FAQ: Serpentine Belts - Brands and Types

cool. have any of you guys used a gates s/c belt? do they last longer?

Nothing wrong with a Gates belt, and most guys seem to want to recommend whichever brand they have experience with. I replaced my belts with Goodyear Gatorbacks a few weeks ago.

I had both Gatorbacks and Gates.

Gates were better, IMO. A more "solid" belt. I don't like all those notches cut in my belts. That's less surface area on the pulley, and I didn't spend no $100 on that pulley to not use it.

Quote :

cool. have any of you guys used a gates s/c belt? do they last longer?

I got over 90k miles out of a pair of Gates belts, including one episode where an idler fragged and the belt slipped off. It was able to be reused. Both belts were still holding up well when I replaced - with Gates again, of course!

looks like im going with gates!

I don't think any/either choice would be a mistake. They should all last and perform well as long as they are installed properly and pulleys are aligned.

1998 Riv wrote:

I don't think any/either choice would be a mistake. They should all last and perform well as long as they are installed properly and pulleys are aligned.

I agree



I've been using the gatorbacks for a bit with no problems at all but I haven't had them on a car nearly as long as Aaron has had Gates belts on at one time. I've now switched to Gates only because the company I work for has done so and I wanted to replace my accessory belt because my tensioner pulley quit last winter and basically melted its self all over the back of my belt. The belt was fine functionally.

Anyway the reason I've come back to this thread is because I was trying to find out what I would have bought for my gatorback replacement for the S/C. I wasn't sure if it was a 72.0" belt or 72.5" belt. I'm using this to base my new size 8rib belt on right now. Using various idler pulleys and such, I've had no problem going from the stock 3.8" to 3.0" and I'd say I could even run a 2.9" or 2.8" on the stock size belt.


Here's whats been pissing me off. The stores can't quite agree on what size this cars s/c belt is. Here's basically what I've found...

Autozone - 72.5" available in Gatorback and Duralast
Advance - 72.0" available in Dayco
O'reillys - 72.1" available in Gates and Masterpro
Napa - 72.1" available in Gates

the Delco part I've been seeing in this thread is 72.1" or 72.2"

Based off of what information I have, I would surmise that my Gatorback that's currently on the car is probably a 72.5". The part number is worn off the back so I can't read it and I bought it at Murrays which is now O'reilly so I have no way to actually check.

I've got a Gates K080716 belt for my 8-rib that I think is my best bet to start with since the S/C pulleys I'll be using right now with this belt will be in the 3.2"-3.0" range. This is about the best guess I could come up with so we'll see how it fits. I have some extra grooved and smooth 8-rib pulleys so I'll have a little room to play with.

All of those belt sizes will work, because the tensioner takes up the slack. I think the reason for the variance is different vendors measuring the belts using different methods.

I've always used Gates K060721, listed by Rockauto and Jeggs as 72 5/8" long. The Car Connection lists it as: Effective Length 72.07", Outside Circumference 72.632". I've used this belt to drive various pulleys from 3.4" down to 3.1", using different combinations of idler & tensioner pulleys.

I once personally measured a used OEM belt at 72" long (cut, end-to-end).

Ummm... Codith - there's not enough difference in those belt sizes to fret about.

Albertj

albertj wrote:

Ummm... Codith - there's not enough difference in those belt sizes to fret about.

Albertj

I need to be pretty accurate because I'm making a judgement on the new size based entirely off the size I'm using and it's hard to do if I don't know what size that is.

turtleman wrote:

albertj wrote:

Ummm... Codith - there's not enough difference in those belt sizes to fret about.

Albertj

I need to be pretty accurate because I'm making a judgement on the new size based entirely off the size I'm using and it's hard to do if I don't know what size that is.

I think I get it - if there is a doubt then use a belt about the middle of the range for those you measured. That way the tensioner should keep it properly tight. To a point shorter is better because the belt won't float off the SC pulley.

Albertj

If you consider the largest and smallest variance you found (72.5" vs. 72.0"), that really means 72.25 +/- .25", or a tolerance of +/- 0.3%.

One third of one percent - that is a stunningly accurate spec for a large rubber band, better than some electronic equipment. You probably couldn't tell the difference when installed.

AA wrote:

If you consider the largest and smallest variance you found (72.5" vs. 72.0"), that really means 72.25 +/- .25", or a tolerance of +/- 0.3%.

One third of one percent - that is a stunningly accurate spec for a large rubber band, better than some electronic equipment. You probably couldn't tell the difference when installed.

...yep. What he said.

