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custom90

Member Since: 21 Jan 2010
Location: South West, England.
Posts: 19611

Puma ground lead to chassis / frame rail connection

I tried to have a look for anything relating to this on here, but came up drawing a blank.

This is the crimp between the battery ground lead and the inner chassis frame rail, it acts as a captive connection for the clamping of the battery ground cable and holds it captivity in place whilst grounding the chassis / frame also.
I’m aware of the internal conductor corrosion issue inside the adhesive heatshrink, due to the gap between the crimp and the cable.

Just out of interest, there is two ways I can think of to fit the adhesive heatshrink with that connection which is the preferred?
To get the adhesive lined heatshrink to fit central,
1) A small cut on the lowest edge to clear the right angle mounting bracket that affixes to the chassis frame.
2) Or, a small vertical cut on the rear rhs of the heatshrink piece, just big enough to fit the width of the mounting bracket width, slide it up from the transfer box lug side then heat to affix.
The cable needs to be bent to follow the bracket temporarily to slip the sleeve over.
(So the rhs of the heatshink goes right around the cable, the bracket comes out the gap behind).

Regarding sealing internally on top of the external adhesive heatshink, I could use;
3) epoxy resin,
4) rtv silicone on the shoulder joints and gap,
5) hot glue the same as above.

I’m leaning towards the 5th option here, as that would amalgamate with the hot glue on the heatshrink when heated with proper heat gun.
The water seems to get in the joint via the gap around the cable bracket exit.
Waterproofing / elec Greases aren’t an option, except for externally once complete or it’ll stop the heatshink glue adhering.

I’m tending to look at option 2 & 5, as even though it’s two stage the hot glue underneath would reactivate.
Strong, but some flexibility, the epoxy resin would be strong and hold hard but not sure how well the adhesive heatshrink would stick or if it may crack or react.
Silicone is flexible, once set, it sticks well before the heatshrink is fitted.
Would be not be too good with the adhesive heatshink, would only leave some of the area of the adhesive heatshrink to stick to, probably 50% Approx.

I’m upgrading the cable dia, so this is why I’m not going to just buy another LR offering.
Though they are fine, I wanted to upgrade it.

If anyone has other ideas you are welcome to share regarding the joint, I was just wondering what other people have done?
I do know it has been known, when the LR factory battery ground lead has been removed and the factory heatshrink taken off carefully, that the cable conductor inside the crimp is corroded, as water had got into the joint via the bracket gap sealing failure.
If this joint fails, you’ll get ground issues, poor starting behaviour, with the starter motor, slower cranking etc. Though likely not catastrophic I.e. a complete failure, but higher resistance, increased current draw. Etc. Diesel$ Live$ Matter. ⛽️🛢️👨‍🔧🧰⚙️ RED, WHITE & BOOST! 🇬🇧

18th Mar 2024 8:05pm

blackwolf

Member Since: 03 Nov 2009
Location: South West England
Posts: 16894

2007 Defender 110 Puma 2.4 DCPU Stornoway Grey

Simpler to replace the single continuous cable with the central lug with two separate cables if you're having problems. It is also in my opinion worth fitting at least one additional engine earth and one extra chassis earth.

Although I don't like the standard combined engine-to-chassis-to-battery lead arrangement it is generally pretty reliable and seldom gives problems.

I ran a very hefty earth connection from my winch straight to the battery which provides a secondary chassis earth connection. It is very easy also to fit an additional engine-to-chassis connection.

18th Mar 2024 8:43pm

custom90

Member Since: 21 Jan 2010
Location: South West, England.
Posts: 19611

BW Wrote: “ Although I don't like the standard combined engine-to-chassis-to-battery lead arrangement it is generally pretty reliable and seldom gives problems. ”

I agree, never had a problem which is why I copied it just with a larger gauge cable.
I like that the conductor isn’t cut, the only downside is waterproofing, I’m just trying to make my mind up as to which waterproofing technique to settle on.

Waterproofing problems are a rare issue to have, heard of it once before, but could just be a one off.
Some kind of injection moulding would work, but it can easily not reach where it should or set before it fills all voids a bit like underground gel fill joints.

I’d imagine LR just heatshrinked over it with adhesive heatshrink, it’s just possibly a slight leak of moisture ingress can get in between the bracket, cable sheath.
I think a bit of extra hot glue should do the trick in that gap.

