Latest victim of the 348 gearbox curse

There are few , less expensive options. The time , which equals money , for fabrication to develop less expensive alternatives is expensive . Therefore with a limited market to cater to , it is a viscious cycle .
I am having a gear & for my trans made now , a much less expensive alternative , but not cheap , from now on , all transmission parts will be fabricated from scratch for me from a private facility , even shafts . I am fortunate enough to live in city that industry is ample & it took an afternoon of pitstops at mills & machinists to hit a homerun . 7-8 days for fabrication of all parts ,monetary compensation can speed the process , heat treating being the longest process .
Research fabricators in your areas for all parts , it pays off .

 

Dude .....I assure you there is never a moment of boredom when driving the 348 , I spent many yrs doing burnouts , using nitrous , installing turbos on cars Ive owned , taking them to tracks ,racing them at tracks , blowing them up , fixing them again , blowing them up ,fixing them again , driving other peoples cars , blowing them up, fixing them , towed here , trailered there , so , if thats excitement , Ive had enough to stave off boredom for many life times . A good top speed run is enough for now , turbos would help .

 

Ernie and I disagree on the cause. He thinks it is a bearing problem in the GBs. I say it is a torque problem on the ringnuts. I think the answer is more torque on the ringnuts and 271 locktite on properly prepared surfaces followed by staking the nuts. I've raced my gb for over 5 years not blowups and I ran my car as a street car before that. I've watched mechanics use locktite improperly often wiping threads with an oily rag calling it clean then torquing nuts with a non-beam torque wrench which sets you up for massive improper torue like 30% on a typical sear taiwan wrench then poor locktite use and the job only "looks" like it was done right.

 

Hey chubba, I haven't totally ruled out poorly torqued ring nuts, but I still say that the bearings are still to blame. Actually the bearing cage. Well, since both you and I have the 271 and the ring nuts torqued down good we'll find out. But if mine grenades again I'm slapping in a 6 speed.

 

is there enough room to double nut plus locktite. I believe I remember you on another thread discussing the nut issue and also over torquing. Since you race guess this was a practical approach.

somehow that thread ended with philosphical discussion between the doers, the mechs, and the engineers? something about a dead horse too....

 

This site says that it's just $5,000 for an entire new 348 transmission/differential unit, complete: http://www.eurospares.co.uk/partsListing.asp?M=1&Mo=693&A=1&B=41179&S=&ID4=1687304

 

I have a feeling that the part number you are referencing (153693), which they show with a price of 2,446 Pounds ($4900+), is actually the transmission HOUSING only, not a complete transmission with all of the parts inside it.

If you punch up the transmission mainshaft (150901), it is shown as costing more than that all by itself!

 

Yes, you are right.

I have a newly rebuilt 355 6spd gearbox/differential complete(less flywheel,clutch/presure plate, and clutch cover), which has been upgrade to CH specifications(3rd/4th rod control small forks) for sale for $3,950. It is still in the wooden shipping crate.

PM if interested.

 

Odd. The add says complete gear box and differential. Same site lists this used transmission for 355's as being $6,000: http://www.usedferraris.net/catalog/product_info.php?cPath=28_73&products_id=673

No gears in there, either?

 

That price is old, and to get it for that you have to furnish a complete exchange gearbox.

 

no tellin' what the price is now

you'd also have to factor in shipping to and from across the pond

could get alot more expensive

 

Post the part number and I'll see if I can find it.

 

I agree with you. I think we need to not only look at Ferrari recommendations but look at what is technically possible. So if we see giant fastener torqued to spec well below the ultimate torque by the standard engineering tables for said fastener, and the thing is coming loose...I think the obvious fix is to up the torque. It has always worked for me anyway.

If you take the mainshaft with 1.25 pitch thread you find 8 degrees of rotation is about 1 thousandth. Tolerances in the GB are clearly in the range of thousandths and 8 degrees is not much. So in a gross sort of way dispite dimpling the ringnut to stake it it can move because this land and dimple are not very precise. This will blow the tolerances off and change the loads on the gears=grenading box. I think that proper torque and locktite is what is holding the nut sand the dimple is the last resort like the safety wire on a aircraft nut. Anyway I am not a fan of dimpling to stake either. I smash the lockring lip so that the metal actually breaks and ends up to the shape of the land in the shaft. I think there is less to move this way if torque is lost.

 

Here is what I found... What say you experts? I think I found the issue 'eh.
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Is that a trick of the flash, or was your gearbox full of muddy water?

Is hard to believe that a properly lubricated bearing would get that kind of wear. Interesting.

 

Your pictures show pits from debris/shrapnel rather than stress cracks...so much for the theory that "burnouts" (i.e. stress) are the cause of gearbox failures.

 

Huh? There are two totally different issues which can cause catastrophic failure, and are not related.

1. Bearings on the pump
2. Thick splined clutch shaft

I'm sorry, but if a person thinks burnouts are 'o.k.' in their 348, that's terrific! I have large inventory of bearings and gears ready for shipment.

 

That is a grossly undermaintained and abused box. Even a Toyota could not take that!

 

Fatbillybob, in your opinion did this bearing fail in situ or did another component fail and the resultant debris cause this bearing's failure?
You use your transmission for racing. Loads are about as extreme as they can get I would surmise. Is the bearing under engineered for the required loads? Have you ever experienced a transmission shaft bearing failure? Just curious.

 

Okay first off where have you guys been??

This site is FULL of people singing the praises about the no-shock gear lube. This lube pictured (as some describe as muddy water) is FRESH 15 minute drive NO-SHOCK lube. In fact it looks exactly like it did right out of the bottle.

Secondly this is not a under maintained or abused gearbox (I think you were joking Billy but...). Its a 26,000 mile excellent shifting / wonderful to use system. It only had a slight whine while in higher gears. I luv ya Billybob, but this box is a honey. No other wear ANYWHERE other than what you see here. None of the bearing baskets were hurt, and the shafts look flawless.

So... Any other thoughts or suggestions?

 

More photos to help this thread along:
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Based on your above information I think that you've identified *the* 348 tranny weak point (especially since Reinerkaiser concurs same point that you make).

No other damage *anywhere* in the tranny...no stress fractures from side-loads or overforce...just pitting in one bearing/race.