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Hi all,non frequency method says only adjust when ambient temperature between 15 and 25 degrees C. I am going to use frequency method 100 to 110 Hz at 30 before TDC.Opinions on what frequency I should set when the ambient temperature is 4 to6 degrees C,does the low temperature shrink the belt,not affect it,lessen the distance between the pulleys?Can I ignore the temperature ?Thanks for any help

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I would think if you do get the tension correct as per the spec for 15-25 deg C then let the engine idle for about 30 mins everything should be nice and warm. Then check the temp and tension of the belt.

 

Would that make sense?

 

buddsy

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I’ve never understood this frequency method - and it depends on the belt type also.

if twisting the belt on its longest midway between 45-90 deg is good enough for the prancing pony brigade - it’s good enough for me

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Very true Mr Kearly,   not sure i would chace it on a v8 esprit though :P

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The colder the engine the lower the frequency will be (i.e the belt will appear 'slacker').  I'd therefore set at the mid/lower end of the range and recheck when temp is correct ambient. 

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not sure about that, string instruments go flat at higher temperature, so the belt should expand or go slacker at higher temperature. ???

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IIRC,   Cambelts become tigher when they warm up, that is why they sometimes whine when warm when tensioned to tightly ?

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As the engine warms up it expands and increases the tension on the cam belt. I install the belt to the lower range of the frequency and then run the engine briefly until the coolant gets to about 20 deg C, then check the tension and adjust if required. Then, as Steve said above, I recheck the tension when the ambient temperature is with the specified 15 to 25 deg C range.

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This is why I asked the question. I was thinking if the material of the  belt does not expand the distance around its run would be shorter at lower temperatures than higher temperatures since metal contracts as the temperature drops.Therefore if I am setting at 4 degrees C I should set it at most 100Hz,anyone have a reason for me to set less than this?  Then when it heats up the belt would become tighter and the frequency would increase.   Also am I correct in thinking that the marks on the flywheel to the left of TDC are 10 degrees apart ie 10 before ,20 before,30 before TDC,are there any more?If this is correct,I have tried to set “30 before”at least a dozen times and it will not settle in the exact position,lobe/spring interaction?I have not turned the engine backwards.Any comments please.My first setting was 141 Hz and I have stopped for the day

Edited by [email protected]

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How much twist do you get on the belt when it’s frequency tuned ??

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I have a rough idea...

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double check using the timing marks at the crank pulley, or even better make a diy timing disc.  if you are seeing 140hz under any circumstance, I suspect you are already too tight

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It really wont matter if the temp is at 6°C.

I think you should tension the belt , when new, in the 110hz range. It will loose a bit of tension by using it. A belt that is a bit to tight will tell you anyway by whining when the engine is hot. It wont hurt.

What is really important when using the frequency method is the weight of the belt. f.e. if you use a blue belt this weights more than the OEM belt, so to get the same tension, the frequency should be lower. I think that is why the blue belts tend to whine because people tension them to hard.

In a giugiaro topic about tensioning belts with the frequency method I gave this formulas. Sadly I do not have the weight of a blue racing gates belt, otherwise i could give the min and max frequency for that belt.

 

image.png.0ae3d66add1f734512e722629e66b92a.png

 

 

Edited by gvy

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