Hello all!
I have spent the last month exploring my new,to me Bus. ( Scenicruiser) I have been learning how much I don't know. The short version of my question to the group is should I gut out ALL existing electrical and start over or try to repair and clean up what exists. The long version is almost everything does not work! Extensive rodent damage from years of storage in a garbage dump, along with extensive prior owner/shade tree mechanic repairs. I started by removing abandoned wires, as the last persons idea of terminating a loom is to cut it off and stuff what is left in the wall. ( I wondered why I had so many shorts) My original plan was to clean up any unused wiring, repair what is left to identify what I really needed. I am starting to wonder if it may be better to remove everthing and start from the wire diagram I have and replace what I need. I am not the engineering type to be able to design a wiring system myself from scratch but I have enough experience to copy an existing wire diagram and build what I need. ( At least I think so) Just looking for a little input , what have others done. Has anyone had to start from scratch?
Thanks
Tom
Tom,
The wiring in your coach is 55 years old. Do you feel lucky?
Additionally, the Scenicruisers were rebuilt a couple of times plus the various 'updates' along the way.
There is lots of original wiring you won't need for a conversion.
I'm going to remove all existing wiring in mine because I don't trust the old insulation. I'll rewire only what is currently needed plus several spares for future needs.
I'm planning on drawing up new schematics/ wiring diagrams & wiring to that so I'll have that to assist in the future.
Good luck!
Because it's an old Scenicruiser with rubber insulated, cloth covered wires, I would start over.
It's a daunting and expensive task. It will take a LOT of planning and design. You can use the original wiring diagrams for a base, retain the stud panels if they are in good shape, and replace just about everything else. Use good quality name brand terminals (my preference is T&B Stakon) with the proper tooling.
If you know your way around electrical projects, it is a big job. If you don't then it is a very big job. I have rewired a couple of buses using the original schematics as a guide and then drawing up my own. A computer drafting program is a big help but another learning curve if you are not already there.
Break the job up into sections. Lighting, Engine Controls, Instruments, Heating and Cooling, etc.
Replace all the old relays with new cube relays and consider adding a few new ones. Use relays for the headlights, tail lights, Markers etc. so that you can run smaller wire to the switches.
Len
What everyone else said, then add at least 10% for spares or more. You can never have too many spare wires as you change/add down the road.
Make it easy on yourself and get a labeler, document with pictures/notes of everything you do.
Paul
Scenicruisers only need engine start and stop, then anything else you can add like
a relay for disconnecting the voltage regulator when the engine main switch is off.
I would add air pressure senders, oil pressure and temperature for the basics
and extras for things like emergency cutoff solenoid and skinner valve wires
for run, stop and fast idle.
Then it's just lights, stop, turn,, brake, running and whatever else you fancy.
If you still have the reverse solenoid on the tranny then you will need a long wire
to the front for that.( Heavy duty one! ).
Trailer wires like brakes and such.
Rear start button and selector switch...
The other 1/2 mile of wires is optional.
Like Dave said,
Break it down to simple circuts so you don't get overwhelmed with too many things at one time. 8)
I'd use relays where possible to reduce the need for long runs of heavy wire. . . Mine have relays in the rear for all kinds of stuff - including the reverse solenoid.
If you approach it one circut at a time, it should be doable.
Gary posted a good read concerning terminating wires in the "Wiring Methods" thread :
http://www.busconversions.com/bbs/index.php?topic=13383.msg141222#new (http://www.busconversions.com/bbs/index.php?topic=13383.msg141222#new)
You'll have to decide for yourself wether or not to solder the crimped connections . . . ::)
I suggest that you "not" run any wires that are "heavy duty" form front to back. All the wires, such as the reverse solinoid, should get a "control signal" from thr front that operates a relay that drives the solinoid. Install a heavy "buss" wire from the front to the back bats that will provide all the power for stuff up front like defrost blowers and such. Even those should be powered thru a relay that is controlled by a low power switch.
I don't see this as such a daunting task so much as a tedious one. Good luck for you on the offer to share the diagram being drawn up. Really good news.
John
Well I was trying to simplify. ;) ;) ;)
Yes load relays should always be used and only control wires need to be run all the way.
Most stuff can use the cube type relays that will handle a 30 amp load.
The only thing besides the battery buss line that if you decide to wire it for would
be electric trailer brakes and a #10 wire should be sufficient to run from the controller
to the plug.
Be sure to add a battery disconnect switch just in case you need to shut stuff off that
is misbehaving....
There are alot of wires that are just plainly not needed for a motorhome conversion. If you pull out all the miles of wiring, you'll be surprised at how few wires you need to run the bus down the road. The rest of the wiring, weather it be 12vdc or 120vac will be used for the house part. I don't know if it is a 24 vdc system, but this would be a good time to make everything back to 12vdc that's in use for most all vehicles except buses. Good Luck, TomC
Thank you all for your input!
I guess my best bet is to gut and start from scratch. I have done quite a few street rods, so I feel this is very doable, just a bit larger. As any project I will start with a list of what I really need. My question here is would you pitch the original wire diagram and start by enginering a whole new wire plan, or copy a new plan of only needed items off the original wire diagram. My concern is I copy well, though I don't have a design or engineering experience.
This brings up a whole new group of questions.
Should I consider copying from a new bus wire diagram so as to be using newer technology
Should I consider 24 volt systems
Thank You
Tom
12 volts is an easier standard to get things for. The only drawback is the amps are double that of a 24volt system, so the wire size may need to be larger to avoid voltage drop problems.
You have done custom cars - so, you're over half way there, just study up a little on the load isolation relays & you'll be all set.
