512TR Differential failure causes crash - diff parts needed!

Paul- I agree with you. Litigation is out of control. I see this as the typical pendulum swinging too far to the left. There was a purpose to it at one time however. If manufacturers could produce faulty parts without quality control and not be responsible for the aftermath, we would live in Russia. The fact that there is some penalty for irresponsibility makes the manufacturing process better. Of course, since the lawyers became in charge of the legislation process, it is out of control. Similar to the unions of the 1930's. They were sorely needed back then as an employee would lose his life due to negligence of the employer without any benefits going to his family. Flash forward to the 2000's with crazy work rules and unreasonable demands.

 

at least 3, it gets expensive fast

 

I'm curious if that's the same one that I bought and posted a pic of that is out of the 308 diff ... they weren't that expensive brand new.

Someone send me one.

Also did you see I posted something about the TR diff failure in the TR section? You familiar with the internals/thrust washer arrangement?

Cheers,

Sean

 

Why wouldn't insurance pay for this????

Your motor starts a fire due to a ruptured fuel line... they pay.

As stone kicks up and takes out a radiator hose and you overheat... they pay.

A tie rod breaks off, and you kill a family of 4... they pay.

A wheel comes off at speed... they pay.

You drive like a moron and hit a tree... they pay.

You are on your cell phone and whack into a bridge... they pay.

The oil plug comes out and you don't realize it... they pay.

You are driving down the road and an accident happens in your testarossa... they total it out and pay.


As my insurance agent once said in a candid conversation... we can't decline coverage for stupidity or bad luck... You have the latter.

Seems like a totally covered event.

 

A few weeks ago the intermediate gear in the gearbox transmission started to make a noise. When dismantled I found out that the steel ring that holts the innerbearing covered some aluminium (residue from fabrication when putting it in) behind it. See pictures. For shure the mecanic hat a bad mondaymorning...
Who is responsable for this ? Those bearing are already changed several time because of metal fatique...but now I understand why. The steel ring and bearing war'nt in the right angle to its gear since the beginning. For me it proves again the poor fabrication procedure inside the Ferrariplant.
Image Unavailable, Please Login
Image Unavailable, Please Login
Image Unavailable, Please Login

 

Thank you very much for all the responses. If I ever need a lawyer to sue someone I know where to come (joke). Okay, let me respond to a few points raised. In truth, the cause of the crash was unknown for a long time. There was one broken rear wheel, flat-tyres on 3 corners, smashed axle, etc. Any of which could have been a possible cause. The broken diff sun-gear was only found during the restoration process a few weeks ago. Then the question arose, did it cause the crash or was it broken during the crash?

Artvonne: When the sun-gear let go, any power going from the engine would be channelled to just 1 rear wheel. In fact the axle shaft was still firmly attached to the diff housing flange and to half of a sun-gear since the flange bolts into it. So the shaft would just be freewheeling around polishing the sun-gear joint at the point of breakage. Anyway, this failure caused the car to turn, at a speed of around 120 kph on a motorway/highway with concrete barriers. The car bounced twice, once hard at the front against the concrete. Note: The sun-gear that broke was on the passenger side while all damage was sustained on the driver's side hence the conclusion the sun-gear was the cause and not a result.

For those who think a breaking diff would cause the car to just cruise, this might be the case if there was no acceleration. But it doesn't take much acceleration to dislodge the rear from a straight line in the wet when you've got a 500hp engine driving just 1 wheel. The crash was heavy not because of animal acceleration but because of the momentum of hitting concrete at 120kph. Interestingly if a sun-gear fails in a burnout then I guess the low speed would minimize any damage. Just my bad luck it let go at motorway speeds. Sigh.

Guido: I did indeed put my damaged car up for sale after the crash and just got some time-wasting responses so I took it off the market and decided to restore it. No hidden motives - remember, I wrote this post just looking to buy some affordable sun-gears.

Saw1998: Interesting point about getting a University metallurgist to take a look. Or I might just contact ZF, send a few photos, etc. and see if they might be willing to supply the parts at a better price. Hiring a lawyer is probably a bad idea as they are usually the only ones to come out as winners in my experience.

