348 Clutch removal - Update

John, had similar issues with my 348 spider. The clutch was replaced approximately 3k miles ago but the SOB mechanic failed to replace the shaft seals. Since the seals were leaking prior to clutch replacement, an inexcusable omission.
Shaft seals. If I recall correctly from my recent gearbox rebuild, the shaft is removed and installed from the engine crank end. If I am correct the gearbox must be removed to service the seals. Bad news. Although gearbox only removal on a 348 is not a bad job.
Shaft seals. Personally I was concerned, reading how difficult the job was. Perhaps I was just fortunate but I found the job easy. Patience, simply work each seal up the shaft into the 3 grooves. Lube and install back in the gearbox. Mine do not leak a drop.
Clutch. My workshop manual shows a starting disc thickness of 7.7mm with a wear limit of 1.5mm. If yours is 5mm, and these figures are accurate, you should replace the disc at a minimum.
My clutch being relatively new, I was able to carefully clean all the parts in solvent, dry and reinstall with no ill effects. Clutch is now operates flawlessly.
Please remember everything I tell you rely on my woefully poor memory. My opinions are worth exactly what you paid for them.
Good luck, John.

 

The t/o bearing seals can be a pain, but heres how: soak the seals in very warm water to make them pliable. DO NOT gouge or nick them under any circumstance. Remember which way the stepped seals go, do these one at a time, with the o rings in first. (if you are even replacing them) When reinstalling, make sure the t/o bearing slides freely and the shafron which it rides is dust free. When you go to bleed it, the bearing can stick, and the pedal will never 'pump up'

 

Hi John. You do not need to remove the flywheel from the bell housing unless you are rebuilding/repacking it (which I wouldn't mess with unless you're having hot start problems or the flywheel rattles on shutdown). But to answer your question, Use an impact wrench to remove the large nut - it just spins off on the bench. I let my mechanic remove it rather than buy the special socket from Baum Tools - it's pricey. Good luck.

Shan

 

you can buy a whole assembly for big ferrari dollars or you can send the whole unit to a rebuilder. He cna replace the springs too. If you want to save yourself some bucks just take him the clutch discs and give him the compressed specs per the WSM and have him reline them. The cost is about 20 bucks per plate plus a few bucks for springs. He can replace springs on a pressure plate too. You are not clears as to where the springs are broken. Look up on the web for Friction material company. There are many around the contry. Also, try Fort Wayne clutch in Indiana.

 

When I did my clutch and FW I had the clutch resurfaced in SOcal. It's a AP racing clutch and a shop should be able to do it. I had a broken spring and we robbed one from a parts car, drilled the rivets and put it in.

If your seals have been leaking I would inspect and repack the FW while you're at it. It's an easy job and you'll have the time while the clutch is being resurfaced.

As far as I know you don't need to remove the gearbox to slide out the output shaft and replace the seals.

good luck, check the old archives as well there are some good pics of the fw and other parts.

 

Hi,
with the small hex nut you have to adjust the clearance for the flywheel bearing after mounting the large nut: screw the small hex until it stops and then a little bit (around 10 minutes) back , finish.
Good luck & best regards, Georg

 

good news you can almost tighten it all back up and be ok. the bad news is almost. the poster above me is not quite correct. the large nut controls the FW into the bellhouse. the small nut controls the position of the FW pressure plate fingers to the t/o bearing. the good news is you can push the small nut in so far that you can actuall ride your clutch but not damage it. the bad news is this is bad and you need to set the small screw so that the PP just about touchs or touches the t/o bearing surface but does not activate the fingers of the PP or you get poor clutch action and slipping. you can actually adjust a mostly worn clutch for more life by screwing the small screw in and moving the FW assembly closer to the t/o bearing. the bad news is you can't be sure how much you have moved the unit in because you can't see it. Also, done right you adjust the small screw then torque the large one. If you want to be lazy you can torque the large one first with the small screw out all the way. Then tighten the small screw and I bet 90% it will work fine.

