[xk] Brighter Headlights

I’ve been reading about headlight relays and how they can be used
to increase headlight brightness while at the same time taking most
of the electrical load off of the headlight switch. It would seem
that an XK 120 would be a good candidate for a headlight relay
since the batteries are located so far from the headlights. There
is bound to be voltage loss between the batteries and headlights.

From what I’ve read, a small amount of voltage loss equates to
substantial lumem loss.

Has anyone installed a headlight relay on their XK? If so, I’m
wondering if the installation can be done without appearing too
obvious.

Mike Balch–
'53 OTS
Des Moines, Iowa, United States
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Mike,

The “insertion” of a relay is a fine idea to supply more “battery” to the
head lights but where electrically do you put it and how do you protect
the “heavy lead” from a safety (fused) stand point.

You also have to consider the foot operated “dipper switch” as an
integral part of the circuitry if you want both upper and lowers. With
all of this to consider, the relay and heavy feed idea IMHO, becomes a
bit of a trick to hide and yet allow service access. Doable, yes!, but
perhaps beyond an amateur.

Regards,

Rick

In reply to a message from holland-rick@juno.com sent Sat 2 Dec 2006:

The weak link in an XKs headlight system is the headlight switch
itself. It will not handle the increased amperage of higher output
lights. (It will melt the internal connectors - -I know.)
The wiring and dipper switch is easily capable of handling more
amperage than needed to use high output lights.
I installed relays on my 120 very easily. I connected a 12 ga.
wire to the A2 terminal on the control box, pulled it through the
firewall into the cars interior behind the dashboard and connected
it to the load input terminal of the relay. I then disconnected
the wire from the headlight switch to the dipper switch and
connected it to the load output terminal of the new relay. I then
connected a 14 ga. wire to the headlight terminal of the headlight
switch and to the signal terminal of the relay. I connected a
short wire to the ground terminal of the relay and grounded the
wire under the mount of the relay behind the dashboard, well out of
sight.
Simple and easy.
I run 80/100 halogen bulbs in my 120 along with a pair of 7’’ Lucas
(the real) Flamethrowers. Even with my aged eyes, I can see well
at night.

An easy thing to add brightness to your car is to clean all the
terminals, fuses, and connections on the car. It’s surprising how
much can be lost with many connection points taking a little bit at
each point.
Finally be certain to have your voltage regulator (control box)
adjusted to the correct voltage. It should yield 14.5 volts with a
fully charged battery. Anything less will definitely dim your
lights.

Roger–
Roger, 1954 120 DHC BRG, S678300
Tamarac, South Fla., United States
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There is a “bright” side to the standard headlights on the 120 - I don’t
have to worry about switching to my low beams when approaching other cars
because they think I’m already using my low beams :-)-----
Eident youth maks easy age.(Scottish proverb)
Bruce Cunningham - Slainte Mhath

In reply to a message from Velocette sent Sat 2 Dec 2006:

Roger,

Thanks for providing a detailed description on connecting a
headlight relay in an XK. Your wiring of the relay is much simpler
and straight-forward than the wiring scheme I had dreamed-up. A
couple of questions:

  1. Whose relay did you use and about how much did it cost?
  2. Can you provide a little more description on setting the
    voltage regulator at 14.5 volts? I tried the method described in
    the service manual but was unable to obtain a reading on my digital
    voltmeter with the engine running. After driving with the
    headlights on, a little mist of battery acid was appearing on one
    of my batteries. So I ended up turning-down the voltage regulator
    about 1/2 turn. Now after driving the car for some distance, the
    batteries are charging to about 13.3 volts. Before I turned down
    the regulator, they were charging to 13.7 volts. Misting seems to
    have abated.

Mike Balch–
The original message included these comments:

I installed relays on my 120 very easily. I connected a 12 ga.
Finally be certain to have your voltage regulator (control box)
adjusted to the correct voltage. It should yield 14.5 volts with a
fully charged battery. Anything less will definitely dim your


'53 OTS
Des Moines, Iowa, United States
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In reply to a message from Velocette sent Sat 2 Dec 2006:

Roger,

Good on you, I wish I could say the same!

Reminds me of a friend who when he went to get his eyes
checked was asked if he had ever noticed bumps and noises as
he drove. He said no, then asked why the question. The
answer was the noises were probably pedestrians!

Regards

Keith–
The original message included these comments:

I run 80/100 halogen bulbs in my 120 along with a pair of 7’’ Lucas
(the real) Flamethrowers. Even with my aged eyes, I can see well
at night.


Keith Bertenshaw
Rockaway, NJ, United States
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Roger,
Good advice. Another approach is to locate a relay as close as possible to
the lights. Run a good heavy wire direct from the battery to the relay and
use the regular active wire that would normally go direct to the lights to
excite the relay. Again, no extra load on the switch and real good power to
the lights via the relay.

