Correct positions for earths please

[kenny]

Back on the wiring again on this EARLY +2. we've got loom in and trying to power up various items via a 12v transformer.
I can get solenoid to click and cigar lighter firing up.

I know it needs earthing properly but I'm struggling with the diagram.

1) I have 2 old tatty copper braided ribbon type earth straps which I'm about to remake, where do these go please? Is one for petrol tank.....again to a numpty like me manual is not specific.

2) I also have 2 lots of 4 black wires on either end of dash.......does the lot on the steering side go into the black wire off harness on steering wheel and where do the others go? It is the cortina binnacle car with horn on the stalk.

3) Does the starter motor earth cable (I assume the one about a foot long just go the chassis bolt towards rear of car.

4) Final daft point but the bobbin under dash which I assumed to be an earthing point will not earth so I am messing about with a long lead earthing it to chassis in engine bay for trial purposes.

It's hard putting all the hassles down in writing but any thoughts whatsoever would be valued to get this job done.

I'm a self-confessed electrical idiot but I am trying my best

Thanks a lot,

Kenny

[lotusfan]

Kenny

Just a comment on your item 3 - the starter has no earth lead, it is earthed by bolting it to the engine rear plate. The foot long cable, assuming it comes from the insulated terminal on the back of the starter, sounds like the lead that goes to the starter solenoid.

Mike

[kenny]

Cheers for that Mike. It's just that previous guy has bolted this 1/2" diameter earth cable to chassis near g/box and the only thing it reaches is the starter. Maybe it's a g/box earth

Thanks for reply anyway.
Regards,

Kenny

[Dave-M]

Kenny, It does not sound original but it will serve well for the main engine earth. It could be fixed to a starter fixing bolt or a bell housing bolt and work well. I think the original engine earth was a 1" wide heavy braided stap which went from an oil pump bolt to an engine mount to chassis fixing bolt.
I would suggest what you have will be better than the original.
Regards
Dave

[kenny]

Cheers Dave, will try and call you this week for a chat.

All the best.

Kenny

[chrishewett]

It may be that the 1/2 inch cable near the gearbox went to the dash earth underneath if you say that the original didn't work. For the dash earth I have put a bolt through and connected an earth from that underneath to a starter motor mounting bolt. This now works very well.
Chris

[rgh0]

Kenny

My cooments on your specific questions below


>1) I have 2 old tatty copper braided ribbon type earth straps which I'm >about to remake, where do these go please? Is one for petrol >tank.....again to a numpty like me manual is not specific.

The only heavy braid style earth connection originally on the cars I believe was a short (about 150mm long) oval braided earth connection that went across the right hand engine mount from block to chassis, this earthed all the engine components including the starter motor. Any flat style braided earths in other locations are probably a later addition as the DPO struggled with earth problems as we all do.



>2) I also have 2 lots of 4 black wires on either end of dash.......does the >lot on the steering side go into the black wire off harness on steering >wheel and where do the others go? It is the cortina binnacle car with >horn on the stalk.

I dont know the early plus 2 wiring details but I suspect these wires are earths for the door switches and door lights and window motors, at least they are on my later 1973 plus 2. The are the non earth ends of earth cables and go back to the common earth point on the bobbin under the dash.

>3) Does the starter motor earth cable (I assume the one about a foot >long just go the chassis bolt towards rear of car.

No starter motor earth cable orginally, as stated above the starter was earth via the strap across the RH engine mount

4) Final daft point but the bobbin under dash which I assumed to be an earthing point will not earth so I am messing about with a long lead earthing it to chassis in engine bay for trial purposes.

The bobbin under the dash on the top of the centre tunnel is the main earthing point for all the earth cables in the dash wiring ( including those at each end of the dash you referred to above). This should have a bolt going all the way through it to the chassis that the earths the wires connect to it, if that bolt is not earthed then you have a more major problem that needs fixing to find out why it is not properly connected to the chassis, or maybe why the chassis is not properly earth to your temporary test setup.


hope this helps a little, electrical trouble shooting by the net is always hard

cheers
Rohan

[kenny]

Chris, many thanks for the input, I will double check that cable later.

Rohan, superb point by point answers once more.......thank you.

I'm putting a couple of hours in this afternoon and will follow all you have said.
I also agree it is so difficult to ask and to anwer questions of this type via typing.
I will start off by finding out why I can't earth via the bolt under dash.............must be a simple explanation.

Many thanks once more.

Regards,

Kenny

[Dave-M]

Kenny,
If you are testing for an earth at the bobbin without the 3/8 bolt tightened you may well find you don't get an earth reading.
Hope the following makes sense:-
The earth at the bottom of the dash should be as follows
1) On the chassis directly below both bobbins should be 2 holes 1 on either side. Below the top lip of the chassis are two 6mm plates welded on to the chassis and the holes through the cassis and these plates should be tapped with a 3/8 unf thread.
2) The 2 bobbins on the shell should have a 90 degree angle strip of 16 swg steel with 2 holes which line up with the bobbins. This this bolted with two 3/8 bolts to the chassis. The vertical face of the 90 strip is towards the rear of the car and is used to secure the bottom of the dash.
3) Under the head of one of the 3/8 bolts ( usually the right hand side) is trapped The group of earth wires.
4) If you are unable to tighten either of these bolts The threads are stripped or incorrect and it's dash out and re-tap a suitable size or alternativley used a nut and bolt if you can get access (I don't know if this is possible as I have never had to do it)

The following is from memory but I am fairly sure it's correct:-
At either end of the dash are groups of earth wires that are crimped together in an eylet terminal. Each of these has an earth wire included which leads back to the main earth terminal at the dash base. I have seen these eylets secured in different places on the body but as it is essentialy just a junction block for the wires it does not have to be earthed it's self and you can fix them wherever it's convenient.

Also behind the dash are other odd eylet terminals which are instrument earths and these connect behind the knurled fixing nuts for the instrument clamp.
Hope this helps
Give me a bell anytime and I'll do my best to help if I can.
Regards
Dave

[inxs]

Hi Kenny,

I am in the midst of doing up my dash of my early +2 (0100). Looking at my wiring which is original I would go with Rohan that the thick braided wire is the one that goes to the bottom support for the dash, this is then attached to the speedo or tacho?? and then all the other earth wires are looped from there the other wires (black) would be for the light switch and the electric windows.

Regards Darren

[bcmc33]

With the dash out of my Sprint I have completely rewired the earth connections to the extent of adding a number of double female bullet connectors to make it a parallel circuit with the ends connected to both lower dash fixing bolts. A little OTT I know, but from my past experience ? you can?t have too many earth returns to the chassis.

With regard to braided straps ? my car has one connecting the steering rack cross member to the radiator RH fixing bracket, and all the front end earth connections from the relays etc. fix to the LH bracket. As previously described, the engine is earthed with a strap across the exhaust side engine mount.


Brian Clarke

[chrishewett]

Dave and Kenny,
If the threads in the underdash earth are stripped it is possible to put in a smaller bolt from inside and bolt through. I had my son inside holding the nut while I fed the bolt and earth through from underneath with a socket extension and torch ( freezing cold, muck in the eyes etc), such are the delights of classic lotus ownership.
Chris

[kenny]

Many thanks for above comments, I get the feeling my problem is lack of confidence with this project, If it were someone elses car I'd dive in and do it. I forever seem to be worrying if "this bit went there originally".

The comments above have made me realise that as long as I make good earths throughout the car and try to keep them hidden and I can get everything working then job's a goodun'

Cheers,

Kenny