Rewiring car

JS Robinson · 07-05-2009, 07:12 AM

I'm going to rewire my car this weekend. I bought K & R's panel kit. I would like to know what best practices people have. Especially for grounds. Do you want to ground everything to the battery ground? If so. What's the best way to go about this? Whats the best kind of quick disconnects to use for the fan and water pump?

I will take any suggestions and help.

My experience level is 19 yrs. But, it's been all Stretch wrap machines and water chillers. I've wired cars before. But, reading different posts lately and I'm seeing where things are being done differently. I just want to do it right the first time.

Jeff Robinson

Lou SG2340 · 07-05-2009, 10:50 AM

I like Weather Pack for disconects. I ground to bolts welded or tapped to the chassis Use relays for any thing with a high curent draw. Fuel pumps, water pumps, fans etc

Chris Williams · 07-05-2009, 06:45 PM

Rewired our S/C dragster this winter. Went with WeatherPak connectors as well.

Also used the Dedenbear Multiple Relay Center and love it. Can't have too many relays... And it helps to have the fuses and diagnostic capabilities it gives you.

Don't rely entirely on crimp connectors. Preferred is crimp it, solder it, then heat shrink cover it. PITA? You bet, but it will last.

Also use bigger wire than you think. If you think 18 is good, use 16, etc. Can't possibly go wrong with bigger wire.

Grounds to the chassis are good, to panels are always bad. Ran a separate ground from the dash all the way back to the battery. Dash stuff is so picky.

Rewired the car completely, built an entirely new dash, all new components (racepak dash, delay box, switches, etc.), and proud to say it worked first time perfectly, and haven't had an issue all year. So it can be done.

Bill Baer · 07-05-2009, 06:47 PM

Lou is right on target with the connectors and the relays but I don't consider the Chassis a good ground. Also I have seen several cases of grounding to the block and through the motor plate cause electrical problems (trans brake solenoid, ignition miss, gauges etc)
I would suggest that you ground the battery to the starter ( I drill and tap a hole in mine

) and run a #8 or larger wire from there to a ground buss ( a piece of 1/4" thick brass or un-anodized aluminum) and ground everything important to it. This may seem like over kill but bad grounds can be the toughest things to locate/identify so why guess.

Just my 2 cents worth

Ron Finney · 07-05-2009, 07:51 PM

There is nothing wrong with the chassis ground if done properly. Sorry to disagree Bill, but grounding to the starter still connects the ground to the block, motor plate etc. Usually most ground issues are too small wire or bad connections, not cleaning the chassis, rollbar, block etc. wherever the ground is attaching. Any bad connection creates resistance which provides for a voltage drop. That is the voltage that is creating the oddities in other systems. In an electrical circuit the load should consume all of the voltage, not the wiring, connections, etc. I have seen many people run a big power wire and then a small ground. THEY MUST BE THE SAME SIZE! Now lets blow your mind for a minute, if you study electricity, (electron theory shows that the voltage leaves the battery through the negative terminal and returns through the positive!). Hard to convince people of that but it does kinda explain why most problems are on the ground side of the circuit. Definitely having redundant grounds is not a bad thing, just make sure they are big enough.

The relay advice is excellent. A relay is, is a remote electrical switch. It allows you to use a small current and to control a much larger one. Relays are used to keep from running big wires for every component into the dash or switch. Without a relay, all switches would have to be large enough to handle all of the current the load uses. If we did this, the wiring harness would be huge and we wouldn't have much room. You can use a smaller wire on the control side of the relay because it doesn't take much current to energize the relay and therefore a smaller current switch. Also, by not having to run the high current wires as far, you have less voltage drop in the wires and more available current to the component you are operating. Makes things much nicer.

Good Luck!

Ron

33 S/C

Chris Williams · 07-05-2009, 10:13 PM

Quote:

Originally Posted by Bill Baer

I don't consider the Chassis a good ground. Also I have seen several cases of grounding to the block and through the motor plate cause electrical problems (trans brake solenoid, ignition miss, gauges etc)

But grounding to the block or the motor plate aren't a chassis ground... They are connected to the chassis (via the motor plate) and many folks anodize or powdercoat the plate, and that's a recipe for a bad ground. A chassis ground (to the, um... chassis) is fine, it's a big solid welded together wire -- of a pretty good gauge.

Electrical connectivity is pretty simple -- just make sure you make metal to metal contact, through a conductor that's larger than you need. No paint, powercoat, anodizing, gaps, etc.

I run a separate ground wire to the dash, but that's because of ignition noise and sensitive equipment -- a bad mix. And I have several spots on the chassis carefully prepped for grounds (sanded clean, solid connectors, etc.). S'all good.

Ron Finney · 07-06-2009, 09:12 AM

Chris is correct, however who installs an engine without grounding it to the chassis?

Chris Williams · 07-06-2009, 09:46 AM

Quote:

Originally Posted by Ron Finney

Chris is correct, however who installs an engine without grounding it to the chassis?

People who assume the motor plate handles that responsibility. Then they powdercoat the motor plate. Oops.

JS Robinson · 07-06-2009, 04:11 PM

Thank you for all the great tips. One more question. Where is the best place to get weather pack connectors?

Chris Williams · 07-06-2009, 04:24 PM

Quote:

Originally Posted by JS Robinson

Thank you for all the great tips. One more question. Where is the best place to get weather pack connectors?

