| Author | Message | |||
| Gary Pasternak (Cessna5354)
Registered Member Username: Cessna5354 Post Number: 36 Registered: 2-2007 Posted From: 64.12.117.73 Rating: N/A |
Back from a week trip to SC & NC. But on the return trip, we lost the alternator drive belts. BUT, My question is that this is the second time in 4 years that the pulley sheave on the alternator loosened and wobbled enough to throw the belts, and ruining the splined armature shaft. It backed off the locknut which baffles me. I need direction on my solution, which I see there are three. 1. I can pick up a replacement from Nimco and reinstall without warranty. Hopefully not repeating the same episode as described above... 2. I can pick up a 24V truck alternator ie 75 - 100 amp would be plenty. I would have to fabricate a bracket to mount the alternator, which I am thinking would bolt up to the existing pivoting cradle. Bus air has been removed. The alternator charges the start batts & thru a Vanner also charges the house batts. 3. I could take the existing alternator, remove the armature and have the shaft turned down to about 7/8 inch, cut a keyway, and source a sheeve which matches the original with a taper lock bushing inside to mate to the newly cut 7/8 inch shaft & keyway. Install with proper belts and go. I am really bummed about this repeat failure, but I did pull the alternator much quicker this time. It is a heavy unit. All thoughts much appreciated, Thanks, Gary | |||
| RJ Long (Rjlong)
Registered Member Username: Rjlong Post Number: 1471 Registered: 12-2000 Posted From: 67.181.166.160  Rating: N/A |
Gary - A fourth alternative: Make it a gear-driven unit like the later model MCIs and all GMCs - very, very rare to have one of these fail. OTOH, the truck alternator is a good idea, too. Especially since you don't need the heavy electrical output for the OEM HVAC. I suspect you run the genset to power the A/Cs in the summer while running? Have you got a 71 or 92 in your 5C? FWIW & HTH. . .  | |||
| Gary Pasternak (Cessna5354)
Registered Member Username: Cessna5354 Post Number: 37 Registered: 2-2007 Posted From: 64.12.117.73 Rating: N/A |
RJ, You are in agreement with Luke's suggestion, I do use the genset for roof air op's. Actually do not run in the dead of summer and use the roof airs sparringly. I have a 6V92 TA. How much work to install the gear off the cam etc ?? I have the pulley takeoff now, and was looking to work with that. I get your point on the geared alternator, however, That is a lot of hung weight off that geared mounting. But done often. I will have to tend to providing the tach another signal as I believe (NO I know) my tach is supplied a sig from the alternator. It was the initial indication of failure. Thanks, | |||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 726 Registered: 7-2006 Posted From: 70.152.204.47  Rating: N/A |
Re: "3. I could take the existing alternator, remove the armature and have the shaft turned down to about 7/8 inch, cut a keyway, and source a sheeve which matches the original with a taper lock bushing inside to mate to the newly cut 7/8 inch shaft & keyway. Install with proper belts and go. " Am I reading this right? It sounds like the alternator is being driven backwards? Is this an aux alternator? Need reverse threads, or -drill and pin- the nut and shaft? The keyway is good, but the nut's still not going to like being spun against it's "on" direction. (Message edited by john_mc9 on December 18, 2008) | |||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1432 Registered: 12-2000 Posted From: 76.66.18.42  Rating: N/A |
Hmmm... I'm wondering if the nut was properly torqued? Some loktite might be in order, I know I used the blue on the fan screws on my belt drive, they were loosening and you could hear it ringing. If you can get an inexpensive gear drive set-up, go for it, MCI lagged along with the belt drive for far too long, GM had theirs gear driven for many years. Good set-up, no worries. Otherwise, a more conventional alternator would be a less expensive option, as you don't have the need for that big alternator. happy coaching! buswarrior | |||
| Mark Renner (Boomer)
Registered Member Username: Boomer Post Number: 135 Registered: 11-2006 Posted From: 75.216.71.151  Rating: N/A |
There is a much simpler, cheaper and lighter alternative, if you can find the right part. Detroit Diesel made an alternator bracket that mounts at the left hand front of the engine (right side as you are looking at it) using the 4 bolts at the block heater plate. This bracket accommodates a regular truck type alternator, with the belt being driven from the front LH cam pully. The trick is finding the bracket. I used it on a 6V and it really was slick. A long time DD parts man looked it up for me. I suppose now it would have to be sourced from someone who has a lot of surplus 2 stroke parts. That way you can lose the problamatic 50DN. You will have to extend and relocate the cables. If you want I can post a picture of the application. Sorry, don't have the bracket part number. It's not common to the bus world. | |||
| Gary Pasternak (Cessna5354)
Registered Member Username: Cessna5354 Post Number: 38 Registered: 2-2007 Posted From: 205.188.117.73 Rating: N/A |
