50-N alternater for Scenicruiser?????

jackhartjr · May 16, 2009, 08:01:00 PM

Hi folks, I am not near my books right now.
Did the Scenicruiser come with the 50-N alternator? It would have had to be a 12 volt.
Thanks
Jack

roadrunnertex · May 16, 2009, 08:27:27 PM

Yes a 50 DN positive ground alternator.
Check with Tom McNally he might have a spare core in his collection.

jlv/roadrunnertex

jackhartjr · May 16, 2009, 08:34:02 PM

Thanks buddy...now the question would be this...would you rather have the gear driven 50-N or a belt driven alternator?
My thinking is that the gear driven would be more dependable?
Any thought?
Thanks again!
Jack

luvrbus · May 16, 2009, 08:43:15 PM

Belt drive Jack when a 50DN gear driven brakes a gear or the nut comes of the shaft they will destroy a engine doesn't happen often but when it does not a pretty sight, plus you don't have the oil leaks to deal with good luck

JackConrad · May 17, 2009, 04:50:13 AM

Quote from: jackhartjr on May 16, 2009, 08:34:02 PM
Thanks buddy...now the question would be this...would you rather have the gear driven 50-N or a belt driven alternator?
My thinking is that the gear driven would be more dependable?
Any thought?
Thanks again!
Jack

When we installed our new 8V71, we changed from a gear drive 50DN to a smaller belt driven, air cooled alternator. We never had any problems or oil leaks, BUT??. Better safe than sorry. Another factor in our decision is that we now have very little 24 load on our coach. Jack

RJ · May 17, 2009, 10:31:04 AM

Quote from: luvrbus on May 16, 2009, 08:43:15 PM

Belt drive Jack when a 50DN gear driven brakes a gear or the nut comes of the shaft they will destroy a engine doesn't happen often but when it does not a pretty sight, plus you don't have the oil leaks to deal with good luck

Luvrbus -

In my 25+ years in the bus industry, I never ran across a gear-driven 50DN that failed in the manner you describe.

Can it happen? Sure, just like anything else can break.

GMC (and others) built thousands of buses with a gear-driven 50DN - even MCI switched.

Guess the factory didn't know any better. . .

Jack -

To answer your original question, yes, the Scenics did have a gear-driven 12v 50DN alternator, but that was AFTER they were re-powered with the 8V71s in 1961-1962. Not sure what they had with the original twin 4-71 set-up.

FWIW & HTH. . .

luvrbus · May 17, 2009, 10:57:42 AM

RJ, I have seen 2 V692'S destroyed were the gear failed and one were the nut came loose and destroyed it, but don't take my word for it call A&A Diesel in Needles Ca (928-788-0068 and talk to Andy he did the 25,000 repair for the school were the nut came loose.FWIW Cat had problems with the gear driven and did away with in the 70's good luck

zubzub · May 17, 2009, 12:25:49 PM

The reason I would suggest the belt driven is that there is more of a chance you can find a change out/whatever if needs be on the road. A few hardware mods and your off. I've had to change in different alts on gas engines and generally a few bolts and washers maybe another piece of slotted steel bolted on and away I go.....OTOH a decent alt lasts a long long time....

Busted Knuckle · May 17, 2009, 07:15:46 PM

Quote from: luvrbus on May 16, 2009, 08:43:15 PM
Belt drive Jack when a 50DN gear driven brakes a gear or the nut comes of the shaft they will destroy a engine doesn't happen often but when it does not a pretty sight, plus you don't have the oil leaks to deal with good luck

Quote from: RJ on May 17, 2009, 10:31:04 AM
Luvrbus -

In my 25+ years in the bus industry, I never ran across a gear-driven 50DN that failed in the manner you describe.
Can it happen? Sure, just like anything else can break.
GMC (and others) built thousands of buses with a gear-driven 50DN - even MCI switched.
Guess the factory didn't know any better. . .
Jack -

To answer your original question, yes, the Scenics did have a gear-driven 12v 50DN alternator, but that was AFTER they were re-powered with the 8V71s in 1961-1962. Not sure what they had with the original twin 4-71 set-up.
FWIW & HTH. . .

RJ,
I know you've been around these things much more and longer than I have, but I personally have seen it twice myself. And it also happened to a member here on the board a couple yrs ago. I can't recall who it was right off but I remember reading about it.
It may not be common, but it can & does happen, and it causes some serious damage.

BK

jackhartjr · May 17, 2009, 07:30:02 PM

Thanks for all of the replys!
Looks like I will stick with the belt driven alternator.
Being that there is one there that can be rebuilt...not a hard choice.
Thanks again.
Jack

Airbag · May 17, 2009, 07:37:15 PM

Is there no cotter pin on the nut? I am not real experienced with these type of engines but I been working on engines for aircraft with over 2000 hp with all accessories being gear driven and all with cotter pinned nuts, I have never run across one that did that. Perhaps it's because of the constant rpm changes that occur in a bus.

RJ · May 17, 2009, 10:13:52 PM

Quote from: Busted Knuckle on May 17, 2009, 07:15:46 PM

I know you've been around these things much more and longer than I have, but I personally have seen it twice myself.

BK & Lin -

On the engines that failed, were they low mileage or high mileage units?

Lin · May 17, 2009, 10:27:28 PM

RJ,

I think that you meant Luvrbus, not me. I have no experience with this stuff. I am routing for the gear driven since I have one to sell (shameless commercialism).

Zeroclearance · May 17, 2009, 11:05:35 PM

The speed of the rotor is around 6000 to 6500 RPM's.. If the nose bearings have worn, there will be motion/movement. This will create a imbalance>and will/can shake the nut right off the shaft. I have seen it happen with turbochargers. I have actually tore down a belt driven unit this weekend. If one goes to the Delco site you can read up on the various upgrades that have been implemented with this alternator. Rotor upgrades, stator upgrades, oiling, bearings. I think that it's a nice piece of hardware.

Busted Knuckle · May 18, 2009, 07:45:48 AM

RJ,
In the case of the 2 I have personally witnessed it was definitely high mileage! Our friends and us are poor folks who started out with nothing and still have most of it left!

BTW even the new junk we bought has troubles now and then. Just last week a fitting on the main hose coming out of the air compressor vibrated out and I couldn't build air pressure. It took us a while to find it, no cost to fix, but in the 90 mins it took to find & fix it we lost a $5,000 trip. (huh oddly enough that's almost the amount of the payment on that junker! $4978.00)

BK

50-N alternater for Scenicruiser?????

Airbag