Wondering about gearbox mount earth

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vanhatter
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Wondering about gearbox mount earth

Post by vanhatter »

Hi all,

So having seen some posts relating to starting problems (in particular the start motor), I saw suggestions to make sure the earth wasn't corroded. Mine isn't, but I did see what looks like a bit of wear from contact with the handbrake cable. I'm wondering if anyone has seen this before / if it's a problem?

Any thoughts appreciated!

Thanks :ok
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tommin
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Re: Wondering about gearbox mount earth

Post by tommin »

That needs replacing simple as that, aslo I would run a new earth cable from the starter to the engine earth.
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Re: Wondering about gearbox mount earth

Post by Oldiebut goodie »

That terminal is corroded to my eyes! You haven't even taken it off. :shock:
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Re: Wondering about gearbox mount earth

Post by California Dreamin »

vanhatter wrote:Hi all,

So having seen some posts relating to starting problems (in particular the start motor), I saw suggestions to make sure the earth wasn't corroded. Mine isn't, but I did see what looks like a bit of wear from contact with the handbrake cable. I'm wondering if anyone has seen this before / if it's a problem?

Any thoughts appreciated!

Thanks :ok

Certainly doesn't look to be in A1 condition. What you need to appreciate is that the starter circuit can draw upwards of 160 amps and these heavy 'chassis return' cables need to be in perfect condition otherwise they will create massive resistance resulting in slow cranking etc.

My own advice would be to leave this cable alone and just fit a second braided earth cable from one of the starter motor bolts to the bodywork (area taken to bare metal for good body connection).

Something like: Note* this supplier will alter length and eyelet end size to suit.
http://www.ebay.co.uk/itm/UP-TO-610-MM- ... 339033ffca" onclick="window.open(this.href);return false;

Martin
Last edited by California Dreamin on 01 Jul 2014, 10:10, edited 1 time in total.
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Re: Wondering about gearbox mount earth

Post by ghost123uk »

California Dreamin wrote:My own advice would be to leave this cable alone and just fit a second braided earth cable from one of the starter motor bolts to the bodywork (area taken to bare metal for good body connection).

http://www.ebay.co.uk/itm/UP-TO-610-MM- ... 339033ffca" onclick="window.open(this.href);return false;

Martin

Proper coincidence there, I have just ordered a very similar cable to do just the same with :)
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Re: Wondering about gearbox mount earth

Post by Oldiebut goodie »

I note that Aidan is advocating removing the gearbox earth due to electrolysis and corrosion of the case that he has seen in that area and using an earth from the engine to the bulkhead.
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Re: Wondering about gearbox mount earth

Post by ghost123uk »

Oldiebut goodie wrote:I note that Aidan is advocating removing the gearbox earth due to electrolysis and corrosion of the case that he has seen in that area and using an earth from the engine to the bulkhead.

Jolly good point !! (and one that now you have mentioned it I will attend to :))
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Re: Wondering about gearbox mount earth

Post by vanhatter »

Thanks for the input guys!

California: do you suggest anywhere in particular to attach the other end to? Do you think I'd need to drill through the bodywork to attach a bolt? Sorry if this is all basic stuff - I'm learning everything as I go along!

California Dreamin wrote:
Certainly doesn't look to be in A1 condition. What you need to appreciate is that the starter circuit can draw upwards of 160 amps and these heavy 'chassis return' cables need to be in perfect condition otherwise they will create massive resistance resulting in slow cranking etc.

My own advice would be to leave this cable alone and just fit a second braided earth cable from one of the starter motor bolts to the bodywork (area taken to bare metal for good body connection).

Something like: Note* this supplier will alter length and eyelet end size to suit.
http://www.ebay.co.uk/itm/UP-TO-610-MM- ... 339033ffca" onclick="window.open(this.href);return false;

Martin

Oldie: Again, sorry if this is a simple thing, but do you mean that if the gearbox earth is removed, the gearbox mount won't get so corroded?

Oldiebut goodie wrote:I note that Aidan is advocating removing the gearbox earth due to electrolysis and corrosion of the case that he has seen in that area and using an earth from the engine to the bulkhead.

Cheers!
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Re: Wondering about gearbox mount earth

Post by Oldiebut goodie »

Aidan is the " gearbox man " - repairs them as an occupation so has greater insight on the problem as he sees it every day. The magnesium alloy gets eroded in this area.
Do as California Dreamin suggests but remove the gearbox one then there is no chance of the electrolysis starting. Just drill a hole in the bulkhead if there isn't a suitable one already there, clean all the paint off so that you get a good electrical contact and bolt the new cable to it. Coat with grease/ vaseline to keep the rust at bay.
You don't say what engine you have but on the diesels there is usually a spare bolt hole just above the sump on the bottom of the engine block that can be utilized, but the starter bolt is a short and easy route although a pain to get at the starter bolt IMHO.
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Re: Wondering about gearbox mount earth

Post by vanhatter »

Oldiebut goodie wrote:Aidan is the " gearbox man " - repairs them as an occupation so has greater insight on the problem as he sees it every day. The magnesium alloy gets eroded in this area.
Do as California Dreamin suggests but remove the gearbox one then there is no chance of the electrolysis starting. Just drill a hole in the bulkhead if there isn't a suitable one already there, clean all the paint off so that you get a good electrical contact and bolt the new cable to it. Coat with grease/ vaseline to keep the rust at bay.
You don't say what engine you have but on the diesels there is usually a spare bolt hole just above the sump on the bottom of the engine block that can be utilized, but the starter bolt is a short and easy route although a pain to get at the starter bolt IMHO.

Thanks for that Oldie - makes sense! It's a petrol but I guess a direct connection to the starter would be better anyway? Does it matter if I use the bigger bolt on the starter motor or the one on the solenoid? The bigger bottom one is much easier to get at!
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Re: Wondering about gearbox mount earth

Post by Oldiebut goodie »

Use one of the two big starter ones that go through into the engine block. There isn't an earthing bolt on the solenoid - it is all live.
Someone with a petrol engine will be able to confirm which is easiest.
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Re: Wondering about gearbox mount earth

Post by vanhatter »

Oldiebut goodie wrote:Use one of the two big starter ones that go through into the engine block. There isn't an earthing bolt on the solenoid - it is all live.
Someone with a petrol engine will be able to confirm which is easiest.

good point re the solenoid :oops: long day I guess.

I think there's only one bolt through to the block (that I could see anyway).

Cheers
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Re: Wondering about gearbox mount earth

Post by ermie571 »

Oldiebut goodie wrote:I note that Aidan is advocating removing the gearbox earth due to electrolysis and corrosion of the case that he has seen in that area and using an earth from the engine to the bulkhead.

yep done this on my petrol engine. its on the left hand side of the block and goes to the side of the engine bay. Will try and get a picture....but iirc it a proper earth connection cable x

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Re: Wondering about gearbox mount earth

Post by ghost123uk »

vanhatter wrote:I think there's only one bolt through to the block (that I could see anyway).

There definitely are 2 ;) (or there should be two !)
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Re: Wondering about gearbox mount earth

Post by California Dreamin »

Yup...lower starter bolt and over to the chassis..can't remember exactly where but I know I didn't drill anything. There are enough suitable pre-drilled holes to insert a nut/bolt through....baring back to metal around the hole for a good contact and then paint over once the strap is fitted.
Just be careful to use a flexible braided strap as the constant movement will break anything less flexible.
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