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TR7 Headlamp Flash CCT & LED headlights

The all purpose forum for any TR7/8 related topics.
Howard_B
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TR7 Headlamp Flash CCT & LED headlights

Postby Howard_B » 22 May 2020 20:41

In case anyone is planning on fitting LED headlights to a 7 fitted with the PEKTRONIC flash relay there is a problem. The flash system does not correctly raise the headlamp pods but causes them to rapidly raise and lower.

I have developed a simple & easy solution & will post the full details in directly I get time.

Howard

manny
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Location: West Midlands UK

Re: TR7 Headlamp Flash CCT & LED headlights

Postby manny » 23 May 2020 09:43

Howard_B wrote:In case anyone is planning on fitting LED headlights to a 7 fitted with the PEKTRONIC flash relay there is a problem. The flash system does not correctly raise the headlamp pods but causes them to rapidly raise and lower.

I have developed a simple & easy solution & will post the full details in directly I get time.

Howard


Or do what i did..?
Flash mod
details on the video comments

Ta

Manny
TR7 V8 1982
Reliant Scimitar GTE 6a 1978
Reliant SS1 1800ti 1987
Reliant SS1 1600 1985
Reliant Scimitar GTC 1981
Mercedes 190E 1985

Howard_B
Rust Hunter
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Re: TR7 Headlamp Flash CCT & LED headlights

Postby Howard_B » 23 May 2020 11:06

Hi Manny

Nice modification and works very well with driving lights like yours. What I have developed is a generic solution that works for anyone irrespective of having suitable driving lights (like me).

By installing a single 6.8 Ohm 50 W resistor between the live wire to one of the dipped beam lights & earth the flash will work correctly again.This is what I used https://uk.rs-online.com/web/p/panel-mount-fixed-resistors/1311284/ and fixed it to the inside of the front wing.

If the dashboard is out for any reason, there is an even tidier solution involving a modification to the Pektron wiring with the addition another diode and 0.5 W resistor, but as I don't want to completely dismantle mine until I have, the basic solution will do for now.

An annotated circuit drawing will be posted once I get around to finishing it.

Cheers & happy motoring

Howard

manny
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Location: West Midlands UK

Re: TR7 Headlamp Flash CCT & LED headlights

Postby manny » 23 May 2020 12:03

Howard_B wrote:Hi Manny

Nice modification and works very well with driving lights like yours. What I have developed is a generic solution that works for anyone irrespective of having suitable driving lights (like me)...
Cheers & happy motoring

Howard


Very true, driving lights present...so your resistor drops the voltage to the flash circuit..?
TR7 V8 1982
Reliant Scimitar GTE 6a 1978
Reliant SS1 1800ti 1987
Reliant SS1 1600 1985
Reliant Scimitar GTC 1981
Mercedes 190E 1985

Howard_B
Rust Hunter
Posts: 116
Joined: 09 May 2015 16:11

Re: TR7 Headlamp Flash CCT & LED headlights

Postby Howard_B » 23 May 2020 17:09

The dip bulbs are used in the standard circuit to provide the earth for the Pektron which is why the LED bulbs (Light Emitting Diodes) stop it functioning. The resistor provides an alternative path to earth for the Pektron.

If you have an 80/81 wiring diagram, the logic is as explained below:-

The wiring diagram has a blue wire from the "master light switch" which connects to both the Pektron and the "Flash/Dip/Main beam" switch.

When the "master light switch" is set to the "headlight" position, the blue wire is at +12v and feeds the headlamp rise circuits via a diode in the Pektron. When the "master light switch" is set to the "OFF or sidelights" position, the blue wire is not energised so the headlamps do not rise. However when the "headlight main/dip/flash" switch is in the "Dip" or flash position the blue wire is connected to earth via the dip bulbs. Operating the flash switch energises the blue/white wire to the Pektron, and the return path for the electronic timer circuit is the blue wire to earth via the Dip bulb.

Hope this helps, but full drawing will follow asap.

Cheers

manny
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Posts: 500
Joined: 11 Sep 2010 15:52
Location: West Midlands UK

Re: TR7 Headlamp Flash CCT & LED headlights

Postby manny » 23 May 2020 17:20

Got it...so my next question...have you fitted LED headlight units or just bulbs, if bulbs which ones?
TR7 V8 1982
Reliant Scimitar GTE 6a 1978
Reliant SS1 1800ti 1987
Reliant SS1 1600 1985
Reliant Scimitar GTC 1981
Mercedes 190E 1985

Howard_B
Rust Hunter
Posts: 116
Joined: 09 May 2015 16:11

Re: TR7 Headlamp Flash CCT & LED headlights

Postby Howard_B » 23 May 2020 22:58

Since I use the car on Club Triumph overnight events good lighting is important. I selected them after an article in Triumph World and have found them to be an improvement on the previous halogen bulbs. The light is pure white and noticeably brighter than the originals, but passed its regular MOT without any issues.

I have the H4 Classic Car LED headlight upgrade kit from www.bettercarlighting.co.uk & have found Gil Keane very helpful to deal with. They are not cheap but are good & they fit the TR7/TR8 pods without any heating problems.

All my other bulbs are LED, mainly from www.superbrightleds.com in the USA who provide good bulbs and detailed technical information. They list the bulbs for the TR7, but not sure if they supply direct to the UK.

