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Over-tightening Alternator Belt (V-belt)

holdmypocket

holdmypocket

nil
Joined
May 24, 2020
Member Number
1298
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522
Loc
OC, CA
I have a 78 F150 with a 400/6.6. I recently finished a Vintage Air install which involves smaller water pump/crank pulley. I previously had a 1-wire alternator (130 amp) which worked great until I finished the AC install. With the new pulleys it began to squeal at start up (if I blip the throttle and let it warm up, it stops).

I decided to install a 95 Taurus 3g Alternator because it has a soft-start regulator which should reduce the load at start up. I also got a nicer pulley from CVF (to match the water pump/crank pulley) which may have even corrected some offset issues. I tightened the shit out of this and the squeal was gone, until a week or so later.. I suspect it needs to be tightened again after the initial install but I'm concerned about damaging the alternator. The behavior is the same, if i blip the throttle after start-up it will stop and won't come back if I let it warm up.

Regarding over-tightening/damaging the alternator, there's a little blip here: https://www.motortrend.com/how-to/1612-ford-alternator-upgrade-for-more-battery-charging-power/
Over-tightening a belt will not affect a modern alternator’s bearings.
Click to expand...
but I can't find anything else on the internet supporting that.

Thoughts?
 
Is the crank drive pulley wore? That’s where the squeak might be comming from. If the center of the v is shiny time for a new one. Is it a solid belt or cogged belt?
 
try some belt dressing, see if it makes a difference.

Over tightening the belt does not affect the alternator but it still affects the water pump, power steering pump and AC compressor bearings.

Second the crank pulley check. Maybe just swap it.

While back I was trying to find someone who reground pulleys. Apparently nobody does that anymore.
 
The crank pulley is a brand new CVF brand billet pulley (so are the water pump and alternator pulleys).

The belt(s) are all Gates clogged belts.

Maybe I just need to run them for awhile because these pulleys are just too damn slippery compared to the original steel pulleys?

Inadequate belt wrap makes sense, I did have to go to a smaller crank and water pump pulley for clearance for the AC install.
 
Is the belt the correct width? My 78 460 uses a narrower alt belt than the H20/PS and A/C. If too wide, it won't sit down in pulley and make as much contact.

It is likely the smaller pulley that is slipping/squeaking.

I had hell with squeaking supercharger serpentine belt on another vehicle. Must use a Conti belt, other brands make a lot of noise. So maybe try a different brand of belt. cheap and easy
 
Yeah, I verified the belt size with CVF tech support, even got the belts they recommended. I’ve been reading about top cog belts and people having good luck with them, worth a try.
 
Let's see some pictures. I'm betting that you simply don't have enough wrap. Alternators have a decent amount of mass and making one go from cranking speed to idle speed takes some pretty decent forces that you're gonna have a hard time applying with 30deg of contact.

ThePanzerFuhrer said:
If the center of the v is shiny time for a new one.
Click to expand...
Or it's just time for a new belt.

If you constantly slip belts you'll bottom them because the sides wear out over time and the belt becomes narrower.
 
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holdmypocket said:
Maybe I just need to run them for awhile because these pulleys are just too damn slippery compared to the original steel pulleys?
Click to expand...
I read people had great success by sandblasting pulleys to rough up belt contact surface for more grip.
holdmypocket said:
Inadequate belt wrap makes sense, I did have to go to a smaller crank and water pump pulley for clearance for the AC install.
Click to expand...
How much smaller? Alternator spin slower from smaller crank pulley as well.
 
arse_sidewards said:
Let's see some pictures. I'm betting that you simply don't have enough wrap. Alternators have a decent amount of mass and making one go from cranking speed to idle speed takes some pretty decent forces that you're gonna have a hard time applying with 30deg of contact.


Or it's just time for a new belt.

If you constantly slip belts you'll bottom them because the sides wear out over time and the belt becomes narrower.
Click to expand...
Are you referring to belt wrap on just the alternator pulley or all pulleys in the path of the alternator belt? The water pump and crank pulley are noticeably (significantly even) smaller.

IMG_3708.jpg

IMG_3712.jpg
 
Honestly I'll try a normal V-belt. That thing look very gothic and most likely not helping much for grippness.

Also that V-belt don't look to be sitting in your alternator pulley properly, as it's sticking out a little.
 
holdmypocket said:
Are you referring to belt wrap on just the alternator pulley or all pulleys in the path of the alternator belt? The water pump and crank pulley are noticeably (significantly even) smaller.

IMG_3708.jpg

IMG_3712.jpg
Click to expand...
If the alternator is the one slipping skip going around the water pump pulley. Just go crank to alternator.
 
Secondly that belt at the alternator is pretty far out of the groove while the rear most belt at the crank is way down in the groove. Is that a indication there is a belt width mismatch?
 
TrailTamer said:
Honestly I'll try a normal V-belt. That thing look very gothic and most likely not helping much for grippness.

Also that V-belt don't look to be sitting in your alternator pulley properly, as it's sticking out a little.
Click to expand...
That's my bad, old picture with the old alternator pulley and belt.

