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Replacement Transmission and New Clutch

9/20/05 —

The stock clutch was still doing alright for normal driving after 120k miles, but it would slip when beat on. I bought a Spec Stage 2 Kevlar Disc kit to replace it. I had considered an ACT unit but since I live in north Jersey, I get stuck in traffic quite a bit, so pedal effort was a concern. From what I had heard the Spec clutches have easier pedal effort than the ACT clutches, but the ACT ones will hold a bit better. The Spec unit I chose is rated for over 400 ft-lbs, so I doubt i'll have a problem.

So, I'd had the clutch sitting around for a couple months, when one day driving home from work, I lost 5th gear on the highway. I could hold it in 5th, but it would immediately pop out once I let off. I could hear pieces of the transmission grinding around inside the case as I limped it home... Not good. Luckily, I had picked up a replacement FS5W71C the previous summer. A quick phone call home to my brother, and the transmission was on its way up to my new garage. Time to get started.

I began by cleaning up the replacement transmission, and replacing the input and output shaft seals (which I had previously ordered). The seals are easy to take out with a punch or small prybar, but be careful not to damage the seating surfaces.

Needs a little cleaning

Output shaft seal removed

Spec's replacement throwout bearing. It is quite a bit larger than the Nissan bearing.

The input shaft cover

More shavings than I would have liked to see... I guess we'll see how long this trans lasts

The front cover holding the input shaft seal was stuck in place, and it took me about an hour to finally remove with a prybar so that I could replace the input shaft oil seal. I had also previously ordered a new gasket for the front cover.

Finally removed... now some gasket scraping to do

Front cover cleaned up and ready for installation of new shaft oil seal and gasket

Reinstalled the front cover, and that wrapped up the preparation of the replacement trans. It was time to begin removing the damaged transmission from the Z. Removal of the transmission is actually pretty simple, it just takes a while.

  • Put the car up in the air. I used 4 jackstands as high as I could get them with my floor jack.
  • Remove the 4 bolts connecting the driveshaft to the differential and remove the driveshaft.
  • Remove the 2 bolts holding the clutch slave cylinder to the transmission housing and wire the slave out of the way
  • Remove the starter
  • Remove the exhaust downpipe
  • Remove the transmission mount to body bolts
  • Loosen the 9 or so bolts holding the transmission bellhousing to the engine
  • Support the engine with a block of wood under the oil pan, and the transmission with a floor jack or trans jack and remove the bolts
  • Slide the transmission back and out of the engine/clutch and lower it down
  • Done

Flying Z

Transmission removed

Next was to pull the old clutch, pressure plate, and flywheel. They looked well worn, but not too bad for their mileage and age. I did not see any indication that they had been replaced before.

The flywheel

Stock clutch and pressure plate

The flywheel after a visit to the machine shop to have its face ground

The Spec Stage 2 Kevlar disc and pressure plate

From this point on, it is basically installation as reverse of removal. It is important to follow proper torquing procedures for the driveline components, so make sure to consult a Haynes manual or the FSM when reinstalling your parts.

Flywheel reinstalled

Clutch installed. Don't forget to center the disc with the centering tool that comes with the kit.

Bringing the trans back up to level...

And sliding into place. Don't forget to install the shim plates.

Bolts reinstalled

I put the rest of the parts back in, filled the trans up to the level with lube, and hit the road. The kevlar clutch requires a 500 mile break in period, which I followed to the letter. No slipping the clutch, no full throttle, no fast downshifts, basically babying it as much as possible and giving it a chance to mate with the new surfaces on the flywheel and pressure plate. After the 500 miles was up and I was able to really test the clutch, and it is great. It holds and holds, and the pedal effort is as light as stock. I am happy with the decision.

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Service & Upgrades Cosmetic & Random Electronics & Computer Northeast z31s