Albertj

Basically I'm going to a slightly shorter belt so that I can use go about 3.4 to 3.0 S/C pulleys without using the monster grooved pulley (since it's not available in 8-rib) I got a 716 belt on hand because It's only about a half inch shorter so I know it will work but I'm thinking I may want to get one that's say another half inch shorter than that? a 710 is the next step down for the gates 8-ribs.

The thing is I am having trouble trying to picture how much of a difference at the tensioner markings does a half inch in belt length actually make. With the stock size belt, I cannot use the 3.5" tensioner pulley and 3.5" grooved pulley with the 3.0" S/C pulley because the belt is so close it rubs against its self. I'm thinking I need to be able to run that 3.0" pulley with the 3.0" tensioner pulley. Sorry - I know this is probably hard to picture for anyone that hasn't just looked at it.

You can calculate teh amount you need to remove as teh difference in pulley sizes. Formula for circumference is 2*pi*radius. Radius of a 3" pulley is 1.5" so the whole circumference is 2*3.14159*1.5=circ(1). Calculate circ(2) using the radius of the stock pulley. Then look at the stock pulleys installed and reckon how much of the pulley circumference they cover - say it's half. Then you take the 1/2 of circ 1, that woudl be the length of the belt that touches the 3" puley, and you subtract circ(1) from circ(2). That amount is approximately the amount shorter you ahve to go to keep the same relationship across the belts and pullies. My guess is it's in the neighborhood of 1.5 to 2 inches...

someone please check my math and reckoning.

Albertj

Using albert's method can work, but pay attention to the fact that the tensioner can move up and down, creating the potential for belt rub (it sounds like codith is finding this out).

Usually, a shorter belt is required for 3.0 and smaller. You might try a 4" idler with stock tensioner pulley and stock belt. The bigger idler will help lesson the belt rub.

A smaller belt will also help lesson belt rub by pushing down on the tensioner.

Having the belt almost rubbing is good because you get a nice wrap around the SC pulley.

turtleman wrote:

Basically I'm going to a slightly shorter belt so that I can use go about 3.4 to 3.0 S/C pulleys without using the monster grooved pulley (since it's not available in 8-rib)

Smoothflowpulleys will make you any size pulley diameter you want in 6 or 8 rib with removable / replaceable bearings.
Just another option.

AA wrote:

Using albert's method can work, but pay attention to the fact that the tensioner can move up and down, creating the potential for belt rub (it sounds like codith is finding this out).

Usually, a shorter belt is required for 3.0 and smaller. You might try a 4" idler with stock tensioner pulley and stock belt. The bigger idler will help lesson the belt rub.

A smaller belt will also help lesson belt rub by pushing down on the tensioner.

Having the belt almost rubbing is good because you get a nice wrap around the SC pulley.

Right!

Alb

I ran into a problem

8rib balancer's on. Mount didn't drive me too crazy. Oh wait I spoke too soon. The lower idler pulley in 8rib touches the motor mount bracket. What now?





Ewolfe, what did you do here??

I can't remember right off hand, it was done last year. I know there wasn't any grinding involved. I tried going out to my garage to check but my key doesn't work and the garage door opener is over at my parent's place inside my Bronco. I will stop by their place this afternoon to grab it and let you know how much room I have with my pulley. With all the photos I have, I can't find one good one that shows the 8rib tensioner either. You should have plenty of room looking at some of my other photos with the OEM pulley on. Call Paul 317-436-4004

found a photo but not a very good one. At first I though I might have used the original because its almost wide engough but that wasn't the case. My idler is not a plastic one like the one you have but a metal one instead. Paul should have the PN.

The lower idler in your picture looks like the original 6rib width. I'm thinking that's the way it's gotta be but I'll check with Paul. My S/C idler pulleys are all metal. The only pulley that's plastic is the accessory belt tensioner. The original pulley has a little extra edge room so I guess it wouldn't be too bad.

*Happy!*

Ok I've got the solution and I couldn't have prayed for a more perfect one. The answer is 38033 by Gates!





All 90mm pulleys - The left one is the stock lower idler pulley (6rib). The right pulley is an 8rib (that doesn't fit under the motor mount bracket) The middle one is a compromise. It might be for a 7rib belt but I didn't check the actual application. It does fit under the bracket though, barely and it also lets you use the crazy OEM bolt with the giant flange and built in shank, unlike the 8rib.

That's the 8rib belt on the 38033 pulley - looks fine to me



That's ZZP's powerbond 8rib balancer - no problems with that.





Looks like the 716 belt is the one. Along with the 3" and 3.5" tensioner and grooved idler pulleys, it handles the 3.2-2.8 S/C pullies beautifully.

That half inch or inch in my case goes a pretty long way for the belt.

Is the ZZP balancer oversized?