Earthing a galvanised chassis

[cypermethrin]

I have suffered from poor starting for a while - and today I finally solved it - down to a bad earth - nothing remarkable so far.

I have a brand new galvanised chassis (not a refurbed) - and it was earthed in all the normal places for a 300 tdi (battery to crimp on chassis then onto bellhousing; starter bolt to chassis).

But all this was not sufficient - which begs the question does the galvanised layer actually reduce the earth potential ??

Do a really need to remove a small part of the galv and get down to the metal and use that as a contact....

Thanks for your help once again

[bishbosh]

You need to remove any white zinc oxide, but the zinc will conduct adequately. Give it a quick rub with some emery paper and it should be fine. No need to get down to the steel.

[crwoody]

Like Bosh says, zinc oxide is a no-no but zinc metal itself is a perfectly good electrical conductor with a similar conductivity to brass, so there should be no problems there.

[cypermethrin]

Thanks chaps much appreciated

[cackshifter]

One other thing on the subject of galvanising & electrics.. I've just fitted a new galvanised rear X member to my 90, and inside it it was very obvious there were long needles of zinc, very sharp, where presumably it had stood to drain while hot, and formed stalactites. That wouldn't matter except for the chassis loom running inside, the tape binding on which is about as much use as wet tissue paper. I presume a chassis might have them inside, but you wouldn't see them.

Nigel

[Disco-Ron]

I am waiting for my new chassis to arrive, and have bought a brand new chassis loom, and some ducting to put over the loom before i feed it through the chassis...... just in case!

[LandyManLuke]

I'd be more concerned with what you're using as the earth path, rather than the fact the chassis is galved.

As has been pointed out, as long as the connection is clean, galv shouldn't be a problem.

The braided earth straps are cheap and nasty and are not particularly suited to life under a landrover.

[jbs]

When I did my chassis swap on my 90 I earthed mine out from the battery to the chassis, then battery to the rear of the gearbox, also from the chassis to the block 200 tdi-and now also from the block to the back end of the starter motor too and so far it's been good not had any problems for a while but I did'nt originally earth from the block to the starter motor which caused me to have a charging problem and also it looked like my exhaust was having welding done to it at night across Salisbury plain( nice blue sparks) but you live and learn, i will be putting some more onto the 90 at some stage-next time I'm home I think as i want to do the uprated wiring for my headlights etc which mmgemini has done to his vehicles

[Ally V8]

I am waiting for my new chassis to arrive, and have bought a brand new chassis loom, and some ducting to put over the loom before i feed it through the chassis...... just in case!

I really wouldnt bother trying to put the loom back through the chassis - its much better clipped along the top or even the inside face of the chassis.The inside of the chassis even on a standard car is full of sharp edges where you cannot even see let alone do anything about them.Its an easy task to route the loom and brake pipes carefully along the chassis where they will be protected - but also easy to inspect or repair.

[ajh]

Something I learned is that there really should be several stainless steel studs welded to the chassis where the ground points are going to be, then galvanized and the zinc stripped and a die run down them to provide a solid, corrosion proof, easy grounding point for the chassis. Came across this doing research on ground up chassis building. Would be nice to see it done on the replacement ones as standard.

[LandyManLuke]

Something I learned is that there really should be several stainless steel studs welded to the chassis where the ground points are going to be, then galvanized and the zinc stripped and a die run down them to provide a solid, corrosion proof, easy grounding point for the chassis. Came across this doing research on ground up chassis building. Would be nice to see it done on the replacement ones as standard.

That would indeed be very nice to see!

[Disco-Ron]

I really wouldnt bother trying to put the loom back through the chassis - its much better clipped along the top or even the inside face of the chassis.The inside of the chassis even on a standard car is full of sharp edges where you cannot even see let alone do anything about them.Its an easy task to route the loom and brake pipes carefully along the chassis where they will be protected - but also easy to inspect or repair.

So, bearing in mind that i would clearly have to drill the new chassis to fix the clips on, what is the best means of securing them... alloy rivet..?? self tapper...???

[Retroanaconda]

I just drilled a 3mm hole, put a blob of silicon sealant on said hole, then screwed the P-clip on with a self tapper.

Just normal self-tappers, not stainless ones, which I may come to regret in the future

[WarPig]

I recently had a new galv chassis and from memory, there is no earth lead from my battery to the chassis.

Am I looking in the right place? Should I be able to see an earth cable coming from one of thre battery terminals?

[western]

battery earth from negative terminal to the gearbox/transferbox joint

engine earth from LH engine mount on block to chassis LH mount bracket

[WarPig]

battery earth from negative terminal to the gearbox/transferbox joint

engine earth from LH engine mount on block to chassis LH mount bracket

Cheers western, Ill have to get that sorted.

Whats the worst that could happen if not earthed? Will the mother-in-law get more than a shock when she jumps in?

[LandyManLuke]

Cheers western, Ill have to get that sorted.

Whats the worst that could happen if not earthed? Will the mother-in-law get more than a shock when she jumps in?

Often, when a proper earth is missing, it is possible for the handbrake cable to carry current. Given that it's not designed to do this, it can suffer damage, either by melting, or setting fire, in extreme cases.

[western]

no reasson why you cannot add extra earth cables between chassis/battery/engine. entirely your choice, but might give rise to more earthing faults later.

[ajh]

Your major issues are ground loops or stray current, you'll want to read up on http://www.epanorama.net/documents/groundloop/ so that you're familiar with why they occur and how to prevent them because next to an intermittent ground (loose connector usually) a ground loop is the most frustrating gremlin to squash and they present with all kinds of wacky behaviours.

[rusty_wingnut]

interesting thread this, as my 300tdi has only got one earth cable - and only ever has done as long as I've owned it. There is, and never has been any sign of the one from the starter bolts to the chassis.

Can anyone confirm if this was original to all 300tdi 90s?

[Dads Toy]

Same here on my 300Tdi 90, only the one from the battery - chassis - gearbox. Nothing at all in the engine compartment (apart from a 300Tdi engine of course!) No strap on engine mounts or starter.

Malcolm

[Jamondo]

I've got one battery-chassis-transfer box, and one from engine mount bracket to chassis rail. I did build it myself though so I just went with old school thinking.

However, I've had a new battery for it this morning because I've started having slow starting symptoms, charged it up in work couple of weeks ago and it died again yesterday so wether I've also got bad ground causing charging issues? She won't start with sidelights on either, stop solenoid doesn't energise..... Green oval=headache 

[Orgasmic Farmer]

Holy thread revival :-)

 

Interesting that I had starting issues from the outset after fitting a new glav chassis. Not bad enough to make me do anything about it until after 4 years i got so fed up I did some tests and found it was losing 3 volts btween the battery and starter (1.5 volts on both + & - leads). I bought all new cable and ran them from both = & - direct from battery to Starter. Result? Perfect. In 6 month I have not had a single slow crank moment or any other strange electrical issues either.

[western]

not had any starting problems with my 200tdi engine after fitting a galv chassis in late 2013, I have the 2 main earth cables as I mentioned in my earlier reply above. 

[Troll Hunter]

In another age, I had a fibre-glass bodied kit car and I seem to remember that it had a complete earth network, just like the supply looms, with the engine and starter, and all the normal earth leads from lights, etc, being connected to it and hence back to the battery negative post.  I don't remember ever having any earthing problems with that car.  Has anybody taken that approach with a Land Rover?  Apart from the added complexity of the wiring, and extra cost, are there any technical disadvantages?

Mike