Testarossa fixed & running after Diff Failure.

About 3 years ago the differential of my 1990 Testarossa let go. This was a huge surprise for me because I had no idea that the Testarossa was prone to diff Failure. It's with the help of many people on this forum that have supplied me with the proper ressources that I have been able to get my testarossa up and running again. Oh and let's not forget my patient mechanic who kept the car laying around his garage for the past 3 years who's been waiting after me for parts. Huge thanks to Mr Newman for all his knowledge about the testarossa and users Philwozza, Godabitibi and Richard at Competizione in MD for supplying me with different contacts for parts.

Testarossa work done
Timing belts
Replaced diff
Installed straight cats.

 

More pictures to come !

 

What was the mileage when it went?

Oh and sorry for your luck and glad you're back on the road

 

Thank you! Let go at 36k miles

 

Feel free to ask questions !

 

Ezio, happy to hear your car is back on the road. I remember your story very clearly. But I never realized it is already 3 years ago, time flies.

 

Interesting. Your failure mileage coincides with our study

http://www.ferrarichat.com/forum/boxers-tr-m/523391-testarossa-dreaded-differential-issues-questions-8.html
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So how bad was the carnage? Shrapnel everywhere inside?


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That histogram is delicious. Thank you for that.

 

THAT is now exactly why we need to continue to tell new owners about the broken diffs imo !

 

Yes! Fragments were all over the place. I'll post a picture of the left side diff cover as soon as I get to the office.

 

Wish I saw this chart 3 years ago! Had I know I would've had my diff replaced as a preventative. My diff gave out at exactly 36 250 miles . Luckily my crown and pinion remained intact which saved me quite abit of money!

 

cool. with this data we could find a failure rate and figure out the odds of failure.

 

Curious to know if certain years were more prone to failures. Did this became more of an issue as Tr production ramped up in higher numbers in the later years?

 

Could it be a certain run of VIN numbers? Did ZF miss a stress relieving or normalizing step in a batch? Had an engineer look at a broken diff. In conclusive without testing. But it looks like the weld had enough penetration. I'm no expert, but that is a heavy weld to let go. So maybe the weld was too brittle.

 

If our analysis is accurate, it suggests that the majority of the diffs have barely hit the hazard point. For further explanation of the chart below, refer to the quoted thread above
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Right on James. The Survivability Plot below best represents risk based on current miles driven (extrapolated from your original survey) and amount of known aftermarket diffs supplied with their corresponding failure mileage.

It's hard to accept that the engineers involved in this project were not aware of the diffs shortcomings. A simple fatigue test would have uncovered it very quickly and corrections would have been pulled way ahead of the 1994 512TR upgrade.
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It's hard to accept that the engineers involved in this project were not aware of the diffs shortcomings. A simple fatigue test would have uncovered it very quickly and corrections would have been pulled way ahead of the 1994 512TR upgrade.

I read the same diff. was used all the way back to the Daytona. As the tires got wider the stress was more. I have a magazine test of the TR when it was new, and factory driver in Maranello doing a burn out. On the engineers involved: Maybe not enough miles on the cars sold at that time.

 

^^
I hear ya Dave, no way would burn-out tests qualify for validation testing today

 

Same design with welded end cap but not interchangeable. I supplied one for a 4 cam 275 a number of years ago and it was a welded design. Why a Dino and 308 use a proper solid diff and not the higher powered cars is a mystery.

 

Here are some pictures of my mishap!
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Left side diff cover
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Luckily my pinion remained intact !
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A close up of the left side diff cover
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What the left side cover should look like!
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