Horn issues

[BillyB62]

As I'm readying my car for registration, I need to address the horn, which is barely audible. I was going to replace the horn, but realized there are actually two horns, a high and low tone. I would think it odd that both horns would go at the same time.

Any tips on troubleshooting the horns would be appreciated.

Thanks in advance,

 

[Dale]

Mine on my TR7 had little pebbles that had worked their way around the bell and lodged against the diaphragm. Removing them made a big difference, though the horns I've heard on most LBC's are not very impressive.

 

[dklawson]

From memory, the power for the two horns is daisy-chained and each horn is grounded. Some horns ground through their mounting brackets, some have two terminals and a second ground wire. So, make sure the connectors on each horn are clean and that each horn has a good ground.

The horn circuit typically passes an earth connection up through the steering column. If your car has a rubber steering shaft coupler (joint), there is a braided cable inside the joint that passes the ground connection from one part of the steering column shaft to the other. Be sure to check the braid because it can fail. A test would be to temporarily run a ground wire between the car chassis and the upper part of the steering column shaft. The bottom part of the steering column shaft is grounded through the steering rack. Make sure the rack has its ground cable intact.

Lastly... if your car does not have a horn relay, corrosion in the horn button contacts can be a problem.

 

[BillyB62]

The signals do not automatically shut off after making a turn and the control head assembly "appears" to be the original. Maybe I'll take a peek in there this weekend.

 

[mrv8q]

though the horns I've heard on most LBC's are not very impressive.

Wait 'til you hear a TR3's hi/lo horns. a loud, instant transport back to the '50s!

 

[Tr3aguy]

t. On earlier models Lucss hams t y p WT 614 were fitted
but on the later cars type- WT 618 were fitted instead.
2To check the horn adjustment connect a 0 to 30
amrnetar into rerim with the horns at glme convenient
point.
3. Operate the horm and note th current msurnption for
both horns. The WT 614 type horn should have a current
224
consumption of 13 amps, and the WT 618 type should have
a c u m t consumption of 16 amps.
4. If the consumption exceeds this amount disconnect the
horns from each other and test each of them in turn. A
single WT 614 horn should requjre 6% amps, w operate
correctly and a WT 678 horn requires 8 amps.
5. If a horn is to be adjusted away from the car make sure
it is made secure in a bench vice with good electrical
connections.
6. Rsrnwe the cover by undoing the centre screw and
lifting off.
7. Remove the fuse from the AT-A2 terminals and replace
with a piece of stout wire. Using a suitable size open ended
spanner undo the adjusting nut locknut (Fig. 10.14). Turn
the adjusting nut in a clockwise direction until the m t a c t
points are jusl apart. Test this setting by closing the horn
circuit and the horn should not operate.
8. Turn the adjusting nut half a turn in an anti-clockwise
direction and tighten the locknut whilst hold~ngth e adjusting
nut. Insert a 0-30a mmeter into the circu~tI n series and
by very carefully mating the adjusting nut in a clockwise
direction decrease the current or anticlockwise to incream
the current; adjust the nut accordingly untiE the figuw in
operation 4 of this Section are achieved.
9. When correct adjustment is achieved tighten the locknut
and replace the cover.
10 If the contacts are badly worn they should be removed
but before fitting the new set check the stel pushrod for
freedom of movement and, if excessive, a new pushrod can
be obtained. If movement i5 still excessive a new horn wrll
have to be fitted. Lubricate the pushrod with a little grease.
11 The armature should not touch the base plate but have a
clearance of 0.020 inch between them. To adjust this
slacken the screws ?hat secure the armature and mow it
centrally in the base plate. Use feeler gauges to set the gap
when retightening the screws.
12 Generally inspect the horn wiring for loose or broken
connections of chafed ~nsulation.O n WT 61 4 type horns a
resistance was fiW across the horn coil but on the WT 618
type the contact breaker terminal was made of a resistance
material. If the res~fianceis inoperative excesive arcing will
occur bttween the two contact points.
13 If there are any other faults with the horn it is recommended
that a new horn be fitted.
34. Horns - Sewicing and Adjustment ITR4,4AI
1. The horn should never b? dismantled but it is possible
to adjun it. This adjustment is to compensate for wear only
and will not affect the tone. At the rear of the horn is a
small adjustment screw on the broad rim, nerdy opposite
the two terminais, Do not confuse this with the large screw
in the centre.
2. Turn the adjustment screw anti-crockwise until the horn
just fails to sound. Then turn the screw a quarter of a turn
clockwise, wh~chis the optimum setting

 

[John_Mc]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:] 1. The horn should never be dismantled but it is possible
to adjust it. This adjustment is to compensate for wear only
and will not affect the tone. At the rear of the horn is a
small adjustment screw on the broad rim, nearly opposite
the two terminals, Do not confuse this with the large screw
in the centre.
2. Turn the adjustment screw anti-clockwise until the horn
just fails to sound. Then turn the screw a quarter of a turn
clockwise, which is the optimum setting[/QUOTE]
This is where I'd begin after making sure I had power to the horns (which it already sounds like you do if you are getting a little bit of sound). My horns failed to sound and it was just that they were out of adjustment. Once I adjusted them per these instructions, I had two perfectly good sounding horns.

Here is the location of the adjustment screw as seen on my passenger side horn:

 

[TR3driver]

Actually, many cars have two horns that sound at the same time, with different notes. The resulting mixture of sounds is more noticeable than either horn by itself.

