Timing Belt Question

I do not have the answer to the belt question. My question is where did the info about 200hz come from? Can you please explain how you measure the 200hz?
Thnaks
CK

 

Frequency or sonic tensiometer.
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If you have a GoPro I'd suggest you shoot a bit of footage at the highest frame-rate you've got and post on-line (effectively in slow-motion). That might assist one of the pro's in helping you.

 

With the engine not running you can move the belt a little bit with one finger. In fact you can twist the belt to about 45 degrees.How would the belt then not move around a little bit when running?

 

I will let one of the F-tech experts here, who have made direct observations of running 360 t-belts, comment as to whether this is a "normal" amount for that particular system.

However, I can tell you that it is typical of most any belt-drive system ---- to have some significant movement / deflection of the belt, in between pulley spans, as you are observing there. As the belt exits off the pulley, there is a certain amount of stiction (between the contact surfaces of the belt and of the pulley) suddenly releasing plus belt relaxation (rapidly transitioning from bend / flex to straight) that causes this ---- sets up an oscillating wave in the belt.

 

Well done on the video, very clear. Seems to me that from 1:17 is where one gets the best view of the issue that's causing you concern?

I'm not qualified to advise, but this is the internet ( ) so for the time being I'll say, relax, it looks good to me! I'm sure someone will be along shortly to give you the low-down.

Did you carry out the work yourself and if so are you a mechanic by trade or a DIY'r?

 

Well done yourself! Planning and patience can get you a long way on these cars. Looks all very nicely buttoned up and tight.

 

Looks normal to me.
The load on the belt is not constant, it varies as the valves are opened and closed. Of you plot the load on the belt it would look like a series of sinusoidal curves, the peak load being when the valves are opened. The fluctuation in load is what causes the belt to "vibrate".

Also , the belts are not under the same load at the same time, this is why Ferrari specify a "cumulative" frequency for the belts. Good practice to check the belt tension at various crankshaft positions, what you are looking for is that each belt reaches similar high & low frequency readings that add up to the specificed total at the various crank positions.

M

 

Yes.

Cool video, though. Mechanics at work.