factory '70 alternator belt - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**americanmusc1e** · 06-22-2009, 10:48 AM

OK my truck rolled the old alternator belt. I went to Autozone and bought another one. I had to stretch the belt on to get it to fit, then I adjusted the alternator all the way out to tighten it. The new belt rolled too.

why does my alternator not seem to have enough adjustment?????????

does anyone else have this problem??????

pictures to follow

thanks in advance,

Josh

EDIT: the truck has vortec heads now, but I had the same problem with the old heads

**americanmusc1e** · 06-22-2009, 11:07 AM

**nightmare** · 06-22-2009, 02:13 PM

it seems as if there is an alignment issue. try posting a pic from the drivers side showing the belt and all the pulleys it goes around.

Gray Ghost · 06-22-2009, 03:08 PM

Those newer belts are really not made right to fit these old pulleys. Mine sang like a siren when the throttle was down until I found an older one without the 'teeth'. Try Napa for the older style belt and see if that helps.

vectorit · 06-22-2009, 03:20 PM

If it were me...
I'd pitch that lower bracket. (Looks like a BBC bracket).
It's placing your alternator to low, and the upper bracket is over extended.

I'd then set up the correct bracketry for your year, and being that you have the holes in the cyl. heads that's no problem.

Longhorn Man · 06-22-2009, 04:04 PM

he has the right brackets.
However, I hope that's the old belt... since it is on upside down??

Wrenchbender Ret · 06-22-2009, 04:07 PM

Make sure the alignment is correct. Sometimes you need to shim it forward a little. Then get a shorter belt. A good parts man tell the length of the belt by the part no. Dont get it much shorter, it seems like a little goes a long way. About 1-2 in.

**El Jay** · 06-22-2009, 05:28 PM

Quote:

Originally Posted by Longhorn Man

he has the right brackets.
However, I hope that's the old belt... since it is on upside down??

Maybe it's a 'gator back.

Take the belt off and stand beside the truck & then give the alternator a "good" spin by hand & watch for run out (pulley wobble).

As I was standing at the side of I-5 last year coming home from camping & waiting for "the hook", I did just that.
Said, "Dang, that has got a bunch of run out."
Changed the alternator (also converted to internal regulator at the same time) and no problems in the last 10 months.

71 super · 06-22-2009, 06:54 PM

Check that one of your other pulleys is no bent in some way. I had a motor several years ago that had no problems then one day could not keep alt belt on it, turns out the crank pulley had gotten bent some how and it was throwing the belt off. check it out if it is not a big deal to fix I used a pair of pliars to bend it back out and no problems.

**americanmusc1e** · 06-23-2009, 11:35 AM

Quote:

Originally Posted by Longhorn Man

he has the right brackets.
However, I hope that's the old belt... since it is on upside down??

NO, thats the new belt, I put it on right side up, then I tightened it up. When I got home, it was like this!!

I guess I'll get a smaller belt like I did last time, then I'll look for a serpentine setup for the truck!!!

Longhorn Man · 06-23-2009, 04:27 PM

wow.

Sammy · 06-23-2009, 06:43 PM

Never seen one twist it inside out before without throwing it off.

Hottrucks · 06-23-2009, 08:06 PM

Quote:

Originally Posted by vectorit

If it were me...
I'd pitch that lower bracket. (Looks like a BBC bracket).
It's placing your alternator to low, and the upper bracket is over extended.

I'd then set up the correct bracketry for your year, and being that you have the holes in the cyl. heads that's no problem.

I have a 70 also and my alt is hung by a piece of coat hanger and I can't tight'n it any more with out twisting the junk hanger up...my roblem is NO HOLES in the heads fro the stock bracket any Ideas.....oh and i have headers too

drmiller1 · 06-24-2009, 08:18 AM

I had a similar issue on my 69. Advanced Auto Parts has a belt-
Drive Rite # 51015- It's made by Dayco. This belt stays.

06-22-2009, 10:48 AM	#1
americanmusc1e Senior Member Join Date: Jan 2009 Location: Austin, TX Posts: 1,079	factory '70 alternator belt OK my truck rolled the old alternator belt. I went to Autozone and bought another one. I had to stretch the belt on to get it to fit, then I adjusted the alternator all the way out to tighten it. The new belt rolled too. why does my alternator not seem to have enough adjustment????????? does anyone else have this problem?????? pictures to follow thanks in advance, Josh EDIT: the truck has vortec heads now, but I had the same problem with the old heads __________________ -- Josh Instagram: @americanmusc1e OLD SKOOL-- 1970 C10. 454/Th400/3.07 posi Build Thread FARM TRUCK----1949 Chevrolet 3800 Power Wagon Hauler Build Thread 1999 4wd OBS Tahoe - daily. DM me if you can't see photos i posted Last edited by americanmusc1e; 06-22-2009 at 10:50 AM.

