Home » Public Forums » GMCnet » Belts and tensioning
| Belts and tensioning [message #133549] |
Wed, 06 July 2011 18:36  |
Andrew
Messages: 213
Registered: April 2011
Location: Connecticut
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I just replaced my power steering pump, and associated hosery.
I was putting the belts back and noticed that I have two belts on the power steering pump (double pulley), and the same on the alternator. In fact, the two belts follow exactly the same path (crankshaft-fan-alternator-pspump) and are the same model number (Gates 7570 XL). They were installed a few weeks ago when the coach was in the shop for major suspension surgery.
Is this a modification? Possibly to get more bite on the power steering pump pulley? The docs I can find say that the power steering pump should have a 7450 belt, but that would imply that it would follow a different path too, right?
The third belt (Gates XL 7619) goes to the A/C compressor, and appears normal.
The other problem I'm having is that one of the 7570s is looser than the other (3/4" deflection), and is slipping. I can't tighten it further because the tighter one is ...well, tight. I don't want to damage anything (alternator, pspump), and it's at the limit of my two-handed tensioning abilities. I haven't tried swapping the belts to see if the looser one got stretched on the drive home...should I? Or is something bigger wrong?
The Gates belts are the narrow ones, and I've already bought a replacement set from NAPA for when they fail, but I'm not ready to blame them for the problems yet.
Would a belt tensioner be a worthwhile purchase?
1973 Sequoia 260 (since 2011)
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| Re: [GMCnet] Belts and tensioning [message #133551 is a reply to message #133549] |
Wed, 06 July 2011 18:52  |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Andrew,
You apparently missed the discussions which went on here over the past
few days. They covered this topic:
What you've got is a dual alternator pulley, a common modification to
alleviate slippage there. It does indeed change the PS pump drive to
dual belt drive at the same time. In addition to improving the drive of the
alternator, it allows you to set and forget the PS pump -- preferably
at its all-the-way-out position. Then use the alternator's more
convenient adjustment arrangement.
But, the two belts must be matched, as yours are not. Truly matched
belts are difficult to find these days; the best alternative is to buy
two which are marked identically; i.e., have come from the same
production run. JimK can provide the belts.
Ken H.
On Wed, Jul 6, 2011 at 7:36 PM, Andrew <reynhout@quesera.com> wrote:
>
>
> I just replaced my power steering pump, and associated hosery.
>
> I was putting the belts back and noticed that I have two belts on the power steering pump (double pulley), and the same on the alternator. In fact, the two belts follow exactly the same path (crankshaft-fan-alternator-pspump) and are the same model number (Gates 7570 XL). They were installed a few weeks ago when the coach was in the shop for major suspension surgery.
>
> Is this a modification? Possibly to get more bite on the power steering pump pulley? The docs I can find say that the power steering pump should have a 7450 belt, but that would imply that it would follow a different path too, right?
>
> The third belt (Gates XL 7619) goes to the A/C compressor, and appears normal.
>
> The other problem I'm having is that one of the 7570s is looser than the other (3/4" deflection), and is slipping. I can't tighten it further because the tighter one is ...well, tight. I don't want to damage anything (alternator, pspump), and it's at the limit of my two-handed tensioning abilities. I haven't tried swapping the belts to see if the looser one got stretched on the drive home...should I? Or is something bigger wrong?
>
> The Gates belts are the narrow ones, and I've already bought a replacement set from NAPA for when they fail, but I'm not ready to blame them for the problems yet.
>
> Would a belt tensioner be a worthwhile purchase?
>
> --
> 1973 Sequoia 260 (since 2011)
> Savannah, GA
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www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Belts and tensioning [message #133552 is a reply to message #133551] |
Wed, 06 July 2011 19:04 |
Andrew
Messages: 213
Registered: April 2011
Location: Connecticut
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Thanks, Ken. I thought I had read that recently, but couldn't find the thread to confirm.
The two 7570s were put on by the shop, and I drove it for a few hundred miles before taking off the PS pump and necessitating the current retensioning..
Apparently the belts were matched closely enough for the first trip, or maybe the shop's tensioning was just more aggressive than mine.
Thanks for the help.
