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post #1 of 19 (permalink) Old 07-20-2018, 08:44 AM Thread Starter
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AC drive belt "slap"--Help!

Ever since I restored the AC in my 68 Galaxie I've had problems with the drive belt "slapping" (for lack of a better term) when the AC compressor clutch is engaged. I've included links to two videos below, one showing the drive belt when the AC compressor clutch is disengaged, the other with it engaged. Forgive the crazy angle. AC tensioner pulley is in the bottom right of the screen, alternator is in the top center. The pulley you see almost dead center of the video is actually the lower main crankshaft pulley. It's a crazy angle and I probably wouldn't be able to get this twisted view again if I tried!

Video with AC OFF
https://youtu.be/CXROvsvthqg

Video with AC ON
https://youtu.be/hxuN2IzP8Ag

I've set the belt tension as tight as it could possible make it and still get the slap. In fact, I've set it so tight that I burned out the bearing in the tensioner pulley and had to replace it. The belt tension made NO DIFFERENCE what so ever on this "slap" issue. The "slap" occurs in the space between the main pulley on the front of the crankshaft and the tensioner pulley at the top of the engine. There isn't any noticeable issue between the lower idler pulley below the compressor or in the space between the lower idler and compressor pulley. Certainly this much play isn't normal (see the second video to see it at its worst) but I've got no idea how to fix it. And the "slapping" noise you hear in the second video isn't always present. It comes and goes. But the belt is this wiggly all the time. Anyone got any ideas?
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post #2 of 19 (permalink) Old 07-20-2018, 10:24 AM
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Re: AC drive belt "slap"--Help!

must be a 2 cyl compressor. check high side for too much pressure(overfill, condenser plugged etc.)
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post #3 of 19 (permalink) Old 07-20-2018, 11:41 AM
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Re: AC drive belt "slap"--Help!

Quote:
Originally Posted by bowdidge View Post
Ever since I restored the AC in my 68 Galaxie I've had problems with the drive belt "slapping" (for lack of a better term) when the AC compressor clutch is engaged. I've included links to two videos below, one showing the drive belt when the AC compressor clutch is disengaged, the other with it engaged. Forgive the crazy angle. AC tensioner pulley is in the bottom right of the screen, alternator is in the top center. The pulley you see almost dead center of the video is actually the lower main crankshaft pulley. It's a crazy angle and I probably wouldn't be able to get this twisted view again if I tried!

Video with AC OFF
https://youtu.be/CXROvsvthqg

Video with AC ON
https://youtu.be/hxuN2IzP8Ag

I've set the belt tension as tight as it could possible make it and still get the slap. In fact, I've set it so tight that I burned out the bearing in the tensioner pulley and had to replace it. The belt tension made NO DIFFERENCE what so ever on this "slap" issue. The "slap" occurs in the space between the main pulley on the front of the crankshaft and the tensioner pulley at the top of the engine. There isn't any noticeable issue between the lower idler pulley below the compressor or in the space between the lower idler and compressor pulley. Certainly this much play isn't normal (see the second video to see it at its worst) but I've got no idea how to fix it. And the "slapping" noise you hear in the second video isn't always present. It comes and goes. But the belt is this wiggly all the time. Anyone got any ideas?
Hello bowdidge,

Two things here in your video. First you have a 15 series belt driving the air con when it's supposed to be a 17 series (wider) than what's installed. It's not sitting in the pulley's properly.

Secondly and least important, how do the bearings feel in the tensioner and idler pulley's?

As long as the pulley bearings feel ok, then just put the correct width and length belt on it and it should be fine.

Cheers
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post #4 of 19 (permalink) Old 07-21-2018, 11:22 AM Thread Starter
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Re: AC drive belt "slap"--Help!

