Clling on the brotherhood - a 348 Gerbox problem...

Yes... 15% more splines would look like the new style shaft!


(yes, I'll get a better picture eventually...)
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Something tells me these errant gearboxes, aka the threaded nut problem, is ONLY a certain range of SNs. Many NEVER experience this issue.

THere seems to be a factory change in procedure that when pressing that gear on, they used the nut for the last seating, rather than a press machine: wrong.

I'll almost bet, if the failed tranny, persons came fwd, with their build-dates/SNs that we'd trace the issue to just that.

I've had mine inspected and it's perfect. '90 Mondial T NOW [I've trippled the mileage since I've owned it] to 33k.

ok, now having said that: knock on wood

 

Mine blew at 47k miles. s/n 86426

 

Hmm: Mine 1990, 33k miles s/n 86247

 

Thanks for letting us know what came about with the gear whine.

Your mechanic is totally correct in telling you that you are looking at some big quid to change that rear out put shaft. It is totally in the back of the gear box and you must remove EVERYTHING to get it out. There is no other way about it.

However........

Maybe the Stooges are game for another gearbox tear down session? What do ya think fellers? A Stooge trip to Jolly 'Ol England? Though you are gonna have to get ahold of the pinion gear first.

 

Mine came out without dismantling the entire gearbox.... but it cannot be swapped without a dismantle. Mine was simply 'fixed' (until other gremlins got the box)
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Okay wait a minute here. Are we talking about the same "pinion" gear? I'm talking about the one that runs the ring gear on the main shaft.

 

NO they be all messed up with terms. Clutch shaft is what Ricambi has posted. IMO that is easy to fix too. I actually replaced my 348 clutchshaft with the same 348 thick spline shaft. The spline is not the issue but again the staking of the ring nut is because there is force on it because the gear is not straightcut. If this nut is staked properly there is no play to eat the shaft. This splines increase friction and reduce the need for tight ringnut. But why would you leave it loose anyway. To me I would buy whichever shaft is cheaper. I have pictures of my destroyed shaft just like Ricambi's with my stake ring UNSTAKED as it came from the Ferrari factory. Obviously too much vino at lunchtime... When I sent my pictures to Ferrari they could care less. The thin spline shaft adds more friction and removes the needed torque to the ringnut. So they redesigned the part to make up for sloppy install....typical Ferrari. This is why I asked Marco if a stethescope was used because you can hear the difference between a pinion gear AKA Bevel gear (that huge ice cream cone looking thing ) and play in the clutch transfer gears. Marco, DO NOT underestimate that small noise if it is in the transfer gears. Huge force goes through there and that can eat itself and crack a gearbox case then you can't even rebuild it. Once the gear box is together you can prusian blue the Bevel gear to see how it mates. Bad mating could be your noise. Good mating would point to the clutch shaft gears. This is why I am big on diagnosis before repair. You don't do heart surgery then suddenly decide to replace a kidney too. This shaft is easy to remove at this time to inspect the gear integrity and tighten that ringnut as well. These problems are easily solved if people think first and act second and it will cost you alot less too.

 

Thanks for the update Marco, and I'm glad you listened and stopped driving the car.

Just so you don't feel bad, you got off relatively easy. The main ring and pinion (bevel) gear in my transmission when out and it was retarded money to buy a new one and, NO ONE in the United States had that part. I was finally able to get one through Ricambi, and Daniel was a BIG TIME help in sourcing it through his guy, who knows a guy, who knows a guys cousin. If you would have had that gear go bad, and had to pay to fix that one (only sold in a set) you can just multiply your repair price by x3, no joke.

Glad you're getting it fixed.

 

This is really valuable reference material for 348 owners. Thanks Marco! Sorry you had problems, but glad you caught it before things became even worse.

 

Loctite makes a product to help the fitment of worn parts of gear 8 with clutchshaft 9. I am glad you have read my lockring assembly method. So far I have not had one box come back and my box was extensively raced. Please make sure you feeler guage the synchros since your box is partly apart. If gear 8 has any play on shaft 9 it will blow up in a short time and replacing the shaft and the gear would require you chage it's pair on the bevel gear = big bucks!!!

 

Great followup, Marco!

 

the type of gearbox issue that is being shown up is this limited to earlier models of the 348, like tb/ts? or later models like GTC/Spider? My 348 will going in for its 30k service soon and the gearbox will be looked at so should have something to report with regard to internal condition.

 

I'm not sure if it is just a particular year or not? My car is a '90 and had the problem. I think it has more to do with whoever was putting together the gearbox at the factory more than the build date. Not every car has the problem, but it is becoming more and more common, and almost always it's the same problem with the ring nuts not being tightened and/or staked properly.

 

interesting, in the words of that Candian comedy programme from years ago. As I say mine is in for a 30k soonish and there is a very slight gear whine which will go to the gearbox 'expert' for a looksee, apart from that the box is a beaute all the gears slip in easily, including 2nd on a cold day, will post the results when known.

 

Well if yours is whining then FOR SURE get those side covers off and have a look at the ring nuts. May as well check the clutch shaft ring nut while you're at it. The worse thing you can do is drive the car and think the whining will go away.

But first things first.

Check to make sure that you are not low on gear box oil, because low oil will also result in gear whine.

 

Gentlemen:

I just finished reading this post. Although I have an F355, it was highly informative nonetheless. I am just posting to say: (i) congradulatoins Marco on your attention to detail and mechanical knowledge/ability - you really averted a potential tragedy (I'm glad you are still a Ferrari owner/fan!) and (ii) I am absolutely amazed at the level of mechanical sophistication and diagnostic ability of some of you FChat members (Marco, Ernie, FBB, No Doubt, etc...)!!! Considering that you are not full-time/factory-trained Ferrari mechanics, you guys are really amazing!! Thank you for sharing you knowledge with us lesser mortals.

 

Thanks, and.......

That's RIGHT!!! We are Stooges. I'm just an average guy that turns his own wrenches. Nothing special about this stuff, it's still a car. Lefty loosey/righty tighty You just have to get over the fear of the name, that's all.

 

+1!! I bought the shop/parts manuals for my 308s and 328 - and dug right in! You just have to do your research, take your time, do things right, and be proactive (that than reactive) with these cars. Really no different than any other... except mistakes can be very, very costly!

 

Well said - It is because of f-chat and people on this board who do the heavy lifting that make ownership possible for me. I feel fortunate and am looking forward to a time when I can start giving back...

 

Nova Scotia??? How about just telling us where the big salmon are?

 

haha - yes fbb, just about as far east as one can get. To rise an atlantic salmon is second to none - much nastier attitudes than the pacifics. Biggest problem with this neck of the woods is that there is no f-service (of any kind). Ferrari of Quebec is the closest. That being said I just finished installing my new lift.

 

Great thread, thanks for all the info and particularly the pictures!!
Yes having looked into it, my 348ts 1991, 55k miles---- clutch shaft ring nut dimpled but loose, gear rotational movement on the shaft!

What would you recommend as a retaining/fill compound to take up the play?
Cheers
Pete