Detailed Instructions on How To Improve Your Cars Ground Cables WHY ARE GROUNDS IMPORTANT ------------------------- A good ground from the battery to chassis is very important for the proper operation of your entire electrical system. A proper ground, believe it or not, will also aid in your engine idling properly, and that a proper spark gets to the spark plug. A proper ground will also ensure that your starter will work properly and will actually help lengthen its life. STOCK PROBLEM ------------- The main problem that I have seen is that stock, from the factory the NEGATIVE cable is bolted to a nut that is welded to the chassis. The problem with this being that it is relying on, for the most part, contact through the threads. As some know, the contact patch around where the cable lug touches the chassis, is usually painted. This does not make a good conducter. Also for most of the upgrades, and addons that the average enthusiast installs, adds on even more electrical load. Also the stock cable is usually cheap, and not very well made. SOLUTION -------- I will explain what I did to my 1993 MR2 Turbo, and you can easily apply this to just about any car. On the MR2T 3S-GTE engine, there are two main points to concentrate on, these are the NEGATIVE battery terminal, and the chassis to transmission cable in the engine compartment. First off, there are different types of cable, and different types of cable lugs. Welding cable lugs are typically larger, and will be more difficult to work with, as some of the standard sized welding cable lugs have very large eyelets in them, and will be far too large to fit the stock bolt. On the other hand there are battery cable lugs, that will work great as they are typically smaller, and the eyelets are well within the range of the stock bolt size for proper fit. Also welding cable is typically much more flexable than battery cable. So the solution I chose was to use welding cable with battery lugs. I purchased the flexable welding cable at a local welding supply shop. It is priced fairly cheap, and for this application on an MR2 you will need only one foot for the NEG battery cable, and about 18 to 20 inches for the chassis to transmission cable. I purchased the lugs at a local battery shop. It is best to remove the stock bolt and check it for diameter, that way you will get the proper lug. For the NEG battery terminal, I used 2/0 (pronounced two ott) welding cable. The total length of the cable and the lugs was only 7 inches for the 1993 MR2, you will want to measure your specific application to make sure that you have the proper length, but don't forget to include a little for the length of the lug. My cable is somewhat shorter, as I have a larger than stock battery. For the chassis to transmission cable, I used #1 welding cable. Again, make sure that you, "measure twice, and cut once". NOTE: you may be able to find a battery shop that will make these cables up for you if you don't want to solder the lugs on yourself. I then used a MAP gas torch, some leadless solder, and some solder paste. After you have properly measured the cable, then use a knife or exacto knife, or what ever you have and trim back a sufficient amount of the cable insulation so that the lug will be completely filled with the bare cable end. Once you have both ends preped, then using a small brush, brush on a little of the solder paste on the inside of the lug, and on the bare cable end. Then fit the lug over the end of the cable making sure that all of the wire ends go inside the lug, sometimes this may be a bit difficult to do, if you need to dress or twist the cable end to get all of the wires to fit then do that. Now roll out a good length of solder wire, and light your MAPP gas torch and heat the lug, where the cable is inserted. As you see the lug and cable heat up, you will push the end of the solder wire into the inside of the cable lug, so that the solder flows freely. Make sure that you are directing the heat from the torch on the lug so that the solder will flow where the heat is. Once you have a sufficient amount of solder on the cable then turn off the MAPP gas torch and cool off the lug and cable, I usually just run a little water on the cable to cool it off. Now do the same to the other end of the cable, and solder the lug on to that cable. Provided that you have measured the chassis to transmission cable then you can go ahead and solder the lugs onto that cable also. Once you have all of the soldering done, then we are ready to install the cables. On the 1993 MR2T the NEG battery terminal is a bit of a job to get at as it is behind the EHPS unit, (assuming you have one). If not then your job will be much easier. First make sure that you don't have codes entered into your stereo system if you do you will need to remove them. Using the proper wrenches, remove the NEG terminal from the battery, and then from the chassis wall. Now using a coarse grit sand paper, remove all of the paint just around the contact patch area where the new lug will be screwed down to the chassis. You can use the new lug to judge the size of the area that you need to sand. Make sure that you get all of the paint off, as any little bit will keep the cable from its maximum current capacity. Also if you have a wire brush, brush the cable lug on both sides. It is probably going to have some burnt solder paste, and some oxidation on it from the heat of the soldering. Now also wire brush the bolt before you screw it back in, this will allow for the maximum conduction. Fit the new cable in place, screwing down the lug to the chassis first and then put the cable end on the battery and tighten it down. Now we are ready to remove the stock chassis to transmission cable. I used a long extension on the socket so it was easier to reach but I am sure that each specific application will be different. After having removed the stock cable then sand the area on the chassis where the cable will screw down, and make sure that there is nothing but bare metal. You may want to wire brush the area on the transmission, as it typically will not be painted, but as always, your specific area may be different. After having done that, then also wire brush the cable lugs and you are ready to install the new cable. After having installed the cable, if you are concerned about rusting as we all are, then a good smearing of silicone grease will keep the water off the area for quite a while. If that is not sufficient for your area, then you may want to spray paint a little bit of primer on the area or some rust proofer. FOR THOSE THAT HAVE THE NOLOGY SPARK PLUG WIRES ----------------------------------------------- For my Nology wire installation, I added another ground wire made from 2/0 welding cable, that runs from the engine hood latch over the the throttle body intake. This ensures that the Nology wires have an excellent chassis ground point and will also ensure that you get the maximum performance out of your Nology wires. For further information on installing your Nology wires, check out the MR2 WEB site and see my detailed instructions on the Nology spark plug wire installation.
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