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Author Topic: Electrical question...  (Read 3129 times)
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1954 Scenicruiser PD4501-227

« Reply #15 on: May 08, 2011, 11:19:46 AM »

John I was going to do some calling next week about the diodes. If you have the numbers handy though, it would be 12 volt negative ground diodes for the 50DN.

Luvrbus I was concerned about the gear failure issue to with this thing. I wonder as a percentage, do they have a high failure rate? Is it common enough I should lose sleep over it? I dunno? I have a spare belt driven alternator I was going to make a mount and put it on and eliminate the gear driven one, but it is only 85amps. When the gear driven one started charging I was actually excited about a simpler solution...maybe


Boyce Rampey
Columbia, SC
Scenicruiser 227
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'75 MC8 8V71 HT740

« Reply #16 on: May 08, 2011, 12:37:51 PM »

As with many busnut circulated myths, lack of preventive maintenance or re-using parts that shouldn't be re-used are the root cause.

Fascinating that these warnings surface after the configuration has substantially left commercial service?

The commercial carriers carped about oil leaks with the gear drive alternators, those with ruined gear trains had themselves to blame for re-using drives. Fresh drive goes with a fresh alternator, fresh drive goes with engine re-build, job done.

Short cuts and "cost savings" have their risks. If you don't want to spend the money, by all means, convert to a belt drive to minimize the risk.

However, I'd rather correctly blame the flawed methodology rather than a unit that served the industry quite satisfactorily for a couple of decades.

happy coaching!

Frozen North, Greater Toronto Area
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« Reply #17 on: May 08, 2011, 08:06:10 PM »

What BW said.....for absolutely sure.  My only intent was to caution you about turning a blind eye to a piece of equip that might ruin your next two years.  You seem to be in there and kicking around so I got you what i have learned about it and the dangers.

The engines that get rebuilt are often done by a shop that has given a quote and wants to live within the bounds of that quote.  I guess to be generious to all the shops in the world they "thought it would be OK if used by a private party for recreation"....bus Knut.  If it were a customer like BK they would simply pic up the phone and say "your gears look a bit iffy and expect him to ask why they haven't installed new ones.  hen there is the "home grown shade tree mech", such as myself, that just doesn't understand all the pitfalls.

I think Clifford once said that the alt gears have a lash adjust.  That adjust must have a limit and should flag gears that are near the end of their life and are close to ending the life of your engine.  I think Don Fairchild or Clifford or Luke at US coach or HTRN could answer these questions and a couple of those have shops that will do the job for a reasonable cost.

You get to altitude on a cold day and the bats might start to be worked really hard and get depleted in a single start effort.  85 amps might not be enuff in some sever circumstance and they put in that monster alt for a reason.  If it was going to cost me over $400 i would have that belted job installed and connected.  My battery charger and the genny is for emergencies.  But if it were within reasonable costs I'd stick with the BW advice....."it worked for 20 or 30 years so it isn't a bad design".


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