[tamathumper]

I've searched the forum, other forums, and the workshop manual, and I can't find a particular spec for the power steering and serpentine A/C-alternator belts, other than a very general "5mm of deflection on the longest span with moderate pressure" kind of description. That's so subjective as to be useless.



The Krikit/Gates tensioner I bought has some guidelines for belts based on their type and the number of elements they drive, but I just want to make sure I'm not over-tightening something and doing some damage to very expensive alternator or A/C compressor bits.



Does anyone have a suggestion as to tension on these belts?

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[Darryl]

I'm sure there is a spec in the shop manual somewhere. I've always gone by the general rule of "90 degrees twist" for flat belts but don't know of any shade tree techniques for V belts. I just replaced both of mine and went by feel for both. I used a brand new in the wrapper Porsche belt for the A/C but it squealed like a pig went I turned the A/C on, so I went to my local CarQuest and picked up their house brand (which is made by Gates for CarQuest) and put it on. No more squeal. I guess the new Porsche branded belt sat on my shelf too long and was a little on the dry side. While you're in there, pull apart both tensioners and clean them up....it makes all the difference being able to move these back and forth easily.

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[Lear35A]

The A/C serpentine belt has a spec for the P9201 tool. It is 9.5 plus 1 turn. That is very tight, so if you go by feel it will probably squeal. (No rhyme intended.)

The PS belt is a deflection of approx. 5mm.

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[tamathumper]

Darryl,



I just put on the D1R power steering tensioner a month ago, and I'll be putting on the other one in a few days, so there's no cleaning to do (yet).



Using the Krikit, I set the A/C belt to something like 70 lbs. which is what was recommended, and while it seemed very tight there's no squealing so far.

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[MB968]

Yeah, you are right the smaller ones have to reach further to connect Just too used to looking at drawings and critiquing them. You may want to show the ends of the small ones sticking out further so the guy actually making the harness won't be misled.

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[tamathumper]

I think you meant to post that over in the thread about the alternator-to-starter cable. <img src="/forum/images/smilies/968/smile.png" class="smilie" alt="" />

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[MB968]

Continue to have frustrating issues posting on this site, taking repeated tries even if I can get it to go at all. I've tried unsuccessfully to edit my above post which was meant for the wiring thread. Decided to give up after about 8 tries. I'm using Windows 7 and Internet Explorer. Don't know if anyone else is having issues, and if there is a solution I can envoke.

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[mbardeen]

I have no problems (other than uploading pictures) using Firefox on Linux. I don't advocate changing OS, but Firefox for windows should work similarly.

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[MB968]

[quote name='tamathumper' timestamp='1342465656' post='129449']

I've searched the forum, other forums, and the workshop manual, and I can't find a particular spec for the power steering and serpentine A/C-alternator belts, other than a very general "5mm of deflection on the longest span with moderate pressure" kind of description. That's so subjective as to be useless.



[/quote]



Tama, I think what Porsche is trying to tell us is that the setting isn't that critical. The bearings in all the components on our cars should be able to withstand way more force than the hundreds of pounds of tension even if you're way over the spec. The belt tension is more for belt life, and to insure there is enough "grip" of the belt to drive the expected loads.





For reference , my Mazda engine has a similar spec. albeit a bit more specific. The alternator/A/c belt has a similar span between the crank pully and the A/C compressor of about 10 inches and similar pulley diameters. It is a 5 rib, rather than the 6 rib that is on the 968. The Mazda spec calls for 10Kg/22lbs of force applied mid span and a corresponding deflection of 6mm +/-.5mm for a new belt (corresponds to 160 - 190 lbs of belt tension), 7mm +/- for a used belt (corresponds to 110 - 150 lbs of belt tension), with a limit of deflection of 8 mm (99 lbs mimimum). The belts are to be measured with the engine cold, or after it has been stopped for at least 30 min. Since our belt is a 6 rib, I can see the spec. being 5mm deflection that you mention above, for a similar load of 10Kg/22lbs. I have a small push spring scale that I've used for years to set belts this way, measuring the deflection by laying a straightedge over the pulleys.



You can see from the large range that is "OK" on my Mazda, the belt tension isn't all that critical.

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[tamathumper]

That's good to know - and thank you for posting specific numbers! Much appreciated. Also thank you for the comment about the bearings being sturdy enough to handle any reasonable over-tension situation.



Using the Krikit, the A/C belt has 70 lbs. of tension right now, and it seems to be OK. Driving around lately with the A/C running, I can hear a very slight whine when the compressor is engaged, and I was wondering if I either had the belt too loose, or if the bearings were complaining that it was too tight!



But, according to your figures, at 70 pounds it would seem that it is maybe too loose?



EDIT: Sorry, I meant to comment as well that I have been able to post without problems for some time now - probably the last month at least has been good. Using Chrome on Windows 7.

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