1973 Sequoia 260 (since 2011)
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| Re: [GMCnet] Belts and tensioning [message #133560 is a reply to message #133552] |
Wed, 06 July 2011 20:17 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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I doubt that the shop put in matched belts. When I wanted matched belts I went to AutoZone and compared the production numbers on the belts and measured them with their belt measurement tool. They only had two in stock and they did not match. I bought those two and ordered two more knowing that the next morning they would get 4 more in from the warehouse. I went back the next day and looked at the ones that they received. They actually received 6 and all 6 were the same production number. They also measured exactly the same on their belt measurement stick. I traded in the two I bought the day before for two matched ones and that took care of it.
Do not use NAPA or Gates belts. They are too thin. You need 7/16" or 11mm. wide belts. Gates (who makes most NAPA belts) shut down the 7/16" belt line a few years back and are now substituting 3/8" belts in their place. NAPA does handle another line that you can order that is the correct width. Take a 10mm. open end wrench with you when you go to buy a belt. If it fits across the belt then it it too thin. Go find another brand.
When installing a double belt on the power steering and alternator, first adjust the power steering unit all the way to the right when viewed front front. Then install the belts and adjust the tension on the belts using the alternator.
Right now you have the worse of both worlds. A single belt contacting a limited distance on the power steering pulley and a belt that is too thin.
Goodyear, Duralast, Kelly-Springfield, and others make belts that work on your GMC.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Belts and tensioning [message #133568 is a reply to message #133560] |
Wed, 06 July 2011 20:42 |
Andrew
Messages: 213
Registered: April 2011
Location: Connecticut
Karma: 0
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| Ken Burton wrote on Wed, 06 July 2011 20:17 |
I doubt that the shop put in matched belts. When I wanted matched belts I went to AutoZone and compared the production numbers on the belts and measured them with their belt measurement tool. They only had two in stock and they did not match. I bought those two and ordered two more knowing that the next morning they would get 4 more in from the warehouse. I went back the next day and looked at the ones that they received. They actually received 6 and all 6 were the same production number. They also measured exactly the same on their belt measurement stick. I traded in the two I bought the day before for two matched ones and that took care of it.
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That's exactly the trick I was considering in AutoZone this afternoon. They only had one in stock, but "could get another" from their local warehouse by the morning. I could see from their inventory system that the local warehouse only had one too though, otherwise I'd have given it a shot.
| Ken Burton wrote on Wed, 06 July 2011 20:17 |
Do not use NAPA or Gates belts. They are too thin. You need 7/16" or 11mm. wide belts. Gates (who makes most NAPA belts) shut down the 7/16" belt line a few years back and are now substituting 3/8" belts in their place. NAPA does handle another line that you can order that is the correct width. Take a 10mm. open end wrench with you when you go to buy a belt. If it fits across the belt then it it too thin. Go find another brand.
|
I bought a set at NAPA today that DID pass. They were about $20 each, NBH line. They might have been from the old Gates runs (they have a NAPA logo, but the rest of the printing looks just like a Gates belt). NAPA only had one of the 7570s, too. I'll be back there returning my extraneous PS pump belt tomorrow, so I'll ask them what they can do for me.
The 10mm wrench slides onto my current Gates belts with only a little resistance. I wasn't initially sure how much resistance was "right", but after checking the NAPA belts today at the store (before buying!), it became clear that the right answer is "doesn't slide on at all!"
| Ken Burton wrote on Wed, 06 July 2011 20:17 |
Right now you have the worse of both worlds. A single belt contacting a limited distance on the power steering pulley and a belt that is too thin.
Goodyear, Duralast, Kelly-Springfield, and others make belts that work on your GMC.
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Thanks again.
1973 Sequoia 260 (since 2011)
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| Re: [GMCnet] Belts and tensioning [message #133570 is a reply to message #133552] |
Wed, 06 July 2011 20:45 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Andrew,
I checked the MM and it provides the following Burroughs Tool to check belt
tension BT-33-73F.
I did a Google search and found one on eBay, it is handled by Snap on and it
ONLY costs $101.00! - PASS!
I then did a Google search for "Belt Tension Tool" and up popped this:
http://tinyurl.com/3synbhu
I read the reviews and they are at both ends of the pole.
Do we reckon it's worth a shot?
