Ac alt belt coming off

[lasvegas69charg]

At high rpm I keep throwing my Ac alt belt. I noticed the vbelt doesn't sit in the alt groove all the way.  I looked for a thinner vbelt but couldn't find one that long. Anyone else have this problem?

[resq302]

what kind of belt are you running?  If it is a repro Quanta belt, they are known to stretch (even though they claim they have had no reports of it) and will either twist or get thrown off your pulleys.

[lasvegas69charg]

I am running autozone dura last belts. What I notice is the vbelt rides high on the alt pulley. It doesn't fit inside the groove of the pulley.

[resq302]

have you tried running a different belt such as a Gates or a Dayco?

[Just 6T9 CHGR]

The Quanta belts are junk.

The best belts that have the correct V-groove are the now disco'd Mopar V-Belts.

The second best are the Gates XL 

I am running the Gates on the compressor (#7603)& some Mopar belts for the WP and the PS

[ACUDANUT]

Don't they have 2 belts ?  Gates is the best.

[Just 6T9 CHGR]

Don't they have 2 belts ?  Gates is the best.

Yes

[lasvegas69charg]

I am picking up two gates from oriellys tomorrow. I will keep you guys posted. I thought all vbelt a were the same

[A383Wing]

I am running autozone dura last belts. What I notice is the vbelt rides high on the alt pulley. It doesn't fit inside the groove of the pulley.

Maybe you got the wrong alt pulley?

Bryan

[Pete in NH]

Hi,

The last time I replaced the dual belts on my 71, I recall they came as a matched set. Maybe thats the issue. Also, I have the tool to grab the alternator to tension them properly. They make quite a racket and dance around if too loose.

[Just 6T9 CHGR]

I am picking up two gates from oriellys tomorrow. I will keep you guys posted. I thought all vbelt a were the same

You realize there are 2 different AC compressor pulley diameters for our engines correct?   I have the larger 6 1/8" pulley that calls for the 7603 belt... 

[471_Magnum]

Use a straight edge to check your belt alignment. Matched belts are important, but good alignment is even more important. Don't be surprised if you find 1/4" or more of misalignment. Couple of well placed washers can get everything lined up.

[red69superbee]

i had that problem for a while, you could get back and eyeball towards the alternater and down to the crankshaft and see the belts looked crooked,so i loosened up all the brackets and mounting points where the compressor was loose.I could twist the whole thing around where it needed to be and then tightened all the mounts with the belt tight.

[471_Magnum]

Until I figure out the problem on my 69, every time I did a full throttle 1-2 upshift, belts would go flying. Invariably, the alt/ac belts would come off, and then tangle taking out the ps belt. Wouldn't realize what happened until I tried to turn. Then I'd have to pull off and the hike back down the road 1/2 mile to pick up my belts. No fun.

[lasvegas69charg]

my compressor pulley(aftermarket sanden by classic auto air) is 5 1/8" in diameter.  i went to oreillys and pick up 2 of the 7603 and 2 of the 7612(what oreillys computer is calling for).  I will try  the 7603 first.  one of the problems i found was that my belt that is on there now is 11mm wide and the 7603 and 7612 is 10mm wide.  i hope this is going to make the difference.

[Just 6T9 CHGR]

my compressor pulley(aftermarket sanden by classic auto air) is 5 1/8" in diameter.  i went to oreillys and pick up 2 of the 7603 and 2 of the 7612(what oreillys computer is calling for).  I will try  the 7603 first.  one of the problems i found was that my belt that is on there now is 11mm wide and the 7603 and 7612 is 10mm wide.  i hope this is going to make the difference.

Ugh....aftermarket Sanden huh?  I have no idea what belt you should be running then.... the 7603 is 60.5" in length if that helps...the 7612 is 1" longer

[John_Kunkel]

If the belt alignment is correct and it still tosses the belt, I would find an alternator pulley for a 1/2" belt...these were used on some trucks. The 1/2" pulley groove will seat the 3/8" belt deeper.

[lasvegas69charg]

So far so good.  They are staying on. Have taken it over 4000 rpm yet but staying on.

[Just 6T9 CHGR]

So far so good.  They are staying on. Have taken it over 4000 rpm yet but staying on.

Which ones did you go with?

[lasvegas69charg]

The 7612. It seemed to put more belt on the pulley.

[471_Magnum]

Give it the 5500 rpm upshift. If that doesn't throw the belt, you're good.