Hey Desert, thanks for the response. I've got a 17530 belt on it right now (that pulls up on the AutoZone website but not O'Reilly). What belt should I have? I'm not having any luck searching for "17 series" and when I go to O'Reilly the numbers they show me (and are totally different. Can you point me to the right one?
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post #5 of 19 (permalink) Old 07-21-2018, 08:52 PM
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Re: AC drive belt "slap"--Help!

If you have a 17530 then it is a 17 series belt. Right there in the first part of the number, that's the width, 530 is roughly 53.0" long

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post #6 of 19 (permalink) Old 07-22-2018, 07:58 AM
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Re: AC drive belt "slap"--Help!

Hello,

Well, I'd probably recheck the belt you bought from Autozone. It shouldn't be sitting that low in the pulleys. The belt just looks too narrow from the video.

Also parts from Autozone I have found to be of dubious quality from the start. Attached is a picture of what the AC belt should look like sitting in the pulleys. This is a '66 engine but it's close enough to yours. Notice how wide the belt is and how it sits in the air con pulleys. Even with a 17 series wide belt, it will still want to flutter a bit with the compressor on, hence the need for a good idler and tensioner pulley.

The brand of belts I used are Gates, they are more expensive but the quality is rather good.

Hope this helps a bit more.

Cheers
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post #7 of 19 (permalink) Old 07-26-2018, 03:55 PM Thread Starter
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Re: AC drive belt "slap"--Help!

Thanks to everyone for all the assistance so far. It is very much appreciated.

I purchased a new belt (a MasterPro from O'Reilly--I would have had to have waited several days to get a Gates of this size and since the MasterPro was only $7 I went ahead and bought it to give it a try). I've posted some photos of the new belt. It is much wider (see the two pics with the tape measure--1/8" difference in the same size belt!). I noticed, however, that I wasn't able to get the tensioner pulley to the same location as the old belt. This makes me wonder if the old belt had stretched or had been worn down and thus decreasing its width.

I've included three video links. The first is with the AC OFF using the new belt. The second two are with the AC ON using the new belt. I'm still getting the clattering noises I had with the old belt.

New belt, AC OFF
https://youtu.be/NKKmJPWxNTI

New Belt, AC ON clip 1
https://youtu.be/5aYgUDm_t_8

New Belt, AC ON clip 2
https://youtu.be/wHgzxEV5q4I

I'm pulling my hair out of my head one at a time . . . .
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post #8 of 19 (permalink) Old 07-26-2018, 06:15 PM
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Re: AC drive belt "slap"--Help!

This sounds much more like bearing noise to me.

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post #9 of 19 (permalink) Old 07-26-2018, 07:29 PM
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Re: AC drive belt "slap"--Help!

looks like a problem with maybe alignment? belt doesn't run smoothly with compressor off.
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post #10 of 19 (permalink) Old 07-27-2018, 08:31 AM Thread Starter
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Re: AC drive belt "slap"--Help!

Yeah, the alignment issue is kind of what I've been thinking too but the question is how do you adjust it? The "slap" issue isn't occurring (thinking clockwise here) between the compressor pulley and the lower idler pulley, the lower idler pulley and the main crankshaft pulley, but is occurring between the main crankshaft pulley and the tensioner pulley (as seen in the videos), and is not occurring between the tensioner pulley and the compressor pulley (a very short distance). The problem is there is no adjustment that I know of on the main crankshaft pulley (and, if one did adjust it it would through off the adjustment between the main crankshaft pulley and the lower idler pulley). I've thought about inserting washers between the tensioner pulley and the bracket to which the tensioner bolts but my concern there is it would then misalign the short span between the tensioner and compressor pulleys and, since that is such a short span, I would think the belt would be less "forgiving" of a misalignment.
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post #11 of 19 (permalink) Old 07-27-2018, 08:57 AM
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Re: AC drive belt "slap"--Help!

Sight down the belt with the engine not running to check for misalignment. Both pulleys need to be in the same plane and within 1/16" of each other laterally. I had problems with the factory power steering pump on an FE motor and had to use shims on the brackets to get it lined up correctly.

