[Battery terminals - bulkhead or engine side]

...and an insulator boot on the +ve

[Battery terminals - bulkhead or engine side]

Wouldn't you normally fit the battery isolator to the -ve terminal?

David

[Any idea what this is?]

yup, just discovered that; mystery solved thank you

David

[Any idea what this is?]

Apologies, my bad.

Thanks Rob, that's a possible although all the carb return springs seem to be present (later type HS6)

David

[Any idea what this is?]

I found this sitting on top of the chassis (4a) just to the rear of the front right suspension assy, any idea what it is? I can't see anything missing...

Many thanks

David

[Serious electrical short, TR4a]

Thanks chaps, I'm going to order a black stalk one from Duncan LLoyd and hope the black is removeable.

Thanks Tony, I got that from you when I was building the car and still use it as my main reference

Regards

David

[Serious electrical short, TR4a]

Thanks Stuart, yes that's always possible although I would have said it was installed with the wires all pointing the same way. 

What is the best source for replacement RHD chrome stalk switches?

[Serious electrical short, TR4a]

I've now managed to remove the damaged loom and dismantle the steering column wiring/switches. I now believe that the original cause of the problem was that the indicator self-cancelling clip was not sitting flush to the steering column shaft and stick proud allowing it to come in contact with the 12v live/main beam contact on the lighting switch causing a short and cable melting along the Brown/Blue. Subsequently a melted section of the Brown/Blue under the dash happening to cross paths with, and was touching an earth wire to the body causing the earth insulation to melt and then to short out 12v live to the body leading to further extensive insulation melting and the white smoke that was visible, Interestingly a number of items of bare metal are showing signs of surface "rust" which is very localised and wasn't there before; is that part of the chemical reaction to the short circuit?

Many lessons

David

[Air compressor advice please]

Yes I got a 100l one from SGS, and whilst it's a good bit of kit, you will find it is running much of the time. With hindsight I would have gone for the bigger capacity

David

 

[Happy Birthday Bob Lebro]

Many Happy Returns  Hope you've had a good day

David

[Serious electrical short, TR4a]

Thanks Rob, no ammeter, voltmeter instead 

David

[Serious electrical short, TR4a]

So I'm considering the in-line fuse option, Rob would you put the fuse between the starter solenoid connection and the supply wire to the lights? Autosparks tell me that the Brown/Blue is 28 strand of 0.3mm rated at 17.5a continuous, so would a 15a in-line fuse be appropriate?

All my lights are led, I have an alternator and no control box, just to clarify for those offering advice, but thank you, it is much appreciated. Once I can get the steering column clamp loosened off and the lighting wires pulled out I will have a better idea of where the original issue lay

David

[Serious electrical short, TR4a]

Hi Andy, indeed the thought did cross my mind, but in the end I've bitten the bullet and ordered a new loom from Autosparks while I continue dismantling the interior to find the root cause of the failure

David 

[Serious electrical short, TR4a]

Thanks guys, helpful advice. Having built the car from scratch I know exactly what's involved. I never thought the running of the 12v permanent live in that bundle of cables which is then jammed between the 2 halves of the steering column clamp was a particularly great idea!

David

[Serious electrical short, TR4a]

Thanks Dic, I tend to agree. Having looked further behind the dash I was able to see several additional areas of melted loom + insulation on the permanent 12v cable. I have decided that the risk to having the loom compromised isn't worth it, so a new loom was ordered from Autosparks this morning; the pain is the lead time can be up to 10 weeks so that's going to write off a fair chunk of the season, hey ho

David

[Serious electrical short, TR4a]

Also looking at the 'Flash to Pass' wiring which I know has been covered on this Forum as well as those Stateside. The alternative wiring arrangement which I have used without issue since rebuild is attached, showing the connection of an unfused live to the flash terminal on the column switch. I'm wondering whether the live supply should come from a permanent 12v fused supply so the fuse would blow before any serious cable damage occurred? Any thoughts on the pros/cons of these arrangements

David

[Serious electrical short, TR4a]

4 hours ago, Z320 said:

David,

I’m even more confused…..

You used a standard new loom, which is made for a TR4A with generator.

And you used the brown-blue cable to connect the battery with the solenoid?

It has not the dimensions to do this!

And I don’t know where you can buy the colour combination in the needed dimension to use it for this.

Your photo is from under the dash?

Some more and better photos are needed, please.

Ciao, Marco 

Marco, Autosparks provide a new loom which is designed for an alternator and with no Control Box. I'm going to strip back the loom tape as Charlie suggests and look at the condition of the other adjacent wires; then decide how to proceed

David

[Serious electrical short, TR4a]

1 hour ago, gloide69 said:

Because the main beam was flashing on, it suggests a problem with the lighting switch rather than a short to earth, as the lights are earthed at the lamps.

I'm guessing the lighting switch on the 4a is on the steering column. During your investigation, could you have trapped the Brown/Blue wire near the lighting switch or on part of the steering column loom?

Paul

Yes that is possible, thank you

[Serious electrical short, TR4a]

Charlie, that is my thought process. Interesting that certain parts of the Brown /Blue cable run are showing insulation melting, others are not, I don't fully understand what creates the difference

David 

[Serious electrical short, TR4a]

Marco, I have an alternator so the cables are slightly different. The Brown/Blue is from the starter solenoid but a common connection to the battery main feed so effectively direct from the battery

[Serious electrical short, TR4a]

That's interesting Ian, they clearly saw the issue. I added an extra fuse box during the build, but unfortunately the Brown/Blue is un-fused, straight off the battery via the starter solenoid

David

[Serious electrical short, TR4a]

Hi Marco, the last thing before this fault first appeared was a visit to a Bodyshop, however I can't see why or how that would have affected anything in the wiring under the dash/steering column. The worst of the melting is at the starter solenoid connection, but also I've found melting where the Brown/Blue crossed over an earth wire which has melted through causing a direct short to the body!

David

[Serious electrical short, TR4a]

I have a almost new Autosparks loom in my 4a, installed during rebuild and worked fine for 3yrs. Recently after a visit to a body shop, I noticed that the main beam flashed on occasionally when turning the steering wheel. I suspected that an earth was occurring in the vicinity of the column lighting switch, possibly contacting the indicator cancelling clip and shorting through the steering column. After some investigation, I managed to move the indicator clip slightly further down the steering shaft; it seemed to be sorted. However, today during final checks before the first show of the season, I noticed the main beam came on again, followed closely by white smoke from under the dash. I quickly isolated the battery and had a good look under the dash and the engine bay. I can see significant melting on the Blue/Brown wire at the starter solenoid terminal, on the Blue/Brown connection to the lighting switch wires and a section of melting on the main loom under the dash (Brown wire) which had melted through the wire insulation and the loom tape.

Obviously I need to find the original cause of the short, but further downstream than that I'm thinking I may need to replace the entire run of the Blue/Brown wire, or even the full loom if other damage might have been done within the body of the loom

Any helpful thoughts on this?

David

[Another OverDrive Switch]

Assuming that's my switch being modified, it came from J Duncan Lloyd (Classic Bits); thanks Roger

David

[Header rails]

Pete, I have a spare TR5/6 front header bar if you want to go down that route and some spare locking handles

Rgds

David