Help with dual v-belt setup

[drdano]

I'm running a double v-belt setup on my 428.  Upgraded my damper to an ATI unit and a double v-belt pulley from CVF.  I have two Gates 7425 (11A1080) belts that are now too long, but just barely and I'm at the end of the adjuster for the alternator.

1.  Is there such a thing as a banded v-belt that would take the place of two individual v-belts?  My thinking here is a single type belt would mean equal size of the prior two belts and carrying one belt as a backup would be convenient.  Unsure if such a thing exists though.

2.  Am I reading the Gates part number 7425 as meaning 42.5" belt and if I need to step down by maybe a half or full inch, I would go to 7420 or 7415?

Thanks gurus!

[wayne]

You may want to check rock auto they have closeouts on cobra jet belts

[338Raptor]

You are correct about the part number including the belt length. 

They make double v-belts. They are called “power bands”. They’ll only work if all your pulleys are designed to accept them.  The pulley grooves must have correct spacing and depth.  They’re more popular in industrial applications. I can’t recall ever seeing one on an automobile. 

[cjshaker]

You are correct about the part number including the belt length. 

They make double v-belts. They are called “power bands”. They’ll only work if all your pulleys are designed to accept them.  The pulley grooves must have correct spacing and depth.  They’re more popular in industrial applications. I can’t recall ever seeing one on an automobile.

Ditto on that. They're typically used on big electric motors that drive industrial equipment, like air handlers (BIG air handlers), HVAC pumps, drive systems etc etc. And they require special pulleys that are designed to work with them.

[drdano]

Ok, I'll stick with the dual belts set up I have and order a half inch shorter pair and see if that gets me in the midrange of adjustment.  Thanks for the info from everyone.  Oh, and not sure about anyone else in Colorado, but Rock Auto refuses to ship here and wont do business.  I think it has to do with our state requiring internet sales shipped here to have state sales tax included.  Bummer, I used to use them all the time.  Hopefully they will fix that in the future so I can use them again.

[Thumperbird]

Each individual belt will stretch anyways over time to it's own happy tension.  Sure when you first tighten things up one is going to be primary, I would just snug again after some drive time.

[pbf777]

      And, if possible when running parallel belt mountings, never replace only one belt at a time; and one should attempt to acquire belts exhibiting the same batch or band number, as the manufacture will generally mark them for this reason (among others), thereby ensuring a more equal sizing.         

      Scott.

[wayne]

Back when i worked at a gas station in 72-74 Goodyear made matched sets for them.

[drdano]

I should have a pair delivered tomorrow and can check if they came from the same production run.  I called and tried to ask the kid behind the counter if when they fill the order they could check the numbers and try to see if they're from the same batch and if not try to match two up from the rack that are.....silence.  Then had to explain what I was talking about.  Just sorta gave up after trying to explain that yes, they are the same part number, but may not be identical.  Anyway, one positive is a lot of the parts stores are doing free next day delivery to keep folks out of their stores, so I'll know tomorrow if I got lucky or not. 

[TomP]

The two belts being a slight different length is not a big issue unless you have a high amperage alternator, then it's critical.
I guess Colorado was one of the places that sued about the sales tax. I think it was Jeg's or Speedway Motors that was hit with huge fines for it. Since then other states have jumped on the bandwagon making a huge boondoggle for mail order businesses. Some states tax, others don't... different rates, some have certain items taxed while other items aren't or at a different rate.

[Falcon67]

When I worked the part counter back in the 70s, Gates matched sets were common.  Haven't seen anything like that in a long time.   Good luck, I would just order the length you need and go with it.  Manufacturing is a lot different now than it was in the 70s.  In most cases, way more precise. 

[427Fastback]

I just went through this.I run dual belts on the 427.I could not find a matched pair any where.CJ belts are the wrong length as I have a dual groove 271HP size alternator pulley (I machined one)...According to one of the belt manufactures std tolerance on the belts are +or- .150....I ordered two belts and got lucky.Its a crap shoot....

[C6AE]

You are correct about the part number including the belt length. 

They make double v-belts. They are called “power bands”. They’ll only work if all your pulleys are designed to accept them.  The pulley grooves must have correct spacing and depth.  They’re more popular in industrial applications. I can’t recall ever seeing one on an automobile.

Yes, and you can separate them with a razor knife and have an exact matched pair

More here;
http://www.filtechinc.com/customer/filinc/images/pdfs/Belt%20-%20Identification%20Literature.pdf

[Chrisss31]

There is a belt wholesaler a few towns over from us that we deal with through NAPA.  I was looking for a set of 3 matched belts for our wood chipper.  They told me the numbers on the belt are part number followed by series or order of production number.  If you get sequential numbers they are matched sets.  In short... if you want a matched set you need to find someone that buys a lot of belts and is willing to check the numbers for you.