I have always gone by the rule of thumb that a belt is tensioned correctly
if you can twist a belt 1/2 turn and feel resistance. More than a 1/2 turn,
it's too loose, less than 1/2 turn it's too tight.
Comments?
Regards,
Rob M.
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Andrew
Sent: Thursday, 7 July 2011 10:04 AM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Belts and tensioning
Thanks, Ken. I thought I had read that recently, but couldn't find the
thread to confirm.
The two 7570s were put on by the shop, and I drove it for a few hundred
miles before taking off the PS pump and necessitating the current
retensioning..
Apparently the belts were matched closely enough for the first trip, or
maybe the shop's tensioning was just more aggressive than mine.
Thanks for the help.
--
1973 Sequoia 260 (since 2011)
Savannah, GA
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Belts and tensioning [message #133574 is a reply to message #133570] |
Wed, 06 July 2011 21:02 |
Andrew
Messages: 213
Registered: April 2011
Location: Connecticut
Karma: 0
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| Robert Mueller wrote on Wed, 06 July 2011 20:45 |
I then did a Google search for "Belt Tension Tool" and up popped this:
http://tinyurl.com/3synbhu
I read the reviews and they are at both ends of the pole.
Do we reckon it's worth a shot?
|
I saw that tension checker too. Krikit makes a couple different ranges of that sort of thing as well.
It seems to me that measuring deflection and required force is only an approximation of the real measurement in question. Deflection will vary with the length of the belt between pulleys, even when the tension is correct. Maybe for the normal range of pulley separations, this isn't an issue.
But that's a limitation of the finger tests too. If you need to set different ranges (like for newer cars), those clicker things would be more reliable, I think.
I started off looking for a "tensioning tool" that you'd use to rotate the parts on their pivots to create and hold the tension while your other hand tightened the slider bolt. I don't know if that tool actually exists, but it should. 
| Robert Mueller wrote on Wed, 06 July 2011 20:45 |
I have always gone by the rule of thumb that a belt is tensioned correctly
if you can twist a belt 1/2 turn and feel resistance. More than a 1/2 turn,
it's too loose, less than 1/2 turn it's too tight.
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I've gone by the 1/2" deflection rule. One of my belts is currently a little under that, and the other is at about 3/4". The 3/4" one is slipping.
1973 Sequoia 260 (since 2011)
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| Re: [GMCnet] Belts and tensioning [message #133603 is a reply to message #133568] |
Thu, 07 July 2011 00:34 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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Senior Member |
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| Andrew wrote on Wed, 06 July 2011 20:42 |
| Ken Burton wrote on Wed, 06 July 2011 20:17 |
I doubt that the shop put in matched belts. When I wanted matched belts I went to AutoZone and compared the production numbers on the belts and measured them with their belt measurement tool. They only had two in stock and they did not match. I bought those two and ordered two more knowing that the next morning they would get 4 more in from the warehouse. I went back the next day and looked at the ones that they received. They actually received 6 and all 6 were the same production number. They also measured exactly the same on their belt measurement stick. I traded in the two I bought the day before for two matched ones and that took care of it.
|
That's exactly the trick I was considering in AutoZone this afternoon. They only had one in stock, but "could get another" from their local warehouse by the morning. I could see from their inventory system that the local warehouse only had one too though, otherwise I'd have given it a shot.
| Ken Burton wrote on Wed, 06 July 2011 20:17 |
Do not use NAPA or Gates belts. They are too thin. You need 7/16" or 11mm. wide belts. Gates (who makes most NAPA belts) shut down the 7/16" belt line a few years back and are now substituting 3/8" belts in their place. NAPA does handle another line that you can order that is the correct width. Take a 10mm. open end wrench with you when you go to buy a belt. If it fits across the belt then it it too thin. Go find another brand.
|
I bought a set at NAPA today that DID pass. They were about $20 each, NBH line. They might have been from the old Gates runs (they have a NAPA logo, but the rest of the printing looks just like a Gates belt). NAPA only had one of the 7570s, too. I'll be back there returning my extraneous PS pump belt tomorrow, so I'll ask them what they can do for me.