Regards
Len Brighton
150fhc S824101BW
Wheelers Hill
Victoria Australia 3150
(15 miles south east of Melbourne)

Len’s web site address.
http://www.members.optusnet.com.au/minerva45/

The weak link in an XKs headlight system is the headlight switch
itself. It will not handle the increased amperage of higher output
lights. (It will melt the internal connectors - -I know.)
The wiring and dipper switch is easily capable of handling more
amperage than needed to use high output lights.
I installed relays on my 120 very easily. I connected a 12 ga.
wire to the A2 terminal on the control box, pulled it through the
firewall into the cars interior behind the dashboard and connected
it to the load input terminal of the relay. I then disconnected
the wire from the headlight switch to the dipper switch and
connected it to the load output terminal of the new relay. I then
connected a 14 ga. wire to the headlight terminal of the headlight
switch and to the signal terminal of the relay. I connected a
short wire to the ground terminal of the relay and grounded the
wire under the mount of the relay behind the dashboard, well out of
sight.
Simple and easy.
I run 80/100 halogen bulbs in my 120 along with a pair of 7’’ Lucas
(the real) Flamethrowers. Even with my aged eyes, I can see well
at night.

An easy thing to add brightness to your car is to clean all the
terminals, fuses, and connections on the car. It’s surprising how
much can be lost with many connection points taking a little bit at
each point.
Finally be certain to have your voltage regulator (control box)
adjusted to the correct voltage. It should yield 14.5 volts with a
fully charged battery. Anything less will definitely dim your
lights.

Roger–
Roger, 1954 120 DHC BRG, S678300
Tamarac, South Fla., United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php


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In reply to a message from Len Brighton sent Tue 5 Dec 2006:

I see Ebay has the ‘‘J’’ lamps on sale for $59 a pair. Unlike the
originals, these are equipped to handle the 9000 series halogen
bulbs, the same type used in late model cars. Not only would these
look good, but they would be much brighter than what we’re using
now.
Joel–
ex jag, '66 E-type S1 4.2, '56 XK140dhc
Denison, TX, United States
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In reply to a message from Len Brighton sent Tue 5 Dec 2006:

That’s good, but the power source is on the firewall and so are the
fuses. Taking the power source from the battery direct, will then
cause the ammeter to read a continous heavy charge. Therefore
taking the load from the A2 terminal keeps the load before ammeter
and thus will read correctly.
The wires are quite capable of handling the amperage load.
The ‘‘Off, Side, Head’’ switch is NOT. That’s the function of the
headlight relay, to take the current load off the switch.
Now if you’re talking about a modern car with every possible means
of saving a penny excercised, yes the wiring is barely adequate and
running a heavy wire and a relay near the lights is a good thing.
Our old Jags have wiring that is well beyond the needs of the load
and even the load of higher wattage bulbs.

Happy days
Roger–
The original message included these comments:

Good advice. Another approach is to locate a relay as close as possible to
the lights. Run a good heavy wire direct from the battery to the relay and
use the regular active wire that would normally go direct to the lights to
excite the relay. Again, no extra load on the switch and real good power to
the lights via the relay.


Roger, 1954 120 DHC BRG, S678300
Tamarac, South Fla., United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

OK, guys…I’m feeling insecure. Help me out.

Last summer ,among other things, my 120 developed a shimmy when going
over bumps that was too severe to tolerate. I’d basically have bring
the car to a stop to make it go away.

Last winter I replaced the bushings in the steering arms (C3045/46)
with those fancy ones from XKs. The old ones were toast, and they were
the only component I hadn’t already replaced. It all went well, and
the car no longer has any shimmy. It’s very nice.

But I was never 100% certain I got the steering arms in the correct
position, left and right. I am pretty sure there’s only one way they
can go, but I continue to have a nagging insecurity. And if it is
possible to mount them on the wrong side, and I DID that, what would be
the symptom?

What I seem to notice now, is that when I turn the wheels sharp in a
parking lot at low speed, one of the tires seems to drag a bit…like
the front wheels are each in a different radius turn. Maybe it was
always like that…I’m just fretting because I just got some gorgeous
chrome wire wheels with Firestone Cavallinos mounted (thanks to
JagXCHANGE) and I don’t want to grind those groovy tires away
unnecessarily.

Thanks for your collective wisdom. I look forward to a flood of
detailed insights.

Tom Carson
1954 XK 120SE OTS S674946
1962 3.8 Mark 2 MOD, chrome wires
1970 XJ6 1L55441BW
Juneau, Alaska

In reply to a message from Tom Carson sent Tue 22 May 2007:

Tom,

Just so we are on the same page, are we talking about the bushings
for the tapered pins that fix the track rod (or drag link?) that
runs between the Pitman arm from the steering box and the idler arm
on the opposite side of the chassis?–
The original message included these comments:

Last winter I replaced the bushings in the steering arms (C3045/46)
with those fancy ones from XKs. The old ones were toast, and they were
But I was never 100% certain I got the steering arms in the correct
position, left and right. I am pretty sure there’s only one way they
can go, but I continue to have a nagging insecurity. And if it is


Mike Spoelker 672027
Louisville, KY, United States
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–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

Mike,

You are correct.