Here's pictures from today which i just noticed show some belt wear on the front of the alt and PS belt, looks like I need to replace them again and I barely have 20 miles on them:

IMG_3885.jpg

IMG_3881.jpg

IMG_3882.jpg

IMG_3883.jpg

IMG_3884.jpg

I'm pretty stumped about where to go from here. Apart from the squealing I also have this belt wear issue where the front edge gets all ragged. The alt, water, crank pulley are all from CVF and according to support are all of the same spec/offset/whatever which makes me wonder if I'm stuck with the squealing and the wear comes from over-tightening the ALT and PS belts.
 
Are they aligned correctly? Wear on one side of belt leads me to believe there could be an alignment issue.

I snagged one of these off eBay for $500 a few months back.

www.ebay.com

VibrAlign 100-BH2 Belt Hog II Laser Belt Alignment Tool | eBay

VibrAlign 100-BH2 Belt Hog II Laser Belt Alignment Tool. Condition is Used. Shipped with USPS Ground Advantage.
www.ebay.com

It works awesome for aligning belt drives. It would be neat to see what they say on your drive.
 
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ThePanzerFuhrer said:
Are they aligned correctly? Wear on one side of belt leads me to believe there could be an alignment issue.
Click to expand...
I agree, but apart from eye-balling it is there a tried-and-true method of checking? Call me uncreative but I can't come up with a reliable way.
 
Also if you look at the alternator belt, you can see how the front rides up just a little higher in the groove of the pulleys (water and alt pulleys).
 
holdmypocket said:
Also if you look at the alternator belt, you can see how the front rides up just a little higher in the groove of the pulleys (water and alt pulleys).
Click to expand...
Higher in groove is better than lower in groove. Higher in the groove you know the sides are doing the pulling not the center of the v.
 
ThePanzerFuhrer said:
Higher in groove is better than lower in groove. Higher in the groove you know the sides are doing the pulling not the center of the v.
Click to expand...
That makes sense, I am concerned that it's just on the front of the belt though. Only the front rides up higher, and only the front wears/frays like that.
 
So I heard back from CVF support (they're very responsive by the way) and they had this to say:

I think I see what your issue is. You purchased a water pump pulley from us, not a crank pulley. Both of our water pump pulley grooves have the same diameter. You are running a crank pulley that has 2 different diameters up to the same water pump. Both of those belts are going to spin at 2 different RPMs. You need to go with a crank pulley that has the same OD across all belt grooves like our part number BBFL3CR.
Click to expand...

This is my current crankshaft pulley that Vintage Air recommends when installing this set-up:

This is the pulley CVF recommended:
www.cvfracing.com

Ford Big Block Crank Pulley 3V

Big Block Crankshaft Pulley 3 Groove Ford Pulley V-Belt 429 or 460
www.cvfracing.com www.cvfracing.com

Not sure if the belt riding up higher on the front of the pulley is worth worrying about, or if it's affected by this.
 
holdmypocket said:
So I heard back from CVF support (they're very responsive by the way) and they had this to say:



This is my current crankshaft pulley that Vintage Air recommends when installing this set-up:

This is the pulley CVF recommended:
www.cvfracing.com

Ford Big Block Crank Pulley 3V

Big Block Crankshaft Pulley 3 Groove Ford Pulley V-Belt 429 or 460
www.cvfracing.com www.cvfracing.com

Not sure if the belt riding up higher on the front of the pulley is worth worrying about, or if it's affected by this.
Click to expand...
They’re not wrong. Different diameters on crank vs same diameter on water pump is a problem. I’d get that crank pulley and go from there before doing ANYTHING else.
 
Should have mentioned I ordered the new pulley :homer:.

Was supposed to go on a lame little fire-road trip with occasional obstacles on October 1st but I don't think I'll be able to get this pulley in, and the right sized belts in time. Seems like a bad idea to drive the truck like this as i'll probably throw a belt.
 
What does that very inside belt all run? Can you flip the crank pulley so both big pulleys are to the back that go over the fan.
 
ThePanzerFuhrer said:
What does that very inside belt all run? Can you flip the crank pulley so both big pulleys are to the back that go over the fan.
Click to expand...
Flipping it wouldn't work, it's a very deep pulley and would not bolt up at all. The inside groove runs my power steering pump:

IMG_3892.jpg
 
The last pic, I would just get a belt to drive the PS pump off the crank only, problem solved.
You aren't running a mechanical fan so you don't need a lot of water pump belt.
 
CarterKraft said:
The last pic, I would just get a belt to drive the PS pump off the crank only, problem solved.
You aren't running a mechanical fan so you don't need a lot of water pump belt.
Click to expand...
Fuck, good catch. I just looked at that with a piece of wire to mock it up and it looks like that will absolutely work. I swore I tried that and it didn't but who knows.. I probably just opted to follow the Vintage Air diagram for belt-routing without giving it a second thought.

I will wait until the new crank pulley comes to work on it just so that I have all the options when the time comes.

Engine swap (LS, Godzilla, wtf ever the flavor of the year is) will be possible when I move everything to a smog-exempt frame later on down the road.
 
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