Amount of tension for AC/PS belt and crank/alternator belt

[The Platypus]

I'm changing both the AC/PS belt and alternator/crank belt tomorrow (because of occasional squealing after cold start, and it's probably time to change them) and I was wondering how much tension should be put on the belts when I tighten them. I've done a bunch of searching but haven't been able to find a definite answer. Should I just start the car and judge it by ear/eye?

Thanks.

Edit :
With a couple more hours of searching, I found that the "Belt tension for both accessory drive belts, either V-belt or multi-rib design is 10-11mm (.38"-.4") deflection in the middle of the highest run between pulleys with a force of 10Kg (22lbs) against the flat outside of the belt."

[Keep]

To be honest the only time i checked deflection was when I worked for a dealership. I normally just make sure it isnt to tight or to loose. If is slips when you first crank it then tighten it a couple of turns and lock it back down.

[revlimiter]

I pluck the belt to judge tension. You hear a twang or a plink. This sounds stupid, but I started doing it when I had a supercharger and had a program on my laptop that would tell you belt tension from a pluck. I tensioned that damn thing so many times, I didn't really need the program anymore.

You want sort of a plink, at least on the alt/WP belt. The power steering belt can be more of a twang.

[The Platypus]

So you actually want the plink/twang? That means it's perfect? So I should start looser and retension it until I get the noise, correct? Sounds good.

[The Platypus]

Thanks guys, I did it. A lot easier than I expected.

[WASABI]

I'm changing both the AC/PS belt and alternator/crank belt tomorrow (because of occasional squealing after cold start, and it's probably time to change them) ...I found that the "Belt tension for both accessory drive belts, either V-belt or multi-rib design is 10-11mm (.38"-.4") deflection in the middle of the highest run between pulleys with a force of 10Kg (22lbs) against the flat outside of the belt."


Thanks guys, I did it. A lot easier than I expected.

Remember, when you put new belts on your car, they can stretch a little. After a couple weeks of use, recheck, and adjust if necessary. I had my new alternator belt stretch, and never rechecked it all summer (never squealed) but, I didn't find this out one very cold night half way through a 50 mile drive at night. My lights went dim, the alt light came on, and my car stopped running. ALWAYS RECHECK YOUR NEW BELTS!

-Jim

P.S. Also make sure you lock the adjustment bolts as well.

[The Platypus]

Thanks man. I'll be sure to check it this week.

[zenkimrS]

the way I check for deflection is if you can twist the belt and if it flips over 180, then there is not enough tension. I usually aim between 90-120 degrees. I'm no expert but this has worked for me all the time.