Yes really. A picture of a clapped out bearing does not mean much. It happens just not often. When we track C5/C6 corvettes the wheels fall off unless we use an aftermarket bearing. Now that is an issue. I can't remember ever hearing about a failure like that on a Ferrari of any model. Yet Fchat is full of T-belt failure stories.
It really isn't a hijack. It is a discussion on a decision making process to decide how to asses a service life. You can blindly follow a manufacturer's service interval or do something else. If you do something else you need to base that decision on many factors from a little science to what it costs, to risks of resultant part failure. In the old days we had these 960 volvo sedans with 60,000miles right on the engine cover as T-belt replacement interval. That's what the well funded engineers at Volvo decided. Yet the bets were breaking 30k destroying motors. It made sense as an owner to pick a new interval. We knew the interval had to be changed before Volvo made it official. It must have killed them to be wrong.
Here's one caused by a fare token: http://www.ferrarichat.com/forum/137646023-post105.html Here's the thread: http://www.ferrarichat.com/forum/technical-q-sponsored-algar-ferrari/194092-timing-belt-failure-after-only-150mi-wtf-10.html . Image Unavailable, Please Login
Ask Rob Lay about these bearings While the failure probably won't be catastrophic as in my photos above, the bearing had serious play which I could feel by hand, hence the reason to open it up. And, much more fear of T belt failure than actual failures but in no way am I denying it happens.
Barry, I remember that one and the one with the rock hole in the belt. It is more common that we think. I always cringed when flying off the track on rocky west of the rockies racetracks we I raced my 348.
Great advice from an john the engineer! For those reading please follow John at your own peril. While john and others can't let go the fact that we disagree on GCK, the horror attributed to gold pins will never destroy your valve train like a thrown T-belt.
Who can forget, FBB?! You'll remember it prompted our friend Gleggy down under to design rear cam belt shields... . Image Unavailable, Please Login
Right. Here's the result of a right bank tensioner bearing/timing belt failure in my 550 at 29,000 miles and 2 years 10 months after factory installation when new. There are 23 more just like it... . Image Unavailable, Please Login
I did recommend that to anyone. Just threw it out as a field example. You know, a data point. You can change your tensioner bearing as often as you change your under ware if you like. As for the GCK, it might not destroy the valve train, but who knows, might destroy the ECU, MAF, injectors,.... Oh the horror!!!!
Where did I say it was an argument? All I've posted is exactly what Roger Collingwood told Me in respect of the timing belts and tensioners when it comes to the 348 and 355, and then posted: That doesn't make it an argument - That just states that if you don't agree with what I was told, it won't change what I was told from people who deal with Ferrari timing belt servicing on a daily basis. You don't believe the tensioners are the cause of belt failures, The Ferrari Centre told Me otherwise. BTW, the primary cause of most bearing failures is actually due to poor storage, poor handling, poor assembly procedures, poor lubrication, poor fitting tolerances, poor component design, poor protection from contamination and poor choice of bearing specification for the job in hand. A failure to ensure all of the the above items are correct will create the initial damage to the bearing, shortening its life expectancy dramatically. The usage is actually a secondary cause of failure as it extenuates the primary damage. If the loading specification of the bearing is beyond the requirement of the job in hand (as it should be), and the bearing has been stored, fitted, lubricated and protected from contamination correctly, and there is no initial damage to the bearing in any way shape or form, then standard usage of the bearing should not cause a failure. The reason uprated bearings are suggested for use on the belt tensioners is because the loading specification of the standard factory bearings can be marginal for their application, whereas the uprated bearings loading specification is well beyond the application that it is used for. Here's some light reading that should shed some light into the causes of bearing failures: http://www.nskamericas.com/cps/rde/dtr/na_en/EN-New_Bearing_Doctor.pdf In My area of expertise I find it quite useful as a reference tool (amongst many others!) - Enjoy! As it seems that yet again My posting has somehow been misconstrued I'll leave it at that and bail out of this thread!
Don't bail out yet Phil you make some good points! In my time working with Ferrari's I learned to tension belts by feel. I still do that today. I could never find a staeger tensiometer to buy and never saw one at an FNA dealer. Some dealers claimed to use it but I have never seen one. I had to pro friends worked at 2 different dealers. There was a spot in the tool room for the steager but there was never anything on that hook. A famous indy in Socal also did not own the staeger. Their head mechanic left to start his own place and I apprenticed with that head mechanic and learned the by feel method. The next in line at that famous Indy shop moved up the chain. He was taken from another so cal indy who used lots of black RTV. That guy also never saw a steager. By the time sonics came around many Ferrari specs where challenged by non-FNA pros because they were seeing belt tension issues. Guys like SRI closely hold their hard fought data of success. Oh and no body I know believes just releasing the spring tension in the tensioner is the way to go. What this means is belt tensions are all over the map! That can be a huge factor in belt and tensioner life and exactly why a Hill bearing can do more if it has a higher operational range.
Belts can go at any time due to foreign bodies... I know folks talk about the time a belt is on a car, but mileage rarely gets factored in...nor where it's stored. My testarossas belts were 10 years old when I just changed them. Garage stored. Car had 4000 miles since its last change. Bearings and belt looked like new. My next change will be 10 years again... I know this is a data point of one. But it's the data point that most effects my car, as it reflects usage, storage, and mileage... If I could change the belts without dropping he motor, I would be happy to reconsider...
Which is why we build the stoutest packages that we can. Whatever can break will eventually break on the track, and lots of things that we figured will never break will do so as well. So you always look for the parts that are designed for extreme use cases, even though you gotta figure they're at risk as well. The main thing is to keep strengthening the weakest link in the chain...
Phill, you did not say it was an argument, I said it so you would not think I (I) was arguing with you
Generally speaking, Dayco (manufacturer of the timing belts) states belts should be changed every 96,000 kilometers or 7 years, whichever comes first.
I see this thread is being revived. So, I'm now 10 years, 5k miles into the belts on my 308 and 7 years, 8k miles into them on my 355. Just FYI.
Not Ferrari based but my Aussie muscle car has a toothed belt driven dry sump system and the belt tension is simply this. You need to be able to twist the belt 90°. No tensioner at all. Belts break that's life. I think the environment they live in has a lot to do with their life as does racing and road driving duties