Next I'd take the pulleys off and inspect them for true. Make sure that the groove angle is the same as the belt. Check for dents in the circumference. Check for crud and corrosion in the groove.

Once you get the pulley cleaned and de-rusted, polish a new finish in the groove. Set the pulley in a large vise, use shims to hold it by the center only. Saturate a cotton rope of the appropriate size with coarse polishing compound, wrap it around the grove and pull it back and forth. Turn the pulley in the vice several times to make an even polish.

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post #12 of 19 (permalink) Old 07-27-2018, 02:19 PM
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Re: AC drive belt "slap"--Help!

Quote:
Originally Posted by BrewBoy View Post
This sounds much more like bearing noise to me.
+1.

Now that the right size belt is on there, you are right there is no adjustment for belt alignment. Like I mentioned earlier before, how are the bearings in the idler and tensioner? The reason I ask, all of our '66 and '68 tensioners and idlers are, "stick a fork in them, they're done". The grease was never meant to last 50 years and they are an odd specialty bearing (half English/half metric). Yuppers metric.

And whilst they turn freely the bearings feel awful. There should be no radial or axial play or gritty feeling in the bearings. I couldn't tell if it's the frame rate of the video but it looked like the tensioner was moving around slightly. It could be just slightly out of round and the frame rate causing the intermittent visual jitter.

How is the York compressor? How is the bearing in the clutch assembly? That bearing in the clutch assembly too can be dry and need replacing. If it's original, it probably needs changing. Any worn bearing wobble will cause the belt to move about as well. And of course it goes without saying that belt in particular needs to be rather tight.

Any alignment problems are going to stem from the wrong crankshaft pulley or the wrong clutch on the York compressor (assuming the idler and tensioner are correct for your year). The clutch should at least be the kind with the coil affixed to the York and not integrated into the pulley which also has a brush cartridge. The distance of the "V" from the compressor front mounting bolts is different between the two. So '65 and '66 use the integrated coil into the pulley and has one specific belt spacing and the '67/'68 have the coil mounted on the York/Tecumseh with another belt spacing. It isn't much but can lead to belt misalignment.

The crank pulley outer air con drive sheeve is also spaced slightly different, at least for FE big blocks between the '65/'66 and '67/'68. I noticed you had a little Windsor, so might want to research that or if anyone else knows for sure please chime in.

Hope that helps in areas to look for.

Good luck and please keep us apprised.
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post #13 of 19 (permalink) Old 07-28-2018, 08:04 AM Thread Starter
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Re: AC drive belt "slap"--Help!

Again, thanks to everyone for the responses thus far.

The bearings are all less than one year old. I reinstalled the AC system last summer and had new bearings pressed in the AC clutch pulley, idler pulley, and tensioner pulley. They all now turn smoothly and silently with no wobble. Around two weeks ago I replaced the bearing in the tensioner pulley so it is less than two weeks old. I replaced it because in an attempt to make the belt tighter (hoping then to avoid the "flop") I overtightened and burned out the bearing. Lesson learned.

The integrated clutch design lasted into the 68 model year and spanned two idler/tensioner pulley designs. Anything built before March 1 1968 used the older pulley setup (the lower idler pulley made two points of contact with the engine block, the tensioner pulley looked like the attached photo). After March 1 1968 the tensioner and idler pulley design changed (the lower idler made three points of contact with the engine block, the tensioner bracket connected at two points on TOP of the compressor and one one the side as well as the engine block). The integrated compressor pulley spanned both idler/tensioner designs only later to be replaced with the magnet separate from the pulley. My Galaxie came off the line "06C" which I assume is March 6 1968.

