Don Ridley Posted August 28, 2019 Share Posted August 28, 2019 I found this in the Focus RS forum. The TC has a painted ground connection like the Focus. I removed the paint with a sanding wheel on a Dremel to improve the connection. I used a jumper cable to maintain the ground connection during the procedure so none of the vehicle's memory would be lost. https://www.focusrs.org/threads/how-well-are-we-electrically-grounded.115556/ I will add some corrosion inhibitor later but it's not essential here in dry California. All the electricity flows through the ground bolt thread contact area. You can decide if corrosion of bare metal is more of a problem than a bolt thread-only ground connection. Quote Link to comment Share on other sites More sharing options...
DonShockley Posted August 28, 2019 Share Posted August 28, 2019 Year ago I had a problem with F150 where it would just randomly stop running as I was traveling down the road. Towed it to the dealer, no problem found, pick it up, less than a mile down the road dies again. Eventually figured out it was "loose" bolt holding the engine ground to the frame that the dealer tightened. A few weeks later, dies again. At least now I knew how to get it running again so I could get home. Checked more thoroughly and found it was to a painted frame with the only connection via the bolt threads and they were stripping out. Dremeled the paint off so there would be a direct cable to frame path and also replaced the self tapper bolt with a stainless bolt, nut, and lock washer and never had a problem again. I might have to do a little proactive Dremel work again based on this post. Maybe use a little of that protective battery terminal spray too. Quote Link to comment Share on other sites More sharing options...
Willygee Posted August 28, 2019 Share Posted August 28, 2019 Do gen2 TC's need inspection? Quote Link to comment Share on other sites More sharing options...
Don Ridley Posted August 28, 2019 Author Share Posted August 28, 2019 Yes. I am referencing Gen 2 TC to equivalent model year Focus. Quote Link to comment Share on other sites More sharing options...
Don Ridley Posted August 30, 2019 Author Share Posted August 30, 2019 I removed the paint under the main ground lug and two other grounds under the air box. I added a 2ft ground cable from the main lug to an unused hole under the air box (similar to the Focus mods). I coated the bare metal with Corrosion X. The discussions about harmonics, inductance and ground loops missed the point that up to 100+ amps needs to flow though the lug and into the negative terminal of the battery. These mods ensure this can happen without any problems. Quote Link to comment Share on other sites More sharing options...
Fifty150 Posted August 31, 2019 Share Posted August 31, 2019 Have Focus owners encountered problems with poor grounding? Is that an issue unique to just Focus, or other late model cars as well? I'm a little behind in the game with that issue. I haven't heard of inadequate OEM grounding. I'm only aware of poor grounding with aftermarket stereo, off road lights, and winch installation.....but that's almost always because the installer did a bad job. And usually, I only have myself to blame, since I did the install. Quote Link to comment Share on other sites More sharing options...
Don Ridley Posted August 31, 2019 Author Share Posted August 31, 2019 (edited) Yes and no.... Read the RS forum post. Then read some of the ST forum post (link in the RS post). Some have claimed it cured poor idle and other things. Some say it made no difference. But the ground is weak since it relies on bolt and nut thread contact only. Removing the paint probably is all that's necessary. No electrician would ever make a connection to a painted surface without removing the paint. Edited August 31, 2019 by Don Ridley Quote Link to comment Share on other sites More sharing options...
DavisTremblay Posted September 26, 2019 Share Posted September 26, 2019 I have read the RS post but doesn't find it much useful, i consider contacting an electrician to improve such ground connections. Quote Link to comment Share on other sites More sharing options...
Don Ridley Posted September 26, 2019 Author Share Posted September 26, 2019 The RS and ST guys got into a long discussion that became too technical. This photo simplifies things. The surface in contact with the lug on the cable should not be painted if electrical conductivity is most important. Quote Link to comment Share on other sites More sharing options...
Don Ridley Posted September 27, 2019 Author Share Posted September 27, 2019 I evaluated the connections between the ground strap and the painted frame ground mount. The lug and the cable make good contact by a cylinder-in-cylinder connection and a crimp. The ground bolt and the frame nut are also a cylinder-in-cylinder connection (slight loss in contact due to threads). Both the cable/lug and bolt are about the same diameter so why is the bolt a bad connection? The problem is the only contact between the lug (and all the power in the cable) and the bolt are on the bottom of the bolt head. I estimated some dimensions and calculated the surface area of electrical contact for each connection. The more contact area, the better the connection. Contact surface area of ground bolt and nut (cylinder-in-cylinder) = 226 mm2 Contact surface area of the bottom of the bolt head = 69 mm2 All the current has to flow through only 69 mm2 of metal to metal contact. If you sand the paint off the frame you will greatly increase the contact area. Contact surface area of sanded connection = 209 mm2 + 69 mm2 = 278 mm2 The sanded connection can carry much more current for a longer time than the painted connection. Sanding this connection increased the contact area by a factor of 3. All these numbers are approximate but shows there are measurable gains to this modification. windguy 1 Quote Link to comment Share on other sites More sharing options...
Fifty150 Posted September 27, 2019 Share Posted September 27, 2019 Good work, Mr. Ridley. This information will serve everyone who is planning on upgrades which require better grounding. Quote Link to comment Share on other sites More sharing options...
Don Ridley Posted September 27, 2019 Author Share Posted September 27, 2019 After looking at the ground stud I underestimated the surface area of the ground bolt-to-lug connection. A washer increases the contact area so it is approximately the same as the contact area of the bolt and nut that mount to the frame. So, the original design is adequate and the only gain in sanding paint off the frame would be a backup to deterioration of the nut and bolt connection. FYI, I was more careful when I sanded the frame. I don't have any bare metal showing when the lug is attached. Quote Link to comment Share on other sites More sharing options...
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