I know there's treads about the issue posted before, but it's no good updated posts on what the problem was. So here we go again. 1991 348ts. Do you guys know the symptoms of a loose mainshaft nut? The reason I ask is that I have a rattle noise when the clutch is engaged. Stops when I push in the clutch pedal. I also have vibration in 4th and 5th gear at low revs. Disappear when revs increase. I thought it was the flywheel Kluber grease, so I changed it, and the tripple seals because they had a leak. I was so shore it would solve the problem, so I didn't take of the bottom cover for the nut and check the nut when the pumpkin was off. I don't have any gearbox noise when I drive. What do you think, guy's?
For you guys searching for a issu like this and find this thread, I can confirm that it was a loose ringnut on the clutch shaft. I changed the gear on clutch shaft due to damage, filled the splines with loctite 660, and welded together gear, ringnut and shaft. All noise and vibration is gone.
Where is this ringnut? Right underneath the input/output shaft that cannot be seen until the pumpkin is removed?
Yes.It is located on this clutchshaft/input shaft. From behind, so you need to pull out the shaft. Sent fra min SM-G935F via Tapatalk
While talking about the ringnut, I think he's using the photos from the previous job; "I changed the gear on clutch shaft due to damage, filled the splines with loctite 660, and welded together gear, ringnut and shaft."
Got it. You have to remove the TO bearing, the flange, pull out the propeller shaft, and then you can see the ring nut on the back side of the gears.
Yeah, to have that ringnut come loose is disturbing indeed. . Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
I am sorry for making it a bit confusing. When I started the tread I thought it was a loose ringnut on the bevel gear shaft. Located behind the small cover on the housing underneath the clutch shaft/(or input shaft is maybe a better name for it). But it turned out to be another ringnut... The one on the backside of the cluch shaft. When this nut is loose the gear on this shaft starts to travel back and forth. And is being destroyed on the outside on the teeth and on the inside on the splines. The splines on the shaft will also be destroyed. But it is possible to use the shaft further if the gear, ringnut and shaft is welded together as one massive part. I hope it's not making it even more confusing now.. Thanks for uploading my fotos the right way guys. I have this awful Taptalk app... Sent fra min SM-G935F via Tapatalk
Thanks ernie, and thank you so much for helping me out with getting my hands on a usable gear. The car and I have never been better. Sent fra min SM-G935F via Tapatalk
I dig out that post coz we experience something like that down there. However, we were told that this particular pb only occured on phase 1 348. We have a 92' 348, that's to say phase 2, and have some noise like that. Thx for your kind help.
Just got an important (?) info from Pozzi : Welding the shaft could lead to its failure. Any experience for 6 years since last post ? Thx.
This is a common repair when the shaft and gear had too much damage and could not be loctite and stake ring torqued and staked. This was a factory defect first found in the challenge cars putting max torque through the gearbox racing. If caught early the solution was to torque everything properly. 348 gearbox prevention became torquing all ring nuts include side case ring nuts. I would be surprised any 348s still not had this done unless really low miles.
It is not idea to weld but it works. I have not seen a failure in these low mile cars. This fix it defacto permanent if done well. I have done it several times and also fixed them right with new shaft and new gear. I doubt any new old stock parts exist. There may be no option unless you custom make shaft and gear.
A quick update. It finally was not a screw onto the shaft in our case. It was the clutch release bearing. Because of a forgotten seal. We had it replaced by one from F355. It's what they use to do down there in these cases.
A new update... The official Ferarri Dealer in Lyon has not tested the 348 accurately. And the noise is still there... They will open the gearbox in early September...
