[xj-s] Wing/Spoiler on trunk lid....optional?

My 94 2+2 has a wing/spoiler mounted on the deck lid.

Adds an element of distinction to the car, compared to ones without it.

If you’re playing the radio, when you open the trunk the antenna automatically retracts so as to not
interfere.

Can anyone tell me if this was a special edition XJS or just a dealer (or factory) added option?

Thanks!

James Kocmoud, Daytona Beach, FL
1994 XJS 2+2 Convertible

// please trim quoted text to context only

In reply to a message from Jim Kocmoud sent Sun 3 Jul 2016:

When l first acquired my '94 convertible, the first thing
tht came to mind was to add that beautiful rear spoiler of
the last 3 or 4 years. It is my understanding that this
spoiler came standard with the V12 cars and as an option
on the 4.0L six. The local Jag dealer explained to me that
the unit included an electronic module to control
operation in a manner that kept the trunk lid and the
antenna from interfering with each other. The joke was
this antenna assy’s price tag: $12,000, so l found one on
eBay for a little less… $300. You just need to be aware
that you don’t want to open or close the trunk lid with
the radio on, or you may inflict irreversable damage on
your antenna. I understand that this little magic module
is available somewhere, so if l find it I may not have to
design my own from scratch after all.

Cheers,–
'94 XJS 4.0L - '02 XJR
Redondo Beach, California, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

// please trim quoted text to context only

In reply to a message from Jim Kocmoud sent Sun 3 Jul 2016:

Simply a cosmetic styling flare. Has no actual claimed or
demonstrated functional value of any nature. I think it was OEM on
the V12 6.0 cars only.–
lockheed 92 XJS Cpe, OB rear brakes, 97 LT1/4L60E
Austin, TX, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

// please trim quoted text to context only

In reply to a message from Jim Kocmoud sent Sun 3 Jul 2016:

James,

Since yours has the antenna control to lower it when
opening that was done at the factory. All V12’s had
spoilers, it was possibly an option on the straight 6
cars.
The problem is the controller in the antenna likes to burn
out and you can not get parts. Also it is up anytime the
radio is on even for CD’s when you do not need an antenna.

Dan
94 coupe 6.0L–
The original message included these comments:

Can anyone tell me if this was a special edition XJS or just a dealer (or factory) added option?


DanS
columbus ga. usa, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

// please trim quoted text to context only

In reply to a message from lockheed sent Sun 3 Jul 2016:

Yes, pretty much cosmetics/styling for most, but I believe I read
somewhere that it is functionally there to keep proper down force at
the rather high speeds where the 6.0L V12 engine could potentially
take this car. If the air path under this wing is longer than above it,
then there will be a down force applied to the wing (and therefore to
the car) for certain and increasing as speeds increase. The wing
total surface isn’t that big, but it may not need to be that big in order
to keep the already heavy >4,000 lbs car glued to the pavement.
at higher speeds. Uh, but it makes such an impact to the car
looks…

Cheers,–
'94 XJS 4.0L - '02 XJR
Redondo Beach, California, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

// please trim quoted text to context only

In reply to a message from DanS sent Sun 3 Jul 2016:

That’s one fo the perks of some after market radios. The
Kenwood on my XJS will not raise the antenna in any of the
available modes, except for radio mode.

In regards to that controller, it shouldn’t be that much of a
problem to put together. First, most radios put 12 volts to the
antenna when turned on. Second, the trunk lock is electrically
operated (in addition to the key), Third, all trunks have a light
come on when the lid is open. That’s all you need to, then, to sit
down and figure out a simple diagram to do what that little
$12,000 module does and with probably longer lasting
components (a relay or two may be all one needs for this).

Cheers,–
'94 XJS 4.0L - '02 XJR
Redondo Beach, California, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

// please trim quoted text to context only

In reply to Lockheed Monday, 4 July 2016 6:48 AM

Subject: Re: [xj-s] Wing/Spoiler on trunk lid…optional?

Simply a cosmetic styling flare. Has no actual claimed or demonstrated
functional value of any nature. I think it was OEM on the V12 6.0 cars
only.

