alternator belts

christopher · July 25, 2018, 08:41:47 PM

hi
just replaced the 4 belts that drive the alternator.
What would cause one of the inside belts to wear so quickly on the edges to the point of failing?

thanks Much
Chris
MCI5C 78

Ed Hackenbruch · July 25, 2018, 08:54:02 PM

Check the big bolt that acts as the pivot for the alternator, if it is worn down or one of the ears that it goes thru is worn down and it wiggles just a little, it will throw off the alignment. You might have to shim it to take out the slop.

buswarrior · July 26, 2018, 06:40:56 AM

Alignment is everything.

Very hard to "eyeball" in there, too many angles.

Get a carpenter's straight edge and be sure it touches the front and back of both pullies.

It is pretty easy to knock those out of alignment, you invariably put your weight on it, climbing in there to reach, combined with a less than tight fastener on the mounts...

The life of the belts is the proof of your attempts.

Happy coaching!
Buswarrior

Dave5Cs · July 28, 2018, 04:57:22 PM

I feel inferior now my 5C only has 2 belts on the alternator, LOL

chessie4905 · July 28, 2018, 05:01:05 PM

I don't feel bad and my alternator has...................NONE!😁

Geoff · July 28, 2018, 05:56:22 PM

Quote from: chessie4905 on July 28, 2018, 05:01:05 PM
I don't feel bad and my alternator has...................NONE!😁

You don't have to feel bad, but you need to be worried about your 50DN seizing up. Before I replaced mine with two belt driven alternators, I was always worried.

Geoff · July 28, 2018, 06:03:20 PM

Quote from: christopher on July 25, 2018, 08:41:47 PM
hi
just replaced the 4 belts that drive the alternator.
What would cause one of the inside belts to wear so quickly on the edges to the point of failing?
thanks Much
Chris
MCI5C 78

You know that you can buy a new belt that has 4 drives/links so it is one belt instead of 4 individual ones. It is in the belt number. I had to call Dayco and they gave me the full number for one belt.

chessie4905 · July 28, 2018, 06:49:57 PM

Thousands of gear drive 50 Dn's put on millions of miles. Some believe half of them failed. Yes, they can fail and it can be costly. I wonder how many have checked theirs or updated the oiling or bearings.

luvrbus · July 28, 2018, 07:40:56 PM

A 2 stroke bus engine is the only place you will find a 50 gear driven ,they fail more often than you hear about,LVMCI was the latest causality that I know of the 50D cost him a 8v92TA

richard5933 · July 29, 2018, 04:32:53 AM

Quote from: luvrbus on July 28, 2018, 07:40:56 PM
A 2 stroke bus engine is the only place you will find a 50 gear driven ,they fail more often than you hear about,LVMCI was the latest causality that I know of the 50D cost him a 8v92TA

Are there warning signs of a gear driven 50 about to fail? Is there a normal life span after which they should be rebuilt as a precaution?

When they were in commercial service I doubt they just waited for them to seize up, so perhaps there is something we (that have the gear driven 50s) can do to help protect them.

chessie4905 · July 29, 2018, 05:15:05 AM

They did recognize some failure issues. They modified the oiling with an additional line to the drive end bearing and redesigned drive end bearing to be more durable with tighter clearances. They still sell them, even new ones. Gear and belt driven.

Here's some info on it.
http://busfixx.tripod.com/busservice/id23.html

luvrbus · July 29, 2018, 06:11:27 AM

The biggest improvement made on the 50's is when they went to the drum style sun drive,then that took awhile for Detroit to figure out how to stop the cam breakage caused by it and they still break cams just not as often now ,belts are a better option

chessie4905 · July 29, 2018, 06:22:44 AM

There was a service bulletin for city busses to change idle speed or fast idle speed. Apparently the harmonics at a particular low speed caused camshaft breakage.

luvrbus · July 29, 2018, 06:43:16 AM

I don't know about the city buses but they tried the higher idle speeds on the T drives with DDEC engines and electronic transmissions. When the 700 series electronic transmission saw a idle speed over 600 rpm they would go into gear.I still run across that people get a rock or something under the pedal and the idle goes up they cannot shift to make it move and the transmission can behind a mechanical engine and still do that

DominicM · July 29, 2018, 05:35:52 PM

On my trip from Houston to Midland TX, I burnt up 4 belts. The PO claimed I must not have waited for the air to build up enough to pressurize the tensioner. I replaced the belts, drove to Nashville and burnt up another set of belts. When I went to replace the belts I discovered the 50D was seized. I ordered another one, put it on and no more issues so far and I have driven from Nashville to Houston, to Big Spring. This one does have a grease zert. How often do I need to grease tithes unit?

Im glad mine was belt drive, belts cost me $28 for all 4.