Per Gates: Step 2 Place the new belt over the pulleys, but be careful not to force it. Never reinstall a used belt, as tension values are calculated for new belts. Something to think about.
I change my belts every seven years with a few hundred miles on them. I've never done 1K miles a year.
well I would still check and see how much twist is in the belt with the tensioners you have o the car. im not saying that mine weren't close to being beyond useable
Well then in my eyes you are a true Mechanic with technical ability and knowledge of mechanics. Not just a parts changer. Ferrari or not, mechanics are all the same until you get into technical electronic gizmoz
Are you using new tensioner springs and if so did you test them for spring rate and what literature did you refer to for that specific belt and did you just pluck the belt like a guitar string to establish the correct tension?
I get your point and if you were broke down in Namibia or someplace like that I'd say sure, reuse the belt, it's okay but the fact is you are this deep into it and a new belt from Ricambi is less than eighteen bucks so why are you even thinking about this? Why are you expending so much thought and energy on it? Just get a new belt and move on. Don't let it bother you. I'm pretty sure you've already told yourself this.
the question is why? Is the Info based on a 43 yr old WSM or what is the reason? in other words if someone like me had a 85% rebuild and the cam seals are leaking in a few hours we need to throw the belt away?, and besides I don't think this has ever been asked before other than that WSM says so
Ya know I can see a belt sitting for years in one position against the tensioner not being equal in tension, but one that has been driven recently and only 500 miles just seems strange
The tension values are for brand new belts. Once they have been run, those values are no longer valid due to belt stretch. Technically you will over-tension the belt if you reuse it setting at the tension for new belts. If you had measured the tension in the belt with a frequency meter before you removed it, then you could reinstall it at the exact same frequency/tension and it would be as if you had never removed the belt. It is basically a liability thing. You can reuse the belt and it will probably be fine, but if it breaks it will be very expensive. Ferrari never wants that to happen, especially when the car is under warranty or if the repair is being done by a dealership (in which the work would be under warranty), so they always want it to be replaced if it has been used.
That's a good comment from a factory stand point. and I like the frequency idea. im sure that a 500 mile belt would be the same frequency as a new belt or close enough where a phone app wouldn't know the difference.
You're never going to get an answer backed by hard evidence as to why. Why not use them,...because it's a $25 part why take the chance. Well I kind of did. My first belt change on my ex 308 was in early 2k's I installed new belts but not tensioners. I putting everything back together and I developed pretty good "squeal" shortly after. So I picked up some new tensioner bearings and installed them and reused the belts. I was lambasted for reusing/re-tensioning the recently installed belts.... those belts lasted another 7 years without incident and looked as fresh as the day i put them on when I did the job again. My squeal, BTW was a loose alt/h20 belt.
Can’t you just turn the crank backwards for say 10 minutes and reestablish the belts tension from new? Similar to putting your vehicle in reverse and winding back the odometer? Or playing ELO’s “ fire on high” backwards?
years ago there was a listing on ebay for used timing belts. Most likely a joke but a legit ebay listing none the less. I don't recall most of the description details but one part of it went" blah...blah...or you are one cheap bastard for buying these belts"
I have been R&R ing my belts and tensioners every 3 years for 20 years. But in all honesty I have secretly felt that this in some way was more risky than leaving them alone and just driving the car regularly. What I mean is it seems that I'm taking a chance on a bad bearing or a belt with a defect vs belts and bearings that have been field tested and passed for the past X number of years. That sort of thing.
To be honest I think someone just put "never re-use belts" in the WSM as a common sense thing and people have parsed and over-analyzed it and turned it into some sort of gospel. You are just going to have to make this decision on your own because nobody here is going to tell you it's okay. Why would we? and if we did what would we base it on?
Yes that makes sense. All this came up because of leaking cam seals that are new. Now all this stuff needs to come apart If there is anyone in Chicago area that can guide me through this that would be great. Believe it or not. I'm planning on pulling the motor again probably in the fall. I know it doesn't need to come out but I'll feel better being able to see what I'm doing on the front bank. The GT4 has a difficult reach on the front bank.
Timing belts go from tension to slack every revolution. And the tension is variable from cycle to cycle as well. Additionally, belt tension is substantially higher at start up when you are accelerating a system at rest almost impulsively than when the belts are tensioned statically at installation. Springs do wear out from simply being compressed for long periods of time. It is called creep. Even though the stress in the spring may be below the yield stress of the metal, over the long term the metal will deform and the spring will weaken. All that said, would I reuse belts with 450 miles on them? Probably not. On the other hand, unless oil was getting on the belts or there were puddles of oil on the garage floor, I wouldn't bother replacing leaking cam seals before a major was due.
Paper? No. But bearings (as well as belts) too have a 'shelf life,' installed and used (driven), installed and not used or literally just sitting on a shelf. Don't be one of 'those' 308 owners.
Call it semantics. When running tension is much higher on the driven side than on the tensioner bearing side. so you are going from tension to "slack". Here is a picture, the distance between the dotted line and the belt surface indicates the belt tension when the belt is stationary. Note that, in this picture, on the tensioner side, a dynamic tensioner, which can move in and out as required to maintain tension, is shown; and the belt surface and tensioner position when stationary is shown by the inner dotted line. When the belt is rotating, under load, the tension is indicated by the distance from the belt surface to the outer, solid line. Note that the tension is much higher than the static tension on the left (direction of rotation of pulleys is clockwise so the left is the tension side). Due to the dynamic tensioner, the tension on the "slack" side remains constant. However, a 3x8 does not have dynamic tensioners. Thus the position of the tensioner bearing remains fixed and the tension on the "slack" side will drop below the static tension. In either cars, when running the belt tension varies as the belt rotates. The only difference is a matter of degree. Image Unavailable, Please Login
Anent to your cam seal leakage. While "you're in there" make sure the oil drain back holes are not clogged. Years ago I took someone's good advice here at FC and enlarged the drain back oil holes and have not leakage since. I would not reuse the cam belts and let mine go about 7 years before changing. I let the tensioners go longer after close inspection deems nothing amiss. However, my Porsche manual says to re-tension the timing belt after 1800 miles. This is for the 2 valve 951 turbo, a 4 cylinder engine.