16valves: It's a pity you think my story is 'BS'. I wish it was, but I've got the bills to prove it and I'm not a burn-out type of guy. By the way, 16 valves sounds a bit of a low count for a Ferrari. Unless it's an MR2 based kit-car.

 

Hugh,

When you write to this person and ask for the parts (with partnumbers), they will find it for you at a Ferrari dealership in the UK.

[email protected]

Be frank and ask for a discount... for a new gear I needed, the have give me 60 % discount.

Guido

 

Differentials split torque 50/50, the torque is ALWAYS equal. Once your disconnected from one side, there is no power to the other side (( except the breakaway torque in the limited slip clutch pack, which is only about 30 or so ft. lbs. At that point, it wouldnt matter if you had 5000 HP, your only going to get 30 ft. lbs. of max torque to the still connected wheel.

However, accelerating (or deacellerating), fast driving, if it was wet, in a turn, etc., etc., the sudden loss of power and a 30 ft. lb torque shift to the side still connected, the fact the car lost virtually all engine braking, could certainly throw a car out of control with the very best of drivers behind the wheel. The 308 is bad enough if its posterior gets out of line, the TR, with all that extra mass in the back must surely have a mind of its own.

I once saw an Indy car lose a driveaxle on the front straight, it sent it immediately into the wall. So for anyone to say it shouldnt cause loss of control is being a bit simplistic.

 

I think Ferrari made a few thousand 308s with 16 valves. Worked at the time.

 

Artvonne/Paul: Thanks for your explanation, maybe that's what happened in reality. I just know the rear end shifted and then control was lost. I presumed it was due to power going to just one wheel, although as you said it could be more subtle than that. Still, it all happened in a fraction of a second. I'm convinced that the diff letting go at motorway speeds in the wet with (even mild) acceleration was the trigger for the loss of control. In any case I'm picking up the pieces now.

Brian Harper: Oops, you're right - I forgot about the 8-cyl 2-valve jobs out there. In truth I was just reacting to member '16valve' who said "I smell BS, just like always when guys tell fishing stories or accident stories". What does he expect? Photos of the bruises, close-ups of the damage, and photocopies of the parts bills maybe. So I'm sorry, I mean no insult to the 2-valvers out there. I was just irritated by '16vavle' and his unhelpful comment. Looking at his past postings they seem to be along the same lines. The most postive contribution he made seems to be this one: http://www.ferrarichat.com/forum/showthread.php?t=172920 Nuff said.

Guido: Thank you for the e-mail address of a UK supplier. Ferrari doesn't sell those sun-gear diff parts separately, only the entire differential. That's why I was enquiring to see if anyone had those bits lying around or could get them from ZF for a fair price. But hey, I've nothing to lose so I'll definitely write to the contact you gave me. Thanks again for the tip.

 

Didn't you read my post? I bought brand new ones for my 308 that look identical???? ... for cheap and they are ZF parts.

 

I didn't see anybody mention this yet, but wasn't the 512TR supposed to have the improved stronger diff over the original Testarossa?

If so, then this is kind of ominous - maybe it is hardly worth trying to upgrade to the new parts?

 

Sean/Luckydynes: Yes, I did indeed read your earlier post. I just had my doubts about using 308 sun-gears in a 512TR. Even though they are also from ZF, you pointed out they had different part numbers. I'm no expert but I presume their specifications would be different. After all the 512TR setup was apparently an improvement over the earlier Testarossa and the 308 is even an older model again. Even if they did physically fit, I'd still hesitate to use them considering the consequences of one snapping, never mind the work to change these things. Thank you for your understanding of my cautious approach. Of course we'll probably learn they are exactly the same and half the price, but I need to be sure.

James: From what I read earlier, the overall diff design was improved from the Testarossa and is probably still worth considering. Perhaps I was just unlucky in having a part break due to metal fatigue, maybe even a construction fault. I'll try to organize a metallurgist to take a look. I see no reason for others to worry unduly. Look on the bright side. When a sun-gear snaps, at least the axle shaft is held in position and the wheel doesn't come off. Just don't try "steering on the throttle" to correct any deviation. ;-)

 

Give ZF both those part numbers like a parts supplier substituted them and see if they give you a thumbs up or not.

