Earthing Issues Since Body Off Chassis Restoration
Discussion
Hi all, I'm looking for a little advice from anyone who may have suffered similar earthing issues following a body off chassis restoration, since getting my car back its thrown up some strange grounding faults the car never exhibited before. Clearly I have one or more bad grounds introduced when the car was reassembled, I need to chase the faults down and make good so any help identifying the likely culprit will speed up this process greatly.
THE FAULTS:
1. With the ignition off, the horn button grounds through the offside front turn signal circuit illuminating that indicator bulb for each press of the horn
2. With the ignition on, the horn grounds through the wiper motor activating one wiper intermittent cycle for each press of the horn button, it also grounds through the high beam headlight circuit
In both cases the horn relay pulls in as normal, occasionally the horns will sound but mostly the easiest path to ground is found through the indicator bulb, the wiper motor, and the headlight main beam circuit,
3. With the ignition on and the headlights on the headlights work correctly, but the offside front indicator bulb is permanently illuminated
So where to start
MY THEORY:
It's my understanding is the headlights and the horns are grounded at the front offside body to chassis mounting point, I'm assuming there is an indicator ground there too?
So my money is on a loose body mounting bolt and poor ground at the above body mounting point hidden under the offside lower corner of the radiator, I believe to get at that bolt and tighten it I will need to remove the radiator?
What a royal PITA
Frustratingly it's taken me months now to get the car right since getting it back from the chassis restoration, and loose bolts do seem to be a feature of the work. For example my rear anti-roll bar got torn off by a gate lock keep I've driven over many times before the chassis work without issue. When I investigated I found all my ARB mounting bolts were loose including every single exhaust tray bolt too, some of which were were so loose they were about to fall out. Clearly the tightening of all bolts in that whole rear area had been completely overlooked, making it highly likely a loose grounding bolt is what's causing all my electrical issues
I've now spent over four months and many many hours of my own time snagging the car since I got it it back, within the first 24 hours of it arriving home I did suggest to the restorer it needed to go back to him as even within the first day I'd already identified and photographed over 20 assembly faults, unfortunately said restorer didn't want to do the right thing so I was left to sort it all out myself. As the list of faults grew to over 30 assembly errors I found myself spending most evenings and every weekend on the car to get it to where it is now, fortunately having worked in classic and vintage restoration myself I was able to sort the car myself, but as I was a paying customer that's hardly the point.
I really shouldn't have been put in this position of being forced to snag the car myself, quite honestly the restorer was extremely lucky I have the skills to correct all his assembly mistakes and lack of attention to detail, I shudder to think what the bill would have been if the had needed to go to local to me TVR specialist like St8Six, I've added up all the hours I've spent on the car now and if I chose to write up a counter invoice to the restorer it would total thousands of pounds
Anyway, lesson learned and enough of my moaning, if anyone has any helpful comments on my grounding issues I'd be grateful, especially my theory on the front body mounting point being the most logical place to start. My final point would be I did challenge the restorer on the fact he was merely painting this grounding faces on the chassis with highly insulating 2k epoxy mastic before the body went back on, but he reassured me the grounding passed down the threads of the bolt. However, I was unconvinced by this answer as I was always taught the flat faces of ring terminals used on grounding wires need to contact the base steel chassis over the same surface area as the ring terminal diameter if an effective and reliable ground is to be created.
Thanks in advance of your comments and advice.
Dave.
THE FAULTS:
1. With the ignition off, the horn button grounds through the offside front turn signal circuit illuminating that indicator bulb for each press of the horn
2. With the ignition on, the horn grounds through the wiper motor activating one wiper intermittent cycle for each press of the horn button, it also grounds through the high beam headlight circuit
In both cases the horn relay pulls in as normal, occasionally the horns will sound but mostly the easiest path to ground is found through the indicator bulb, the wiper motor, and the headlight main beam circuit,
3. With the ignition on and the headlights on the headlights work correctly, but the offside front indicator bulb is permanently illuminated
So where to start
MY THEORY:
It's my understanding is the headlights and the horns are grounded at the front offside body to chassis mounting point, I'm assuming there is an indicator ground there too?