The 10mm wrench slides onto my current Gates belts with only a little resistance. I wasn't initially sure how much resistance was "right", but after checking the NAPA belts today at the store (before buying!), it became clear that the right answer is "doesn't slide on at all!"
| Ken Burton wrote on Wed, 06 July 2011 20:17 |
Right now you have the worse of both worlds. A single belt contacting a limited distance on the power steering pulley and a belt that is too thin.
Goodyear, Duralast, Kelly-Springfield, and others make belts that work on your GMC.
|
Thanks again.
|
Emery reported some time ago that NAPA did have a second line (not manufactured by Gates) that was special order and they were indeed 7/16" wide. I do not know what the name of that line is.
On the 10mm. wrench, it should not go over the belt all. On the Gates belts and maybe the NAPA ones, if you look at the package in very small print you will see they labeled the too thin belts as being 9.5/10mm. Look carefully as the print is very small. The 10mm. open end is still the best way to check them.
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: [GMCnet] Belts and tensioning [message #133610 is a reply to message #133570] |
Thu, 07 July 2011 02:31 |
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mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
Karma: 0
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| Robert Mueller wrote on Wed, 06 July 2011 18:45 |
... I have always gone by the rule of thumb that a belt is tensioned correctly
if you can twist a belt 1/2 turn and feel resistance. More than a 1/2 turn,
it's too loose, less than 1/2 turn it's too tight. ...
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That is how I check when I am adjusting the belts. (The belt >TURN< method.) For just checking, I just push and check deflection... close enough. At work, I use this fancy gadget that measures the sound waves when the belt is plucked. (But that is on "robots"...)
My method of "prying" is to have a scissors jack under the coach and a 2x2 about 4 foot long. Put one end under the alternator (or AC pump) and jack until I get the "1/2 >TURN<" at the mid point between the pulleys on the longest side. Then tighten everything down. If you use a jack, be careful, it is VERY easy to over tighten the belts. ... But the whole operation is MUCH easier than prying with anything. (Much more controlled also.)
As Gene says, check your brackets and ensure your pulleys are lined up. PO's and their mechanics have had lots of opportunity to "rearrange things. I also understand the brackets changed some over the years and the earlier ones are more likely to be out of whack... (I'll have to double check that statement sometime.)
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
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| Re: [GMCnet] Belts and tensioning [message #133612 is a reply to message #133600] |
Thu, 07 July 2011 04:59 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Gene,
Aha! That's the secret to keeping a single belt from squealing! ;-)
Before you mess with putting spacers anywhere it's a good idea to check and
see if the bolt that holds the alternator is parallel to the engine center
line.
If it is then I would suggest you remove the alternator and check the hole
in the front of the alternator housing. I found the one in Double Trouble
was oblong which allowed the alternator to sit cockeyed and tear up belts.
I drilled the hole from 3/8" to 7/16" and used a new bolt.
Go VERY slowly when you drill through the steel bushing at the rear or the
drill can grab the bushing, it's formed around an 3/8 pin (or something) and
has a "slot" in it.
I drilled it two steps from; from 3/8" to 13/32" to 7/16"
Regards,
Rob M.
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Mr.erf ERFisher
Sent: Thursday, 7 July 2011 2:53 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] Belts and tensioning
I am big on calibration:
I use a 2x4 between the alternator and the valve cover , give it all I can
and tighten the bolts.
the real trick , is put a straight edge on the alternator pulley, and the
belt better leave the pulley straight, or you have a problem
http://gmcmotorhome.info/engine.html#bracket
gene
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Belts and tensioning [message #133617 is a reply to message #133560] |
Thu, 07 July 2011 06:33 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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I just replaced the pulleys and belts on a SWUD (Big air conditioner) which drive the blower with a 25HP electric motor. In a year, they had worn such that the vee was wider at the bottom than the top i.e. the angle had increased via wear. After cleaning the crud off, I find the contact zone had recuded itself to about an eigth of an inch at the top of the sheave. That was the only shiny part, the rest of th vee was caked with tidbits of belt, and when they were removed, no contact shiny to be seen, just the circle around the top. This circle corresponded to the fabric plies in the belt. I suspect the previous belts had been the wrong angle, and had therefore worn the pulleys. The point being, now and again when you're checking the engine on your coach, take a rag, clean the pulleys, and have a look at the contact patch.
