The Combine Forum banner

1 - 16 of 16 Posts

·
Registered
Joined
·
4,081 Posts
Discussion Starter #1
Lots of different ways to go about this and being a mid 1970s truck it is time to get into it. So will post some info on what I am doing in case others are considering doing something to revamp the aging systems.

I attached a document with the factory wiring diagram and summary of wire numbers and color coding. Too bad I just found it a few weeks ago as it would have been handy over the years. This one you can zoom right in on while keeping resolution so can print off the one page diagram into 9 separate pages and read everything.

New lights and gauge clusters not in the budget this year. Next winter I will do that. I removed all the wiring except the cab roof since that can be done some other day.

Made a distribution center in the battery box with a relay switched with the key to feed up to the Eaton 31S-001 mounted on the firewall. This power center has some relays that will supply headlights and has all fuse protection for wires feeding into the cab. The battery box distribution is a gang of bolt in fuses for the alternator to feed into, fused feed for relay to Eaton unit, hot 12v lead into cab. Also keeping the 12/24v series/parallel switch as that works fine.

Put terminal blocks by the steering wheel to wire key switch, turn signals, brake switch, head light dimmer and flasher into. Another terminal block on firewall with a fused panel to distribute the 12v always hot lead from battery. Will have terminal blocks on the gauge panel door to further distribute the fused leads from Eaton unit.

As with all such projects I didn't plan on getting into work such as brake lines but with all things opened up I got into re plumbing the ones in the cab area. Didn't plan to pull the dash either but wanted to paint it somehow in the future and realized I had everything off except the screws holding it so that came out the other day.
 

Attachments

·
Registered
Joined
·
3,583 Posts
Looks nice! That's no small task you are undertaking, you are making it nice and tidy, I like that! Wiring is one thing I can't stand, especially if someone has been at it before me.
 

·
Registered
Joined
·
464 Posts
Looks really good. I run all new cloth air lines on my 78 w900a last winter that was time cosuming. But we'll worth it. Next is to improve he heater in it
 

·
Registered
Joined
·
1,111 Posts
Aah yes... wiring... not a chore for the faint of heart.......
I just so happen to have the same kinda project going on.....
158334

It will get many zip ties when its done.
 

·
Registered
Joined
·
3,583 Posts
My brother and I just removed about 100 feet of old unused wires and air lines out of the Mack we bought to put a grain box on. God it bugs me when someone rewires something then leaves the old wires there. There were things spliced in and went nowhere, huge wires run from the back of the truck then tied into the fuse panel with a rinky dink little wire and only taped together, no connectors! Getting it tidied up a little now.
 

·
Registered
Joined
·
1,111 Posts
This makes me think of maretts.....
I will strangle anyone who uses a marette on a stranded wire... especially on the back end of a truck or trailer.....?
 

·
Registered
Joined
·
4,081 Posts
Discussion Starter #9
I will post some pics of the drawings I made up when I get it all done and proven out. Learnt a long time ago that no matter how much time a guy spends designing something there is always something I missed so wires need to be relocated. A guy can do a nice job if you knew 100% that when you land a wire that is where it stays. But over the years things change and I may want to refeed a circuit differently so there is extra wire and space to move to a different terminal or add a terminal block some where. Have room in the battery box to add another fuse holder to the gang if needed later on, say a guy wants to install a 1000w inverter for example.

Anvils rat rod thread is kind of what I am thinking here when posting. Always had plans to build another car but last couple years been selling all my collected parts. Still have some 351c blocks and a couple sets of 4v heads to sell off, not many people into that stuff anymore. Going to spend my time on the KW instead. Not a resto by any means. It is a farm truck. But can fix up the wiring, spend some dollars on the interior and eventually try my hand at exterior paint. Did the grain box with an air less sprayer and tremclad which turned out ok for my needs.

The wiring was all functional meaning all lights worked. But in its first 25 years people did more than enough changes and butt splices to have me wonder what was going on. Maybe the factory wiring isn't that good. Also the truck changed from a tractor unit, to picker truck, to finally a grain box so some changes were made for those applications. There were 5 plugs on the driver side firewall with about 35 wires all combined, when I pulled all that out there were 6 in use going to the tail lights and rear flood lights and 5 to front lights. More could be used if the truck was set up for those accessories. But now I am wiring for how the truck will be used vs what it could be used.

