I recieved my 8274 today, it only has a positive wire attached to go to battery. Does it need a negative cable going to battery, or does it ground through the case/frame. I did check it out with jumper cables and just hooked the ground cable to the housing and the winch worked fine. Just want to make sure of the correct way to do this.
Yes, it needs a heavy cable (at least the same gauge as the positive cable) going straight from the motor to the battery. Those things pull a huge amount of amps on start-up (600+). You don't want that much current going through your frame.
There should be a ground screw hole in the bottom of the motor housing. Clean it off and land your negative cable there. I also recommend running a dedicated ground wire from that motor case ground to the solenoids so they have a good negative connection. It was intended that they ground through the mounting plate to the motor case but that is not a very reliable connection.
On the very old ones with the Prestolite motor, there isn't a ground. The mount and frame are the ground. I agree this is not optimal.
It is possible to establish a ground-the long machine screws that mount the motor are fairly easy to get out. Take one out, clean up the metal in the immediate area, and install your cable under this bolt head. It grounds the motor directly. Works fine.
Another way I have seen, but not done, it to pull off the motor and take the coils out of it. then, weld a bolt onto the housing of the motor, then re-install the coils, and attach the ground cable to the bolt you just welded on.
It is possible to establish a ground-the long machine screws that mount the motor are fairly easy to get out. Take one out, clean up the metal in the immediate area, and install your cable under this bolt head. It grounds the motor directly. Works fine.
So you have a motor that is grounded to an aluminum case that is grounded to the frame that is grounded to the battery, (assuming that there is a ground from the battery to the frame, which there should be) why would you need to run a ground from the battery to the winch motor bolt?
Are we assuming that any of these connections would not be as adequate as the 1/4" bolt that holds the motor on?
Well, paint, rust, road grime, mud, all will tend to degrade the frame ground. A wire with clean connections is easier to inspect, maintain and assure a good return path to the (-) terminal of the battery. There is a reason that Warn went to a cabled ground after the first few years of production.
I have an older 8074 and it doesn't have a ground lug on the motor. I didn't like the idea of relying on the ground path thru the body of the winch and into my chassis.... So tapped a thread into the motor housing. And also run a dedicated earth wire to the battery. Using the frame / chassis as a ground for a winch is not ideal... doesn't conduct anywhere near as good as a copper wire! And your winch will stall... been there done that.
More likely all the incidental grounds caused really high voltage drops and they were probably replacing too many motors on warranty. A piece of cable and a couple lugs are a lot cheaper than entire motors. Will it work without a ground cable, sure. Will it work reliably every time? Not a chance.
Re-stating what has already been posted, the lowest impedance connection from the motor to the battery will result in the best winch motor performance. Doing anything short of that is asking for issues. For those keeping score at home; Warn also used to use incidental grounding for the old "trash can" solenoid packs through the bracket that mounted the pack to the motor on 8274s. That also results in poor connections and Warn later provided a ground in the control circuit to eliminate that problem as well.