Mark, It is a small world, I was looking at the bracket you speak of last nite @ Lukes. He was working on a 8V92 engine, which was a truck takeout. First thing I noticed. It made the alt. sit fairly high, which the 5's have little headroom. But you are right on as it does not get any simpler. I will check it out at a truck graveyard. BW, been thinking about the torque spec, I tighten beyond my 1/2 inch T wrench. I used a 3/4 socket. Straight on locknut with nylon ring, no room for cotter pin and castelation nut as it sits within and inside the pulley. Gary | |||
| Mark Renner (Boomer)
Registered Member Username: Boomer Post Number: 136 Registered: 11-2006 Posted From: 206.58.200.38 Rating: N/A |
Here is a picture of the alternator mounted with this bracket.  | |||
| Gary Pasternak (Cessna5354)
Registered Member Username: Cessna5354 Post Number: 39 Registered: 2-2007 Posted From: 65.90.202.10 Rating: N/A |
That is different than the bracket I looked at which came off the rear of the engine. I do have more space in the rear curb side & a pulley avail as the OTR air has been removed. Need to look thru some truck graveyards. I like this which mounts the alt. on the engine, not the frame. Thanks & always a pleasure to see your bus in your sign. What a beauty !! Gary | |||
| Glenn Williams (Glenn)
Registered Member Username: Glenn Post Number: 176 Registered: 6-2006 Posted From: 35.13.214.231 Rating: N/A |
Gary, We found that bracket on an 8v92 and planned to mount it on my 8v71. It will not fit. The exhaust manifold and fuel lines are in the way. we placed it on top of the cradle as I posted on the other bbs. Good luck! glenn | |||
| Arnie Smith (Arniemc5a)
Registered Member Username: Arniemc5a Post Number: 4 Registered: 11-2008 Posted From: 24.71.46.230  Rating: N/A |
Something to think about regarding a gear driven alternator/generator... In the 1970's I owned a Freightliner powered be DD 8-71 which had a gear driven air compressor which was driven off the gear train that you are talking about. There was metal fatigue in the Splined collar that turned the compressor. the end result was the debris went thru the gear train on the back of the engine. It could mean replacing the cam shafts, and the crankshaft, as well as the housing that covers the back of the engine.. I was fortunate.. Only replaced one gear and the housing cover.. but I had to pull the transmission out, to effect the repairs.. On a coach, that means pulling the engine.. Chances are that it will never happen.... But I prefer the belts... Just something to think about Arnie | |||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 792 Registered: 11-2005 Posted From: 208.54.200.89 Rating: N/A |
As Arnie says, I will take a belt drive every time. There is nothing worse than bits and pieces of gears throughout the oil passages and in the crankcase. This is an old story with small aircraft engines and those are really big bucks. When a belt driven alt seizes only the belt gets damaged. | |||
| Mark Renner (Boomer)
Registered Member Username: Boomer Post Number: 137 Registered: 11-2006 Posted From: 206.58.200.38 Rating: N/A |
That is the downside of the gear driven alts, especially the ones that MCI mounted with the adaptor (there are two more bearings to fail in the adaptor). Bus owners quite often run the alts and adaptors more miles than they should, and if any of the bearings fail, the debris falls straight down into the gear train; one large chunk going thru these gears and the whole engine is ruined-visualize valves taking out the heads, etc. When I ran MCI's with 8V's and 6V's we overhauled the gear driven alts at 75K which is way less than they are supposed to live to, but an alternator kit is a whole lot less than an engine. We never had an alternator fail on the road. Good preventitive maintenance for anyone with a 50DN. | |||
| Gary Pasternak (Cessna5354)
Registered Member Username: Cessna5354 Post Number: 40 Registered: 2-2007 Posted From: 64.12.117.73 Rating: N/A |
I am staying with a belt driven alt. for all the above mentioned reasons. I looked this AM and there little room to accomodate a direct drive on this 5C. I spoke to Bob of the North,Gosh he is tall, yesterday and I am not looking to a tear down for mechanical reasons inflicted by a gear driven. I am looking at a Delco 24V truck unit 100A as to what brackets I must fabricate. Or I will turn down the existing shaft and install the taperlock sheave. A great friend who is a great machinist, needs security work on his building, which I can provide, a great barter. Thanks all again for your support and experience. | |||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1266 Registered: 10-2003 Posted From: 71.58.110.9 Rating: N/A |
Turning down that shaft will probably weaken a highly stressed area. Use a locknut without a nylon patch and TORQUE it to proper specs. Then it'll stay on. A T bar doesn't cut it. You could also use green LocTite on the clean threads for extra insurance. BTW, was that nylon locknut reused from the last time? You can get that non nylon locknut from McMaster-Carr on line if you can't get a good one locally.