The problems I have in following the factory bus electrical schematics are many & include;
- was designed with an emphasis on economy of materials which leads to some very confusing current paths for non-electrical engineers. :o
- included many things not needed if you're not hauling passangers- so the stock circuits are no longer sized correctly.
- obtuse junctions & ground paths.
By all means, look at other wiring diagrams to get ideas.
Gather some schematics from motorhome manufacturers - compare the differences from the ones that are built on a purchased chassis VS. the ones built on their own custom chassis.
Have fun!
If you replace the wiring, figure how many circuits you need and double that number. You will be surprised how many circuits you will add as you find new bells & whistles that you did not know you could not live without. Jack
I also suggest that you keep the bus wiring completely separate from your house wiring. No matter how tempting it may be down the road, don't borrow a "bus" spare for a house circuit. You will save yourself or someone else a lot of grief a few years down the road.
Quote from: tpboj on September 17, 2009, 01:35:32 PM
Hello all!
I have spent the last month exploring my new,to me Bus. ( Scenicruiser) I have been learning how much I don't know. The short version of my question to the group is should I gut out ALL existing electrical and start over or try to repair and clean up what exists.
As you describe it, I would strip it all out. Remember that a lot of the wiring is of no value to you anyhow, because it was there for things like passenger lighting and signaling, factory environmental (I'm assuming that's all gone) and so on, so you don't need to replace it, just yank that out.
Job One in doing your new electrical plan is to take a big (11x17) piece of graph paper. Draw an outline of the coach shell on it, in 1/4" = 1 foot scale, with a felt marker. Now put letters in circles to indicate the rough location of every switch, load, gauge, etc., and keep a list on a separate sheet of paper to tell you what each letter means (for instance, A might be the starter circuit, so there will be an A at the rear, and A at the front, and a note identifying A as the starter and starter switch).
Do one of these for each voltage you are going to use (12, 24, 110), before you pick up a single tool. You may discover that you have to pull several wires at a time through a bad part of the system.
I also advise using conduit everywhere. Since you have a rodent problem, you might want to use metal conduit. Use the largest diameter which will fit through where it needs to go at any one place (sometimes you need to run more than one conduit). The three advantages of conduit are first, you can poke a wire at one end and you know where it's going to come out, second, it protects it between taps, and third, it keeps all of your wiring in one bundle, so you don't have to go hunting for the one lead that's next to connect.
I would also recommend to run your low voltage in separate conduits than the 120v. Best to keep them separated. Don't forget about a separate conduit for any TV/Sat cable, I did and I paid for it.
Just a thought.
Paul
Is the Bus interior stripped out? That would make it a lot easier., then you can check the frame and insulation etc.
Well I spent some more time tracing wires and have started pulling the everything out. The interior is all out by previous owner.
The fun with an old bus is every day is a new surprise. In tracing the loom under the floor I found the last owner thought he could fix rotted wood with Bondo. Well at least I can get to the loom now that I pulled the whole floor out.
Thanks for the help.
Tom
Quote from: kyle4501 on September 18, 2009, 05:32:57 AM
12 volts is an easier standard to get things for. The only drawback is the amps are double that of a 24volt system, so the wire size may need to be larger to avoid voltage drop problems.
You have done custom cars - so, you're over half way there, just study up a little on the load isolation relays & you'll be all set.
The problems I have in following the factory bus electrical schematics are many & include;
- was designed with an emphasis on economy of materials which leads to some very confusing current paths for non-electrical engineers. :o
- included many things not needed if you're not hauling passangers- so the stock circuits are no longer sized correctly.
- obtuse junctions & ground paths.
By all means, look at other wiring diagrams to get ideas.
Gather some schematics from motorhome manufacturers - compare the differences from the ones that are built on a purchased chassis VS. the ones built on their own custom chassis.
Have fun!
If it is a true scenicruiser PD4501 it was originally a 12 volt positive ground system, Later they rewired for a negative ground system on most. That apparently didn't take much to do since
electronics and computers were only just getting started.
Go with the 12 volt system. then your house system can also be 12 volts and can be switched to charge from the bus alternator more readily.
Gotta remember too that the original PD4501's had 2-engines sitting side by side so there is still
all that additional wiring in there to confuse and amaze. They didn't get the 8V71 engines until somewhere around the late 60's to early 70's ( I think?? )
Imagine the racket that 2 4-71 engines made. I loved that sound when I rode them in the 50's & 60's ... Up Hwy 301 across Mt Airy NC.... Very cool ride at night...
I believe 1958 is when Detroit brought out the V blocks. Around '59-'61 is when Marmon-Herrington brought the 1000 buses in and exchanged the 2 4-71's for the 8V-71. So the actual usage that those buses were using the twin engines was short lived. On paper it was a good idea, but without the aide of electronics of today to manage the power, the driver's were not up to the task of keeping the bus running smoothly down the road. Having a 3 spd trans with a two spd splitter was just too much-throw in the option of being able to cut out one engine on the flats-too much problems. The simplicity of the 4 spd with the 8V-71 has been demonstrated by the billions of bus miles over the years with that setup. The only problem from our stand point is that first gear isn't low enough for some of our exploring ways. Course, in my opinion, switching to an Allison takes care of all that, and some fuel mileage. Good Luck, TomC
Tom,
I think you are probably correct on the timing of the greyhound fleet changing over, I had heard that it was in the 60's but it may have been in the late 50's and early 60's..
Sorry. My apologies to anyone that may have been confused by my random thoughts... My brain is somewhat damaged more than usual lately.
Dave...
Yep, it was 1961 & 1962 when they Marmon-Herrington did the first rebuild of the 984 Scenicruisers still in service. 17 had been lost due to collisions by then.
The rebuild included repainting the bus inside & out along with new insulation & floor covering. When M-H was done, it was essentially a new bus.