Eagle 05 Fan Belt Expert/Advice/Engineer

[eagle19952]

Well i finally figured out how to get admin posting approval, so here is my first post here,I have got help in the past over at BNO,some of you know me some don't,I'll post an intro soon.
I fulltime,been in the coach (primarily since 2005).
If there is anything that I dislike about my Coach,this is it.
Facts:
1977/8 Eagle 05
8v71n
mitre box drives fan (plastic) and alternator.
Fan belts two (Gates B86) 89 inch circumfrance
21/32 wide.
Problem:I average less 6000 miles per set.
Are these the correct belt ?
My adjuster/adjustment is a pivotal idler with a stub dowel ON THE BEARING/SHEAVE PLATE that appears to be a/the fulcrum point to utilize a pry bar to accomplish the tension adjustment.Is this the stock/original set-up ? IIRC, THE PIVOT BOLT IS 3/4" and the holding bolt is 5/8"
I have tried (in vain) to find EXACT Matched sets.
Currently one belt is in the sheave groove (properly),the other is rolled over in the sheave.
The longest lasting (current)set was installed using a small bottle jack to adj.the tensioner,(jacking on stub/pivot pry point)...pry bar installed belts have never made 6K miles,even with a cheater pipe....they have slipped and burned up,(lol,i can smell it starting 40 feet away,gives me maybe a mile and a half to get to a safer place so i can put out the triangles and flares...lol)
I am wondering if a C86 belt which has a 7/8 top width is the correct belt vs the 21/32 that is there.
the cost of replacement is no big deal,but the location of replacement can be a PITA...
any thoughts,I don't want a hyd/air clutch fan,I just want to get a real life expectancy from my belts.
I have replaced a LOT of belts in my time but these have me stumped.
Any thoughts ?
PS.I KNOW THAT THERE ARE SEQUENCING NUMBERS ON BELTS,THAT THEY ARE CUT FROM A "PIPE" AND THAT MATCHED SETS ARE NUMERICALLY CORRESPONDING.
DOES ANYONE KNOW A DISTRIBUTOR THAT WILL SHIP MATCHED SETS,I think that is my problem....but
any thoughts or education or experiance APPRECIATED !!!!.
PS hope i have made an understandable post,getting my thoughts on paper isn't my strong suit....
i rode in the small yellow bus

[SmoothJazz]

The B-86 matched set of two belts was used on bus serial numbers 7444-8653. Starting with bus serial no. 8654 and higher, it changed to part number 449-X-S also a matched set of two belts. Not sure what the difference between them are, but there was a change and the 449-X-S was also used on the Eagle Model 10's and 15's with the miter box drive. There was also a siamese belt used on later models.

[beltguy]

The industry adopted a "no match" system many years ago. What this means is that INDUSTRIAL belts (the B86 is an industrial belt) does not have to be ordered as a matched set. The manufacturers tightened their length standards and that allowed the "no match" system to work. Worked well for many years. My guess is that one or more of your pulleys is badly worn, or the drive has somehow become misaligned. It is very hard to check alignment, but you can sight along the strand of the belt to see if there is any kinking.

Once a belt has turned over, it will not stay upright. The edge cords will have been damaged on one side.

I can't tell if you were saying that you "pried" the belts are. Any significant forcing will damage the belt. If you can't get them on easily, remove one of the pulleys, put the belts in the groove and then install the sheave.

I did not check, but many of the "B" sizes have a "BX" equivalent. That belt has notches in the bottom of the belt and premium material. The "B" section belts worked for years and should work on yours if you have properly installed them and checked to makes sure the grooves are not overly worn or that the belts are not misaligned.

Would not be a bad idea to check the bearings in the fan stub shaft or the idled to make sure there is not an issue there.

Jim (34 years at Gates)

[eagle19952]

First Thank-you all,I am posting over on BNO too...
a little more added info...
Instant responses,gotta love it.
My coach has an oversized radiator.
The fan shroud to blade tip clearance is less than 21/32....I just walked out to make sure I wasn't cookoo...it is plastic.
The miter box is not adjustable,the diveshaft has no effect.....the sheave bearing box "ie:approx. 8" round with grease fits is not adjustable,one side drives the alt, inside sheaves drives the fan..)..it is bolted no slots...
the super structure angle posts (2" square tube)support member for the adguster seems true...tho perhaps i might could shim it out towards the radiator....the fan "hub" is a pillow block bolted into what appears to be a 1/2" plate..
I just don't see much facility to move the alignment.
On my coach with the adjuster pulley slacked off all the way it is a tight squeeze to slip the belts over the pulley edge.I know I am not bottoming out the adj.
Does/is my fan drive system stock ??.
The coach was maintained by Krause Bus sales in San Antonio,since the day it was new,I am told,and that they did maintenance for Trailways almost from the beginning.....
If it is an alighnment problem
how would you go about re-alighning....there ain't much room in there...I will check with a straight edge tho...

PS.by pried i mean that I use a bar to pry on the adjuster "stub"but never the belts.
Thanks again
I am near Pensacola/FT. Walton,all is well, I got plenty of time,actually parked up in Milton.

[eagle19952]

The B-86 matched set of two belts was used on bus serial numbers 7444-8653. Starting with bus serial no. 8654 and higher, it changed to part number 449-X-S also a matched set of two belts. Not sure what the difference between them are, but there was a change and the 449-X-S was also used on the Eagle Model 10's and 15's with the miter box drive. There was also a siamese belt used on later models.

MY COACH IS #19952.But seriously what would the collective expertise consider the "tolerance" of true alighnment? .060"....more .125 sounds a bit much maybe...

[akroyaleagle]

I've read your threads on both boards.

I'm with Clifford. I believe you will find the problem to be worn Pulleys.

I may still have the stock pillow block pulley from mine. You can have it for postage, if interested, and I can find it. I had an oversized one made to speed up my fan when I was trying to solve a cooling problem when I first got the bus.

You will have to locate the idler and fan pulleys. Shouldn't be too hard.

My Eagle is 19902

[eagle19952]

I've read your threads on both boards.

I'm with Clifford. I believe you will find the problem to be worn Pulleys.

I may still have the stock pillow block pulley from mine. You can have it for postage, if interested, and I can find it. I had an oversized one made to speed up my fan when I was trying to solve a cooling problem when I first got the bus.

You will have to locate the idler and fan pulleys. Shouldn't be too hard.

My Eagle is 19902

Wow they are almost sisters.I will certainly keep your offer in mind.
I am thinking that you are right. I just like to sort things out before taking a leap.Lots of expertiseon these boards to sound off ideas.

[buscrazyinFL]

I have a 1972 Eagle 05 and my fan belt # is Gate# B85, 21/82" X 88". If the pulleys are not aligned your belts will flip over. I experienced this with my alternator. I had to change the belts and had trouble adjusting the tension on the pulleys because the adjuster arm was worn, so I had to take it in to the shop and they put a turn buckle (see pic). That corrected the problem.When I have my blower replaced and the engine out of the way, I'm going to replace my fan belts. Hopefully, I won't have the problem you are having.

[beltguy]

Bumping another fan drive thread to the top.

Jim