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| Gary Pasternak (Cessna5354)
Registered Member Username: Cessna5354 Post Number: 41 Registered: 2-2007 Posted From: 64.12.117.73 Rating: N/A |
John, I provided insuffcient info, T bar, I meant torque wrench 1/2 inch. I used a 3/4 inch socket to tighten with my 245 lbs. To your point this design worked for years without major problems, but they did transition to direct drive for some reason. The shaft at 7/8 dia. I beleive will take the load of what I am using, but I agree that I am taking metal out of area which was beat up. But if I keep the belt tension correct, I think the load on this shaft will be managable. A new nylon locknut and sheeve was used, from MCI. Thanks still looking at options, If I go to an aftermarket smaller one wire alternator, I will need to find another source signal for the tachometer, currently feed from the stock alternator. Suggestions for the alt tach source ?? Thanks All, | |||
| Tom Caffrey (Pvcces)
Registered Member Username: Pvcces Post Number: 1241 Registered: 5-2001 Posted From: 65.74.69.188 Rating: N/A |
Depending on how handy you are, Gary, you can take another alternator apart and make the same connections in it for your tach. Finding a good place to anchor the lead will be as hard as anything; the feed is through one or two diodes, and the diagram is in our service manual. A one wire alternator has the disadvantage of being kind of dumb about how it charges batteries. Good luck on your setup. Tom Caffrey PD4106-2576 Suncatcher Ketchikan, Alaska | |||
| Gary Pasternak (Cessna5354)
Registered Member Username: Cessna5354 Post Number: 42 Registered: 2-2007 Posted From: 64.12.117.73 Rating: N/A |
Thanks Tom, I did speak to a rebuilder yesterday, and the tach voltage is 1/2 the 24V output. Now I need to mind the pulley ratio to maintain a relative same to insure correct rpm readings, if it was correct before? Today it will be pulling armature from orig. alt. I did source a Delco 25-1S or(S1). This is 100A, with the R term for the tach. signal. I am leaning this way, just need to fab brackets. Enjoy the Day, | |||
| Tom Caffrey (Pvcces)
Registered Member Username: Pvcces Post Number: 1242 Registered: 5-2001 Posted From: 65.74.69.188 Rating: N/A |
Gary, a photo tach will give you an accurate reading on the new installation so that you can set the DIP switches correctly, if you have them. There are other methods, but if you have the instructions for the tach, the switches make it easy. If you don't have them, you may need to do some research to find out how to set them. Good luck. Tom Caffrey PD4106-2576 Suncatcher Ketchikan, Alaska | |||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 793 Registered: 11-2005 Posted From: 12.189.32.58 Rating: N/A |
Tom, I used to think the same thing about one wire alternators until I found one the spring of '07 that is different. It is a 100 amp Leech-Nevill(sp) truck alt and only cost about $150 with no core necessary. I don't know if they are made in higher amp sizes because 100a is plenty for me, but I can say that if has performed flawlessly all this time and I am very happy with it. It charges at low rpm and works just like a three wire alt as far as I can tell so far. It was a revelation to me because all the one-wires I had seen before required pretty high rpms to work and were kind of a pain to use. | |||
| Tom Caffrey (Pvcces)
Registered Member Username: Pvcces Post Number: 1244 Registered: 5-2001 Posted From: 65.74.69.188 Rating: N/A |
Hi, Gus. My comment about one wire alternators being kind of dumb is related to their inability to monitor batteries, not their ability to produce power. If they don't monitor batteries, then there is no really effective charge voltage; it's either too high or too low, much of the time. Leece-Neville makes good alternators, including some that don't need any outside power to start. They're really popular in boats. Tom Caffrey PD4106-2576 Suncatcher Ketchikan, Alaska | |||
