Cleaning chassis ground connections

Split from General / Technical for discussion of anything electrical, electronic... 12v, Inverter, Satellite, Headlights, flashlights etc.
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kdarling
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Joined: October 20th, 2015, 6:57 am
Location: Northern NJ

Cleaning chassis ground connections

Post by kdarling »

Over the past six weekends, I've been slowly cleaning up the underbelly of the beast (while learning where many things are as well).

Using a portable drill with wire brush, rust remover/converter spray, degreaser, and high temp paint, I have finally got much of it looking pretty good. Almost everything from the propane tank to transmission to the exhaust, from inside front bumper and chassis to coil springs to driveshaft to rear axle, all now clean, rust free and protected with new silver, grey and black paint. (Still have the engine and far rear chassis to work on.). I use leveling blocks to raise the whole thing a couple of inches which helps a lot when underneath, as does a work lamp.

Anyway, so I got towards the right rear and saw some of the ground connections, which are on my todo list.

In the photo below, at the lower left is the generator ground, and the upper right are the grounds for most of the electrical panel and converter. (This was taken after washing nearby, that's why it's all wet.). Remember, I'm a '94, so yours will vary.
grounds_rr.jpg
Since the generator has been slow to start at times (it doesn't quite reach the RPMs required), and its ground used a big 1/2" nut, I went for it first. The nut quickly came loose with a socket and began to unscrew off, but then after a few tight turns it suddenly starting turning TOO easily.

To my horror, the nut and the bolt inside the chassis rail that it threads onto, were now turning together! Arrgh. Now I was worse off than ever, with a partially undone ground, and seemingly no way to tighten or remove.

Long story short, fortunately the back end of that chassis box rail is open, and I was able to jam in a long crescent wrench to keep the bolt from turning while I removed the nut, wire brushed clean the rail and ground cable, and put it back together. Then I covered it all with clear Rustoleum spray.

Good news is that now the generator cranks a tiny bit faster and thus starts nearly instantly.

Bad news is that now I'm fearful of messing with those other grounds, as there's no way to reach behind them inside the rail. Does anyone know if they are simply screws into the rail, with nothing inside? I think they are, but you know how it goes: once bitten, twice wary ;)
Last edited by kdarling on June 4th, 2017, 8:59 am, edited 4 times in total.
1994 Concourse dinette, Ford 7.5L (460 V8)
Rokrover
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Re: Cleaning chassis ground connections

Post by Rokrover »

Wise preventive maintenance. My 2002 has 7 ground wires to frame rail as I recall; 3 on the right side rear (for Refer, Gen and 12V circuit board) and 4 on the left side. On the left, one is mid section under the coach battery compartment to batteries and the remaining 3 are at the rear for 110V breaker panel, 12V fuse panel and 12V circuit grounds.

The wires run into copper blocks grounded to frame by a 12x14 sheet metal screw with no backup nut inboard of the frame rail. However, these screws are easily sheared when rusted into the hardened steel frame then a bear to remove. I had to drill one out with much colorful language.

So I suggest soaking the area overnight in penetrating oil like Kroil or PB Blaster. Others swear by a home brew of 50/50 acetone/automatic transmission fluid. Either way, ease out the old screws gently and replace with new ones, then coat the area with some Rust-Oleum.
Ted C. / SW Arizona
"The Blue Chook" 2002 Concourse Owner: 2013-2019
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kdarling
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Location: Northern NJ

Re: Cleaning chassis ground connections

Post by kdarling »

Ted, thanks so much for the info!

PB Blaster it is, then. And I'll keep my fingers crossed... I've rarely had good luck removing broken fasteners that small. Likely easier in this case to tap a new hole instead :)

Regards, Kev

PS. I swear, you'd think by now that I'd learn to allocate at least an hour of actual time, for every ten minutes of predicted work time :lol:

Or in this case, don't get started unless I have all day to go buy any necessary tools and parts if everything needs to be redone! Which means those other grounds will have to wait for next weekend.
1994 Concourse dinette, Ford 7.5L (460 V8)
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Blue~Go
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Re: Cleaning chassis ground connections

Post by Blue~Go »

Another option if you have an issue is to change to a new one. When I ran a new chassis ground from the house bank negative to the chassis (I'm eliminating many of them, but still have one for the combiner wire), I simply found an existing hole in the frame rail, then used a heavy duty lug on the end of the wire, then a machine screw/washer/lockwasher/nut to secure it to the frame (I cleaned the bit of the frame behind the lug for better contact). Since it's a chassis (frame) ground, any bit of the frame should work. I prefer a machine screw/nut to just a pointy through type.

(Of course nothing wrong with those either as long as they are making good contact.)
1999 Concourse
tjmackle
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Joined: August 14th, 2017, 11:48 am
Location: San Diego Marina District

Re: Cleaning chassis ground connections

Post by tjmackle »

I'm thankful I found this subject. My project for 2017 was to upgrade my ham radio station in my 1998 Concourse. Proper ground connections are paramount for this hobby and it is a safety issue for anything electrical.

Getting into the ground connection area is an unpleasent task and unless you are an experienced RV electrical mechanic - get some help. Here are some of the things I found wrong with the system and had all of it corrected:

Engine block to chassis connection: Obviously this Item was not taken seriously. It looked like a piece of gift wrap ribbon! I had it replaced with thick #2 stranded cable and cleaned the corrosion at the terminal points. You can use either copper infused conducted grease or conductive silicon to prevent corrosion returning to the connection. The end result was the alternator and ignition noise was greatly reduced on the AM radio frequencies and the ham radio speakers.

2. Generator to cassis connection: this also had significant corrossion and the the fix was the same as the engine block connection. The result was a noticable reduction of generator noise in the radio and tv
speakers but to get it reduced 100%, you need to connect ferris clamps to each end of the speaker wire.

3. The converter ground was OK but cleaned anyway.

TJM 1998 Concourse
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