--johnny
--- On Thu, 7/7/11, Ken Burton <n9cv@comcast.net> wrote:
From: Ken Burton <n9cv@comcast.net>
Subject: Re: [GMCnet] Belts and tensioning
To: gmclist@temp.gmcnet.org
Date: Thursday, July 7, 2011, 1:17 AM
I doubt that the shop put in matched belts. When I wanted matched belts I went to AutoZone and compared the production numbers on the belts and measured them with their belt measurement tool. They only had two in stock and they did not match. I bought those two and ordered two more knowing that the next morning they would get 4 more in from the warehouse. I went back the next day and looked at the ones that they received. They actually received 6 and all 6 were the same production number. They also measured exactly the same on their belt measurement stick. I traded in the two I bought the day before for two matched ones and that took care of it.
Do not use NAPA or Gates belts. They are too thin. You need 7/16" or 11mm. wide belts. Gates (who makes most NAPA belts) shut down the 7/16" belt line a few years back and are now substituting 3/8" belts in their place. NAPA does handle another line that you can order that is the correct width. Take a 10mm. open end wrench with you when you go to buy a belt. If it fits across the belt then it it too thin. Go find another brand.
When installing a double belt on the power steering and alternator, first adjust the power steering unit all the way to the right when viewed front front. Then install the belts and adjust the tension on the belts using the alternator.
Right now you have the worse of both worlds. A single belt contacting a limited distance on the power steering pulley and a belt that is too thin.
Goodyear, Duralast, Kelly-Springfield, and others make belts that work on your GMC.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] Belts and tensioning [message #133622 is a reply to message #133617] |
Thu, 07 July 2011 07:42 |
fred v
Messages: 999
Registered: April 2006
Location: pensacola, fl.
Karma: 0
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| Johnny Bridges wrote on Thu, 07 July 2011 06:33 |
I just replaced the pulleys and belts on a SWUD (Big air conditioner) which drive the blower with a 25HP electric motor. In a year, they had worn such that the vee was wider at the bottom than the top i.e. the angle had increased via wear. After cleaning the crud off, I find the contact zone had recuded itself to about an eigth of an inch at the top of the sheave. That was the only shiny part, the rest of th vee was caked with tidbits of belt, and when they were removed, no contact shiny to be seen, just the circle around the top. This circle corresponded to the fabric plies in the belt. I suspect the previous belts had been the wrong angle, and had therefore worn the pulleys. The point being, now and again when you're checking the engine on your coach, take a rag, clean the pulleys, and have a look at the contact patch.
--johnny
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Johnny,
industrial belts do have a different V than automotive belts and should not be interchanged. you may also have the pulleys out of alignment which will wear the belt even if it is the right belt.
Fred V
'77 Royale RB 455
P'cola, Fl
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| Re: [GMCnet] Belts and tensioning [message #133626 is a reply to message #133610] |
Thu, 07 July 2011 08:01 |
k2gkk
Messages: 4452
Registered: November 2009
Karma: -8
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Senior Member |
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It's been several decades since I did my own vehicle
maintenance work, but here is the method I always
used for belt tensioning.
Set the devices so that you can push the belt "in"
at its longest span no more than the height of the
belt. "Quick and dirty" but it always worked okay
for me back in the 50s and 60s.
YRMV!
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
~~ ~ D C "Mac" Macdonald ~ ~~
~ ~ Amateur Radio - K2GKK ~ ~
~ ~ USAF and FAA, Retired ~ ~
~ ~ ~ Oklahoma City, OK ~ ~ ~
~~ ~ ~ "The Money Pit" ~ ~ ~~
~~ ~ ~ (TZE166V101966) ~ ~ ~~
~ ~ ~ ex-Palm Beach, 76 ~ ~ ~
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~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
> To: gmclist@temp.gmcnet.org
> From: m000035@gmail.com
> Date: Thu, 7 Jul 2011 02:31:11 -0500
> Subject: Re: [GMCnet] Belts and tensioning
>
>
>
> Robert Mueller wrote on Wed, 06 July 2011 18:45
> > ... I have always gone by the rule of thumb that a belt is tensioned correctly
> > if you can twist a belt 1/2 turn and feel resistance. More than a 1/2 turn,
> > it's too loose, less than 1/2 turn it's too tight. ...