| Mel La Plante (Mel_4104)
Registered Member Username: Mel_4104 Post Number: 107 Registered: 7-2006 Posted From: 64.180.196.23 Rating: N/A |
Gus where do you get leece-nevelle alternators as we only have a source but require part #,and do you have a phone # for the shop? | |||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1270 Registered: 10-2003 Posted From: 71.58.110.9 Rating: N/A |
My 4104 has a Leece-Neville 160 amp 1 wire. Has been on coach for 20 years. Never had a problem with it. It was a reman. unit, about $180 at the time. Replaced the pita 180 amp GM with third brush and large point voltage regulator. It's now belt driven and trouble free. Has a small screw for voltage adjustment. | |||
| Ralph Peters (Ralph_peters)
Registered Member Username: Ralph_peters Post Number: 3 Registered: 12-2008 Posted From: 206.251.11.109 Rating: N/A |
Mel. Here in Pa. the Freightliner dealer has a large dislpay/parts area, seats,lights,exaust parts,starters,alternators,etc. and prices on most all. Yes the alternatorsare there, but I think they were more like $150.00 no core exchange,either type mount. | |||
| Gary Pasternak (Cessna5354)
Registered Member Username: Cessna5354 Post Number: 44 Registered: 2-2007 Posted From: 205.188.117.73 Rating: N/A |
Well I have made the decision to abandon the orignal 50DN, and lighten the bus by 85 - 90 lbs. Pulled out the air lines for tensioner, reg, and capped off the oil lines. Will use the cradle base for the J180 mounting for the Delco alternator. Cheapest LN alternator was a new unit for $965, rebulder in Vineland. No rebuilts avail. I might try the Freightliner in 717 area code. I can source a Delco 25 1S for $ 180. My rebuilder did offer his opinion that Delco and LN designs over the years were not too far apart in robustness. His opinion, not mine, Flamesuit On. I might try to change the PTO pulley as it is only a 3/8" belt, not 1/2". I have a PTO pulley above the crankshaft which I might exchange as it is a 1/2". Some one prev. suggested I mount the alt in this area, but looking I would be able without interference of the coolant piping with this other pulley,but no real substancal structure to mount. Also the rotation was reversed. Have a great day all!! | |||
| Ralph Peters (Ralph_peters)
Registered Member Username: Ralph_peters Post Number: 4 Registered: 12-2008 Posted From: 206.251.11.109 Rating: N/A |
Just called two truck shops both have same 150A.,new about $170.00 -$180.00 no exchange, 3 ear mount. I mounted a 12V. 60A. one wire on the cradle , driven off one of the AC crank pully. Others have done the same. | |||
| Len Silva (Lsilva)
Registered Member Username: Lsilva Post Number: 189 Registered: 12-2000 Posted From: 71.99.25.84  Rating: N/A |
I believe that rotation does not matter on these alternators except for the fan and they are available for either direction. | |||
| Gary Pasternak (Cessna5354)
Registered Member Username: Cessna5354 Post Number: 45 Registered: 2-2007 Posted From: 64.12.117.73 Rating: N/A |
Very good obsevation, OK I must ask if the air is to be scooped and drawn into the alternator, or does the fan expell the air from within using centrifical force ??? Thanks, I need to concentrate on Xmas now, with family and my daughter's Birthday 12/25, time has passed quickly since her birth 27 years ago. | |||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 794 Registered: 11-2005 Posted From: 206.40.238.66 Rating: N/A |
Mel, Pretty much what Ralph said. I'm away from home right now and can't tell you the info until I return after the first of the year. I got mine at an electrical shop west of OKC. I think you can probably find one at any truck shop as it is a standard truck alt. It is a rebuilt one wire, belt driven, Leece-Neville and was around $150. I got a two belt pulley but they come both ways. Drop me an emaill about the second week in Jan if you don't find out before then. |
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