When they work right, the original TR3 horns are loud enough that I worry about disturbing the neighbors (and my hearing!) when testing them inside the garage.

Usually when they kind of "moo", it's either point adjustment or a bad connection in the circuit (or horn button) that keeps them from getting enough current. The literature is somewhat misleading, the current values given are all for average current (what you'd read on a conventional ammeter). But since they draw almost no current when the points are open, the instantaneous draw with the points closed is quite a bit higher. All of the connections need to be capable of passing 30 amps, or the horns won't work properly. I fought with a problem for a long time that turned out to be a bullet connector that was broken inside the sleeve. It would make contact, but not very well, and limit the current to the horns.

The other problem I've seen a lot is dirt and rust keeping the little pushrod from moving as it should.

 

[BillyB62]

You guys are amazing - thanks for the tips, I'll post back after I get a chance to work on them this weekend.

Many thanks!

 

[Geo Hahn]

...Here is the location of the adjustment screw as seen on my passenger side horn:

I don't know TR6's but wouldn't those horns sound better if they were pointed forward? Could it be that the d/s and p/s are switched?

For a possible touch of originality -- the horns on my '4 had a dab of 'don't mess with me' blue paint on each of the adjustment screws:

 

[TR3TomG]

Not sure of the status of your car and if its on the road, but if your battery is low, they usually will not work. You might only get a clicking.

 

[BillyB62]

Although it is not registered, the miles continue to increase - I'm fortunate to live in a small rural town in Connecticut! The car drives good and starts immediately, although the amp gauge does register slightly below "0" when its running.

My plans over the next two to three weeks are to swap it over to negative ground (so I can plug in a GPS) and swap it over to an alternator. I know the purists may cringe to hear this, but I bought the car to run and an alternator (in my humble opinion) would give me piece of mind and I judging by many of the parts, it would not surprise me if the generator is original.

As for the horn(s), it makes a sound sort of like a low dying cow.

 

[BillyB62]

I'm obviously still a novice at posting pic's! Hopefully you all can see the needle is a tad to the left of the "0" - p.s. the car was obviously running at the time.

 

[Geo Hahn]

...My plans over the next two to three weeks are to swap it over to negative ground (so I can plug in a GPS) and swap it over to an alternator. I know the purists may cringe to hear this, but I bought the car to run and an alternator (in my humble opinion) would give me piece of mind...

If your GPS plugs into a 'cigarette lighter' socket -- easy to install one with reversed polarity. I mounted it on a piece of thin plywood (plastic would work too) to isolate it.

Most go to an alternaotr for more juice (amps, lights, heated seats) but for reliability I think the generator/dynamo is pretty solid.

 

[John_Mc]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]I don't know TR6's but wouldn't those horns sound better if they were pointed forward? Could it be that the d/s and p/s are switched?[/QUOTE]
Not sure since this is how they were positioned when I got the car. Anyone know for sure?

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]As for the horn(s), it makes a sound sort of like a low dying cow.
[/QUOTE]
Bill, I seem to recall that's what mine sounded like pre-adjustment. Or sometimes it sounded like lightly compressing an aluminum can and letting it pop out again.

 

[TR3driver]

Hopefully you all can see the needle is a tad to the left of the "0" - p.s. the car was obviously running at the time.

That's actually normal, with the engine idling. The needle should swing to the charge side at higher revs, though. If it doesn't, there may be an issue with the generator or (more likely IMO) the control box.

FWIW, I'm running what I believe to be the original generator on my 56. It's had new bearings and brushes installed, plus some brass sleeves to cover the wear in the mounting holes; but it works fine.

And as noted, a low battery can cause problems with the horns, especially if everything else isn't top-notch. I'd make sure your battery is at least 3/4 charged before doing any more work on horns.

 

[BillyB62]

Thanks Randall, since I'll be working on the car this weekend, I'll plug in the battery charger tonight, just to make sure. ISTR when I bought the car in November the horn worked better (still not great) than it does now. Since the car had been sitting for 4 or 5 years, I'm not sure the status of the battery anyways. It may be a decent $100 insurance policy just to replace it.

 

[TR3driver]

It may be a decent $100 insurance policy just to replace it.

FWIW, many auto parts stores will test it for free. I know O'Reillys (which now owns Checker, Kragen & Shucks) will. Of course they are hoping that, if you need a battery, you'll buy it from them. But there is no legal obligation to do so; and their prices are pretty reasonable anyway.

 

[Geo Hahn]

...Since the car had been sitting for 4 or 5 years, I'm not sure the status of the battery anyways. It may be a decent $100 insurance policy just to replace it.

Quite possibly it is due for replacement if it sat that long. I usually get my batteries from Walmart as it is a pretty common size -- Group 24. Depending on the polarity you end up wanting I think the battery fits best with the posts toward the firewall.

 

[Don Elliott]

The horns on my 1958 TR3A are the ones which came with the car when I bought it brand new in 1958. I rallied it a lot on gravel roads during the summers of 1959 to 1965 and also drove it in salty shushy snow from 1963 to 1972.

While I was dismantling the car for restoration from 1987 to 1990, I found that the sand, gravel and hardened salt residues had totally blocked the open trumpet end about half way back.

After chipping all this out and cleaning them up. I have had no issues since 1990 having driven 108,000 miles of mostly dry summertime driving.