Need to get the Jake's working next year. It was all messed up when we got the truck and I never understood a bit how Jake's worked so threw out some of the components. Am wiring it all back in now but will get throttle and clutch switches as another task some day.

Been enjoying the last few weeks doing it. Reminds me of why I had plans to do a car some day. The cost of wiring isn't that much, probably spending more between the brake lines, painting dash and things on engine like oil pressure and water temp switches. Lots of time spent drawing and specing out components to order and finally installing. Time sspent is free for me, paying someone to do it would be another story.
 

·
Registered
Joined
·
1,111 Posts
It's really nice to be able to do those things yourself. My rat rod would be a 100k dollar vehicle if I had to pay someone to do it.
But I know my wiring is good, (soldered and shrink tube'd) I'm making a schematic and tracking wire colors as I go.
But that is another thing I hate is random loose stray wires and butt connectors.

You got what looks like a fun project!
Keep us posted with pics! ?
Thanks for sharing.
 

·
Registered
Joined
·
4,081 Posts
Discussion Starter #11
I came to appreciate the idea of a Rat Rod a number of years ago. At first I thought it was kind of a cheap way to do what should have been done with more effort but then I realized it can also be a good way to put one's ingenuity and creativity to work. Even working on an old muscle car and modernizing it a bit requires those characteristics. Doing a Rat Rod unchains a guy completely to have fun exercising all the ideas lurking in the back of the brain.

As for the KW, got most of external wiring done. Been working from outside of cab to inside. Either way works but if you can plan it out well enough it's better than running a wire from source to destination and terminate and repeat, repeat.

Keep in mind a truck is a diesel engine on wheels so a wiring scheme can be fairly universal. Just because it is a KW does not mean the exact same scheme can't be used on any other truck. Need 2 wires to run it - one to starter, one to fuel solenoid. Throw in the road lights and most of basics are covered.

Using GXL wire which is xlpe (cross linked polyethylene). The wire I see on the shelves in stores is PVC insulation so softer. SXL has thicker insulation yet, TXL is thinner. At work we used SIS which is much the same but thicker insulation yet because it's rated 600v. If I was still at the old shop I would have took home 30' of the different colors we had and used that.

This XLPE wire lends itself to making loops and curves vs sharp 90s.The Eaton power distribution center (pdc) is done. I went with this model because I liked the front connected wiring. Easy to access in engine bay. I wanted to declutter inside dash. With the air lines cleaned up and dash out before hand I may have gone for a rear connected pdc and cut a hole in firewall just in front of glove box to pass wires from pdc mounted in engine bay to the inside of cab.

10 point terminal block on drivers side handles all the turn signals, hi/low, front led and back up lights. Left an old 3 conductor extension cord on frame if I need more wires in future. Artic flex 14 gauge trailer cable should be adequate. Hi beams run 12 Amps total but that is a 7 foot run before branching to separate headlight assemblies so should be fine. Have 12ga off relays for hi/low in pdc to the 10 pt jb.

Using expandable sleeving mostly. I simply like working with it vs split loom. No other reason.
 

Attachments

·
Registered
Joined
·
4,081 Posts
Discussion Starter #12
10 point block.

Almost painted the frame rail when I had the wiring off. Cleaned it up but figured painting was going too far. Doing such a thing leads to more such things.
 

Attachments

·
Registered
Joined
·
4,081 Posts
Discussion Starter #13
Battery box is done. I don't mind the series/parallel switch on here. I can understand it. The set up on the 2005 STX 450 is an entirely different matter and seems over complex with an expensive switch to do the same role. But you can't use simple components and designs from the 70s on something in the 2000s so there we are.

The starter solenoid takes 20 amps so ran 10ga off battery disconnect, through 30A fuse to contact of series/parallel switch then to starter solenoid. The s/p switch therefore serves two functions here, it changes the battery configuration when the key is turned to start and it closes a contact to feed power to the starter mounted solenoid.

The breakers on left side of battery box are removed. One was the hot lead from battery up to ammeter which also connects to alternator, other breaker protects the feed from battery to starter solenoid.

