Pre-war (up to 1942) 1939 LaSalle 5019 Grounding

[39LaSalleDriver]

I think this may have gotten lost and buried in another thread so I'll put it out there more directly. While having the starter out the other day, I decided to do the suggested modification of adding a grounding stud to the commutator plate. It can drag somewhat while starting when hot.

What is unclear to me though, is where to attach the grounding strap(s). I get the impression that there should be a grounding strap at point "B" in my illustration (top starter bolt to transmission), but I don't have one there. The ground strap on my car attaches to the frame at point "A" and I have one on the left motor mount to the frame at point "D". Should I be connecting a ground strap from point "A" to point "C" (the new stud on my commutator plate)? Or should I run one from point "A" to point "B" on the top starter bolt, and then another short strap from point "B" to point "C" on the commutator plate?

One issue I see is that the strap from point "A" to point "C" is give or take 40", which strikes me as a pretty long distance. Any suggestions?

[Jay Friedman]

Ideally, in my opinion I would run it from Point A to Point C, even though the distance is "give or take 40".  On your car the battery is at a relatively long distance from the starter, so the cables will be long.  (My Master Parts List shows a length of 53" for your other battery cable.) 

On the other hand, this may be impractical because you can't find a ground strap that long or some other reason.  In that case, see if it helps by just running a short ground strap from Point C to either Point D or a new Point E which would be a hole drilled in the frame close to Point C.

[Bob Schuman]

Jon,
I agree with Jay's comments, but you do not need to try to find a long unbraided ground strap. For both battery cables you should use 1/0(called one aught) or preferably 2/0 cable, that is available at welding supply houses and possibly truck parts vendors. The end connections are also readily available and should preferably be soldered, not crimped.
Bob Schuman

[harry s]

Unless I'm missing something, when you connect the battery ground terminal to the frame it (frame) becomes the grounding conduit. You would then connect the newly installed ground stud on the starter directly to the closest point on the frame with double ought (2X0) cable. absent that connection you only have the flat ground connection at the motor mount which in most cases is not adequate. It is also a good idea to heavy up the cable from the power battery terminal to the starter solenoid.      Harry

[Jay Friedman]

Harry, what you wrote is more or less what I suggested as an alternative.  The reason i didn't suggest it as a 1st choice is that I somehow feel a 40" long ground strap, or a long 0/0, 1/0 or 2/0 cable as you and Bob wrote, would be a better grounding conduit than the frame.   

Also, when I saw in the MPL that the battery (negative terminal in a '39 LaS?) to starter solenoid cable is 53" long, my first thought was that there must be a certain amount of voltage drop built right into the system. 

[harry s]

Jay, Sorry. I had too many As, Bs & Cs spinning and I haven't figured out how or if you can toggle back to the thread while replying. Anyway it makes sense that either option would work. The important thing is the additional ground direct to the starter.      Harry

[39LaSalleDriver]

Also, when I saw in the MPL that the battery (negative terminal in a '39 LaS?) to starter solenoid cable is 53" long, my first thought was that there must be a certain amount of voltage drop built right into the system.

Thanks for all the suggestions. I knew about the negative cable being that long too, but wasn't thinking about using a cable vs. strap for the ground. Interesting. I like that idea of using a cable. From what I can see via the kind posters here, it sounds like what I need to do is get rid of the grounding straps (other than the one at point "D") and replace with 1/0 or 2/0 cables. Run from battery to point "A" or "C".

However, if I run a ground "cable" direct from the battery to point "C", I would lose grounding point "A". Wondering if that would cost me a voltage drop throughout the rest of the frame? Knowing that extra distance is my enemy, and that the engine is on rubber mounts which serve as some degree of insulation I could see this as problematic.

If I tie in a longer cable from point "A" to point "C" would I lose voltage using point "A" as a junction if you will, or should it remain relatively the same?

Sorry to have dredged all this up, but everything I read and searched for on this topic tended to reference later model cars which had moved the battery box to the engine compartment making it a little easier to noodle through. I'm sure it's been done, but I didn't find anything from anyone who had done this procedure on a 39 LaSalle. Thanks again,

[tripwire]

Jon,
You don't need giant cables for grounding purposes.  The ground side carries no electrical energy to speak of.  You do, however, need to provide a clean, clear path for this flow to return home, the battery.  Make or buy a strap or cable long enough to go from your positive battery post to a spot on the frame nearby.  There is probably a hole already drilled in the frame somewhere you can use. Once you pick your spot on the frame go at it with sandpaper or something to remove anything that isn't bare steel. You need a clean spot the same size, at least, as the terminal on your ground strap/cable.  Bolt your cable to this spot using a star washer between the strap/cable and the frame and also on the hardware. You'll end up using 3 washers, 2 on the strap side and one on the opposing side of the frame.
At the engine, make or buy some straps to go either from the bellhousing to the body or from the engine mounts to the frame. Again, you'll need clean steel, no paint, no rust surfaces at the attaching points.  Again, the straps don't have to be very big.  I think mine came from ebay & cost $5-$7 each.  Do the same at the starter commutator end plate.
I've attached a photo to show you how I did mine.

Wes in VT

[DaveZ]

I agree with Wes. If your connections are CLEAN and you have the proper gauge wire and a good battery you should have no problem. Most cases like this are caused by dirty connections or undersize wire. 6V needs the heavy gauge wire. Sometimes folks go to the local car parts and ask for a battery cable:-( On our LaSalles there is a ground strap from the battery to the frame and from the engine mount to the frame. They must have CLEAN connection. Neg battery post cable to starter. An additional ground strap from frame to starter is helpful too.  I made new cables and bought the correct cables sheathing etc from Brillmans and made them up. Works like a charm.
Best of luck!:-)

[39LaSalleDriver]

I know all about the clean connections. That is "Owning a LaSalle 101" stuff. 

Up to this point, I hadn't really had any problems at all other than it's pretty slow to turn over if the engine is up to temp. Sometimes to the point that I fear the battery is draining out. Since I was at a point where I had installed the correct solenoid and had the starter off, I decided it would be wise to add the additional stud to the commutator end, and give my battery cables a once over.

The negative cable which came with the car is more or less "getting the job done" but I think it can be better. Unsure of gauge. It looks to be marked as "0", but I suspect a bit too small still. On top of that, it's about 18-24 inches too long and I don't like that.

The positive ground strap runs to the frame, and then from there another strap has been bolted to the bottom of the transmission cover. Works, but I'm not happy with it.

I have now ordered a custom made 2/0 ga. battery, not welding cable of the correct length to run from the battery to the starter solenoid, and a 2/0 ga. cable to run from the ground point on the frame to the stud I added on the starter housing. I'm hoping there won't be much voltage drop at the junction where they meet on the frame, because I didn't want to lose that ground point by bypassing it to go from battery directly to the stud on the starter. While my thinking may well be off, it doesn't seem to make sense to me to run another cable from that starter stud back to the grounding point on the frame.