Go to:

https://www.xksunlimited.com/xks/merchant.ihtml?id=296&step=2

The pin & bush I used is item #5.

There is a picture of the steering arm on page 115 of Urs’ book (figure
3). There is an image of the overall assembly, with both steering arms
in place, on page 142, figure 4. In figure 4, you can see the top of
the bush at either end of the central track rod.

Tom Carson
1954 XK 120SE OTS S674946
1962 3.8 Mark 2 MOD, chrome wires
1970 XJ6 1L55441BW
Juneau, AlaskaOn May 22, 2007, at 4:45 AM, MikeSpoelker wrote:

In reply to a message from Tom Carson sent Tue 22 May 2007:

Tom,

Just so we are on the same page, are we talking about the bushings
for the tapered pins that fix the track rod (or drag link?) that
runs between the Pitman arm from the steering box and the idler arm
on the opposite side of the chassis?

The original message included these comments:

Last winter I replaced the bushings in the steering arms (C3045/46)
with those fancy ones from XKs. …


Mike Spoelker 672027
Louisville, KY, United States

In reply to a message from Tom Carson sent Tue 22 May 2007:

Tom,

You can relax. I don’t think you can get them to go together 180
out. The tie rods are one piece (except for very early 120’s I
believe) so if the track rod was backwards you’d never get the
tapers to fit together.–
Mike Spoelker
Louisville,Kentucky, United States
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Tom,
On mine the arms are bent to the outboard direction, so the nut on the
bottom of the ball joint lines up with the hole in the brake scoop. If I
tried to put them on the wrong sides the error would be obvious to me. If
you don’t have brake scoops, it should be the same way, the bend going
outwards so the ball joint is very close to the tire. If you put them on the
wrong sides the toe-in would be way off, so I would think it would still be
obvious that you had made a mistake.
Better check your alignment again if your problem is that noticeable. We’ve
posted ways to do this yourself with homemade tools.
I think its the nature of the beast that turning circle will not be quite
perfect for both tires at full lock, so you would notice it at slow speeds.
Rob Reilly - 679187

Rob,

I agree with you and Mike S. that it would have been obvious if I had
installed them reversed…and I felt about 90% certain I had it right.
I will check alignment before our road trip in July.

Tom Carson
Juneau, Alaska
1988 325iX coupe, 5 speed
1982 528i Euro, dogleg 5 speed
1987 325iC
1995 318tiOn May 23, 2007, at 5:34 AM, R&J Reilly wrote:

Tom,
… If you put them on the wrong sides the toe-in would be way off, so
I would think it would still be obvious that you had made a mistake.
Better check your alignment again if your problem is that noticeable.
W…Rob Reilly - 679187

In reply to a message from Tom Carson sent Wed 23 May 2007:

Tom,

The fact that one tire turns more than the other when the steering
wheel is turned does not mean you have a problem. You probably
already know this, but one of the standard relationships still in
use today is the Ackerman (sp?) geometry between the steering arm
tie rod ends, steering axis (old king pin centerline) and the rear
axle.

Basically, the correct Ackerman geometry results in the end of the
tie rod, the king pin axis and the center of the rear axle all
falling on a straight line.

The result of this is that when the steering wheel is turned, the
inside tire turns more than the outside tire. It does this so that
it may transcribe an arc with a radius that is shorter than the
outside tire by one-half the track width.

You can verify this by looking at the location of the outer tie rod
end. If the steering drag link (or steering rack if R&P) lies in
front of the front axle centerline, the tie rod ends will fall
outside the king pin axis. If the drag link or rack is behind the
front axle centerline the tie rod ends will lie inside the kingpin
axis.–
Mike Spoelker 672027
Louisville, KY, United States
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I say both rear springs on an XK120 are identical. I have a used set,
both are stamped with the following part number:

C5721

Does everyone agree with me that both are the same?

Tom Carson
1954 XK 120SE OTS S674946
1962 3.8 Mark 2 MOD, chrome wires
1970 XJ6 1L55441BW
Juneau, Alaska

YES!

The two I have are marked the same

Brian---- Tom Carson tcarson@gci.net wrote:

I say both rear springs on an XK120 are identical. I have a used set,
both are stamped with the following part number:

C5721

Does everyone agree with me that both are the same?

Tom Carson
1954 XK 120SE OTS S674946
1962 3.8 Mark 2 MOD, chrome wires
1970 XJ6 1L55441BW
Juneau, Alaska