When I purchased the car a little over three years ago it came with a trunk (and back seat) full of parts. Included in this collection were the elements for the factory AC system attached to the engine block (idler pulley and bracket, two tensioner pulley brackets--one old, one new, compressor with integrated pulley attached, hoses, fittings, etc). They had all been removed at some point (there had at least been a bad engine block repaint at some point) so I assume they were removed at that time but, of course, have no way of knowing. The mounting bracket for the AC compressor was still on the engine (the power steering pump hangs partially from it). But it is interesting to note that there were two tensioner pulley brackets (one old design but missing the tensioner pulley and one new design) but only one idler pulley bracket of the new design. It took me a while to figure out that I had two different tensioner pulleys. As I said the old design tensioner pulley was missing the pulley--I just had the bracket. I was also missing the actual pulley from the idler (the newer design with three legs). So I had parts of things but nothing complete. I found a donor car at a small salvage yard nearby. The yard owner was very helpful. He had two 68 Galaxies (in various condition of partial dismantlement). One of them had a 302 auto factory AC and had a date code for 1968--I don't remember the month. It had all the original AC system intact. He gave me a cost for all the mounting pieces which was extremely reasonable so I got from him the tensioner pulley and bracket and idler pulley and bracket and used them on my Galaxie. Put new bearings in them, got a new compressor, took it to a shop in town to evacuate the system and charge it and, presto, ice cold AC. Except that the belt wobbled.

The first part I replaced in an attempt to fix the problem was the AC compressor pulley. I went back to the same salvage yard from which I got the brackets/pulleys and took the compressor and pulley. Again, very, very reasonable price. I took the pulley off the compressor, replaced the bearing, put it on my Galaxie. Problem still there. It was at this point that I reached out to the community here for help and got the helpful advice to replace the belt.

Several assumptions made here any one of which could be the source of my problem. It is my understanding that the date code stamped on the ID tag wasn't always 100% accurate so my Galaxie might have been earlier or later than "06C". And I assume also that it could be that if the factory still had the old AC parts lying around they could have continued to use them past the March 1 1968 date until they depleted their stock of the old design. I guessed that since I had two pieces of the new design that I was probably looking at a vehicle that had the new design (and mind you, I had to first learn that there were two designs in the first place) and the older tensioner bracket was just a fluke. This was somewhat confirmed when I found another 68 Galaxie with similar specs (power steering, auto, factory AC, 302) manufactured around the same time and saw that it had the newer design pulleys. And, most important perhaps, I assume that the trunk full of parts was from my particular Galaxie and not just random parts that a previous owner had collected. A lot to assume.

So then back to the matter at hand. Is it possible that I actually have a vehicle designed only to work with the older design? Were the design changes from the old bracket/pulley system to the new so radically different that it would cause my problem (that I actually should have the old design parts on the vehicle and not the new)? Since the older integrated AC compressor pulley was used in both old and new bracket/pulley setups I assume that they were interchangeable. And if I've got all the parts from one vehicle that should work together does that mean that the crankshaft pulley is the only possible culprit (that is the only part I didn't install myself or change out)?
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post #14 of 19 (permalink) Old 07-28-2018, 08:16 AM
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Re: AC drive belt "slap"--Help!

i think i'd be swappin out the crank pully
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post #15 of 19 (permalink) Old 08-06-2018, 01:09 PM
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Re: AC drive belt "slap"--Help!

Hello Bowdidge,

I was just curious how this was coming out for you. Were you successful in eliminating the belt slap? Still the damnedest thing I've seen and for all you've done to it.

Also wanted to say thank you for the education on the '68 clutches and pulleys. For my own edification I went and studied the '65-'72 Parts Illustration and Part Number manuals. Kind of sorry I did to be honest. I had no idea there were that many clutch combo's offered. I think there were 5 possibilities for the '65-'66 full size. It was interesting in the '68 year with a Windsor, they only showed the clutch with the integrated field (uses brushes for that), but the FE optioned cars could of had the external field clutches. To me that made no sense, I mean who was in charge of that pulley matching nightmare on the assembly line.

All of the '67 and '68's I've seen with factory air all were FE's and those always had the separate field coil clutches.

Anyway would love to know how it turned out for you.

Cheers
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