I got all mine from Jegs. Just search for "weatherpack".

07-05-2009, 07:12 AM	#1
JS Robinson Junior Member Join Date: Nov 2008 Location: Wyoming Michigan Posts: 21 Likes: 0 Liked 0 Times in 0 Posts	Rewiring car I'm going to rewire my car this weekend. I bought K & R's panel kit. I would like to know what best practices people have. Especially for grounds. Do you want to ground everything to the battery ground? If so. What's the best way to go about this? Whats the best kind of quick disconnects to use for the fan and water pump? I will take any suggestions and help. My experience level is 19 yrs. But, it's been all Stretch wrap machines and water chillers. I've wired cars before. But, reading different posts lately and I'm seeing where things are being done differently. I just want to do it right the first time. Jeff Robinson

07-05-2009, 10:50 AM	#2
Lou SG2340 Member Join Date: May 2008 Location: Disputanta Va (30 minutes from VMP) Posts: 122 Likes: 0 Liked 0 Times in 0 Posts	Re: Rewiring car I like Weather Pack for disconects. I ground to bolts welded or tapped to the chassis Use relays for any thing with a high curent draw. Fuel pumps, water pumps, fans etc

07-05-2009, 06:45 PM	#3
Chris Williams Member Join Date: Mar 2009 Location: Woodinville, WA Posts: 401 Likes: 0 Liked 0 Times in 0 Posts	Re: Rewiring car Rewired our S/C dragster this winter. Went with WeatherPak connectors as well. Also used the Dedenbear Multiple Relay Center and love it. Can't have too many relays... And it helps to have the fuses and diagnostic capabilities it gives you. Don't rely entirely on crimp connectors. Preferred is crimp it, solder it, then heat shrink cover it. PITA? You bet, but it will last. Also use bigger wire than you think. If you think 18 is good, use 16, etc. Can't possibly go wrong with bigger wire. Grounds to the chassis are good, to panels are always bad. Ran a separate ground from the dash all the way back to the battery. Dash stuff is so picky. Rewired the car completely, built an entirely new dash, all new components (racepak dash, delay box, switches, etc.), and proud to say it worked first time perfectly, and haven't had an issue all year. So it can be done. __________________ Chris Williams 6304 SC, TD, ET

07-05-2009, 06:47 PM	#4
Bill Baer Senior Member Join Date: Jul 2007 Location: Nothern IL Posts: 596 Likes: 1 Liked 1 Time in 1 Post	Re: Rewiring car Lou is right on target with the connectors and the relays but I don't consider the Chassis a good ground. Also I have seen several cases of grounding to the block and through the motor plate cause electrical problems (trans brake solenoid, ignition miss, gauges etc) I would suggest that you ground the battery to the starter ( I drill and tap a hole in mine) and run a #8 or larger wire from there to a ground buss ( a piece of 1/4" thick brass or un-anodized aluminum) and ground everything important to it. This may seem like over kill but bad grounds can be the toughest things to locate/identify so why guess. Just my 2 cents worth __________________ Bill Baer 3391 SC, 339B SC, QR

07-05-2009, 07:51 PM	#5
Ron Finney Member Join Date: Jul 2008 Location: Greenwood, IN Posts: 168 Likes: 0 Liked 0 Times in 0 Posts	Re: Rewiring car There is nothing wrong with the chassis ground if done properly. Sorry to disagree Bill, but grounding to the starter still connects the ground to the block, motor plate etc. Usually most ground issues are too small wire or bad connections, not cleaning the chassis, rollbar, block etc. wherever the ground is attaching. Any bad connection creates resistance which provides for a voltage drop. That is the voltage that is creating the oddities in other systems. In an electrical circuit the load should consume all of the voltage, not the wiring, connections, etc. I have seen many people run a big power wire and then a small ground. THEY MUST BE THE SAME SIZE! Now lets blow your mind for a minute, if you study electricity, (electron theory shows that the voltage leaves the battery through the negative terminal and returns through the positive!). Hard to convince people of that but it does kinda explain why most problems are on the ground side of the circuit. Definitely having redundant grounds is not a bad thing, just make sure they are big enough. The relay advice is excellent. A relay is, is a remote electrical switch. It allows you to use a small current and to control a much larger one. Relays are used to keep from running big wires for every component into the dash or switch. Without a relay, all switches would have to be large enough to handle all of the current the load uses. If we did this, the wiring harness would be huge and we wouldn't have much room. You can use a smaller wire on the control side of the relay because it doesn't take much current to energize the relay and therefore a smaller current switch. Also, by not having to run the high current wires as far, you have less voltage drop in the wires and more available current to the component you are operating. Makes things much nicer. Good Luck! Ron 33 S/C __________________ Ron Finney 396V S/C

07-06-2009, 09:12 AM	#7
Ron Finney Member Join Date: Jul 2008 Location: Greenwood, IN Posts: 168 Likes: 0 Liked 0 Times in 0 Posts	Re: Rewiring car Chris is correct, however who installs an engine without grounding it to the chassis? __________________ Ron Finney 396V S/C

07-06-2009, 04:11 PM	#9
JS Robinson Junior Member Join Date: Nov 2008 Location: Wyoming Michigan Posts: 21 Likes: 0 Liked 0 Times in 0 Posts	Re: Rewiring car Thank you for all the great tips. One more question. Where is the best place to get weather pack connectors?