DaveN Posted March 20, 2017 Report Share Posted March 20, 2017 Right, got bored today and have decided to rewire the lights and add relays. got all the correct colour coded wire etc etc But. The question is what do you folks do with the existing loom that runs down from the bulkhead. Do you just cut it somewhere convenient and cap and stow the redundant wires? Quote Link to post Share on other sites
BlueTR3A-5EKT Posted March 20, 2017 Report Share Posted March 20, 2017 (edited) How many relays are you intending to fit? It may be easier to fit one for each filament ie 4 relays. Disconnect the bullet connectors down at the front for the headlamps Blue/white & Blue/red cables. Position the relays at the front near by the headlamp bullet connectors. Use the existing loom supply to the headlamps to trigger the relays (terminal 85 of each relay). Connect terminal 86 to car earth. Then add the new big & fat powering cables from a fused battery source ( to terminal 30 on each relay). Connect the correct colour matching cabling from the headlamps to each contact 2nd posn of each relay as required. (terminal 87 on each relay) Do not forget the earthing for headlamps and the trigger terminal 86 of the relays. No need to chop anything about. Peter W PS Do a web search for headlamp relay circuit image and you will be swamped. Edited March 20, 2017 by BlueTR3A-5EKT Quote Link to post Share on other sites
barkerwilliams Posted March 20, 2017 Report Share Posted March 20, 2017 +1 Couldn't agree more with improving the earth wiring. My headlights got noticeably brighter after improving the earth circuit. Alan Quote Link to post Share on other sites
snowric Posted March 20, 2017 Report Share Posted March 20, 2017 and then you can re-wrap your loom and it all looks pretty afterwards ! Quote Link to post Share on other sites
paul7 Posted March 20, 2017 Report Share Posted March 20, 2017 Where would the new live feed come from. Is the existing fuse box okay or a new fuse box fed from the battery? Quote Link to post Share on other sites
Lebro Posted March 20, 2017 Report Share Posted March 20, 2017 I used the convenient live horn feed, right next to the headlamp wiring. Bob. Quote Link to post Share on other sites
DaveN Posted March 20, 2017 Author Report Share Posted March 20, 2017 (edited) Ahha! More than one way to attack it. I was thinking along the lines of chopping the old loom after separating out the ignition and horn wires. capping off the bare wires with environmental crimps and rewrapping. mounting the relays on the inner wing by the original horn relay and running new wires down from there, with a new feed to switch them. I was also planning on putting a relay in the sidelights circuit. Does that sound feasible? Anyone know why ST put a fuse in the sidelight circuit but not the headlamps? Edited March 20, 2017 by daven Quote Link to post Share on other sites
Lebro Posted March 21, 2017 Report Share Posted March 21, 2017 A lot of work. just use the old wires to trigger the relays as Peter says. I would not bother using a relay for sidelights as they draw a lot less current (especially if you use LED lights) Bob. Quote Link to post Share on other sites
Drewmotty Posted March 21, 2017 Report Share Posted March 21, 2017 Am I correct in thinking that if the headlamp bulbs were replaced with LEDs then a wiring upgrade would not be required? Are suitable direct replacements available? Quote Link to post Share on other sites
barkerwilliams Posted March 21, 2017 Report Share Posted March 21, 2017 Daven, No fuse fitted in headlights in case it blows! Then you're doing 70 on a bendy road in the dark trying to remember a reasonable prayer. However if you are having separate main dip relays perhaps a separate NS & OS 4 relay setup then a number of individual fuses would perhaps be more appropriate - but never only one fuse to kill all the lights. You need to design a bit of lifesaving redundancy into your circuits. Alan Quote Link to post Share on other sites
Lebro Posted March 21, 2017 Report Share Posted March 21, 2017 Am I correct in thinking that if the headlamp bulbs were replaced with LEDs then a wiring upgrade would not be required? Are suitable direct replacements available? Yes, & complete headlamp replacements are available, but expensive, there are some cheap led bulb replacements on the market, but they do not dip the beam down, they just dim, which would not be legal, or desirable. Bob. Quote Link to post Share on other sites
RobinTR6 Posted March 21, 2017 Report Share Posted March 21, 2017 I made a small bracket and added it to the floor dip switch, affixed to relays power direct from starter , job done and no cutting and easy to get wire from back of engine bay and it's onthe some side as dip switch. Quote Link to post Share on other sites
griffipaul Posted March 21, 2017 Report Share Posted March 21, 2017 You might want to think about whether its wise to have the relays close to the front of the car as they are fed by a permanently live wire. Bit of a potential problem in an impact situation. Yes I know the feeds to the lights are live when the lights are on currently, but needs must . This is why relays are normally on a bulkhead or some where safe . Just an observation. Permanently live wires are a potential hazard - their undesirable effect should be mitigated against wherever possible and the installation thereof be made as safe as possible .Not sure if there are any IVA guidelines on this. Quote Link to post Share on other sites
ianc Posted March 21, 2017 Report Share Posted March 21, 2017 The reason that the Lucas technician wired the Works' Rally TR4s with a separate fuse for each headlamp filament (i.e. 4 fuses) was to avoid all the headlamps being killed if a car hit something and shorted the wiring at the front of the car. Spotlamps were (and are still) separately fused. My article in the latest TR Action may assist. Ian Cornish Quote Link to post Share on other sites
Fireman049 Posted March 21, 2017 Report Share Posted March 21, 2017 (edited) Here are two different wiring diagrams which may be of some help. Any comments please. I haven't got round to fitting four relays yet. Tom. Edited March 21, 2017 by Fireman049 Quote Link to post Share on other sites
DaveN Posted March 21, 2017 Author Report Share Posted March 21, 2017 IMHO Tom I think two relays is enough. That's what I've elected to go for now. After all they're rated at 40 amps each. If the car wiring starts drawing that sort of load...you better get your firemans hat on! Quote Link to post Share on other sites
Fireman049 Posted March 21, 2017 Report Share Posted March 21, 2017 Thanks for that Daven ~ That's the way to go then and far less trouble. Tom. Quote Link to post Share on other sites
Robert Sackley Posted March 23, 2017 Report Share Posted March 23, 2017 The easiest way to fit headlamp relays is to use the Moss kit 117-515. This contains two relays, fuses, colour coded wiring and full instructions. Locate the relays on top of the fibreboard radiator air duct and connect into the nearby lighting loom connections. No need to cut the loom. Take the power supply from terminal A1 on the control box. I fitted these relays to my TR4A 12 years ago and noticed a marked improvement to the headlamp brightness. The life of the lighting switch and dipswitch contacts will also have been extended by reducing the switching current by 90%. As the TV Meerkat might say: 'Simples!' If you do this mod. please take the time to use soldered bullet and Lucar connectors; crimps have no place on TR! Quote Link to post Share on other sites
stillp Posted March 23, 2017 Report Share Posted March 23, 2017 "No fuse fitted in headlights in case it blows! Then you're doing 70 on a bendy road in the dark trying to remember a reasonable prayer." Good point, but also the voltage drop due to the resistance of the fuse would have more effect on the headlights due to the higher current. Pete Quote Link to post Share on other sites
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.