In 1982 Tom Walkinshaw Racing (TWR), Brit, became associated with Jag in
1982. They won many prestigious races around the globe and went on to
produce a fiberglass kit to enhance the appearance of street XJS’s.
This kit included, among front and rear bumper additions, a rear spoiler
that was “claimed” to assist with the down force of the rear at speed. He
successfully raced XJS’s with a spoiler similar to the kit so I suppose
there is some truth to the claim at speed.
I considered one of these TWR modified cars when I was buying my 1982 coupe
but modifying the distinctive lines of the XJS to this extent it left me
with the feeling of a Celica on steroids and not an XJS at all. It’s all a
matter of what rings your bell I suppose.


http://13252-presscdn-0-94.pagely.netdna-cdn.com/wp-content/uploads/2010/05/
1988_Jaguar_XJS_Tom_Walkinshaw_Racing_TWR_Edition_For_Sale_1.jpg

Regards Pknellie
1982 XJ6 Daimler Vanden Plas
1982 very very red XJS V12 coupe (Roxanne)
Mangoplah via Wagga Wagga Australia

// please trim quoted text to context only

In reply to a message from Reinaldo sent Sun 3 Jul 2016:

‘‘I believe I read somewhere that it is functionally there to keep
proper down force at the rather high speeds where the 6.0L V12
engine could potentially take this car.’’

And what wind tunnel data supports that theory, and how much down
force at what speed. Porsche does spend time in the wind tunnel
before sticking a spoiler on - Jaguar did not for the XJS. I
believe Dr. Chad Bolles took the spoiler off his 6.0 XJS race car
because of the drag it created without any measurable benefit.–
lockheed 92 XJS Cpe, OB rear brakes, 97 LT1/4L60E
Austin, TX, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

// please trim quoted text to context only

In reply to a message from Trevor Beckwith sent Sun 3 Jul 2016:

‘‘This kit included, among front and rear bumper additions, a rear
spoiler that was ‘‘claimed’’ to assist with the down force of the
rear at speed.’’

Trevor,
True, and I would be willing to bet that TWR did indeed do wind
tunnel and track testing of the rear spoiler on their race cars.
Conversely, Jaguar did not similarly test a garden variety
production 6.0 V12 XJS that will never approach the speeds the TWR
racing cars did., nor do we know that the aftermarket TWR kit
spoiler was designed to the same specs.–
lockheed 92 XJS Cpe, OB rear brakes, 97 LT1/4L60E
Austin, TX, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

// please trim quoted text to context only

In reply to Lockheed Sent: Tuesday, 5 July 2016 8:05 AM

True, and I would be willing to bet that TWR did indeed do wind tunnel and
track testing of the rear spoiler on their race cars.
Conversely, Jaguar did not similarly test a garden variety production 6.0
V12
XJS that will never approach the speeds the TWR racing cars did., nor do
we
know that the aftermarket TWR kit spoiler was designed to the same specs.

Lockheed.
With the risk of a seeming a bit “tit-for-tat”… the TWR kit (retail kit)
was wind tunnel tested, albeit with the entire kit and not just the rear
spoiler alone. I quote from Motor Sport 1984, (from the web page below):-
“Unlike many of the body kits available today, which go beyond the bounds of
good taste, the TWR kit designed by Peter Stevens undoubtedly enhances the
TWR’s graceful styling, updating it might be a better description, involving
a reinforced moulded front air dam and spoiler, a matching rear panel, side
skirts, and a discreet rear wing which is large enough to do a man’s job
without making the Jaguar look too racy. Wind tunnel tests have shown these
body parts to reduce front-end lift by 60% at high speed and rear lift by no
less than 88%, whilst the drag figure is lowered by 12.7%.”


xjs-walkinshaws-coventry-express

Regards Pknellie
1982 XJ6 Daimler Vanden Plas
1982 very very red XJS V12 coupe (Roxanne)
Mangoplah via Wagga Wagga Australia

// please trim quoted text to context onlySubject: RE: [xj-s] Wing/Spoiler on trunk lid…optional?

