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Evening Gents,
As the weather finally turns here in Southwest Ohio, I find myself going stir crazy again. Shoulder still isn't at full strength, so I gotta find something else to do to feed the OD OCD. I am gathering info for a rewire of a 1963 M37b1. I want to keep it 24 v. I have done my research on purchasing an after market one, just cant part with $1,100 for a replacement. Plus I want to upgrade to modern electrical connectors. So to confirm what I "THINK" I know:

1 Replace wire gauge for wire gauge. It it is original 14 gauge wire replace it with 14 gauge etc?
2 Would it help to install a 24 volt fuse panel in the truck?
3 Fuel shut off switch? I have thought of using something like the modern vehicles have, it think it is called an Inertia Fuel Shut-Off Switch. I have an electric fuel pump installed and connected to the starter control

I have read quite a bit on this site. I have an electrician on staff that will be verifying my work prior to install and upon start up.
If there is anyone who has done this and could provide me some pointers it would be greatly appreciated.

MY plan is to pull the old harness off and use it as a template, using the metal circuit numbers on the new wires. Using modern electronic connectors.

Hi Mark,

Well.........there are a few things to consider, I guess. There are two types of latest and greatest automotive wire............PVC and Cross-Linked............the difference between them being the temperature range they can work in. Cross-linked automotive wire can withstand much higher temperatures than PVC automotive wire. PVC and Cross Linked each come in 3 flavors, GPT, TWP, and HDT for PVC and GXL, SXL, and TXL for Cross. Your electrician friend can make the smart decision on which of those suits your application the best.

The biggest practical difference for you will be the OD of the wire and the flexibility of the wire. The 14ga Prestolite wire originally used for your truck has a thicker insulating jacket than any of the newer automotive wire types. This would be a problem if you were using the Douglas or Packard connectors because the shells and grommets wouldn't fit snuggly over the wire. The way to solve that is to use 12ga PVC or Cross, which has the same OD as the original 14ga Prestolite. But since you're moving to automotive connectors that won't be a problem for you. But what will be a problem is how will you connect the new wire to your gauges, horn, lights, distributor, ignition switch, brake switch, senders, etc, etc. For the newer automotive connectors to work they have to mate with their counterpart connector on the components you're mounting the harness to. So what's the plan with regard to all the connectors on all the electrical components in the truck? Is everything going to have a Packard to weatherpack adapter on it?

I'll admit that when I first saw the asking price for a new harness from Vintage Wiring of Maine I balked too. But when you consider how much wire you need and the price per foot, as well as all the connectors, wiring number tags, the proper crimper tool, etc..........it's starts to get paletable. Throw in how much money you'll waste on mistakes you might make and the value of your time in general and it starts to look like something worth saving your pennies for (in my humble opinion, of course). It will be interesting to see how much you end up spending using newer wire and the latest weatherpack type connectors. And I'm not saying that to sound like I'm against using newer wiring/connectors...........just curious what it really costs.

Oh.........almost forgot...........the newer automotive wire is also shiny in color.........if you don't want it to look too strange you can hit it with a Scotch-Brite pad to dull it up a bit.

regards,
bob

Bob,
Thanks for the info on different wire coatings. I am no where near that up to date on these things. More to consider!

Also, thanks for bringing up the connections to gauges and other things like the horn. First response would be to say I would pigtail off the existing connection. That would get me disowned by my Dad and I am sure many on this site as well. More to think on!

I think I am going to build my wiring harness on paper just to see what the cost of materials would cost. Of course will have to figure our time as well. Factor in at least 10% waste.

Looking at it from the perspective you provided I can see where the replacement wiring harness may be the way to go.

Thanks again for the input. It is greatly appreciated.


Mark

I used the Painless Performance wiring harness kit on mine, along with their headlight switch. Kit # 10104. I wasn't worried about the wire tag numbers or connectors and my purchase price was 2/3 less than a new M37 harness from Vintage Wiring. I was able to wire everything but the military headlight switch but plan to tackle that this year. I have no complaints about the kit-it works perfectly, and the fuse block above the clutch pedal came in handy when my wiper motor failed and blew the fuse last week-easy to replace.

Send me a PM if you'd like more detail.
Thanks,
Gary

Hello Mark,

Greetings from a fellow Buckeye Bob and Gary have stated some good points. I would suggest a couple HD 24VDC truck/RV circuit breakers like I used. I have one for the engine circuit and the other for the dash/lights/acc. I used the manual reset style.

http://www.g741.org/photogallery/main.p ... temId=5346

If you are using new style crimp connectors, make sure to incorporate heat shrink tube. This makes a much more durable connection.

D

I have a question too

is there a turn signal add on kit for my early truck
it is gonna be my daily driver and I need directionals

Travis,

Yes there is a kit. Finding it with all the parts may be a bit of a challenge. Try the usual suspects.......John at Midwest and VPW. The kit is an older Military kit, I believe there's a better way to do it with modern components. There was a good discussion on it here a few months back, if memory serves me right. I also think Charles provided the details.....you'd be wise to give him a shout.

regards,
bob

Gary, PM sent

PM back to you Mark!

w30bob wrote:Travis,

Yes there is a kit. Finding it with all the parts may be a bit of a challenge. Try the usual suspects.......John at Midwest and VPW. The kit is an older Military kit, I believe there's a better way to do it with modern components. There was a good discussion on it here a few months back, if memory serves me right. I also think Charles provided the details.....you'd be wise to give him a shout.

regards,
bob

I am going to be rewiring my truck so I should just make one myself

Looks like my wiring harness is going to need replacement or significant repair. VPW/Midwest or other less costly options?

I used the Painless kit and did the turn signal install as well. My fuse box pic was to large to up load?

If you are staying 100% stock, no added circuits, or other changes, but a quality harness. Otherwise build it your self.

Just depends on how handy you are with wiring and/or how deep your pockets are. I believe the MV parts suppliers get their new harnesses from Vintage wiring of Maine. Very nice stuff for those who prefer (and can afford) the Plug-N-Play solution. NOS harnesses are a gamble due to their age, but make the perfect pattern to copy for a new harness, if you find one for cheap. If you enjoy doing such things yourself you can get a generic wiring harness from Summit or Jegs for cheap and have at it.

Overall, the M37 harnesses are pretty simple. If you have all the connectors and a old harness to copy you can bang a new one out in an afternoon. If you drink too many beers while you're doing it you should budget another few hours to fix your mistakes the next day.

regards,
bob

just a note on the signal stat:


the wire that lights up the lights on the stat will wear through and short to ground over time.