It does look like the radius detail that snapped is a bit different on yours at a glance.


Cheers

 

The part that was breaking on the early TR was the carrier, the case that all these parts are contained inside of. Acceleration pushes the outside gears away from each other, and the case has been known to let go in the area of the weld. While it would be easy to argue the carrier was poorly designed, the fact they lasted almost two decades before failing at higher rates speaks well of its original design. The upgrade is an even stronger, better designed carrier, not welded, and is worth its weight. When the old style carried pushed apart, it also pushed apart the gearbox, often destroying it in the process. This is probably the best reason to do the upgrade before the original fails.

This issue is completely different, as this is the side gear itself that failed, the part that sticks out of the carrier and drives the drive axle. We do not know what forces this car was subjected to during its life, previous crash damage etc.. And to be very honest, its just as possible this car lost control for some undetermined reason, and the stub broke as a result of the crash. We just dont know, and we cant ever know. Scroll through the NTSB website researching various aircraft accidents, and read of the ones where the cause is determined that a part failed in flight, and youll be amazed how many reports list the cause of failure as "unknown", or "failed for reasons undetermined". Everything just isnt always black and white when you standing there picking through the wreckage. Its only when you have multiple failures of the same component that you realise something needs to be looked at more deeply. Some may recall it took a couple years, several lost aircraft, and a great deal of research to determine what was causing the DeHaviland Comet to disintegrate over the North Atlantic.

IMHO, I would fix the car and move on. Its really not an issue as much as it was a fluke.

 

Yes, I knew that the upgrade was the carrier from reading about this in the Testarossa section. My point was that if this gear is going to fail, then what is the use worrying about the other part?

On the other hand, reading through all the comments on this post, everybody seems to think this is a once-in-a-million deal, and not something to add to all the other mechanical fears harbored by us Testarossa owners.

I have to say that I have nothing but admiration for the owner of this car and his efforts to put it back together properly and keep it on the road. I think that many of us would have sold it to the insurance company and not looked back.

 

James, I think you're probably right that my diff sun-gear failure was just bad luck. Hopefully I'll have an opportunity to remove the driver's side sun-gear in the near future (while avoiding to drop the rest of the diff into its oil pan), then have them both tested to see what the metallurgist says. Then we should be a little wiser.

Thank you for your words of encouragement to put the car back on the road. It was borderline, financially speaking. But I'd hate to see the car broken up for parts. Besides, I miss the great sound of the flat-12 and nothing quite gets the recognition on the road of a big red-head as I'm sure you'll agree. I was lucky enough to find some guy who had (oddly) converted his 512TR into a 512M and so had most of the front-end body parts I needed second-hand - hood, lights, bumper, etc. The body shop says getting the tubular steel spaceframe chassis perfectly straight will be complex and time consuming but I shall get the car as good as new, or indeed better than new if my sun-gears were 'Monday morning specials'. I'll post some photos of the rebuild later on in case anyone might be curious. Give it plenty of time though.

Cheerio and thanks to all contributors for your suggestions of what to do next on the diff parts. Now where's that super-glue...

 

Because the side gear breaking isnt going to blow the gearbox apart.

I too am impressed Hugh had the interest to fix the car. Its a lot of work, but you will be well satisfied once its back on the road.

I remember back when I first started poking around the internet digging into Ferrari's. Some fellow spun his 348 at high speed and wiped all four corners. But he had liability insurance only, so it was on his nickle to fix it. I never learned the outcome, but I hope he found another Ferrari or found a way to fix that one.

But, I dont understand why some shops have to start off making the work sound soooo dificult except to extort more money from us. Complex and time consuming to align a tube frame chassis? I dont think Ferrari put that much thought into it in the first place. I assume they have a frame rack to hold the chassis in alignment or pull it into alignment. Line it up and weld.