So my money is on a loose body mounting bolt and poor ground at the above body mounting point hidden under the offside lower corner of the radiator, I believe to get at that bolt and tighten it I will need to remove the radiator?
What a royal PITA
Frustratingly it's taken me months now to get the car right since getting it back from the chassis restoration, and loose bolts do seem to be a feature of the work. For example my rear anti-roll bar got torn off by a gate lock keep I've driven over many times before the chassis work without issue. When I investigated I found all my ARB mounting bolts were loose including every single exhaust tray bolt too, some of which were were so loose they were about to fall out. Clearly the tightening of all bolts in that whole rear area had been completely overlooked, making it highly likely a loose grounding bolt is what's causing all my electrical issues
I've now spent over four months and many many hours of my own time snagging the car since I got it it back, within the first 24 hours of it arriving home I did suggest to the restorer it needed to go back to him as even within the first day I'd already identified and photographed over 20 assembly faults, unfortunately said restorer didn't want to do the right thing so I was left to sort it all out myself. As the list of faults grew to over 30 assembly errors I found myself spending most evenings and every weekend on the car to get it to where it is now, fortunately having worked in classic and vintage restoration myself I was able to sort the car myself, but as I was a paying customer that's hardly the point.
I really shouldn't have been put in this position of being forced to snag the car myself, quite honestly the restorer was extremely lucky I have the skills to correct all his assembly mistakes and lack of attention to detail, I shudder to think what the bill would have been if the had needed to go to local to me TVR specialist like St8Six, I've added up all the hours I've spent on the car now and if I chose to write up a counter invoice to the restorer it would total thousands of pounds
Anyway, lesson learned and enough of my moaning, if anyone has any helpful comments on my grounding issues I'd be grateful, especially my theory on the front body mounting point being the most logical place to start. My final point would be I did challenge the restorer on the fact he was merely painting this grounding faces on the chassis with highly insulating 2k epoxy mastic before the body went back on, but he reassured me the grounding passed down the threads of the bolt. However, I was unconvinced by this answer as I was always taught the flat faces of ring terminals used on grounding wires need to contact the base steel chassis over the same surface area as the ring terminal diameter if an effective and reliable ground is to be created.
Thanks in advance of your comments and advice.
Dave.
Edited by ChimpOnGas on Sunday 23 August 09:19
Other earth points ..behind the tank (M10 cap head) and passenger foot well (M10 to right of knee) ...and possible a alarm relay issue holding in single indicator, but more simply a bulb holder and or earth using the earth through the holder...A@
Edited by Adrian@ on Sunday 23 August 09:27
Belle427 said:
I’d be looking in that area too, are the cable lugs as standard bolted direct to the chassis or through the fibreglass?
Thanks, my theory is to start at the point where the items being falsely grounded by the horn are grounded themselves, this would take me straight to that front offside body mounting point shown in my above images.Adrian@ said:
Other earth points ..behind the tank (M10 cap head) and passenger foot well (M10 to left of knee) ...and possible a alarm relay issue holding in single indicator...A@
Thanks, but that wouldn't explain the horn button grounding and so flashing the headlights with every horn press, and the wiper activation on every horn press too. However, I accept your logic and indeed had the same idea myself, so I pulled the two fuses from the Meta unit under the dash thus removing it from the equation, unfortunately this made no difference and the faults persisted.MY CURRENT THINKING:
It does look like I'll have to take the rad out to get at and tighten that front offside body mounting point where all the suspects are grounded, but before I do I'd be grateful to hear from those who've had the body off a Chimaera if they support my theory?
Steve_D is someone I'd like to hear from as he's completed many body off restorations, so I'd imagine he's seen my issue before?
Thanks chaps
Dave.
I am sorry, LOL, but I know what you mean....(I have not done enough TVR body off's, 80 plus but sadly only 5 griff's/chims) ...I started my 3000S re build last week (I lifted the shell to change the rubber fuel lines). The chassis comes back tomorrow, painting the engine bay today ..and I would hope to have it rolling by mid week and running the next. A@
Belle427 said:
I’d perhaps look at relocating them if the cables will allow, maybe even extending them into the engine bay to ground to a more accessible location to keep an eye on.
