# Fan belts



## BryanD1969 (May 7, 2018)

I would like to know what are the best fan belts for a 1969 GTO with air and power steering. I bought some Gates brand and they make noise under mild acceleration. Recommendations ?


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## Nicholas (Jan 16, 2017)

BryanD1969 said:


> I would like to know what are the best fan belts for a 1969 GTO with air and power steering. I bought some Gates brand and they make noise under mild acceleration. Recommendations ?


My '71 GTO, does the same thing. I call it a squeal. I tried everything but the fan belt dressing which I won't use. I asked around different forums and got some advice. I was told to use AC Delco "Professional" replacement belts. They came highly recommended. I found and ordered some from Rock Auto. Just arrived this past week. Not sure when I will be putting them on. Maybe this week. I'll report back if the "music" goes away.


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## BearGFR (Aug 25, 2008)

Belts squeal because of friction on the pulleys, just like a spinning tire on pavement does. Either they're slipping because they aren't tight enough, or the pulleys are badly out of alignment. There is such a thing as getting a belt TOO tight, tight enough so that the upward pressure on the crank causes premature wear on the upper front main bearing. Belt tension is gauged by how far the belt can be deflected 'inward'. It's important to get it correct.

Bear


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## Nicholas (Jan 16, 2017)

BearGFR said:


> Belts squeal because of friction on the pulleys, just like a spinning tire on pavement does. Either they're slipping because they aren't tight enough, or the pulleys are badly out of alignment. There is such a thing as getting a belt TOO tight, tight enough so that the upward pressure on the crank causes premature wear on the upper front main bearing. Belt tension is gauged by how far the belt can be deflected 'inward'. It's important to get it correct.
> 
> Bear


Not meaning to steal this thread, but I'm trying to learn something here. My pulleys are in great alignment. I watch them and the belts as the motor runs. Everything lines up. No wobble. Very straight. As for tightness, I do think they are tight enough. I used a pry bar to get that little extra. The squeal will go away for a while, then return. It's intermittent. Seems after warming up-maybe 10 minutes or so-it goes away. When cold, no noise under 2500 rpm's. Above that yes. Let off the throttle and the squeal goes away. How do you know if a belt is too tight???? How do you measure the tension??? Is there a gauge or tool available for this??? Thanks and again, I don't mean to impose.


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## BearGFR (Aug 25, 2008)

By pulleys out of alignment, I don't mean wobble -- I mean two pulleys whose grooves are not aligned in the same plane. For example one is slightly forward or rearward of the other, or 'tilted' so that its axis isn't parallel. This cause the belt to 'rub' on the side of the groove as it enters/exits the pulley and can cause a squeal. Here's one link that talks about proper tensioning.

https://www.yourmechanic.com/article/how-to-tighten-a-drive-belt-by-spencer-clayton

One spot check is to grab the belt half way between the two pulleys and try to 'twist' it (like trying to roll the inside surface that rides in the bottom of the pulley groove around so that it's on the 'outside' of the belt). If you can twist it more than 90 degrees, it's too loose.

An old 'shade tree' trick to stop belt squeak is to take a bar of hand soap and let the inside edges of the belt rub over it while the engine is running (be careful!)

Bear


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## margozzi (Nov 29, 2013)

MY brother is facing the same issue on his 69 Grand Prix. I have a 68 GTO. We discovered a few things.
My belt is 1/16 of an inch narrower than what they are selling now as a replacement. I believe it was 5/16
whereas his was 3/8. It made the belt ride up a bit higher than the pulley whereas mine was nestled down in the groove fully. Also, it seems that if the belt has ribs on the bottom, you end up with a bit less grip. I don't think we have been able to find the correct belt yet. If anyone else can source a 5/16 belt with no ribs on the bottom, please let me know!


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## BryanD1969 (May 7, 2018)

Thanks for the reply. Let me know how the Delco replacements work out.


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## BryanD1969 (May 7, 2018)

I'm still getting used to how this forum works , lol. My reply was to Nicholas in post # 2. Thanks for all the replies. I have heard that Ames has some correct belts but have not tried them. Any experiences with those from Ames Performance ?


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## Nicholas (Jan 16, 2017)

BryanD1969 said:


> I'm still getting used to how this forum works , lol. My reply was to Nicholas in post # 2. Thanks for all the replies. I have heard that Ames has some correct belts but have not tried them. Any experiences with those from Ames Performance ?


My belts arrived from Rock Auto, but quite honestly, I haven't tried them yet. Been dealing with some transmission issues. Had the car out on a few runs, and all of a sudden realized they weren't squealing anymore. Think I'm going to take a wait and see approach to this. If and when I do make the change, I will advise. Best wishes with yours.


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