Ouch, missed that point. It isn't just DAYCO, it's in every Ferrari WSM, very clear '... not even once'...
I have been wondering for sometime; would be possible to borescope the belt for condition? I understand the "just spend the money" "pay the money you cheap bastard" argument, but many things we used to do on jet engines was an inspection, not just blind replacement. Now, I don't know if there is even physical access to do such a task, but I thought I would ask the question. Gene
What are you going to inspect for? I have removed more belts than I can count that I could rip teeth off of with my abused fingernails that were working just fine the day I removed them and most of the failed belts with no failure other than the belt that looked to be in perfect condition in every way other than the missing teeth. Ferrari has never been able to definitively explain what to inspect for other than tension when forced to take into consideration real life failure modes experienced in the field. Those are the reasons a blanket recommendation of life span has been made. That life has been adjusted downward over the years since the belt drive motors have been in service and a greater data base has been developed. That life is now at 3 years for all Ferrari belt drive motors.
It seems like the most common failure mode for 348 and Testarossa's as well as many 308s is shearing of the belt teeth. Given the increased stress on the belts of the 348 (I understand that they have one belt driving all cams) and TRs (driving cams over 6 cylinders each instead of 4) this seems logical. Valve train loads are directly affected by cam ramp profile, spring forces and number of valves. I wonder if more 308 QVs have failed belts than 2Vs? It is possible that as the rubber ages and is exposed to heat that it hardens, becoming less resilient. This condition would lessen the load sharing between teeth engaged with the toothed pulleys eventually causing one tooth to carry more load than other teeth due to manufacturing tollerences. When that tooth fails the next tooth having the tightest clearance begins carrying the increased load and it too fails causing an unzipping effect. In practice this happen almost instantly. It may be that oil leaks not only chemically harden the rubber but that the heat from the oil and reduced air cooling of the coated belt hasten the hardening. The only test that I know of that might be of value in determining quality of belts on the shelf or in service is a durameter test. This measures the resilience of the rubber using a spring loaded ball tipped needle. It is a common test used on gaskets and o-rings. I know some experts in this field at AECL and will ask their opinion.
i'll chime in for a moment here. in my research i found that the construction of the belt not the materials is the problem. the tooth design has an inherant flaw, there are severe stress risers at the bottom of the tooth due to its cross sectional design. in 1978 the belt manufactures moved over to a curvelinear tooth design to solve this problem. the age of the belt can also be an issue. the belt used on ferraris is also crossed referenced to other makes, fiat etc... but you do have to wonder how often do these belts get replaced and how often are they manufactured? no answer could be supplied for those questions. as a matter of fact it took alot of finageling and sneaky tactics just to get the information i was looking for. belt companies don't like it when we start asking sensitive questions. in the end i chose a common and superior belt to the old trapazodial one. also belt construction is different between interference and non-interference motors. so while the belt leangth and tooth profile might be the same between belts from competing companies i.e. gates/dayco you have to make sure it's spec'd for the ferrari motor or an interfence motor. otherwise the belt will not be up to the task. seems odd, i know and asking more questions became tiresome as i was consedred to be prying. but suffice it to say the non interference engines are easier on belts and if they shread it's no loss to the engine, not so on our beauties! so hence the difference in construction. i tried to keep it short and simple, trust me i could go on and on. but one simply has to do a search and you'll have days of reading ahead of you. scott
This subject has been discussed so many times, and I keep attempting to contribute something worthwhile, but I dont think it will ever stop. To those who own one of these cars, obviously you can do whatever the heck you want. I really could care less what you do. But its those poor fellows coming in here looking for advice and direction before they plunk down hard earned money to own a dream that I am only looking out for. I would have hoped more of you would do the same, but it sure seems there are more than a few out there who want to own one of these cars, but want the maintainence of a Maytag washing machine. I am soon to be 48 years old. I wanted a Ferrari so long ago I couldnt remember. 4 or 5 maybe. Then the 308 was born. Next thing ya knew they were $100K plus and climbing like all the rest, only they were the "cheap" Ferrari. But I did look around for one on occasion to see how many limbs it would cost me. I recall seeing one in Hemmings back in the early 1980's that had thrown a belt and self destructed. Could have bought it for about $30K or something like that. I recall others with blown motors in Hemmings up for sale through the 90's. Around 1997 or so I joined the Flist, and one of the first people I recall was ROLindsey, who has recently come to Fchat. He was the first person I knew personally who lost a motor over a belt. He can probably tell you more of the grief it created than the justice I could do. In 2001 I visited with Margaret, a Flister who then worked at TRutlands. I was shown a pile of engine blocks that were junk. Had to be a pile of about 30 engines, all 308 motors, and most had holes in them or chunked up pistons. I was told most had thrown a belt. I used to chat with a guy who used to work at Norwood, some guy named Jim, IIRC. He told me the same stuff. Belts not only break, they can cause catostrophic failure far beyond simply bending some valves and kissing some pistons. But many of you will either refuse to admit it, or press on regardless as you feel you are somehow saving yourself money. Some have even stated it being cheaper to just run it till it breaks and then fix it. But the point here shouldnt be how far you want to stretch it, but how far do we want to tell our friends to stretch it. I really think Ferrari means well recommending three years. Just my personal opinion. Better safe than sorry might be another way to put it.