In reply to a message from Trevor Beckwith sent Mon 4 Jul 2016:

Trevor,

OK, so the TWR kit was tested, but:

Define ‘‘high speed’’ - how fast is that, faster or slower than a
garden variety 6.0 production XJS? And, how often, and where
do you drive at that undefined ‘‘high speed’’ to justify the cost
of the TRW Kit?
So how much is 88% of how many pounds of rear lift at what
speed - if there were only 40 lbs of rear lift at ‘‘high
speed’’, then the kit would reduce that to 4.8 lbs. Well,
really, just how much of rear lift are we talking about, and
exactly at what speed? I could go on.
So, all this sounds like car salesman talk to me without any
specific data points or demonstrated improvements in car
handling. My point is - and base topic - the Jaguar OEM rear
spoiler/wing on the production 6.0 XJS is merely a cosmetic
add-on with no supporting performance data or claimed
performance benefits.–
lockheed 92 XJS Cpe, OB rear brakes, 97 LT1/4L60E
Austin, TX, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

// please trim quoted text to context only

In reply to a message from Jim Kocmoud sent Sun 3 Jul 2016:

Let’s try to return this thread to the original question.
Yes, the spoiler is standard on the V12 starting with the
introduction of the 6L. And optional on the I6.

Please refer to the Jaguar Technical Guide for MY 1994.
A copy of the .PDF can be downloaded here:

http://tinyurl.com/hn2ndv6

Page 3 of the brochure (page 7 of the file)

Best regards,
Steve–
The original message included these comments:

My 94 2+2 has a wing/spoiler mounted on the deck lid.
Adds an element of distinction to the car, compared to ones without it.
If you’re playing the radio, when you open the trunk the antenna automatically retracts so as to not
interfere.
Can anyone tell me if this was a special edition XJS or just a dealer (or factory) added option?
Thanks!


'95 XJS convertible - V12 6.0L
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

// please trim quoted text to context only

In reply to a message from DanS sent Sun 3 Jul 2016:

Dan:
This is all correct. The solution to the control board –
and adding means to have the antenna up/down when you want -

  • is very simple.
    Please refer to picture 3.
    Someone earlier mentioned a price for the power antenna in
    the thousands. The addition of the switch to the circuit
    will not cost more than $10 in parts.

http://www.jag-lovers.org/v.htm?id=1419988589

Best regards,
Steve–
The original message included these comments:

Since yours has the antenna control to lower it when
opening that was done at the factory. All V12’s had
spoilers, it was possibly an option on the straight 6
cars.
The problem is the controller in the antenna likes to burn
out and you can not get parts. Also it is up anytime the
radio is on even for CD’s when you do not need an antenna.


'95 XJS convertible - V12 6.0L
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

// please trim quoted text to context only

In reply to a message from Trevor Beckwith sent Sun 3 Jul 2016:

Not the same spoiler.
The TWR kit might pay homage to the success of the racing
team, but the one that Jim (original poster) asked about is a
Jaguar item available standard on the 6L V12 cars.

Steve–
The original message included these comments:

I considered one of these TWR modified cars when I was buying my 1982 coupe
but modifying the distinctive lines of the XJS to this extent it left me
with the feeling of a Celica on steroids and not an XJS at all. It’s all a
matter of what rings your bell I suppose.
https://en.wikipedia.org/wiki/Tom_Walkinshaw_Racing
http://13252-presscdn-0-94.pagely.netdna-cdn.com/wp-content/uploads/2010/05/
1988_Jaguar_XJS_Tom_Walkinshaw_Racing_TWR_Edition_For_Sale_1.jpg


'95 XJS convertible - V12 6.0L
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

// please trim quoted text to context only

Not the same spoiler.
The TWR kit might pay homage to the success of the racing
team, but the one that Jim (original poster) asked about is a
Jaguar item available standard on the 6L V12 cars.

Different? Gotta admit, I’m only familiar with one style of spoiler for the XJ-S. Did the 6.0 spoiler LOOK just like the TWR spoiler, or are there visual distinctions? Presumably different part numbers? Do they both involve that automatic retraction of the antenna when the trunk is opened?

– Kirbert

// please trim quoted text to context onlyOn July 5, 2016 at 12:55 PM sbobev shelxtl@yahoo.com wrote:

In reply to a message from palmk@nettally.com sent Tue 5 Jul 2016:

Looking at the pictures provided earlier (http://13252-
presscdn-0-94.pagely.netdna-cdn.com/wp-
content/uploads/2010/05/
1988_Jaguar_XJS_Tom_Walkinshaw_Racing_TWR_Edition_For_Sale_1
.jpg) and mine (http://www.jag-lovers.org/v.htm?
id=1428199053), it is apparent that they are very different.

