How do you determine accessory belt tension?

Yes, no spring so you must set the tension manually. You need a sonic tension meter like the one Moto Reva sells or the Gates Carbon Drive app that can be installed on your smart phone. I used both when "strumming" the belt to check tension when I did my belts. The phone app worked as well as the Moto Reva tool. Search this forum for the procedure or check the shop manual.

 

And be careful which manual you get the specs from.

 

Brian,
I assume the specs in the 360 shop manual are correct? Black 360 posted the section on belt changes from the manual.

 

You can use any Frequency spectrum app on your smartphone.
Your just looking for the freq of the fundamental (typically the biggest frequency spike).

 

They are not. Use the CS manual.

 

From CS workshop manual (BTW, those values are higher than the ones in the 360 WSM) :
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Merci Eric!

 

I forget who posted the definitive 360 belt change guide here on FChat,
but the figures in his doc were.....

Timing belt frequency (sum of two branches) 190-220 Hz
Generator-water pump belt frequency 90-100 Hz
A/C belt frequency 131-145 Hz
P/S pump belt frequency 90-100 Hz

 

These types of inconsistencies in WSMs are common. The 575M WSM has one value for cambelt tension, but the real one (sum of two branches) is in the 612 WSM (same engine essentially). They learn as they write those manuals and many are written using preproduction Ferraris with parts that are later changed.

 

Those belt tensions are incorrect. If you use them, they will slip and squeal!

 

Was there a service bulletin put out for this noting the incorrect tensions for the non-CS cars?

And is that correct, the P/S Pump frequency is nearly 3 times what is listed in the non-CS WSM? That's a huge difference.

Is the difference due to the performance between the CS and non-CS cars?

 

The CS Pwr-Steering number seems too crazy - i think it must be a typo. 167-175 perhaps.

The modena numbers gives what i would expect the belt to feel like and are what i used.
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My two and only criteria whenever I do belts on any car is simply:
1) Is tension enough to turn the pulley and not squeak
2) Is tension not too high that it kills the bearings in the component it serves

Simple. IMHO.

 

RedNeck
Yes the frequency is a result of the tensioner.
So if tensioner gap is in spec. and no other issues, you get the frequency.
I left the box as a question mark as I don't have the CS manual and have no idea what it says.

VRS
Agree, I think the ancillary belt tensions should be no higher than what is needed to not have belt slip.
i just followed the Black360's write up and all seems fine.

 

The WSM says to place the frequency detector to the midpoint of the longest belt branch and with a screwdriver strike the belt near the detector. I used a screwdriver, a wrench, and plucked with my finger all with the same results.

For the AC pump belt that would be the side without the tensioner pulley. The small idler pulley needs to be moved back away from the belt.

For the Alternator belt it is between the Alternator and the water pump. The small idler pulley between the crank pulley and water pump needs to be moved back away from the belt.

For the Power steering belt, either side works because both sides are equal length.
On the cam belts the WSM wants you to add the frequencies from the two longest legs (between driven pulley and cam pulley and between driven pulley and tensioner bearing).

I’d like to see the pages in the CS WSM for the power steering belt tension adjustment, and not just the list of frequencies. I wonder if it has you add the frequencies of both sides of the P/S belt and that’s why the frequency is so outrageous compared to the non-CS WSM.

 

So upon purchasing my 360 this past weekend the previous owner noticed a noise from the engine bay and diagnosed it to the AC tensioner pulley and ordered the parts to be sent to my house. I just got them today and am now reading up on possibly doing this myself.

After finding this thread and reading the CS manual I am thinking I can do this on my own. I am knowledgeable enough to just be dangerous with cars on the basic things. You won't find me doing a timing belt change or a cam adjustment. Is swapping this pulley and replacing the belt something I should be able to do with no issues? If I run into an issue, is there any harm buttoning things up (i.e. without installing the belt) and just taking it to my local Maserati dealer to finish for me? I love my car so far and I love the idea of being able to do as much service on mine as possible. Just don't want to get in over my head.