Can someone with a pre ABS V12 XJS (pre '89) tell me where the
source of vaccum for the vacuum booster comes from - the left
intake manifold (where is the port located, size and fitting),
or the crossover pipe (what size and type of fitting)? Need to
know for the Teves IV vacuum booster vacuum supply. Pictures
of the needed Teves IV components are being uploaded for your
perusal and/or interest.–
lockheed 92 XJS Cpe/97 LT1 Miami FL/ 96 XJS Cv 4.0 Austin TX
Austin, TX, United States
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from lockheed sent Sun 2 Feb 2014:
Here is the link to the photos - which are also in my photo
album: http://www.jag-lovers.org/v.htm?1391378150
The list of needed items is as follows:
Pedal box with pedal - you may also need the dual function
switch that you see near the pedal arm in the photo. This
switch is for the brake lights, and the cruise control &
lock up torque converter (for those that have it) disengage.
I don’t know if the switch from the Teves III will fit or is
adaptable. My suggestion is to get the switch that goes with
the Teves IV.
Vacuum Booster that fits to the pedal box.
Tandem master cylinder with reservoir (has fluid level
switch within) that fits to Booster. At this point you will
have all you need for a non-ABS system for those that are so
inclined. Just some minor brake line plumbing to do near the
firewall.
Pump/valve body & ABS controller - note the mounting plate
for the pump/valve body controller unit. You may be able to
fabricate or adapt your own, but I would suggest to get one
if you can find one. You will need to obtain the
plug/pigtail for the controller to connect all your wiring
to the unit.
You will see my spare controller in foreground to illustrate
the six solenoids for the three channel system (front left
and right, and the rear as with the Teves III). The label on
the bottom indicates the compatible controller you will need
(2210-A). Some XJ’s of similar vintage also use this
controller, but others use a 2210-B which is a version which
includes traction control. The XJS’s don’t have the
additional wiring or circuits to be able to use that
controller - get the 2210-A.
The photos on the green carpet are the rough layout of the
wiring harness - note the pile of extra unneeded wire from
the Teves III at the upper left. Because the controller is
now up front with the pump unit, the harness has to be
remade for the Teves IV. The wheel speed sensors are the
same. The sensor coax from the rear (shorter) is now used
for the front and the front sensor coax (longer) is now used
for the rear to get the length needed. At the bottom of the
first photo are the coax cables to the rear, next up (below
the grommet) are the wires to the fuses and instrument
panel,above the grommet immediately to the right are the
wires to the pump/controller unit, and the upper left are
the are the coax cables to the front sensors. All the wires
will be trimmed for length and connected when in position.
The brake fluid reservoir has a level switch that connects
to ground on one side, and the other side goes directly to
the instrument panel brake warning light to warn of low
fluid. That is its only function in the Teves IV, as there
is no pump/accumulator/system pressure to monitor as in the
Teves III. There is a wiring connection from the controller
to the ABS warning light. Whenever the ABS controller senses
a fault, the ABS system is turned off and you have normal
vacuum boosted brakes with no ABS.–
lockheed 92 XJS Cpe/97 LT1 Miami FL/ 96 XJS Cv 4.0 Austin TX
Austin, TX, United States
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// please trim quoted text to context only
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
3
Can someone with a pre ABS V12 XJS (pre '89) tell me where the
source of vaccum for the vacuum booster comes from - the left
intake manifold (where is the port located, size and fitting),
or the crossover pipe (what size and type of fitting)?
I’m pretty sure the vacuum comes from a vacuum reservoir inside a
hidden compartment forward of the RF wheel well. There’s a line from
there back to the firewall and across to the power brake booster.
The vacuum from the top rear of the RH intake manifold, but it’s not
just a fitting; it’s a check valve that screws into the manifold.
It’s supposed to hold vacuum in the reservoir when the throttle is
opened and vacuum is lost in the manifold. This check valve is
somewhat problematic, has been known to stick open or closed.
