View Full Version : Multiple Ground Wires

07-27-2005, 03:01 PM
Anyone ever try these? eBay Grounding Wires (http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1,1&item=7989179254&sspagename=STRK%3AMEWA%3AIT) I recall some post a month or two ago about multiple grounds

07-27-2005, 04:40 PM
Somehow, I can't see these delivering all the benefits they claim. I am all for grounding everything on a car- like police cruisers do, especially with a car that has extensive electronics- its definitely a plus- but increased current flow, lower resistance, etc...can only translate to certain performance aspects. If you want to go faster, just buy a sh*tload of chrome-

07-27-2005, 05:09 PM
Golly....people will do anything to make a buck :D

I love the line to the effect of, "it may improve starting/throttle response," with the key word being MAY.

Sure, if the current grounds are utterly destroyed/black/corroded, of course it's going to help -- the car will actually work :)

best, whit

07-27-2005, 06:57 PM
Basic reason for adding extra earth straps is to reduce resistance and so voltage drop in both the charging and discharging curcuits coming off the battery... if a wire is too thin, some of the max voltage in the curcuit will be developed across the wire (energy going as heat) rather than being available to the "load"... but in some cases the "wires" are engine blocks, and conduction paths through bolt heads etc etc.

That said, the BMW way is usually to NOT depend on grounding through the cases of the electrical devices - that's why there are so many brown wires everywhere!! Doing that means the electrical power supply is more stable, and less "noisy" (eg the AFM doesn't end up sharing an earth return path with the HT side of the ignition!!). Also, BMW usually specify wiring with good CSAs (cross sectional areas - eg the thickness of the wire, what drives its current carrying capacity)... I've seen Japanese looms that have made me afraid for fires - especially when som bozo hides unsoldered/unwelded crimped joins in high-current lines deep inside heavy plastic protective sleeves...

On the E32 the frame is very good thickness steel & glavanised, so likelihood of a high resistance path through the frame is low... but, a lot of the engine etc is rubber mounted, so there are some very heavy straps already in place - check for the main frame-engine earth wire down by the AC compressor.

However, the only one place I can definitely think that might benefit from an added earth strap would be the alternator, since the ground path for this goes

mounting bracket
engine block
earth strap

(Actually, on the same basis, the AC compressor clutch also returns through the same bracketing arrangements, so a strap from the compressor body there might be good too.)

If you do want to think about it, I've previously used soldered lugs onto high-capacity oxygen-free-copper 3-4mm speaker wire, specifically attached under the screw of the voltage regulator "wing" that also has its earth connection to the alternator body... that way the regulator is seeing the "truest" ground voltage reference too. I will probably be doing this soon myself when I get my upgrade alternator (115A, not the standard 90A, better for lots of round-town driving with lights on!)

Past the extra straps, just look after the ones you've got - remove, wire brush the lugs, get bright metal on the mounts, use a smear of vaseline to seal out water. Check the crimp of the wire to the lug for green copper oxide (not the best). Clean the B+ terminal post under the hood (battery disconnected!!) where the big +12v cable comes up from the battery. Check all the earth "posts" everywhere you can see them - where all the brown wires congregate! - and make sure all lugs are clean, and all nuts are tight.


07-28-2005, 05:31 AM

PS: There is a special compound used in the Power industry, manufactured by Burndy (There are equivalents from some other brands), called "Penetrox E". It is an Oxide-inhibiting compound specially designed for joints on insulated copper wires, a bit expensive though.