Hi, I was trying to set the tension on Ferrari 348 belts by the book with a Staeger tool I borrowed from a Porsche Friend. According to the 348 workshop manual the tension on a (new) AC belt should be 130-135 (?). However, the Staeger tension meter does not specify what kind of units is measuring. Then at the same time looking at the climate section of the book, it says that new AC belts should be set at 47.5-50 Kg. My guess is that they are referring to the same belt, using different tools with different units? On the same page, the recommended tension for a new Alternator belts should be between 120-125 (?) using staeger tool. With the Staeger gauge in order to go more than 100 (?) the needle needs to turn more than 360 degrees, and the belt would obviously get too much tension! (I previously checked the calibration of the tension meter with the bar tool) I ended it tensioning the belt by my own feeling. (Around 65 on the staeger tool). Does anyone ever used the tool on the 348 belts using the workshop manual values? Does anyone actually know which kind units the Staeger tool is measuring? Arthur
Arthur, Your Staeger tensiometer measures the resonant frequency of the belt in Hertz (Hz) when made to vibrate. The WSM should have indicated that for the values it lists. The frequency of vibration of the belt varies with its tension. Barry
I have not seen in the WSM the MHz for the 348 or 355. It seems they started with the 360. ASSuming the 355 is similar to the 360 I do have this info from Gates to determine resonate frequency Formula: T = 4 x M x W x S2 x f2 x 10-9 Where: T = Belt span tension (Newtons) M* = Belt mass constant (g/m) W = Belt width (mm) or number of belt strands S = Length of the span to be measured (mm) f = Natural frequency of the belt (Hz) *Units of mass constant M for synchronous belts is g /(m)(mm) or g /10 cm2 along the belt pitch line. Constant M for V-belts represents the weight in grams of a 1 meter length of belting with a correction factor applied to compensate for internal bending resistance.
If i am right this is in Hz not Mhz. 100-130Hz looks normal. Mhz would be very high i think. You are in radio waves area. Humans can hear till +- 18kHz as reference, your dog a lot higher. Grts Patrick
Umm, Have any of you guys ever used the Staeger belt gauge? It is a mechanical gauge that measures the belt tension in it own (Staeger) units. They did not have belt frequency gauges when they made the 348. The 360 is the first Ferrari to use belt frequency to check the belt tension. To set the tension you tighten the belts until the gauge goes past 100 and then add the amount that it reads past 100. So to tension a belt to 125, the gauge would make a complete circle past 100 and end up with the needle on 25. The belt tensions that Ferrari specs of 130 and 125 are on the tight side. I set them closer to 110 and 100. The 65 that you set them to is too loose.
You are correct. The Staeger tool cannot measure frequency. However, I feel that 100 is too much for both the Alternator or the A/C belts. Having the engine out of the car I saw that the top bracket/tensioner of the A/C compressor is deflecting when the tension is over 87. I do not think that the bearing will last if the tension is over 70. The tool I was using was calibrated, so I guess the workshop manual has a typographical error and I am wondering if Ferrari ever wrote a recall regarding this topic. Definitely 130 is too much and it can't be right.
The Ferrari specs are what they are. They are not a typographical error. All other models of Ferrari have similar Staeger belt tensions on the accessory belts. A recall, Ha ha! Ferrari doesn't issue a recall or tech bulletin unless there is a major safety issue with the car. The manuals are loaded with actual errors, and Ferrari does nothing to correct or acknowledge them. When a racer asked Enzo on producing a manual for a early Ferrari race car, he was quoted as saying "We make cars, not books" As I said those specs are on the tight side. You can set the belt tensions to what ever you feel comfortable with, but I set them to 100 and 110 and that works fine.
Have you ever crossed that reading over to a sonic hz one? For the 348 or 355. I have not had anyone confirm this reading
After I checked the belt tensions on cars that used the Staeger gauge, I would measure them with my belt frequency tester and note the frequency in the shop manual for that particular car. This would make it easier to set the tension the next time I serviced that model of car. But I no longer work in the shop where those shop manuals exist, so that information has been lost. I am doing a 348 belt service this week, so I can recheck the belt frequencies after I set the belt tensions.
It'd be awesome if you'd do that, Brian. The archives/collective knowledge base would benefit from the information. Are you currently in the biz?
Yes, I have been working on Ferraris exclusively (with the exception of an odd Alfa 8c or Maserati 300S here or there) for the last 17 years
Well, I was surprise that the 348 timing belt specs on the book were good. After setting it I felt the tension was correct. I did some belts and I know when its too much tension. In my opinion I would not go 100 for the A/C or Alternator (using an Staeger units).
One of my favorite technologies; Predictive Maintenance using sonic and vibration sensors applied to dynamic operating conditions. That way your car tells you that the bearings are going bad or if the belt is working outside of its specification range.
Amen Brother !!!! I am 100% with you. Like to see some of way you do bearing readings one day, I'm a tweaker not a pro. I been doing it that way forever. Just had my gates system calibrated. Sonic tester and EZ align system. Ran some serious HP through drive belts and proper tension alignment is extremely crucial when you get to the lunatic fringe or should I say "fridge" as one of my mentors said as he went for another beer. LOL Excuse the lemons just picked them they are for the veal and mushrooms tonight Break away torque I also track in my stuff but I'm working on that in therapy Image Unavailable, Please Login
The technologies are almost there, they just haven't been integrated into something we want, nor are they scaled down to suitable, micro sizes. For example, this Vibration Sensing Module for the Arduino platform: Vibration Sensing Module, LM393+SW18020P - ElectroDragon or something more robust from SKF. http://www.skf.com/binary/49-267858/CM-P1-11604-14-EN-Vibration-Sensor-Catalog.pdf Anyway, this is interesting: https://www.digikey.com/en/articles/techzone/2012/oct/what-you-need-to-know-about-vibration-sensors I wish I had the time to play with this idea, just for fun. It certainly isn't marketable unless gold-plated.
I respect everybody's opinion, however the topic of my questions was if anyone know how to use the Staeger tool and if the values for the 348 accessory belts on the workshop manual are correct. I know what is a frequency meter and I used the clavis on 360s and I used Diapaz on 430s and up. Staeger is a different tool and its the one that is recommended on the book.
Old thread I know but did anyone ever get the hz cross reference for a 348 belt tension? If they did it's best to keep it in this thread I estimate. Sent using FerrariChat.com mobile app