Shouldn’t be too hard a job.
Good call and already on the cards Shouldn’t be too hard a job.
To be honest TVR's use of the chassis as a ground path is a pretty poor idea, I've worked on many a Lotus and cabling the grounds directly back to battery negative terminal or a grounding bus bar always sorted such issues. With engine management you do need to be careful creating twin ground paths as you risk generating a potential difference between two grounds, this will generate EMI which can play havoc with a poorly shielded ECU.
The dreaded ground loop as it's known must be avoided, but the benefits of cable grounding with copper always far outweigh the risk on a fiberglass car in my opinion. Back in 90's I was involved in the restoration of a number of Mercedes 190SLs, obviously this is a steel bodied 1950's vehicle but the loom the Germans built for these cars was an amazing feat of auto electrical engineering, it had cabled earth returns for everything and personally I still believe that's the right way to build a loom, it was by far the heaviest loom I've ever had to lay though!
To be frank if TVR had just studied a contemporary or even an earlier Corvette loom and followed Chevrolet's far superior grounding practices a lot of the electrical issues that plague TVRs could have been engineered out. I've already cable grounded my engine block, as predicted this delivered many improvements including better gauge accuracy (coolant temp, oil pressure, ect), smoother idling and better drivability so I will be cable grounding that front body mounting bolt and so everything grounded there too.
However, given the standard grounding path passes from this front chassis to body mounting point through the chassis to the transmission tunnel, where it then meets the main battery ground cable, I'll try tightening the bolt there first, bot only because it needs checking and its easier to get to than the one under the rad that will clearly need tightening too!
When I was involved in restoration it was my job to shake the car down after the work was finished, I was expected to do so over a few weeks before the car was deemed to be in a fit state to be presented to its owner. As a poor young mechanic it was the only chance I had to drive the beautiful cars we spent many months and often years restoring, so I actually looked forward to the process greatly. There were always a few snags which is why this shakedown period was so important, a car is made up of thousands of components and a proper restoration touches most if not all of them, so I fully expected a few issues after my chassis restoration.
However, clearly my car was not shaken down at all beyond driving it up and down a trading estate a few times before it was signed off, that's not a proper shake down by anyone's imagination! Four months on its becoming very tiresome to still find myself completing what should have been done by others, work I paid for in full and on time without complaint by the way so I certainly did my part of being a good client.
Finding myself having to check and tighten up more or less every bolt and correcting so many assembly faults after my chassis restoration was not what I expected.....
[quote=ChimpOnGas]
It does look like I'll have to take the rad out to get at and tighten that front offside body mounting point where all the suspects are grounded.
[quote]
I'm not sure if that bolt is as accessible as a on a Griff but you may be lucky.
Your restorer claims that thread contact is good enough but may be not if he coated the threads with Coppaslip first?
It does look like I'll have to take the rad out to get at and tighten that front offside body mounting point where all the suspects are grounded.
[quote]
I'm not sure if that bolt is as accessible as a on a Griff but you may be lucky.
Your restorer claims that thread contact is good enough but may be not if he coated the threads with Coppaslip first?
I have had wiper, horn, fan and light issues when that front connection on my Griffith worked loose.
On the Griff you can reach it from outside directly underneath the radiator without having to touch the radiator, the Chimaera might be different in this regard. On the Griff the earth wires are on the outside with the bodyshell between the earth ring and the chassis, so the bolt head is in contact with the rings and it earths through the thread into the chassis.
As long as it is tight it works fine.
On the Griff you can reach it from outside directly underneath the radiator without having to touch the radiator, the Chimaera might be different in this regard. On the Griff the earth wires are on the outside with the bodyshell between the earth ring and the chassis, so the bolt head is in contact with the rings and it earths through the thread into the chassis.
As long as it is tight it works fine.
Hedgehopper said:
ChimpOnGas said:
It does look like I'll have to take the rad out to get at and tighten that front offside body mounting point where all the suspects are grounded.
[quote]
I'm not sure if that bolt is as accessible as a on a Griff but you may be lucky.
Your restorer claims that thread contact is good enough but may be not if he coated the threads with Coppaslip first?