Diesel$ Live$ Matter. ⛽️🛢️👨‍🔧🧰⚙️ RED, WHITE & BOOST! 🇬🇧

18th Mar 2024 9:05pm

blackwolf

Member Since: 03 Nov 2009
Location: South West England
Posts: 16894

None of your other cable crimps are waterproofed, and a good crimp should be fine if waterlogged unless corrosion sets in (which shouldn't happen with good cable and lugs). I don't really understand why you think you have a problem!

I don't actually remember any sleeving around the mid-cable lug and since it is an earth lead I don't see why you would need any.

18th Mar 2024 11:22pm

custom90

Member Since: 21 Jan 2010
Location: South West, England.
Posts: 19611

There isn’t a problem, I just wanted to waterproof that connection (was just my preference even though it’s the ground lead) the bracket I have is tinned, as is the cable strands, it’s good stuff.
The LR offering is perfectly good, I never had any issue with it at all.
My only reason for change was to upgrade the diameter for higher current load. (More worthwhile doing with a 2.4).
Does anyone know if the LR offering was tinned strands?

I did what I wanted to today at lunch time, as I mentioned above using the method I thought I’d go for, it was a bit tricky to get the shrink over and around the corner with the bracket, in the method I wanted, but, I did in the end and with the help of proper heat gun afterwards and hot glue gun all is well with that.

The hot glue underneath, followed by the heat gun and adhesive on the heatshrink amalgamated together in one bond sealing it all up nicely.

I’m thinking about what connection methods to use on the transfer box ground stud now, I’ve got three connections one there, I won’t need any more.
Currently have the starter first, then the next back to back and the 3rd to the side so it fits.
I can either get an adaptor for one connection on the stud, and three on the adaptor, or I was thinking possibly two half nuts, then the full full nut. All torqued to spec.

I’m assuming it’s too hot there for a nyloc nut nearest the end, but a tiny bit of Loctite 222 would be okay just a little.

IIRC, the nut and thread on there is M10 x 1.25 thread pitch. I shall have to check.
I do know it’s 45NM Torque on there.
I am thinking if I used a couple of half nuts that would reduce the length of the thread needed to be used and less stress on it, but also give just enough room to fit the lugs inline rather than the two back to back and the last offset.
I prefer them up there, rather than on the chassis / frame rail as they are more out of the way.
I tend to think an adaptor would just be a waste of money.
Naturally the battery ground goes on first, with nearest contact to the transfer box housing.
I tend to use a little bit of Loctite 222, just a tiny bit of threads these days on top of using the correct torque as I think over time these fixings loosen. And the gearbox and transmission inc transfer box have signs in at vibrations and thermal heating and cooling.
It’s like the small stud on the rear lighting loom the opposite side, I had that come loose twice, it comes off when a clutch is replaced but was always refitted and torqued properly but would still come loose over time.
Just a drip of that low strength Loctite 222, on the threads and put in to spec and I’ve not had a problem since.

Mind you, I don’t care much for stronger thread lockers a lot of them can cause far more problems than they are worth!
The 222 is good for small fixings as well, I use it all the time in very small qualities and stops things working loose especially small fixings.

Diesel$ Live$ Matter. ⛽️🛢️👨‍🔧🧰⚙️ RED, WHITE & BOOST! 🇬🇧

19th Mar 2024 4:38pm

blackwolf

Member Since: 03 Nov 2009
Location: South West England
Posts: 16894

You can always fit more than one lead to more than one earth point, that has the benefit that if something comes off you won't melt the handbrake cable or ignite the vehicle.

It would never, I have to say, even occur to me to use a torque wrench for that kind of thing.

There are plenty of all-metal stiff nuts available such as Aerotight, Philidas, Binx, Flexloc, Cleveloc, Stover, Snep, Vargal, Nord-Lock and Pal (although I wouldn't recommend any of the the last three in this case) as well as centre locking nuts many of which include flange nut options, if you want a stiff nut that doesn't involve a nylon insert. Aerotight and Stover nuts are available in brass which is probably better for an electrical connection.

19th Mar 2024 7:10pm

custom90

Member Since: 21 Jan 2010
Location: South West, England.
Posts: 19611

Thank you for the suggestions.

