Differential failure at what mileage?

This argument has gone on forever but I think both camps are correct. Let me explain.

Diffs fail absolutely. There's no argument here. It's a fact. The question then becomes, when?

1. From milage surveys, we estimated that the average as of 2 years ago was ~30,000 - 35,000 miles.
2. From after market diff sales, we estimated that the average milage at failure was ~40,000 miles. Current survey, despite only a few data points, agrees.

With these two bits of information alone, it's easy to deduce that the reason why it's not universally accepted that diffs are likely to fail is because most have not reached the critical mileage amount IF mileage is the main variable.

As milage is accumulated, the distribution changes from Positive Skew to Normal to Negative Skew. I'm guessing we'll hit Normal distribution in about 30-40 years with a Mean of 75,000 miles. By this time, the data suggests there would be a 50% chance of survival amongst owners. It's at this point where the conversation will take a definite turn but that's a discussion for another day....or generation

 

Read my thread buddy .... it has NOTHING to do with poor driving .... nothing with abuse !

This diff was designed for the Ferrari 365 family with 300 HP; in the TR and 512TR confronted with up to 425 HP's ...

That is why the welding is breaking ... and it will ... in almost every car ...

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I don’t disagree
But i have yet to see one impacted.


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Better NOT !

Many have exchanged their diffs to prevent a financial damage of over K$25 !!

Are you willing to spend / invest 5.000 or 20.000 yourself ?

It's not only that money ... you suddenly have a "broken" car, that has to be repaired ...

Who can do it for you ? Where do you find all damaged parts ? Do you realize it can take one year in all .....

When you sell the car, I am sure people are happy to buy it from you when you can prove the upgrade for sure ...

 

if someone needs help in my area with such a problem?
I rebuilt already 3 gearboxes ( 1 from a 512BB and 2 from testarossa ) and all are doing fine

and yes mel, better to invest some money than later pay 5 times more and have no car for driving long time

 

Did u have that issue with ur 512tr Mel as well? Didn’t they upgrade the diff?


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Adding to your post, a friend of mine had a differential failure, we have the same mechanic and I asked my mechanic how can I prevent that of happening to me
Here is what he said (verbatim) via text messages
“Previous shop left shaft nut loose. I told him you could feel pinion gear misalignment told not to drive car ten feet. He drove it home thinking it was an incorrect oil issue I told him was absolutely pinion gear misalignment. It broke badly a couple days later. Turned out nut on lay shaft (pinion) was loose as I said it broke gears. I don't think this will happen to you.
Just be smooth with clutch and avoid drive line shock you can drive the car fast all you want.
Shift fast also just do it in a low shock smooth manner.
Clutch shaft gear , transmission drive shaft ( long shaft out of transfer gearbox in main box and diff basket are weak in this car.
They can be used correctly for a long time driven fast fine it just requires the right throttle timing in shifts.
Learn to shift smooth with no jerking feel.
Gearbox will be fine then”

I don’t doubt people had the problem even driving the car smoothly. But I believe you increase your chances of success if you take care of the car

So what is the consensus mileage number then??


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Agreed; been told the same


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I was -owning a nice 512TR myself- absolutely not aware of this failure and it did happen to me ....
The failing diff in my gearbox was not an oem 512TR one ... but a Testa version. So ... now 3rd diff needed

I went to UK to Testarossa friend Phill and we decided to have an upgraded diff to be produeced/machine in the UK.

The first 10 were sold within ... one week !

You may now inquire at ForzaComponents for that new diff which includes all internals and has life-time warranty.

(Wasn't this all described in my thread ? )

 

Sorry didn’t fully read it)my apologies


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Has anyone presented their car for Classiche Certification with one of the non original diffs?

 

Many have ... they don 't look inside ...

 

for what spent so much money only to get a paper what says what you know by yourself? better to spend this money for better diffhousing what nobody sees but you know you will be on the safe side

 

I read, on here I think, that the diff problem was solved on the F512M. Will the F512M diff fit the earlier Testarossa, 512TR and Boxers?

 

Yes, but where will you find one ?

And we have also seen broken 512M diffs ... get an upgraded one !


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I admire your patience Mel , your original posts years ago led me to make the decision on changing my diff. My mechanic at the time was also in the camp that it wasn't a problem and not to worry but I decided to get one of Newmans diff's and installed it with the help of a good friend and a few nice people here on fchat. I can see when the diff fails why it causes such catastrophic damage and for me it was like buying an insurance policy, I don't think my house is gonna burn down but I buy home insurance every year. You and others have clearly shown here the extensive damage that can be caused and why it happens with the design of the OEM 2 pce diff, thanks for your posts they are great.

 

you may put your old oiginal diff into ebay and I´m sure someone will buy it for good money because of not knowing what we all know here

 

I would NEVER do that !!!

 

would never put in ebay or would never buy such a diff?

one of my ex-customers always wanted to have original F parts but I did not want to put in the original diff, wanted to use a modena diff but the customer wanted an original. so he was going to an other garage and since then never heard from him.

so such kind of people would buy a used original diff I think

 

Diff problem was not solved on the F512M then.

 

Thank you Jeff !!

I wish more peolple think that way, not obsessed by money to NOT do this ....

Good for you that you upgraded your diff ... makes you sleep better ... I understand that

 

Well, our big oem Fdealer first refused to install a Forz diff for that reason.

But after seeing the very nice diff he said it was far better than the (old) diff that was offered by the factory and installed the Forza difff.

He also Certifies all types Ferraris ... and is now confident to do the upgrades of new diff !

 

Looks to me, the unscientific poll thus far reinforces what I’ve been saying for almost 10years....that there’s nothing definitive that it’s a universal issue and the “when” theory crowd is spreading unsubstantiated gloom and doom BS.

Just under half the respondents with higher mileage say no issue and I’m a just over 30k with no issue on original parts.

 

I wish your diff a long life
and also when broken a big money account

 

I agree, a lot of scaremongering and some BS in this thread. Yes there are some failures from natural fatigue and also from abuse such as thrashing the car, but saying every single diff will fail is far fetched. Speaking to some long time Ferrari specialist service and maintenance companies in the UK, has confirmed this is a rare event...