>
>
> That is how I check when I am adjusting the belts. (The belt >TURN< method.) For just checking, I just push and check deflection... close enough. At work, I use this fancy gadget that measures the sound waves when the belt is plucked. (But that is on "robots"...)
>
> My method of "prying" is to have a scissors jack under the coach and a 2x2 about 4 foot long. Put one end under the alternator (or AC pump) and jack until I get the "1/2 >TURN<" at the mid point between the pulleys on the longest side. Then tighten everything down. If you use a jack, be careful, it is VERY easy to over tighten the belts. ... But the whole operation is MUCH easier than prying with anything. (Much more controlled also.)
>
> As Gene says, check your brackets and ensure your pulleys are lined up. PO's and their mechanics have had lots of opportunity to "rearrange things. I also understand the brackets changed some over the years and the earlier ones are more likely to be out of whack... (I'll have to double check that statement sometime.)
> --
> Mike Miller -- Hillsboro, OR -- on the Black list
> (#1)'73 26' exPainted D. -- (#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
> http://m000035.blogspot.com
>
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| Re: [GMCnet] Belts and tensioning [message #133639 is a reply to message #133622] |
Thu, 07 July 2011 10:12 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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There >were< industrial belts - and we check alignment regularly with a string. We're speaking with the manufacturer, I think the pulley diameter is simply too small on the motor and blower. I'm gonna upp the sizes and keep th rario the same.
--johnny
--- On Thu, 7/7/11, fred veenschoten <fredntoni@cox.net> wrote:
From: fred veenschoten <fredntoni@cox.net>
Subject: Re: [GMCnet] Belts and tensioning
To: gmclist@temp.gmcnet.org
Date: Thursday, July 7, 2011, 12:42 PM
Johnny Bridges wrote on Thu, 07 July 2011 06:33
> I just replaced the pulleys and belts on a SWUD (Big air conditioner) which drive the blower with a 25HP electric motor. In a year, they had worn such that the vee was wider at the bottom than the top i.e. the angle had increased via wear. After cleaning the crud off, I find the contact zone had recuded itself to about an eigth of an inch at the top of the sheave. That was the only shiny part, the rest of th vee was caked with tidbits of belt, and when they were removed, no contact shiny to be seen, just the circle around the top. This circle corresponded to the fabric plies in the belt. I suspect the previous belts had been the wrong angle, and had therefore worn the pulleys. The point being, now and again when you're checking the engine on your coach, take a rag, clean the pulleys, and have a look at the contact patch.
>
> --johnny
Johnny,
industrial belts do have a different V than automotive belts and should not be interchanged. you may also have the pulleys out of alignment which will wear the belt even if it is the right belt.
--
Fred V
'77 Royale RB 455
P'cola, Fl
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Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] Belts and tensioning [message #133841 is a reply to message #133603] |
Fri, 08 July 2011 18:36 |
Andrew
Messages: 213
Registered: April 2011
Location: Connecticut
Karma: 0
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Senior Member |
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| Ken Burton wrote on Thu, 07 July 2011 00:34 |
Emery reported some time ago that NAPA did have a second line (not manufactured by Gates) that was special order and they were indeed 7/16" wide. I do not know what the name of that line is.
On the 10mm. wrench, it should not go over the belt all. On the Gates belts and maybe the NAPA ones, if you look at the package in very small print you will see they labeled the too thin belts as being 9.5/10mm. Look carefully as the print is very small. The 10mm. open end is still the best way to check them.
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As a follow-up, I ordered four belts from NAPA. Two pairs came from two different places. They were marked identically, both on the belt and the package. They were made by Gates, and said "10mm" in small print on the back of the cardboard bit.
One pair of belts passed the 10mm wrench test, the other pair failed and were returned.
I don't know what that means, but it's too fiddly for my tastes. Skip NAPA and get belts elsewhere if you can.
My local AutoZone can't do anything to assemble two likely-matched belts in one place for me.
The two good belts are now on the pulleys and tensioned properly. Coach is mechanically ready to go, pending new surprises. Still considering tearing out the carpet before we leave. Departure in six days!
1973 Sequoia 260 (since 2011)
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