Diesel$ Live$ Matter. ⛽️🛢️👨‍🔧🧰⚙️ RED, WHITE & BOOST! 🇬🇧

19th Mar 2024 7:48pm

MadTom

Member Since: 10 Sep 2013
Location: Olomouc
Posts: 579

Two year ago during our trip to Turkey Disco2 started to loose some battery voltage. Problem was in the factory made crimp terminal (eye) on cable between alternator and main fuse box. The cable eye was impossible to open (thick material), but contact was poor resulting in 0,5 V voltage drop just in this crimped connection. On the tip I made my best soldering over the crimp - it was much better. Even back home, I was not able to open the cripm, I had to cut it to see, what is inside. It looked normal. New cable with new crimped eye and volatage drop was les than 0,01 V. For covering just heatschring tube with glue inside. No need to make it waterproof, beter is just cover in to have some mechanical support and let water run out. From my experience, IP68 rated connector means, they are water tight, so water gets inside and stays there much longer, than in open connectors. Good crimp is tight enough, to protect wires inside. "Drobek" = The Small One - Discovery 2, "Blufínek" = The Blue Thing - Defender 130, and for me at least Ford Mondeo

20th Mar 2024 12:45pm

custom90

Member Since: 21 Jan 2010
Location: South West, England.
Posts: 19611

Well it can always be reversed, the adhesive heatshink I used is double wall and semi translucent as well, so if there was any internal leakage it can always come off if needed.
I have a really nice crimp on there so I’m happy with its security.

I shall be having a look at the brass nuts for the transfer box soon, I did some more research on the parts from LR and the thread is M10, but the pitch is 1.5 coarse, NOT 1.25 pitch as I assumed before, so I’m glad I checked that out.

I’d have liked some tinned copper nuts in that size, for conductivity they’d be great, but they are a soft metal really and in that area I think would be very exposed and the thermally stressed as well.
So I think BW is right that brass is a better option for practicality and has a bit better conductivity than other basic options.

You certainly can get some voltage drop, and high resistance issues.
There should be an improvement in the amount of temporary voltage drop on cold cranking, I’m hoping so anyway, but due to many variable factors it’s hard to tell categorically, especially depending on how long it’s sat idle, voltage at point of cranking, ambient temp etc.

The new cable I’m working on has a resistance of 0 Ohms, on all points tested as it should be.
When I get the original out I can test that an see what that that checks out at, being a short section though it may well be the same or very close, but that’s not under load.

I was looking at the parts diagram of the transfer box stud in depth last night.
I see that the threaded stud is available on its own as a replacement if anyone needed one.
There is a spring washer, then a flanged nut.

On mine this is the arrangement currently;
the stud in the T box, then I assume a spring washer, then the flanged genuine nut.
Then the battery ground connection, extra two lugs and then a full nut, the latter I think is a brass one securing that.
I presume the flanged nut butt against the transfer box is meant to be there to secure the threaded stud as a locking nut.
As the arrangement on there I want to change over to three lugs, I’d like to add a bit of separation between the lugs so that I don’t have to have two back to back and one off set.
Then you can nicely fit some use some zip tie tricks so they don’t rub.

There is only so much room on the stud, so I’ll try and get some half and full nuts to see what suits best.
Much preferred to me than having two lugs back, and one off set, as they are more prone to get loose in my opinion.

I’ll report back soon, effect on the starter motor and voltage will be limited if any as I have to fit the rest yet on the live side.

As a lot of you probably know, LR upgraded the gauge of the main battery cables on 2.2 Pumas.
Where 2.4’s had slightly smaller gauge.
What I have fitted is an upgrade on even what a 2.2 has, copper these days isn’t cheap!

Diesel$ Live$ Matter. ⛽️🛢️👨‍🔧🧰⚙️ RED, WHITE & BOOST! 🇬🇧

20th Mar 2024 7:49pm

MadTom

Member Since: 10 Sep 2013
Location: Olomouc
Posts: 579

No need for copper or brass nut if you have steel or stainless bolt.
You can check quality of your cables and crimped terminals. With clamp meter measuren current through cable and with voltmeter and needle probes measure voltage drops. On proper crimp, it will be nearly zero difference between crimped eye and cable. Cable has some resistance, not zero. You can compare measured voltage drop on cable length with cable resistance. You need several Amps of current to get big enough voltage drop for good measurement. "Drobek" = The Small One - Discovery 2, "Blufínek" = The Blue Thing - Defender 130, and for me at least Ford Mondeo

20th Mar 2024 9:37pm

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