Is there a quick & easy way to inspect the diff?

Maybe only with an X-ray but I doubt it .... a dentist ...?

Opening my box it has clear evidence that it all has happened once before .......... !!!

But it is nowhere traceble in the "full" history of the car....

I wonder how many F owners honestly want to show/tell other people that their gearbox was broken...

Are we ashamed to admit this failure ... are we bad drivers maybe ?

Thanx to the Internet and Forums, we now can communicate freely about these dissasters...

And maybe the readers see what we tell and show them .... and it may help to prevent large cotsts for their own F !!


Robert: please mail me; I will send you my shoppinglist ...!

 

In your shoes I would feel the same way and would probably make an inspection of the carrier with every 30k service BUT I wouldn't feel 100% about it without performing a "dye-penetrant" inspection or magnaflux of the weld area. Visual isn't always sufficient.

IIRC a well known Independent Ferrari mechanic on the west coast bought two of Newman's carriers from the first batch and installed one in his own personal TR that has less than 2,000 miles on it, not because it was broken but because it was the smart thing to do.

He has repaired a number of broken carriers on customer's cars and can vouch for the frequency of failures and difficulty in finding parts for the collateral damage.

Another mechanic in the east has posted on this site that he has done FOUR carriers in the last 4 years. (T Bakowski?)

That pretty much clinches it for me.

I wish you luck on yours as well.

 

No David, I wasn't able to get the unit around to the right angle. I've heard that if you remove the clutch cover and slide out the long gearbox drive shaft, this will give you a 20mm hole in a far more accessible area to be able to look at the diff, but not up through the sump hole.

 

I recall talking to a shop maybe Norwoods and they stated they do 10 or so TR diffs a year, that was a few years ago maybe not so many now as TRs are not driven as much.

TRs are heavier than Boxers and stickier rubber along with more power using the same diff is why this happens with them, diff failures are rare with Boxers, Ferrari had issues with the 365BB diffs but not so much with 512BBs.

I am not as concerned with my BB diff, it can happen but so can many other parts failing as well

I think some of these failures can be blamed on previous owners or test drivers hammering on these cars back in the day after all its a Ferrari you should use its performance, when I first got my BB I was flooring it everywhere I went, you could spin the rear tires just by doing that in low gears, who wants to baby a performance car.

 

" I think some of these failures can be blamed on previous owners or test drivers hammering on these cars back in the day. "

Absolutely a NO !

If you read all the threds about what seems to be happening now: we simply believe AGE is one of the causes...T

 

Maybe but all it takes is a hard test drive by someone driving poorly if the car was at a dealer or mechanic, many mechanics I have seen will hammer on a car to make sure its performing well.

Age metal fatigue could have some input but I find it hard to believe Ferrari made such a crappy part these cars are all going to self destruct sooner or later.

 

If you look carefully at Mels failed diff, it is not the weld that has failed but the metal in close proximity. From my limited metallurgical knowledge this tells me that there were stresses caused by the welding that remained until failure. My guess is that if Ferrari had properly heat treated the diff after welding there would have been many less failures.

IMO

P

 

Would a clutch being too strong have anything to do with this? I wonder if some of these diff failures had a rebuilt clutch with Kevlar or the stronger quil shaft.. I am reaching hear but I would be curious to see if there are any simaliarities with those that have had the diff or gear box failure. It just sucks when this happens to good people.

R

 

From what I can see Robbie it happens to cars that have been driven carefully driven as well as other cars and most if not all are standard.

P

 

Hi Robby, I think I have an OEM 512TR clutch, made by Valeo ... (will replace the plate now).

Last picture shows what Phil explained ....
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Wow that is disturbing. Looks like the weld held up but the outer portion failed. Would it help to heat existing diff carriers to a cherry red star then submerge in water to shrink and strengthen or would that weeken even more. Would some class action maybe get Ferrari to acknowledge a manufacturer defect and put a recall in effect. It's very dangerous. That diff breAkes loose on the highway it would get ugly fast.

R

 

I think that is how they look when they fail. When I had my bell housing off and looked through the quill shaft hole with a borescope it appeared that some fine cracking had developed around my weld. From my limited welding experience it looks as if the weld was poor in terms of correct heat and had little penetration into the substrate metal. I did not x ray check my old diff to see how close it was to exploding, but I do not think it had long to live. In the end these sorts of failures will continue to happen and with todays internet we will learn of each failure. I have also researched the damaged caused when they let go and it appears that a the much later M diff repositioned the large O ring groove which resulted in a stronger LH side cover plate.

 

I am now very confused as to what actually fails.

From these pictures, its the crown wheel that fails. and is that where the welding we all talk about?

if not, I have seen pictures of the carrier, that looks one piece, and yet it gets cracks developing on it. what is attributed to that failure?

