My unit had a 6 rib belt on 8 rib pulleys.
As far as I know, it was the original belt as the coach had 31000 miles when I purchased it
There has been some posts relating to these belts and tension'rs.
I wonder if any and all with the 6V92 engine would respond as to what belt (6 or 8 rib )they have on their engine, and if the belt is riding in the center of the tension'r .
Also any troubles with either belt.
bill chaplin
1993 6V92
Hi Bill, I do not remember what was originally on my 6V92 however it broke and I replaced it with a Gates Micro V K080450 which did not hold up ! I then got a - N.A.P.A. Micro V 080450 that now has 10,000 miles on it, I also purchased a spare CarQuest Heavy Duty K 080450HD which I carry with me - Just in Case, So far no more issues I think the original one broke from being old and sitting idle for a long time. I believe that the second digit relates to the number of ribs ( 080450HD)
I was told by two of the old time Foretravel Techs that the six rib belt was originally used by Foretravel on the 8 groove pulleys. This allowed slight offset in pulley alignment without causing any problems. I have chosen to stay with the 6 rib belt as it has performed well for nearly 20 years.
Serpentine belts will have a part number and a metric part number. In the case of a K080450, this is a metric part number with the K indicating automotive use, the next two are the number of ribs, 8 in this case and the 0450 indicating the EFFECTIVE length in cm (centimeters). This length is NOT the outside length but a midway measurement.
I believe the CarQuest and NAPA belts are all manufactured by Gates. The HD model is about $10 more over the counter, less if ordered on-line.
Any misalignment between the crank and hydraulic motor pulley WILL cause wear on the belt and may cause it to jump over a groove. This can be easily measured and corrected. My stock car engine builder was very detail oriented and always used a puller to move the water pump pulley attachment so the top pulley lined up exactly with the crank pulley in blueprinting the engines. He did all of Bob Bondurant's engines and I don't every recall either one of us loosing a engine in SCCA or NASCAR/PRA.
The 8 rib belt will have no choice but to run down the center of the crank and motor pulleys since they are also 8 ribs with shoulders on both sides but should sit right in the middle of the tensioner roller. A new belt should be frequently inspected for any fraying on either the inside or outside of the crank pulley. Any fraying indicates the tensioner roller is at a different angle than the crankshaft/hydraulic motor pulley or the hydraulic motor pulley is also out of alignment. It may be shimmed to correct the angle discrepancy and also to make sure the belt rides in the middle. This will insure a long belt life and keep you off the side of the road.
Pierce
I repeat
I wonder if any and all with the 6V92 engine would respond as to what belt (6 or 8 rib )they have on their engine, and if the belt is riding in the center of the tension'r .
Also any troubles with either belt.
Especially, is the belt riding in the center of the tension'r pulley.
I believe this is ' most important ' in belt wear.
Bill,
Ours came with a 6 rib installed and two more 6 rib spares. Can't get the 8 rib on the road as few spots carry it. As I have posted, the alignment was 3 degrees off. Mounting bracket was square but the 3 degrees was in the tensioner. Belt was riding against the outside shoulder on the crank pulley.
Pierce
@Bill Mine came with a 6 rib belt. Lost it while climbing Wolf Creek pass in Colorado. I replaced with a 6 rib until I could get an 8 rib. I have about a 1,000 miles on the 8 rib. Rides true and clean with no fraying on the sides as of yet.
see ya
ken
Bill, my 6 rib does not run in the center. I have had to raplace one belt since I bought mine in August of 2010. I have over 30,000 miles on the current one and it shows no sign of wear even though it runs "on the edge".
Maybe a good time for a Poll setup for this goofy belt issue/issues, with all the posibilities spelled out. Would allow every one to cast a vote / guess and might give a clue ?
Who sets up the Polls ?
FWIW
Dave M
Just so people know on '91 and prior years of U300's that belt was not used. The hydraulic pump is mounted on the other end of the engine and has no belt. It's direct drive off the internal gear systems of the engine. The pump is used only for power steering. The rear radiator fan is powered directly by a set of V belts.
Looking at the specs for the '95 U300, the CAT engine is standard - I don't know if the Detroit was even an option.
So I think this belt is only used on the '92 - '94 U300 - not a terribly large population.
Yes, on the '91 and earlier, the radiator was at the rear instead of the side and did not need a hydraulic motor to drive the fan so only a small pump for power steering like John said. Rear radiator design was not efficient enough to handle 350 hp and keep the engine cool so it only had 300. The side radiator has enough trouble cooling 350 hp on hills in triple digit temps.
GM buses with Detroits used PTOs to run a very large fan for their large side radiators.
Pierce
My 93 U280 with a Cummins and side radiator has the hydro-static pump. I was having a tough time with that belt fraying until I had the idler changed out. However I am running a six groove belt BUT on six groove pulleys. Interesting that they would use an eight groove pulley on the U300 and a six groove pulley on the U280 with the Cummins.
Roland
The 350 hp Detroit will require more cooling than the lower hp Cummins. Undoubtedly the reason for the 25 percent increase load capacity the 8 groove belt has.
Our U300 has two hydraulic motors. Width (strength) of the belt will also depend on the rated output of the pump, size of the motors, fan size, pitch and fan rpm. The belt requirement will total the strength needed for the gallons per minute required for max fan rpm in the high speed position and the pressure needed to achieve this rpm plus a percentage for a safety margin to minimize failures and achieve long life.
Any explanation by a company employee of a 6 groove belt being used on a 8 groove pulley to correct for a misalignment problem would be a poor solution and a terrible example of the quality of the component assembly process in making the coach ready for delivery to the customer. This kind of methodology would see misalignment on a 6 groove pulley cured by installing a 4 groove belt.
Pierce
Small side note;
Does any one realize the belt has to transfer aprox. 30-35 hp to run the fan and steering system. So why the 8 rib HD belt is so much better. :o
FWIW
Dave M
Bill,
After installing a new 8 ribbed belt and and adding an adjustment washer as prescribed by Pierce to fix the tensioner angle problem I drove the U300 for about 60 miles . When I got back I checked everything with the motor still running and observed the belt centered perfectly on both pulleys and there was hardly any bounce on the tensioner. I feel very confident about the remedy at this point and will check the belt and the tensioner frequently, and also as part of the pre travel checklist.
Jerry