# Haldex earth strap



## Alpine26 (Dec 24, 2017)

Had my car up on ramps this afternoon to work out how easy it is to do the Haldex oil change.

Surprised to see the earth strap hanging loose, having broken off at one end.

So does that mean my Quattro is not working? I hadn't noticed.

Where the strap is attached to the Haldex unit I couldn't get the bolt off, largely because it is jammed up against another nut for the Haldex casing. I'll let my mechanic in the village try to get it off. If he can't is there any other place to fix the strap?


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## David C (Apr 15, 2013)

The earth strap comes off of the side of the rear diff, not the Haldex and goes to a stud on the underside of the spare wheel well.

Mine works without the strap, but will be refitting when I next get it up on ramps.


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## forker (Jul 20, 2012)

I, too, noticed in the last few days, while I was faffing about after MoT brake pipe change, that the infamous diff earth strap had broken on my car.

It had broken away at the shell end, not the diff end. It would be mildly diverting to understand what the failure mode distribution might be, but, life's too short, etc. Bust is bust, and bust means no AWD when we could do with it.

My car is an 02my; fifteen years' plus worth of residence and corrosion implied that the earth stud wouldn't be an easy undo. Goody, I thought.

After a few moments (days..) thought I elected to go after it anyway. As expectable, as soon as I touched the misbegotten item it sheared out of the weld to the shell.

After taking out the spare to see where it attached, expecting to need to drill through the weld stub and install a new bolt - I was thinking stainless - I poked the nvh pack in the spare wheel well only to see it fall apart revealing a hole right through at the stud attachment. It was nice and round, so I may have been lucky enough to experience shear perfectly. That would be convenient so probably isn't true, though. It was certainly not corroded; the spare wheel well floor material shined up real quick and corrosion was largely absent. I guess the bolt or the strap corroded preferentially instead of the shell. Sort of good.

A few mins wire brush action cleaned it all up convincingly; a new bolt with a smear of copper grease through the hole with a clamp nut to fix it in place, then a second nut to secure a new earth strap. I curled it around the diff case and secured it to one of the endplate capture bolts, but not the original one. My earth strap, coming (confession..) not from an Audi, was a bit long.

and, voila! 4wd a-go-go! Tadaa! (smug icon goes here..)

It isn't as bad as it could be.

F


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## Hoggy (May 8, 2002)

Hi Forker, Excellent. Found it & fixed it.  [smiley=thumbsup.gif] 
Hoggy.


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## outdoor stevie (Nov 24, 2013)

As above the nut on the rear diff that holds the earth strap is slightly different to the other nuts on the diff so have a look for the odd one and that's where the strap goes give it a good grind or heavy wire brush to clean it up, similarly on the wheel well you need to get the crud off and attach to bare shiney metal and you may even need to drill another hole to attach the bolt to then once done paint over it to protect it afterwards.

Stevie


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## Alpine26 (Dec 24, 2017)

great, thanks all.

I'll have a another go at it.


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## patriotk11 (Oct 21, 2017)

Does anyone have pics of what it should look like?


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## outdoor stevie (Nov 24, 2013)

This is all that was left of mine when I had a look. It's only about 10 inches long and you can use a stout bit of electrical wire instead!









Stevie

Sent from my iPhone using Tapatalk


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## Alpine26 (Dec 24, 2017)

Hi Stevie, good pic.

Did your bolts come off easily at each end?

I was thinking I would have to get a new strap from Audi, but maybe not? What sort of strap did you use?

...and, have you painted your drive shafts? The plastic coating on mine has all come away and they look pretty rusty.


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## Bouncypete (Feb 3, 2017)

The body shell bolt sheared off on my car and I don't like the idea of drilling holes to 'create' bare metal on the under side of the car, exposed to the elements.

Hence I drilled the hole INSIDE the boot, made a ground point, then drilled one of the plastic grommets in the boot floor through which I've passed the earth lead so that the lead goes from the ground point inside the boot to the haldex unit underneath.

Might seem a bit excessive but It's a damn sight easier to lean down into the boot to drill a hole than it is to lay on your back on the floor and drill overhead getting swarf in your eyes.


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## desertstorm (Apr 25, 2017)

It's a very poor design by Audi. They use an aluminium strap that corrodes because of galvanic corrosion. You get the same issue on aluminium heatshields . Where the steel and aluminium meet it will corrode. On my car the haldex wasn't working. I got under the car and just touched the strap and it broke off at the chassis end.
Went to undo the nut and this sheared off.










Drilled a hole where the stud used to be having first removed everything in the boot. Put a new bolt in and made up a cable with some ring terminals on. Job done.


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## Alpine26 (Dec 24, 2017)

thanks, good idea.

But what are my other options at the other end, if I can't get the old bolt out of the diff/Haldex casing?


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## Hoggy (May 8, 2002)

Alpine26 said:


> thanks, good idea.
> 
> But what are my other options at the other end, if I can't get the old bolt out of the diff/Haldex casing?


Hi, Soak it in penetrating oil & try again or try another bolt.
Hoggy.


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## Alpine26 (Dec 24, 2017)

thanks all. So I would be just as well with an earth strap off eBay, rather than a replacement from Audi?


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## Hoggy (May 8, 2002)

Alpine26 said:


> thanks all. So I would be just as well with an earth strap off eBay, rather than a replacement from Audi?


Hi, Definately.
Hoggy.


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## desertstorm (Apr 25, 2017)

Something like this would do well, I think it's long enough, 250mm is nearly 10 inches.

https://www.ebay.co.uk/itm/Earth-Bondin ... 3061021350?


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## Alpine26 (Dec 24, 2017)

desertstorm said:


> Something like this would do well, I think it's long enough, 250mm is nearly 10 inches.
> 
> https://www.ebay.co.uk/itm/Earth-Bondin ... 3061021350?


thanks, but would that corrode under the car? Does it need a plastic cover/coating?

Or if they are made of copper, maybe not?


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## Hoggy (May 8, 2002)

Alpine26 said:


> desertstorm said:
> 
> 
> > Something like this would do well, I think it's long enough, 250mm is nearly 10 inches.
> ...


Hi Definitely don't get aluminium as that will corrode as did the original. Multistrand steel/copper or tinned copper flexible braid. Vast selection on Ebay.
Hoggy.


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## Alpine26 (Dec 24, 2017)

cheers Hoggy

my original aluminium one is in crumbs


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