Can anyone piece together what all these failures are? they all seem in different places.
Yes maybe one is attributing the failure of the rest. But which is the weak point, the carrier or the crown wheel?

oh, please dont include the quil shaft. that just confuses things more (well me more

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Quite simple really.

Quill shaft fails. This is the 'sacraficial' component designed to save your diff or gearbox mainshaft. But, instead of twisting and returning to shape, they generally shear themselves.
Original quill shaft is too light at 16mm so ferrari replaces this with 19mm 512M shaft. Unfortunately, these are so strong that the loads get passed to the gearbox mainshaft and cause them to fail instead of the quill shaft.

Diff centre carrier fails due to the weld cracking. We all know about this one. Prone to failure on 512BB, 512BBi, Testarossa, 512 TR up to 1994 when the problem was rectified for the last of the 512TR's and the M.

Differential side covers. We have seen these fail many times now. Generally it's the LHS unit and we have seen very small spider vein cracking happening in the casting. This may be caused by a number of things. Too much bearing preload, harmonic vibration from the main bearing, or smashing to pieces due to bearing failure. Also the quill shaft passes through this component and the fit on one side of the quill shaft is near zero tollerance. Most quill shafts have polished areas where they actually rub on the side cover under various conditions.

Crownwheel and pinion failures. Generally only caused when something else fails and falls into the meshing teeth. That will give you a very bad day!

So how do you fix it?

New diff centre carrier from one of the suppliers here.

A new differential side cover, particulalry the LHS one which fails more often and has the quill shaft hole going through it. In my opinion these would be best if someone made them from machined billet but to date I'm not aware of this being done. Maybe Paul Newman is onto this.

Replace the quill shaft. I had 6 made last year out of a very specific material that allowed much more spring or twist. They were 19mm like the Ferrari 512M version, but had far better twist ability so didn't put the load onto the gearbox main shaft. My 6 have all been spoken for now though, although I could get another batch made as required. Need to have pre-purchase orders for 6 to do this.

Now if you do this before one of the above fail, then you save yourself some serious heartache.

Or run the gauntlett!!!!!!!!

 

Anthony the failure that we all pray not to be associated with is the diff carrier ( housing) letting go.This will cause much damage to the rest of the expensive bits. If you are lucky it will only take out the LH side cover. At worst it is possible to take out the crown and pinion and possibly the gearbox case itself along with other associated gearbox gears etc depending on what is happening at the time. Best to get set up for the worst senario and possibly cheap insurance and who knows in 20 years time we may all say the key to longevity was a decent quill shaft to smooooth those loads!! Attatched is my 'good' original diff with quite visible cracking possibly about to let go..16k car only driven to the shops and back..
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Thank you for that.

would you have a photo that is taken a bit further away? just to see the whole thing and get a perspective of where the crack is with respect to the original weld.
that would be appreciated.

 

Like this ...?
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Yes. thank you
But again, that's just the crown wheel letting go. was there a diff housing part (ie the diff carrier, not the diff side cover) to this letting go before this (or developing cracks as well), or did this happened on it's own, ie?


Maybe I am confused as to what part is called what.
sorry for all the questions, but being an engineer, something is still not making sense.
it looks like the crown wheel section is welded, as well as the Diff carrier being a welded peice?

 

The crown wheel sits over the end of the diff centre and is held by bolts from the rear. The picture from Mel above shows his smashed crownwheel, but also shows the end of the diff centre which has clearly cracked open.

 

Maybe this shot puts it all together. This is the complete diff in the case just before the side covers go on to centre and hold everything.
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Ha, now I get it

very cool. many thanks for your patience.

 

so by taking the back cover off (as per picture), we can inspect the the carrier easily?

 

Although it is a fair bit of work it probably gives the best view of the nasties. To take the side cover off you still need to remove the quill (propeller) shaft as it goes through the LH side cover. Remove the rear valance /exhaust / bell housing and crossmember/rear cover in about 3-4hrs safely.

 

I've located a company in Australia who makes a 3.21 ratio crown wheel and pinion set for the Testarossa and 512TR. They are approx $3900 AUD.

They are the only company here that have the machine to create the Hypoid angle on the pinion gear. Not a bad price comparatively though.

 

Since nobody has ask how much does your uprated quill shaft cost?

"Replace the quill shaft. I had 6 made last year out of a very specific material that allowed much more spring or twist. They were 19mm like the Ferrari 512M version, but had far better twist ability so didn't put the load onto the gearbox main shaft. My 6 have all been spoken for now though, although I could get another batch made as required. Need to have pre-purchase orders for 6 to do this."

Jim