If you PM me with your email & I will send you a copy of my drawings which list all the bulbs I have fitted on my card

Cheers

Howard

CamGTS
Wedgling
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Re: TR7 Headlamp Flash CCT & LED headlights

Postby CamGTS » 24 May 2020 12:03

I used Classic LEDs who do a full kit for TR7/8 https://www.classiccarleds.co.uk/collec ... 0110053471
Cam

1980 Talbot Sunbeam Lotus
1991 Peugeot 205 GTi 1.9
2004 Renault Sport Clio 182
2011 Porsche 911 GTS
2017 Porsche Macan GTS

Howard_B
Rust Hunter
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Re: TR7 Headlamp Flash CCT & LED headlights

Postby Howard_B » 24 May 2020 14:28

In response to CAMGTS I haven't used them for LED bulbs but would be cautious about ordering a complete kit from any supplier for a few reasons as I have outlined below.

Firstly the door lights are often replaced with after market equivalents which use a different bulb (on mine its the LED equivalent of the 504 / Capless W3W bulb). Secondly for the flashers to work correctly you have to replace both the indicator AND hazard flashers or fit 6.8 Ohm 50w resistors in parallel with each LED indicator bulb.... (I found this out the hard way!) and you cannot replace the ignition warning light with an LED equivalent. It is also necessary to modify the flash circuit for it to work with LED lights. My last observation is that it took me a few changes of rear and brake lights to get something I was satisfied with.

However I have used "Classic Car Led" for replacement flasher units & found them to be exactly as described on the box, so would recommend them.

Howard

CamGTS
Wedgling
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Re: TR7 Headlamp Flash CCT & LED headlights

Postby CamGTS » 24 May 2020 19:57

I did have an issue with the ignition light but no issues with hazards/indicators if you replace the indicator flasher unit with an electronic version
Cam

1980 Talbot Sunbeam Lotus
1991 Peugeot 205 GTi 1.9
2004 Renault Sport Clio 182
2011 Porsche 911 GTS
2017 Porsche Macan GTS

Howard_B
Rust Hunter
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Re: TR7 Headlamp Flash CCT & LED headlights

Postby Howard_B » 24 May 2020 22:19

I would be very surprised if you still have a standard Hazard Flasher if it works with LED bulbs. Since the original is a thermally operated device it needs a large current to operate & LED's simply don't draw the current necessary. Its quite likely that it has been replaced over the past 40 years with an electronic unit which would explain why it works.

Cheers

Howard

CamGTS
Wedgling
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Re: TR7 Headlamp Flash CCT & LED headlights

Postby CamGTS » 26 May 2020 11:43

That would make sense. Thanks. I'll check
Cam

1980 Talbot Sunbeam Lotus
1991 Peugeot 205 GTi 1.9
2004 Renault Sport Clio 182
2011 Porsche 911 GTS
2017 Porsche Macan GTS

supercass
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Re: TR7 Headlamp Flash CCT & LED headlights

Postby supercass » 26 May 2020 18:04

Can someone answer this for me?
If you swap the flasher unit for a transistorized version which is not thus thermally controlled do you lose the bulb failed warning facility (i.e. the remaining bulb / bulbs flash at a slower rate or not at all).
supercass

Cobber
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Re: TR7 Headlamp Flash CCT & LED headlights

Postby Cobber » 26 May 2020 18:51

The old thermal flasher units would flash quicker with less load (a bulb out) not slower, this "warning feature" was more of an inherent design limitation of the technology than an intentional design feature, a lucky accidental bonus with limitations, hook up a trailer and the flash rate would often be too slow.
Obviously fitting bulbs of different wattage to standard would effect the flash rate.
So imagine this scenario, you're on a trip some where and you notice that a bulb has blown, you go to the only garage for miles, and they don't have any bulbs of the wattage required for you application, you use what you can get as it's better than nothing. The result could be that you now have a flash rate that doesn't meet the legislative requirements.
Normally this wouldn't matter much, but if you to encounter a copper having a bad hair day and a particularly large amount of shit on the liver, he might notice this out of spec flash rate and give you a defect notice (called a canary in these parts because they stick a bloody great yellow defect notice sticker on your windscreen) Most coppers wouldn't notice or even bother hassling you if they did, but there are some real pricks out there.

Bin the shitty old type flasher unit and go for one that will work with your LEDs if you must have them, I see no point in fitting LED bulbs in the indicator circuit, if you have to go to the trouble and expense of fitting ballast resistors into the circuit.
It defeats the purpose of lower wattage LED bulbs if you have to fit ballast resistors to up the wattage just to get the damned things to flash!
I can however see one possible advantage of using LEDs (without ballast resistors) their lower wattage requirements would put less load on the shitty indicator switches used in our cars, as would the binning the thermal flasher can (damned things use a fair bit of current themselves)
"Keep calm, relax, focus on the problem & PULL THE BLOODY TRIGGER"

'80 Triumph TR7, '73 Land Rover (Ford 351. V8),
'97 Ford Falcon Longreach 'S' ute,
'98 MG-F, '69 Ford F250.

saabfast
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Re: TR7 Headlamp Flash CCT & LED headlights

Postby saabfast » 26 May 2020 20:39

I would advocate fitting an electronic flasher unit whether you use LED or normal incandescent bulbs, although agree that there are better things to spend on than LED indicator bulbs, the power saving is minimal when you consider how long they are actually on for. With an electronic flasher unit the flash rate is constant and does not slow at traffic lights, junctions etc and they seem pretty reliable.
Alan
Saab 9-5 2.3t Vector Auto Estate Stage 1
Saab 9-3 2.0 SE Turbo Convertible
'81 TR7 DHC
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