Statistical analysis of belts breaking :)

Posted this in another thread, but thought I would get comments from others...thoughts? :


My attempt at a statistical analysis of changing ferrari belts (or not ):

1) IE. Assuming you spend $10,000 on a major every 5 years (12 cylinder), how much does your risk of breaking a belt decrease? I suspect, not much, at least statistically speaking. If I were to guess, I would say that if you DIDN'T do a major for 10 years, your likelihood of breaking a belt is probably 10% or so. If you did 2 majors in that time ($20,000), the likelihood is 1%. So, you spent 20,000$ to increase the probability that the belt won't break, from 90% to 99%. Wonderful. Statistically, this su*ks.

So, if 100 ferrari owners spent $20,000 to do majors, only 9 (99-90=9) would reap a benefit, though it is to THEM a great cost savings. So, 91 spent the money STATISTICALLY SPEAKING unnecessarily. IE. $1,820,000 was spent to save 9 people from a broken belt. Thats about $202,000 per broken belt.

Thats a HORRIBLE return on investment. The truth is, the pretest probability of a belt breaking is really really low. Sure, someone will get screwed, and it happens all of the time. But if you look at the large scale, it makes no sense.

The break even point, statistically speaking, is when the cost of the engine rebuild equals the cost of the belt change as averaged over the entire community. So, lets assume an engine rebuild is 40,000$ (think testarossa). The stats suggest the current distributed cost is $202,000 per broken belt. So, to break even, the cost is 1/5. IE. If a major cost 1/5 of what it does, then it would be a no brainer to do it...thats $2000 for a major .

The only way to do it for $2000 is to do it yourself .

Now, I am NOT saying folks shouldn't change their belts, get majors, etc. Just pointing out that the ludicrous cost doesn't not make it a straightforward decision. Fortunately, I plan to do my own. If I had to pay $10,000 every 5 years to service the testarossa, I wouldn't have bought it...

For the sake of argument, assume the major wasn't done for oil leaks/etc/etc...but was truly for preventative maintenance.

Thoughts?!

 

Neither does insurance -- I'd be rich now if I hadn't overpaid so long for something that never happens

 

the world doesnt spin like that, sorry.

Look at insurance. Work out how much money you have spent on cars, house, life, medical etc..... Add it up and then work out how much have you claimed back over the years. Scary.

 

Steve, but the numbers are very different.

Auto insurance, testarossa, full coverage 4mm liability...600$.

Total your car, they pay $60,000. Kill a bus load of kids, they pay $4MM.



Belts/major, $10,000, Blow you motor, $40,000. Bad return.


Would you buy car insurance if the cost of coverage were 1/4 the payout? Not too many would shell out $15,000 per year for comprehensive, and 1MM per year for liability. Yet thats what you are essentially doing with the belt change...


Keep in mind I do not want to be the flag bearer for those who don't change their belts. Its just that it is an interesting evaluation when you look at the numbers... Most folks do the majors to ensure that the car is in great shape/safe/not leaking/etc. But for those who are primarily worried about breaking a belt...waiting may make sense .

I plan to do mine every 5-6 years...and thats coming up soon...

 

Actually, the markup on insurance is not that bad...again, look at the numbers, and the math. Your insurance coverage is astronomical. The benefit to cost ratio is totally different.

Lets say you own a 1950's $500,000 house. Would you spend 20% of its value every 5 years to prevent a total loss? Of course not, that would be ridiculous, wouldn't it? You insurance agent likely charges a measely $1000/year...

 

Bo -

problem is that you are applying logic to an illogical concept.

Ferrari does not equal logic.
most of us have been reared to fear the belt breakage.
It nags at you before you sleep. It pains you to contemplate it while looking at your bank account / investments.
have you EVER even thought about belt breakage on any other car?

Due to my current state of affairs, I am postponing the major on my 308 for a year.... oh, that little nagging voice...

 

Sounds to me like an opportunity to start a timing belt insurance pool for fchatters!! If you agree to change your timing belts once every 10 years and pay $XXX per year for the insurance, the pool will pay for the rebuild (up to a certain amount) if the timing belt breaks.

Yes, there would be a few rules required to be sure that nobody cheated. (Proof of most recent and subsequent timing belt changes somehow--perhaps a receipt from a recognized service center). But it could work!

Birdman

 

I'm just quasi-joking bo -- your $ numbers are truly horrible, but insurance is a close 2nd (and, the more responsible you are, the less you benefit).

Seriously, have you priced private health insurance for yourself/family? -- I recently quasi-retired, and I really couldn't make a $ case that made sense for buying it, and have gone uninsured.

 

Didn't we have someone do this and keep the money? Ben-something? Changed his (last) name? Any updates?

 

Bo,
I need to find out who is quoting you these rates I'm getting screwed. I have 8 cars insured and I believe my rate on the TR is around $1200 a year. Not sure what the actual pay out would be, but I haven't had an accident since I was in high school (knock on wood). So assuming I don't use the insurance I would be out a minimum of 6k for a 5 year period. As I noted in another thread the major was done on my TR for $8900 and this had at least $1000 worth of non major related issues. Not too much of a
difference.

 

My car has a chain, so don't take me too seriously.

If I had a belted Ferrari, I'd do the major with all the bells and whistles, then drive the car enough to keep things right, and change the belts in 7 years or 40k miles. That's my opinion based on a lifetime of reading belt threads. YMMV.