– Kirbert
// please trim quoted text to context onlyOn 2 Feb 2014 at 13:31, lockheed wrote:
In reply to a message from lockheed sent Mon 3 Feb 2014:
Yup, it’s always something! That excess wire bundle is to the
upper right, not the left!–
lockheed 92 XJS Cpe/97 LT1 Miami FL/ 96 XJS Cv 4.0 Austin TX
Austin, TX, United States
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In reply to a message from Kirbert sent Mon 3 Feb 2014:
The later XJS’s (with ABS) don’t have that large vacuum
reservoir in the area of the front right, but a much smaller
reservoir for the HVAC vacuum system just below where the ABS
pump resides. There are two types of check valves that are
commonly used for the booster vacuum supply - one is an inline
check valve, and the other is a combination fitting for the
vacuum line to the booster which incorporates a check valve. I
plan to use the latter, and just need a good place to connect
the vacuum supply for the booster to either the left intake
manifold, or the crossover pipe at the rear - probably won’t
make a whole lot of difference.–
lockheed 92 XJS Cpe/97 LT1 Miami FL/ 96 XJS Cv 4.0 Austin TX
Austin, TX, United States
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// please trim quoted text to context only
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
6
The later XJS’s (with ABS) don’t have that large vacuum
reservoir in the area of the front right, but a much smaller
reservoir for the HVAC vacuum system just below where the ABS
pump resides.
The earlier cars have that smaller reservoir TOO. It’s for the
climate control system.
There are two types of check valves that are
commonly used for the booster vacuum supply - one is an inline
check valve, and the other is a combination fitting for the
vacuum line to the booster which incorporates a check valve. I
plan to use the latter…
The latter is what’s OEM on the Jaguar V12. I guess it makes sense
that generic versions are available.
and just need a good place to connect
the vacuum supply for the booster to either the left intake
manifold, or the crossover pipe at the rear - probably won’t
make a whole lot of difference.
On my '83, there were no suitable ports on the crossover pipe. It
would be simple to create a port on an end cover on either manifold.
I take it you’re saying the later manifolds don’t have a place to
install that check valve?
I’m also not real sure how important that vacuum reservoir is. I
seem to recall working on cars in the past with vacuum boosted power
brakes with no such reservoir; the vacuum booster was connected
pretty much directly to the intake manifold. I’m guessing the
difference is in how many boosted stops you’d get after the engine is
off. I’m pretty sure that vacuum booster maintains a vacuum at all
times, has its own check valve, and when the brakes are applied the
vacuum is RELEASED on one side of the diaphragm.
I had one fail in my 1985 Honda once. It had a carb. Start the
engine, it runs great; put your foot on the brake pedal and the
engine dies immediately. Fortunately, I figured out what the problem
was quickly and just pinched off the vacuum line and limped home with
non-boosted brakes. With EFI, the engine would race rather than die.
– Kirbert
// please trim quoted text to context onlyOn 4 Feb 2014 at 4:48, lockheed wrote:
In reply to a message from Kirbert sent Tue 4 Feb 2014:
‘‘I’m also not real sure how important that vacuum reservoir
is’’
Most of the cars I’m familiar with (and the AJ16 XJS with
Teves IV), simply use manifold vacuum to supply the vacuum
booster. The check valve captures the highest vacuum it
sees. As one’s foot is normally off the gas pedal when we
apply the brakes (most of us anyway), manifold vacuum is
pretty high and readily resupplies the booster as needed. If
the engine quits, or for some other reason the manifold
vacuum is lost, then the booster will still function for a
period of time if one can simply hold what he has on the
brake pedal, or use minimal amounts of pedal pressure
variance, but cycling the brake pedal will quickly deplete
any reserve the vacuum booster may have. Things may not be
too bad with loss of engine vacuum, if one pumps the brakes
on wet or icy roads (No ABS) to prevent wheel lockup,
because it would not be good to apply to much brake force
with full boost anyway. You have ABS - just stomp on it,
hold it, and steer - the ABS will do the magic for you.
That was the general rule of thumb with aircraft backup
brakes - apply what you need and hold, because repeated
applications will rapidly deplete the backup brake
accumulator. (the Anti-Skid - ABS) was still operational
with some backup brake systems but not with others - at
least back when I was still doing that stuff.–
lockheed 92 XJS Cpe/97 LT1 Miami FL/ 96 XJS Cv 4.0 Austin TX
Austin, TX, United States
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