 

hi john......have you a part no or description of the 4 point socket ?.....i have two, and am in your neck of the woods on wednesday this week.
cheers, d

 

Jkuk,

Yes it rides. it is ok. doesn't your engine bearing run all the time the engine is on? Same thing no problem. you do not want undue pressure on the PP fingers however because that starts to activeate the clutch

 

Just in case anyone gets to this thread and reads the above, with all due respect to Fat Billy Bob, the guru of the welded flywheel, that I am going to also do someday, his posts here about adjusting the clutch with the small screw are not correct. In other threads he and others went all through this and finally decided that while no one really knows for sure what the small screw is for, the best way to look at is as a lock screw. In other words you back it off, tighten the large ring bolt, and then tighten the small screw, nice and tight. There is no adjustment.

 

Out of respect for the excellent work all the brotherhood has put into helping each other and building up this resource, I took one more look at the grub screw - ring nut, depth adjustment question. As my flywheel is in pieces on my bench, now was a fortuitous time to do so. Please hear me out, as I spent quite some time investigating this with the actual pieces in my hand. First, I took the grub screw completely out of the ring nut, and screwed the ring nut all the way into the center boss on the back of the flywheel. The distance from the inner land on the center boss and the inner land on the ring nut measured 28 mm. The rearmost bearing in the housing cover that the center boss seats in has a width of 30.2 mm. Thus by screwing down the ring nut, with the grub screw out, the center boss is securely affixed to the inner race of the rearmost bearing.

Next, I inserted the grub screw into the ring nut and threaded it in enough so that it contacted the button before the ring nut could be fully threaded in. All this does is increase the distance between the two lands to whatever number you want depending of course on the position of the grub screw before you start screwing in the ring nut. But, if the distance between the two lands is greater than 30.2 mm, all that does is to allow the center boss to float back and forth inside the inner race of the rearmost bearing by the difference between that distance and the width of the bearing, 30.2 mm.

Well, "float" that is, right up until one depresses the clutch pedal. At that time the thrust bearing will thrust rearward, pressing against the fingers. The fingers can't move relative to the pressure plate until the "float" is taken up, as they need the clutch/flywheel braced against rearward movement. That won't happen until the center boss's inner land is braced against the forward face of the center race of the rearmost bearing. The inner brace is braced by the fact that it is part of a two row bearing and thus suitable for handling axial thrust.

Follow this chain of thrust: the thrust bearing presses against the fingers, the fingers press against the fulcrum ring of the pressure plate housing, the fulcrum ring presses against the pressure plate housing (via rivets that secure it to the pressure plate housing), the pressure plate housing presses against the flywheel to which it is bolted, the flywheel presses against the front half of the dampener shell, the front half of the dampener shell presses against the six round spacers inside the dampener shell on the bolts bolting the flywheel and the two haves of the dampener shell together, the six round spacers press against the back half of the dampener shell, the back half of the dampener shell presses against the center boss (via the ten rivets securing the center boss to the rear half of the dampener shell). But the center boss can float, so it will move rearward until its inner land is snug against the inner race of the rearmost bearing.

Thus now the clutch assembly is right back where it started before we tried to adjust it: we have the center boss's inner land pressed up against the forward face of the inner race of the rearmost bearing. Only now there is space, the float, between the ring nut and the rear face of the inner race of the rearmost bearing, which means that if you screwed the grub screw in far enough before tightening the ring nut, the rear face of the ring nut might contact the inner face of the aluminum rearmost bearing securing plate, the one with the Cavallino on it. (With the cover plate on the bench it was very clear that securing the rearmost bearing in its well is the main purpose of the little plate.) If the difference between the distance between the two lands and the width of the bearing is greater than the clearance between the ringnut and the plate, the ring nut would contact that inner face before the inner land of the center boss could seat against the inner race of the rearmost bearing. Since the ring nut spins at engine speed that would not be a good thing.

Thus I state that since, at best you would accomplish no "adjustment", and at worst you would damage your little plate, the best procedure is to treat the grub screw as a lock screw, only to be tightened after first tightening the ring nut to it's recommended torque, the center boss firmly secured to the inner race of the rearmost bearing. Or, if you will, leave the grub screw and the button out entirely. Only, please, whatever you do, do not tighten the ring nut without first backing off so that it is not projecting at all, or removing completely, the grub screw.

Please take this in the spirit in which it offered: respect and open-minded inquiry.

Best regards,

Randy Lee

P. S. The recommended torque for the ring nut, per Ferrari of England, is 152 ft. lbs.