. Darn, no flywheel bolts in stock.
Stock L16 so I reused the old ones (always best to REPLACE them!).
Carefully counter sunk the pressure plate bolt holes on the flywheel
(I should have measured it before and after having it surfaced…
seemed a little lighter!)

To torque the flywheel bolts, I held the flywheel in place using a couple
of bolts threaded into the pressure plate holes. One through the end of
a breaker bar, the other resting against the side of. I have a couple of
socket cap bolts that I use for this and removing stuck drums in my tool
box (8mm x 1.25 threading, 25mm long). Flywheel bolts were clean, and
a drop of red loctite applied to each.

Getting the pressure plate back on… and SNAPPED one of those 8mm x 1.25
bolts holding the pressure plate! @#$%! Odd thing is those bolts are only
torqued to 18 ft-lbs, so SNUG will do it. Backed off the rest (you have
to do those bolts in a star pattern, just a little at a time as you
are clamping down the pressure plate when tightening it).Thankfully
I still have some left hand twist drills… started drill the broken off
bolt… and out it spun! Whew, love those drill bits!

Looked at another head… STRETCHED! What the ???? I had checked the
depth of the threads after resurfacing the flywheel… Uh, oh. All I
can figure is the previous person in there had overtightened the bolts
to ALMOST breaking them. Thankfully I had a spare set for that engine
I never installed. 🙂 New bolts, checked they all fit into the holes
WITHOUT the pressure plate in place, to confirm they were bottoming
(holes go all the way through the flywheel, but threads do not).
Drop of loctite #242 (blue) on each… snugged them in a star pattern
all they way around. Always look back at the pressure plate once those
bolts are snug. are all the p.p. fingers even and at the same angle
(just about flat with a new p.p. and disc)?

Time for a quick break. Use a wire brush, and clean all the crud out
of the transmission to engine bolt threads. Makes getting everything
back together much quicker when you can thread the bolts with your
fingers.

Lightly greased the tranny input shaft splines, ditto for sleeve
and pivot points of the T/O brg arm. Tranny looked dry, still
did the ‘brake cleaner’ and a ton of rags to clear out all the old
black dust. ASBESTOS! Don’t blow it out, just clean as suggested.

Usually this would be the time to replace the front tranny gasket
and seal… everything looked good so I skipped that.

With the engine still tilted, and the tranny on the floor jack…
rolled it back up (tranny was in neutral), and had it SLIDE up
into place… a little jiggle, and it was home! YA HO! [Trick
is to REMOVE the exhaust, tilt the engine, and have a good
industrial floor jack]. Still need to get a 3′ extension for
the 3/8″ drive… as I could put in those two top bolts from
below!

After getting the four engine-tranny bolts in, and the slave
cylinder bolted back up & adjusted…. stepped on the clutch
pedal to confirm it felt “good”. 🙂

Hope this of assistance to who ever does the next clutch job…

I am getting older… my record for doing a clutch was
2 hours (forget the pilot bearing, cleaning out the tranny
bell housing, etc.) running for parts. Just do it!

I think this time it was around 5 hours, excluding the parts
runs. At least I have a garage floor to lay on. I did one job on
gravel… even with card board down it was not fun.

Just need to pickup a couple of U-joints, a rear tranny seal, and
viola I’ll be done. Oh, while I had the starter off… I slipped
out the back cover (two 10mm hex headed bolts, and two screws)
to inspect the amount of brushes still left on them… looked good).
Just like doing those “little inspections” while I have the item
off the car.

Sorry this is so long, but hopefully I have passed a long a few
tricks on how to make a clutch job go easier. Usually I tie a plastic
bag over the tail shaft, holding it in place with rubber bands.
I didn’t this time, as I drained the transmission before removing
it… wish I had, enough gear oil in the back to make a mess when
I pulled off the tranny. 🙁

[Kelvin added:
I usually use the front splined portion of an old driveline as a plug to
avoid having to drain the oil. You can NEVER get enough oil out to avoid
it spilling out the tailhousing. And I’ve had better luck lining up the
splines on the input shaft if the tranny is in gear and I twist the
driveline “plug” to line them up.]

[Rex Jennett commented about using a 30mm (?) socket with duct tape
covered on the whole to keep the fluid from leaking out.]

Cheers,

Tom Walter
Austin, TX.

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