Ken

 

Bought my car in '86; belts had been done in '85. Did track events till '89; then drove it on the street for another 9 years before doing the belts again. Did track events in '99 and haven't done them since. I don't believe they will get done till at least 2010.

 

I would bet that if true/accurate statistics of all cam belt Ferrari's existed, one would find that cars that have an engine out service every three to five years break more often after faulty labor/mistakes, ect.. are factored in. Human mistakes made during a service are much more likely to result in failure than defective parts.

 

Conjecture.
John

 

Can someone Please close this thread? Or move to Off topic oblivion? No offense to the author but the last thing we need is more noise about belts. Just change the damn things in the interval Ferrari recommends and get on with life.

 

Your logic makes perfect sense if I was an insurance company deciding whether to offer extended warranties. Indeed, this is how insurance works.

The problem is that, if your belts break, you become a sample size of one. So on my 1998 Maranello, I can either (1) spend $5K to get the belts done every five years or (2) run the risk of a $35K engine rebuild. For a car that is only worth $85K, a potential $35K repair bill would result in parking the car for a l-o-n-g time. But for $5k, I can keep on keeping on

Dale

 

Anyone who would treat a thoroughbred machine like this doesnt deserve one.

 

People with more money than brains im afraid. These threads keep popping up ever few weeks, nothing will ever stop it except a very low number of 308's. Which between burning to the ground and being cut up for parts at an ever increasing rate, wont be very long.

 

A major is MUCH more than a belt change. To only change belts and bearings and call it a major is to do yourself and your car a great disservice.

If you only want to change the belts, most cars can have this done with the engine in. Many shops in the UK do this on a regular basis. The price is around the $2000 mark. This might change the calculations considerably....

YMMV (literally!)

 

But, your hypothesis above is just that, an opinion based on some assumptions and guesses. It's not a statistical analysis, so there is really nothing that can be drawn from it.

I don't mean any disrespect, I value your opinion, but it is just that, an opinion. I would love to observe a real statistical analysis, but that would mean a study done on real Ferrari owners over years that tracks belt change intervals, and breakages, across various models. Another important variable would be to track who performed the belt change (owner or dealer or independent). The results of such a study would be very valuable to us, as owners, and would serve as the basis for our informed decision making. Short of this study, it is all just conjecture.

One driving notion of having a shop perform the belt change versus DIY, in my mind, is the implied insurance value of the shops warranty. Subsequent to a belt change, if one week/month/year later, the belt breaks and you have a catastrophic condition caused by that failure, was there an implied value to having had a shop perform the belt change - will the cost of repair be honored by that shop? Obviously, this answer will vary by shop, but if such a warranty can be obtained in writing, than the premium of paying a service center for the belt change is the same and paying your for auto insurance. If not, than if you have the skills, perform the belt change yourself.

Phil

 

+1

 

And to add to the above, I would bet less than 1/20th of the cars that strip a belt are ever heard from. They are taken quietly away and either repaired, or sold for salvage, because its either not worth fixing, or nobody wants the mark on thier records that the didnt maintain thier car. It probably seems really easy to imagine passing up two or three engine services, and then blowing the engine and having it overhauled. But those statitics, and there are statistics, are against it ever working. People have been doing that with aircraft since the beginning, piling on the hours past TBO until the engine is tired. Only now instead of having a rebuildable core, they have a worn crank from running the bearings into the copper, and everything else follows suit. A walk around any airport anywhere will find you these old derelicts. Twenty or 30 years of neglecting the engine makes people begin to neglect everything else. Soon the paint looks like crap, the interior is worn, and before you know it its not worth fixing.

Price it out at a dealership, giving the worst case scenario. One mashed head (either it will drop a valve or crash them when the belt lets go), sixteen new valves plus a valve job with guides, eight new pistons, maybe a connecting rod or two, rebore or replace eight liners, and half the cost of a crankshaft (figuring 50/50 chance it will survive), plus a full engine out service with all new hoses. I cant imagine it would be any less that $20K. And nobody on this forum would ever justify doing it or recommend anyone else do it with a car thats barely worth $25K. No matter what you felt you saved in not servicing it, it will all be forgotten when your faced with the cold hard truth. One look at the tatty interior and paint thats crept in, and its curtains for ol Betsy.

I just cant see treating a Ferrari like that.

 

+2

-Peter (not changing the belt on my car according to the factory recommendations, no sir! <grin>)
www.peterkrause.net

 

I am loathe to jump in on this thread, but the use, or should I say misuse, of statistics is rather bothersome. Adding up the potential costs and saving over a diverse group of people is meaningless, and then labeling that a "return on investment" is absurd. Taking the original assumptions (and I'm not sure there is any statistical basis for those numbers whatsoever), as to each individual owner, the odds of a belt breaking if they were not changed at proper service intervals is still 1 in 10. If we accept the original numbers, doing the service reduces that to 1 in 100, or a 10-fold reduction in the likelihood of a belt breaking.

Preventive maintenance always looks like money wasted, because the eventuality that you are working against, i.e., catastrophic failure, never occurs. But that's the point -- avoiding the catastrophic event. And while it may look like, over a large group of owners, that money is wasted, if you are the one in ten who suffers that failure, it's your money and your bad day when it does happen.

Obviously, everyone ultimately does what they deem to be correct in any given situation, whether that is to do the major service or not. However, if you are the one whose engine goes south as a result of not doing the service, 20-20 hindsight is going to tell you that you should have done it rather than bet on the statistics. But then, I'm not into gambling on things like that.