Thanks I'll have another look [quote]
I'm not sure if that bolt is as accessible as a on a Griff but you may be lucky.
Your restorer claims that thread contact is good enough but may be not if he coated the threads with Coppaslip first?
Colin RedGriff said:
I have had wiper, horn, fan and light issues when that front connection on my Griffith worked loose.
On the Griff you can reach it from outside directly underneath the radiator without having to touch the radiator, the Chimaera might be different in this regard. On the Griff the earth wires are on the outside with the bodyshell between the earth ring and the chassis, so the bolt head is in contact with the rings and it earths through the thread into the chassis.
As long as it is tight it works fine.
Nice one Colin, this supports my theory perfectly On the Griff you can reach it from outside directly underneath the radiator without having to touch the radiator, the Chimaera might be different in this regard. On the Griff the earth wires are on the outside with the bodyshell between the earth ring and the chassis, so the bolt head is in contact with the rings and it earths through the thread into the chassis.
As long as it is tight it works fine.
I do appreciate everyone's help though, and @Adrian... I wasn't suggesting you aren't experienced in chassis restoration mate, your help and experience is much respected
NB: I've just found this post that talks of wiper motor and headlight related ground issues being traced to that front chassis body mount/ground point, so it does seem to be Suspect Number One!
https://www.pistonheads.com/gassing/topic.asp?h=0&...
Has anyone with a Mk2 Chimaera managed to tighten this bolt through the grill aperture, thus avoiding removing the rad?
To be honest though I had hoped for better grounds after my chassis restoration, not worse
After sorting so many assembly faults over the last four months I'm fast running out of patience for working on the car, what I should be doing on a Sunday in late August is simply driving the wheels of it
Sadly I'm forced to get my spanners out yet again
Whilst I am not going to discount the front chassis earth points I think your horn issues are related to the O/S tunnel earth point.
Either it has not been tightened or one (or more) of the ring terminals are not on the bolt.
It will be the horn relay trying to find a new earth. It shares the earth point with the indicator so passes through that bulb into the live side of the indicator circuit then uses one of the other indicator bulbs as its earth.
Too get to this bolt the guy most likely had to cut a slit in the carpet to get a spanner through. TVR fitted the carpets before any of the dash moulding were installed. If the guy doing the work left only just enough carpet to go over the tunnel top edge and be hidden by the dash then you can use a trim tool (hook) and pull the carpet out and fold it down to get at the bolt but in most cases they have glued plenty over the top and it won't come out. To find the bolt the slit (if it has one) will be a little over an inch down and directly below the rounded lower edge of the dash.
Note for others doing body off or body lift....do not remove the tunnel bolts. Leave them in the brass bush that is moulded into the body. In this way you cannot loose any of the ring terminals. We replace all the other bolts when we do body off but never replace these as the risk is too high.
Steve
Steve
Either it has not been tightened or one (or more) of the ring terminals are not on the bolt.
It will be the horn relay trying to find a new earth. It shares the earth point with the indicator so passes through that bulb into the live side of the indicator circuit then uses one of the other indicator bulbs as its earth.
Too get to this bolt the guy most likely had to cut a slit in the carpet to get a spanner through. TVR fitted the carpets before any of the dash moulding were installed. If the guy doing the work left only just enough carpet to go over the tunnel top edge and be hidden by the dash then you can use a trim tool (hook) and pull the carpet out and fold it down to get at the bolt but in most cases they have glued plenty over the top and it won't come out. To find the bolt the slit (if it has one) will be a little over an inch down and directly below the rounded lower edge of the dash.
Note for others doing body off or body lift....do not remove the tunnel bolts. Leave them in the brass bush that is moulded into the body. In this way you cannot loose any of the ring terminals. We replace all the other bolts when we do body off but never replace these as the risk is too high.
Steve
Steve
Classic Chim said:
Use a torch and look.
I think you could possibly get an extension on it with rad in place if you can find a woman or small boy to get his arms in there.
Be warned your arm might go in, it’s a f
ker to get it out!
You should be able to get a spanner on the front chassis bolts without touching the rad.I think you could possibly get an extension on it with rad in place if you can find a woman or small boy to get his arms in there.