Getting started on dash now. Will build new gauge panels next year with new gauges and a better lay out so going to leave some extra wire on all panel connections so I can revamp next year. Plan to reuse the triangle piece with the terminal blocks on it so can wire that area up fairly neatly as it will be transferred over to a new panel in the same position it is now.
 

Attachments

·
Registered
Joined
·
4,081 Posts
Discussion Starter #14
Got things almost wrapped up. Proved functionality of circuits. Need to connect some wires from steering column terminal block up to panel for tach, turn signal and high beam indicators. Still waiting for key switch to show up and those wires will land on the left side of that terminal block.

I will clean up the gauge panel when it's redone. The indicating lamps can get solder connected in the new panel, wires to rocker switch can be cut to length, wire bundle moved to make nicer curve. Panel on inside firewall not pretty but is accessible as needed. Overall the dash is a lot more accessible now which was my main goal.

A #8 wire from rear battery to s/p switch may have been better than #10. I see that wire is also used to charge rear battery from alternator as it is a parallel connection. Was looking at it yesterday to see how the battery was charged so redrew it. Had it figured out last month but my memory isn't so good it seems. Have a 90A alternator and the #10 is good for 30A all day and 40 A probably too if i didn't put it in some loom. Looking at the data for 30A MIDI fuse it won't start heating till 42A and would need 45A to go in 100 seconds. I may need to change that to a 40A fuse which is 60A for 300 seconds till fuse goes and then a #8 wire to be sure. If the alternator was larger I would need to go larger on this circuit for sure. Or if problems develop and the front battery stops taking less amperage due to poor connection or something then that 30A fuse is likely to go as more battery charging current will go through that circuit.

Circuit protection is all about heating - have a fuse operate before a wire gets so hot that it melts down and starts a fire. The SGX wire with xlpe insulation is good for 105c, pvc insulated wire is good for usually 75c and maybe 90c. That is a lot of heat before risk of fire. So the fuse is chosen to protect the wire. If all that wire feeds is a 3 amp solenoid and is fed via a 14 Ga wire you can go 5A or 15A fuse. The 15A protects the wire, the 5A just fine tunes things. If running multiple loads off one 14 Ga wire then you definitely want to make sure that wire is protected from overload. That's why I don't like circuit breakers in the truck and why charred wiring is not uncommon. A fuse will definitely go when overheated, circuit breakers not always, especially decades old. Add in the fact people add loads and refeed things over the years and you end up with overloads. Maybe a breaker will operate, maybe it won't. If you don't test then you dont know. A fuse you can only test once.
 

Attachments

·
Registered
Joined
·
713 Posts
This makes me think of maretts.....
I will strangle anyone who uses a marette on a stranded wire... especially on the back end of a truck or trailer.....?
I will take a wire nut over a scotch lock any day.

That looks fantastic. Want to make a trip to Montana to rewire another one? My old Clatterpillar looks even worse than what you started with...
 

·
Registered
Joined
·
4,081 Posts
Discussion Starter #16
Well, not much into travelling these days doing electrical work Redneck but somedays it is nice to get out and make use of things I learned.

Did up my drawings to make them easier to read. I am not a CAD guy so always had someone else take these penciled drawings and make them look nice on computer. These will have to do. Going to get laminated and put under seat in truck.

I prefer using a switch vs relay unless loads are large but was thinking that if a guy wanted to remove a few more wires from the dash area I could have used a power distribution center with more relays so that pretty much all of the dash switches would toggle a relay on the PDC. Loads such as clearance lights, back up lights, back up camera would be good candidates since the wires never need to come into the cab and then exit. Just a small wire (I used 18 Ga) between switch and relay. The switches themselves get fed with 18 Ga rather than 14ga and need one supply (daisy chain together) since switching a few mill-amps vs up to 8 amps with each switch.

No logic for wire color choice. Used the same color for upto 5 different functions. Figured if I was chasing a purple wire in the future I could live with 5 choices. An option was to wire all loads from the "accessory" key position one color, all loads on "run" position another, anything regarding sending units another color, clearance lights another, etc. May have worked ok. I made a choice and went with it.
 

Attachments

1 - 16 of 16 Posts
Top