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Old 01-03-2009, 12:17 AM   #311
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Re: Jacuzzi Bus IV

anybody ever changed gears in the rear end of a bus? I've done so on my first car back in high school, but hmmm the thought is stirring some curiousity. In getting chassis and body information for the parts shop, I saw the 4.56 gear ratio indicated on a plaque. With that ratio I'm surprised this thing doesn't pop wheelies, haha. Some high 3.XXs would make this thing cruise very nicely on the highway. I will throw the question to the shop for a ballpark price. Labor would probably be a major drag.
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Old 01-03-2009, 06:11 PM   #312
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Re: Jacuzzi Bus IV

I wouldn't be so quick to change ratios, at least not as substantially as you're talking about. 4.56 sounds like a really low ratio even for a pickup truck until you realize that a 10.00R20/11R22.5 tire is 42 inches tall. A drop into the low 3.xx range will likely move you out of that high strung Detroit's torque band. A drop to say 4.11 might be ok, but is the few extra miles per hour and slight mileage increase worth the money? I'd be suspicious. That said, doing the gears on the bus is actually a little bit easier than a car in some senses. You don't even have to remove the tires. The axles are unbolted from the hubs and slid out with the assistance of a slide hammer and the whole third member drops out of the axle housing. The problem comes with the shear weight of the parts and the cost of all the other stuff that goes into a gear change besides just the ring and pinion like seals, carrier bearings, pinion bearings, shims, etc.
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Old 01-04-2009, 11:20 PM   #313
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Re: Jacuzzi Bus IV

Very informative. Thanks for the response and I will let you know if/when I decide to do something like that. Honestly it is not a high priority. Ordered new filters and water treatment kit for the jacuzzi. I discovered that the motor overheats without a filter in place (not sure why?). The overheat protection relay tripped back off when I was examining the motor up close and was pleased to see it fire back up when I bumped the power to check. Hope to get all parts that are in need of preventative maintenance (kingpin kit, brake pads, torque arm bushings) and have it back at the shop tomorrow or Tuesday. It is going to be at a big high-end private party coming up later this month so it needs to be it tip-top shape for the event.
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Old 01-31-2009, 02:09 PM   #314
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Re: Jacuzzi Bus IV

If it's tripping off on low voltage, also check all the wires, terminals, and ground straps between the batteries and the inverter. It could be a bad connection ANYWHERE. Take each wire off, clean the connections, and reinstall it, checking for tightness. SUSPECT EVERYTHING!

We just had a 2006 Freightliner with less than 6000 miles on it die from not charging. The battery got so low while detouring to the dealer that the Alison stopped shifting properly. By the time the mechanic looked at it , It wouldn't even come out of neutral. It turns out, nothing was broken. The alternator wasn't bad, but there was a stud hidden on the frame where hot wires are tied together. The ring terminal on the wire coming from the alternator wasn't passing electricity to the stud and the other wires.
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Old 01-31-2009, 06:55 PM   #315
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Re: Jacuzzi Bus IV

Are you sure that you aren't just asking too much of the alternator? The alternator is rated at 165 amps at 24vdc, but that is at maximum speed as is a surge output. The rectifier bridge in there simply can't maintain that kind of output for long. So to be more reasonable we need to cut that output down by a third. 165*.66=108.9 sustainable amps. The 24vdc inverter is capable of supporting 3000 watts, but let's say you are running at 2500, well within the limits. 2500 watts/24volts=104 amps. You certainly would be cutting it close. Heck, to even see the 108.9 amps out of the alternator I think you're going to have to have it spinning pretty good. It's just food for thought.

Get the batteries and the alternator load tested. The best way I think you could check that alternator would be to find someone with a carbon pile load tester that can get on that battery and draw say 125 amps while you monitor the voltage with a voltmeter. I think you might be surprised.

As it is I think your battery voltage is a little low. The 25 volts or so open circuit voltage is ok (25.2 would be ideal), but by the time you hit 23.3 volts your batteries are already 100% stone dead from an operational standpoint. Sure, they'll keep going, but you're doing a lot of damage when they do. 23.6 volts would be considered "fully discharged" from a practical standpoint on a 24 volt system and realistically for the life of the batteries you would want to see them drop no lower than 24.4 volts.

Do me a favor. With some loads on (not all, but some anyway) take a voltmeter and go from the big positive terminal on the back of the alternator to the battery positive terminal. You should see no more than .5 or so volts. Do the same on the ground side going from the battery negative to the alternator case. Again, you shouldn't see more than say half a volt and lower would be better. That will check the integrity of your connections. Heck, even try it at full load if you think you have a problem. More current will show higher voltage drop numbers. Also, make sure the alternator isn't getting hot. I'd expect to see it get warm, but hot is bad.
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Old 02-01-2009, 11:52 AM   #316
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Re: Jacuzzi Bus IV

Thanks much for the post! Reading your comments about the voltage from the two 4D batteries, consider that they are a new pair of batteries only 2-3 months old, and I slap chargers on them everytime after a run. They were freshly charged when I ran those load tests and gave those voltage numbers in my previous post. Does that confuse the matter any?

In any case, since the jacuzzi was nice and warm before it had to go out last night, I disconnected it to save about 1100 watts of load in efforts to prevent the inside from going dark. (The jacuzzi wasn't going to be used anyway.) I was pleased to hear that the power stayed on without any problems. It was a great appointment: local, on standby at a formal (yes, formal!) event, parked out in front. People came out (picture them having drank for 4 hours already) and saw this thing, and they bust out laughing -- in a good way haha. A few even ditched their own hired limousine (SUV stretch) to get into JB4.

Will do your checks listed below, but reconsider my points about about the batteries being new. What gives?
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Old 02-01-2009, 01:01 PM   #317
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Re: Jacuzzi Bus IV

Well...if removing 1100 watts of load made it keep up then I would suspect that your alternator just isn't up to the task. Like I said, those ratings they give them are a bit misleading. Yes, large case alternators are much better at dissipating heat than say a modern GM CS case alternator, but they still have a real hard time putting out their rated output. Do you have an inductive clamp for your multimeter? Putting it on the lead coming from the alternator would give you a good idea of just how much current it is able to provide. Likewise, putting it on the ground cable from the batteries would allow you to see how much is being drawn by the system. I would suspect you will find a discrepancy.

FWIW, the batteries might not be that old, but if they have been damaged by extreme discharging they may well be failed.
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Old 02-01-2009, 02:33 PM   #318
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Re: Jacuzzi Bus IV

i would suggest for a new alternator, try visiting a local alternator repair shop. Not a box chain auto parts store, but a place that actually specializes in rebuilding starters and alternators. ebay also may be a good source, although 24 volt alternators are not as common as 12 volt. Both alternators on the bus are standard GM alternators.
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Old 02-01-2009, 02:45 PM   #319
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Re: Jacuzzi Bus IV

Quote:
Originally Posted by lapeer20m
Both alternators on the bus are standard GM alternators.
You do know how much parts guys hate hearing that, right? There are pages upon pages of various GM alternators, all within the SI cases so they all appear to be "standard." Thankfully in this application not much matters besides output voltage and current.
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Old 02-01-2009, 08:49 PM   #320
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Re: Jacuzzi Bus IV

Thanks guys, for the input. I don't have an inductive clamp on my voltmeter, but I'm taking it to a shop tomorrow that will test that and the batteries. Then on Tuesday I believe that I will ultimately be taking the alternator to an alternator repair shop. There is a sewing machine & alternator repair shop just down the road. (Strange combination I think?)

I'd like to note that the setup has operated fine up until now. Could the alternator just be decreasing in capacity?
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