I am not sure about the antenna, although there has to be a
provision for opening the trunk lid.
I have not seen a TWR model up close, but IIRC, there is a
hole in the TWR spoiler for the antenna.

Steve–
The original message included these comments:

Different? Gotta admit, I’m only familiar with one style of spoiler for the XJ-S. Did the 6.0 spoiler LOOK just like the TWR spoiler, or are there visual distinctions? Presumably different part numbers? Do they both involve that automatic retraction of the antenna when the trunk is opened?


'95 XJS convertible - V12 6.0L
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

// please trim quoted text to context only

In reply to a message from sbobev sent Tue 5 Jul 2016:

There is definitely a hole in the TWR (pre-facelift)
spoiler that the aerial/antenna passes through.

A 1992 UK registered (93 USA MY) facelift XJR-S that I
owned was factory fitted with the later spoiler (very
different in shape) & IIRC when the boot/trunk was opened
with the radio on (i.e. aerial/antenna raised) then the
aerial/antenna would retract within 3 or 4 seconds so if
you quickly opened the boot & didn’t wait for the aerial
to retract then the aerial could easily be damaged by the
spoiler.

My current 93 6.0 convertible is not factory fitted with
the spoiler & whilst I liked the spoiler on the XJR-S, I
would not fit one to my current car - purely as a matter
of personal taste.

Regards

Andy.–
The original message included these comments:

I am not sure about the antenna, although there has to be a
provision for opening the trunk lid.
I have not seen a TWR model up close, but IIRC, there is a
hole in the TWR spoiler for the antenna.


1st reg. 01/08/1993 6.0ltr 2+2 convertible SAJJNAFS3ER188666
Lancashire, United Kingdom
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
–Support Jag-lovers - Donate at http://www.jag-lovers.org/donate04.php

// please trim quoted text to context only

Well, yes, this does come some three years after it was discussed. I just came across this and re-read its interesting subject. Just two things to close this:
First, as I mentioned somewhere above, this spoiler’s design does what an aircraft wing does, which is to create a pressure differential, only that the car needs the pressure differential in the opposite direction as compared to the aircraft wing. If you carefully inspect the XJS spoiler you will see that the bottom surface is rather curved from the front edge to the rear edge. Then, the top surface is rather flat with no curving. This means that, when the front edge of the spoiler splits the incoming ram air, the air flowing under it has a longer path over the curved surface than the air flowing above it, therefore it has to increase its speed in order to arrive on time to meet the over-the-spoiler air flow at the rear edge of the spoiler without creating a vacuum. The faster flowing air under the spoiler decreases the atmospheric pressure under it (Venturi effect), thus creating a pressure differential vs. the pressure above it. This is real. There is no doubt that the XJS rear spoiler meets above criteria having a longer air path under it than above it with the obvious consequence being that the air pressure above the spoiler will always be greater than the pressure under it, thus creating a differential pressure that causes “down force” and which will increase with the car’s speed. How much pressure differential does the spoiler create at, say, 150 mph? I do not know exactly, but I do know that it has to be greater than the down force on an XJS that has no rear spoiler.

Second, I do realize that cosmetics is a matter of personal taste, but, please, my BRG '94 convertible with that beautiful spoiler has no match, really, except for other XJS cars with that magic spoiler.

I have one on my XJR-S, but I don’t think the rear wing adds much downforce. There is perhaps a small degree of Bernoulli effect that would provide downforce, but the wing is pretty close to the deck of the bootlid which would not be conducive to laminar flow under the wing. Too much turbulence here would negate the lift effect of a traditional wing surface. When you see wings that generate serious downforce you will note that they are steeply angled. In this case it is the deflection of the airflow that creates the downforce, but it also creates a lot of drag, and the detachment of the airflow at the trailing wing edge has to be controlled to minimise further drag. It is useful in a race car where you can choose the tradeoff between slow speed downforce, and low drag at high speed, depending on the circuit. On a road car you won’t be worrying about ultimate slow speed downforce, but a little extra downforce at speed adds stability by minimising lift (Audi had to add a bootlid spoiler to the early TT to stop it flying off the road). So a flattish aerofoil section is a good compromise. Plus, it looks bitchin’.

Maybe the angle of attack of the airfoil is held at the optimum angle to minimize turbulence and provide lift (downward force here because of the airfoil shape orientation) at higher speeds where loss of traction likely to occur?