06-22-2009, 11:07 AM	#2
americanmusc1e Senior Member Join Date: Jan 2009 Location: Austin, TX Posts: 1,079	Re: factory '70 alternator belt __________________ -- Josh Instagram: @americanmusc1e OLD SKOOL-- 1970 C10. 454/Th400/3.07 posi Build Thread FARM TRUCK----1949 Chevrolet 3800 Power Wagon Hauler Build Thread 1999 4wd OBS Tahoe - daily. DM me if you can't see photos i posted

06-22-2009, 03:08 PM	#4
Gray Ghost Senior Member Join Date: Sep 2004 Location: Terrell, TX Posts: 1,967	Re: factory '70 alternator belt Those newer belts are really not made right to fit these old pulleys. Mine sang like a siren when the throttle was down until I found an older one without the 'teeth'. Try Napa for the older style belt and see if that helps. __________________ Kelly '05 GMC Sierra SLE Z71 Bone stock except for new bed rail caps.

06-22-2009, 03:20 PM	#5
vectorit What? Join Date: Jun 2007 Location: Southern California Posts: 7,617	Re: factory '70 alternator belt If it were me... I'd pitch that lower bracket. (Looks like a BBC bracket). It's placing your alternator to low, and the upper bracket is over extended. I'd then set up the correct bracketry for your year, and being that you have the holes in the cyl. heads that's no problem. __________________ Chris 1968 K20 Suburban 1972 K10 LWB PU

06-22-2009, 04:04 PM	#6
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Re: factory '70 alternator belt he has the right brackets. However, I hope that's the old belt... since it is on upside down??

06-22-2009, 04:07 PM	#7
Wrenchbender Ret Registered User Join Date: Oct 2005 Location: Overland Park, Ks. Posts: 5,229	Re: factory '70 alternator belt Make sure the alignment is correct. Sometimes you need to shim it forward a little. Then get a shorter belt. A good parts man tell the length of the belt by the part no. Dont get it much shorter, it seems like a little goes a long way. About 1-2 in.

06-22-2009, 06:54 PM	#9
71 super Registered User Join Date: Sep 2005 Location: Canton North carolina Posts: 3,080	Re: factory '70 alternator belt Check that one of your other pulleys is no bent in some way. I had a motor several years ago that had no problems then one day could not keep alt belt on it, turns out the crank pulley had gotten bent some how and it was throwing the belt off. check it out if it is not a big deal to fix I used a pair of pliars to bend it back out and no problems. __________________ 67 blue step side- bb 68 gold and white swb cst anniversary 68 custom swb hot rod Ls swap 69 swb cst 6 cylinder/ overdrive 69 black/black cst bb swb 70 orange and white cst Canada built truck swb bb 71 black and white super swb bb 71 red and white super swb 72 green and white super swb 4x4 62 nova wagon 400 series Ls swapped 68 Camaro 327/4 speed- 1 owner, original paint 66 Volkswagen bettle 69 auto stick Volkswagen Beetle

06-23-2009, 04:27 PM	#11
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,690	Re: factory '70 alternator belt wow.

06-23-2009, 06:43 PM	#12
Sammy Registered User Join Date: Apr 2000 Location: Bonne Terre, Mo Posts: 3,005	Re: factory '70 alternator belt Never seen one twist it inside out before without throwing it off. __________________ '69 Chevy Long Fleet & '71 GMC Short Step & Project "ODD BALL" "You can wash a pig, soak it in most expensive perfume. In the end it is still just a pig." ODD BALL build thread http://67-72chevytrucks.com/vboard/s...d.php?t=478629"

06-24-2009, 08:18 AM	#14
drmiller1 Registered User Join Date: Aug 2008 Location: Mid Michigan Posts: 90	Re: factory '70 alternator belt I had a similar issue on my 69. Advanced Auto Parts has a belt- Drive Rite # 51015- It's made by Dayco. This belt stays. __________________ Nothing better than an old truck... 76 C-10 Silverado 92 Silverado Z71

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