Be warned your arm might go in, it’s a f
ker to get it out! Not so easy to remove the bolt and clean the terminals but you can easily tighten it.
Note to those doing a body off. Get into the engine bay and clean the earth terminals.
Steve
Steve_D said:
Whilst I am not going to discount the front chassis earth points I think your horn issues are related to the O/S tunnel earth point.Either it has not been tightened or one (or more) of the ring terminals are not on the bolt.
It will be the horn relay trying to find a new earth. It shares the earth point with the indicator so passes through that bulb into the live side of the indicator circuit then uses one of the other indicator bulbs as its earth. Steve
Many thanks Steve, I stated the following earlier so were clearly on the same page It will be the horn relay trying to find a new earth. It shares the earth point with the indicator so passes through that bulb into the live side of the indicator circuit then uses one of the other indicator bulbs as its earth. Steve
ChimpOnGas said:
However, given the standard grounding path passes from this front chassis to body mounting point through the chassis to the transmission tunnel, where it then meets the main battery ground cable, I'll try tightening the bolt there first, bot only because it needs checking and its easier to get to than the one under the rad that will clearly need tightening too!
Steve_D said:
Too get to this bolt the guy most likely had to cut a slit in the carpet to get a spanner through. TVR fitted the carpets before any of the dash moulding were installed. If the guy doing the work left only just enough carpet to go over the tunnel top edge and be hidden by the dash then you can use a trim tool (hook) and pull the carpet out and fold it down to get at the bolt but in most cases they have glued plenty over the top and it won't come out. To find the bolt the slit (if it has one) will be a little over an inch down and directly below the rounded lower edge of the dash.
I'm on it, thanks 
Steve_D said:
You should be able to get a spanner on the front chassis bolts without touching the rad.
Not so easy to remove the bolt and clean the terminals but you can easily tighten it.
Note to those doing a body off. Get into the engine bay and clean the earth terminals.
Steve
Quality advice!Not so easy to remove the bolt and clean the terminals but you can easily tighten it.
Note to those doing a body off. Get into the engine bay and clean the earth terminals.
Steve
Steve_D said:
Note for others doing body off or body lift....do not remove the tunnel bolts. Leave them in the brass bush that is moulded into the body. In this way you cannot loose any of the ring terminals. We replace all the other bolts when we do body off but never replace these as the risk is too high. Steve
Excellent advice and support as always, only experience teaches you such things, as a professional making his living from restoring TVR chassis' the sharing of your hard won intellectual property is very generous, I'm currently relearning the age old lesson of 'Pay Cheap, Pay Twice'!There is no substitute for experience...
Thanks, Dave.
Hi Steve, I've just noted you state O/S tunnel earth.
The horn relay definitely pulls in as I can feel it click when I press the horn, good job I've got long arms, but from there the current is clearly finding something easier than the horns to ground through. With the ignition off the easier ground path is the indicator circuit, but with the ignition on the easier path to ground becomes either the wiper motor or the main beams, and sometimes both with a bit of intermittent single horn sounding thrown in for good measure
Your help is very much appreciated Steve.
Thanks again, Dave.
Steve_D said:
Whilst I am not going to discount the front chassis earth points I think your horn issues are related to the O/S tunnel earth point.Steve
I had assumed N/S tunnel to be honest, so I'll start on the O/S now you've pointed me to this side, TBH what I've found to my cost is literally everything needs tightening following my body off restoration, I'll get through it all eventually but so much for the shakedown I paid for The horn relay definitely pulls in as I can feel it click when I press the horn, good job I've got long arms, but from there the current is clearly finding something easier than the horns to ground through. With the ignition off the easier ground path is the indicator circuit, but with the ignition on the easier path to ground becomes either the wiper motor or the main beams, and sometimes both with a bit of intermittent single horn sounding thrown in for good measure
Your help is very much appreciated Steve.
Thanks again, Dave.
