Bruce is right on. If you find after following his instructions that the
disconnect is in the return portion of the horn circuit, here is some more
info. My horn circuit troubles were caused by the wires which go through the
rubber couplings in the steering column. Discussing this horn solution will
then lead me to the loose steering problem.
1) the steering column is is three parts. The 1st first part goes from the
steering wheel through the dash and firewall into a splined metal adaptor
which is bolted (2 bolts) to a rubber coupling. The splines on the column
match the splines in the adaptor. On the other side of the rubber coupling
is bolted another adaptor. The 2nd part of the column fits into this
adaptor. At the other (lower) end of this 2nd part of the column is the same
configuration (i.e. adaptor, coupling, adaptor). The 3rd part of the column
is attached to the lowest adaptor and then finally (on the lowest end of the
3rd part of the column) to the steering box. Because of the way the adaptors
and couplings are configured, the rubber couplings isolate (electrically
insulate) the bottom of the steering colunm (at the steering box and
electrical ground) from the top (where the horn button acts as a switch). To
make a complete circuit down the steering column, a wire was run through each
of the 2 rubber couplings. These wires were then connected from one of the
bolts (the bolts holding the adaptors to the coupling) on the topside to one
of the bolts on the bottom side of the coupling.
Current in the horn circuit runs by wire from the horns to the steering wheel
slip-ring and returns through the steering column to ground when you make the
circuit complete. Depressing the horn button pushes down on the horn brush
and connects the slip-ring to the steering column. In other words,
completing the circuit allows current to travel to ground through the
steering column (that's why you need the wires through the couplings). Hope
that helps so far. Now let's talk about the wires through the rubber
couplings.
2) The wires through the steering column couplings were originally braided
strand - similar to the original battery cables but smaller in width. These
corrode over time thus opening the circuit. One can obtain replacment wires
from TRF,VB or Moss. But you will have a devil of a time getting them
through the middle of the rubber couplings; I couldn't when I tried in the
'70's. I solved the problem then by making up, using several twisted
strands of normal bell wire, several short wires which I connected from the
bolt head on one side of the rubber coupling to the bolt head on the other
side. This completed the circuit and the horns worked just fine - although
the whole thing looked a little strange and I had to check occasionally to be
sure the wires did not get caught on anything when steering. Now here is how
the horn problem is related to loose steering.
3) About three years ago I noticed that my steering was getting loose. My
wife wanted to know why I was "wandering all over the road". What I was
doing was making corrections to play in the column. This play was allowing
the front wheels to move together slightly from side to side. The play was
caused by the rubber couplings. This could have been dangerous if allowed to
continue - as I found out when I replaced the couplings.
The rubber couplings had deteriorated (they were almost 30 years old) to the
point that there was a lot of slop in the steering. It had been gradual and
so I was compensating very nicely. Someone else noticed. Sound familiar?
Some of you are doing the same thing, I'll bet.
I bought new rubber couplings, and while I was at it, the replacement wires
for the horn circuit, from TRF. When I replaced the couplings I threaded the
wires through them so that whole thing was just like the original.
Unbelievable how the steering tightened up. The horns work fine and the
column looks good - with no wires visible.
Caution - If you do this (replace the couplings) be sure to use steel safety
wire (as shown in Haynes and Bentley but not the some of the catalogs) on the
the bolts! But that's another story. (Anyone who needs info on the safety
aspects of the steering column - please yell.)
Diagrams for the TR4 steering column can be found in Bentley, Haynes (p.261)
and in the TRF, Moss and VB catalogs. Prices for the rubber couplings are
from $18 to $20. The wires are a couple of bucks, I think. Hope this helps
you and maybe someone else. Cheers
Art Kelly '64 TR4 CT33118L (original owner )
VTR TR4 Vehicle Consultant
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