TR4/4A TR4 horn trouble - a common complaint.

[TR4nut]

Whoever complains about minor Triumph electrical troubles has never tried to fix a bad horn ground on a TR4. My horns were never strong, and after storing the car for a year they don't make a peep.

I've traced the trouble to the ground in the steering column - the trouble is the bad ground seems to be in the steering couplings themselves. I do have all ground wires installed, but even with those you still have to rely on a good ground through the column and I believe sufficient corrosion has built up in the joints so that I have a lot of resistance and not enough current to run the horns.

Aside from my whining and pleas for pity from the Triumph crowd, I was thinking of converting to a TR4a-6 style relay system. Main current driving the horns would not go through the column, the column ground would only open/close the relay. My hope is with less current draw for the relay the resistance I see in the steering won't be as much an issue.

Does this make electrical sense? I don't have a TR relay, but I do have an aftermarket relay marked L-B-S. I'm also trying to figure out if I can use this 3 prong relay but right now I'm drawing a blank. Ideas/sympathy welcome.

Randy

 

[TexasKnucklehead]

I don't know how much current the horns require, or the relay, but I don't think there will be a huge difference. In either case, to properly function, the ground will have to be working, so you may as well locate it and repair the poor ground.

One of my very first automotive repairs was on my brothers TR4 horn ground. The DPO had converted from positive ground and to an alternator with negative ground and thought it required all the little grounding wires to be cut. As I recall, there are several in and around the steering column.

-I plan to be here Saturday afternoon, if you want to bring it by I'll help you get it working (relay or not).
Jerry

 

[TR3driver]

Adding a relay makes good electrical sense, IMO. Peak current for the horns is pretty high, over 20 amps as I recall, and they are fairly sensitive to reduced voltage. A relay coil will draw less than 0.1 amps, and usually work on 1/2 voltage with no problem.

But you'll need to either rewire the horns or get a 4-wire relay. And ordinary "fog light" relays may not last very long in horn duty, because of the inductive kick-back from the horns.

 

[prb51]

Along the same line.
Everything electrical works on my TR3 but the horns are rather anemic sounding. Would a relay assist in that or...

 

[TR3driver]

I added a relay to my TR3A. It helped some, but what really helped was figuring out that the bullet "sleeve" for the hot side of the horns had broken inside and was not making good contact.

I've also had trouble with the center push-rod inside the horns collecting dirt and rust so it binds in it's hole. That also interferes with the sound. Removing, cleaning and adjusting also helped.

 

[Guest]

Speaking of horns, ya'll might want to look to replacing your old, worn-out clear hooters with FIAMM horns, made in Italy (not china) and available at essentially every automotive store on the planet. They are nicely made, cheap, look very similar to Clear Hooters and use the same mounts. The ones I have are EXTREMELY LOUD and will scare anybody in my path. These are not air horns and use the stock Triumph harness and relay with zero problems.

 

[racingenglishcars]

A long long time ago, I mounted a grounding brush to rub against the column. Then the horn always worked with no problems. Then I switched over to FIAMM horns.

 

[TR4nut]

Thanks for the replies - I have a few options to work through now. I suspected that the 3-wire relay wasn't going to do it, I'm pretty sure I can source a very inexpensive modern 4-wire relay and hide it under the dash near the column. Then I can see if it works.

I haven't seen the FIAMM horns but they might even fix my problem with no further modifications if they don't draw as much current.

I've already thought about a ground brush idea - there is about a 1/8" gap between the upper steering column clamp and the outer steering column shroud near the bulkhead. If I put a screwdriver there and hit the horn it always works. I've considered putting in one or two copper washers to fill that gap. Lubed up with a little dielectric grease I think that would be a consistent ground for the horns and hopefully no noticeable steering drag or noise from the washers when I turn. Downside on the experiment is that I'd need to pull everything apart to get the washers in, which is what I'm trying to avoid in the first place.

Jerry- Thanks for the offer, the horn as well as a small exhaust leak from the joint near the gearbox output shaft are the only things that are keeping me off the road right now - I need to get those fixed to get through the inspection. After that you'll probably see me at least at more TTR events.

Randy

 

[TR3driver]

I haven't seen the FIAMM horns but they might even fix my problem with no further modifications if they don't draw as much current.

Took a quick look at their website. Most of the horns appear to be rated at 5 amps (average) per horn, which I think is only slightly less than the TR4 horns.