If you look at factory pictures of chassis stacked up ready for use (or like me saw them when I visited OR you bought factory powdered items) you would of/will see/seen that factory used to blast and use a chromate wash prior to powder. The factory powder coat was so thick that each and every bolt/pick up point was masked, powder coated then the masking tape removed (and YES, giving a riser point for rust at every pick up ) but then allowing production staff to build the cars quicker. Today, the chassis earth would need to be 'created' (re-builders would need to do this regardless of finish). A@
A quick update with partial success to report, firstly here's a little video to show the location of the O/S transmission tunnel earth point which may serve to help others in the future?
https://youtu.be/rz7Kj0KBz1g
And yes, it was loose!
Tightened it has helped a bit, at least I now have one of the two horns sounding where before I had none, but the second horn is still grounding through the indicator circuit!
A further improvement from tightening this O/S trans tunnel bolt is that the horn button now no longer activates the wipers with the ignition on, sadly the headlights still ground through the indicator circuit so there are clearly more earthing bolts that need to be tightened
More on Results on my O/S transmission tunnel earth bolt tightening here....
https://youtu.be/HZTklEZVdf4
What a pain
I'll keep plugging away at chaps
https://youtu.be/rz7Kj0KBz1g
And yes, it was loose!
Tightened it has helped a bit, at least I now have one of the two horns sounding where before I had none, but the second horn is still grounding through the indicator circuit!
A further improvement from tightening this O/S trans tunnel bolt is that the horn button now no longer activates the wipers with the ignition on, sadly the headlights still ground through the indicator circuit so there are clearly more earthing bolts that need to be tightened
More on Results on my O/S transmission tunnel earth bolt tightening here....
https://youtu.be/HZTklEZVdf4
What a pain
I'll keep plugging away at chaps
Edited by ChimpOnGas on Sunday 23 August 14:41
ChimpOnGas said:
...........
The horn relay definitely pulls in as I can feel it click when I press the horn, good job I've got long arms, but from there the current is clearly finding something easier than the horns to ground through................
I thought O/S tunnel because horn relay coil and indicator warning lights share that same earth point. If the relay is working then that puts the issue to the front O/S chassis bolt.The horn relay definitely pulls in as I can feel it click when I press the horn, good job I've got long arms, but from there the current is clearly finding something easier than the horns to ground through................
Can't, at the moment, see how that gets back to the wipers but car electrics can be a black art at the best of times. The only part of the wiper system that shares the same earth is the washer pump.
Throw a 17mm spanner at the chassis bolt up front and see if anything changes.
Steve
Steve_D said:
I thought O/S tunnel because horn relay coil and indicator warning lights share that same earth point. If the relay is working then that puts the issue to the front O/S chassis bolt.
Can't, at the moment, see how that gets back to the wipers but car electrics can be a black art at the best of times. The only part of the wiper system that shares the same earth is the washer pump.
Throw a 17mm spanner at the chassis bolt up front and see if anything changes.
Steve
Cheers mate, more on the results of tightening the O/S transmission tunnel earth bolt here.Can't, at the moment, see how that gets back to the wipers but car electrics can be a black art at the best of times. The only part of the wiper system that shares the same earth is the washer pump.
Throw a 17mm spanner at the chassis bolt up front and see if anything changes.
Steve
https://youtu.be/HZTklEZVdf4
Things are definitely getting better, at least ai have one horn Steve and the rogue wiper activation seems to be a thing of the past.
I got a good few flats of tightening on the bolt, it was definitely left loose
Just addressed the N/S trans bolt....
It was loose too, but no additional improvements
Edited by ChimpOnGas on Sunday 23 August 14:52
Ok, final update for today, I can just see the offending bolt head!
Of course there's a world of difference between just seeing it and dropping a 17mm a spanner on the thing and tightenin it up
She's buried down there deep boys and my LPG vaporiser sits above reducing access still further, as Alun says the only proper way to sort this is to whip the rad out.
Anyway it's pub o clock now so I'm off for a beer, the rad can come out another day
At least we've made some improvements, and that's both loose trans tunnel bolts righted up!
Of course there's a world of difference between just seeing it and dropping a 17mm a spanner on the thing and tightenin it up
She's buried down there deep boys and my LPG vaporiser sits above reducing access still further, as Alun says the only proper way to sort this is to whip the rad out.
Anyway it's pub o clock now so I'm off for a beer, the rad can come out another day
At least we've made some improvements, and that's both loose trans tunnel bolts righted up!
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