I am getting to the point where I need to upgrade the rear brakes,
I wondered if anyone has installed the later outboard set up to an
earlier car. I know the twr’s had outboard brakes, so it may be
even easier now since the late models have this added advantage ,Art–
Pacific Jaguar Enthusiasts Group 44, Canada.
Pitt Meadows, BC, Canada
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Jagart wrote:
I am getting to the point where I need to upgrade the rear brakes,
I wondered if anyone has installed the later outboard set up to an
earlier car.
You can put X300 type outboard vented brakes on the XJS/XJ IRS. You’ll
need some XJ40/X300 half shafts, complete with hub carriers, X300
outboard vented brakes, and some spacers approximately the same
thickness as the discs you are removing to make up the length. Getting
the handbrake working is a bit more tricky but doable - but you probably
don’t need to bother if it’s a track only car.
I know the twr’s had outboard brakes
No, TWR cars had inboard vented brakes. You can get a replica of this
system from Derek Watson (Google for it), but it’s a lot more expensive
than what you are likely to pay second hand for all the components I
listed above. The outboard system also has the advantage of it being
much easier to change the discs and pads, which you are likely to care
about on a race car.
Gordan
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In reply to a message from Gordan Bobic sent Fri 15 Dec 2006:
Why not simply find a wrecked XJS that is a post-facelift with the
outboard brakes? This is pretty much a bolt-up, isn’t it?
Mike–
Mike, 1990 5.3 XJS Convertible, ‘Caterwaul’
Lakewood, OH, United States
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mike90 wrote:
Why not simply find a wrecked XJS that is a post-facelift with the
outboard brakes? This is pretty much a bolt-up, isn’t it?
Because the outboard brakes were only fitted in '95 and '96 (the early
facelift cars were still inboard), and it is very difficult to find that
late a car for breaking. And even when you do find it, it costs about
10x what the conversion I described would.
Gordan
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We went with an outboard setup on my '88 XJS. I think the donar car was an XJ-40.
It was well worth the effort and really not all that expensive. Changing the pads at the track is pretty easy now and the diff no longer overheats.
Charles-------------- Original message ----------------------
From: Gordan Bobic gordan@bobich.net
mike90 wrote:
Why not simply find a wrecked XJS that is a post-facelift with the
outboard brakes? This is pretty much a bolt-up, isn’t it?Because the outboard brakes were only fitted in '95 and '96 (the early
facelift cars were still inboard), and it is very difficult to find that
late a car for breaking. And even when you do find it, it costs about
10x what the conversion I described would.Gordan
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Jagart wrote:
I am getting to the point where I need to upgrade the rear brakes,
I wondered if anyone has installed the later outboard set up to an
earlier car.You can put X300 type outboard vented brakes on the XJS/XJ IRS. You’ll
need some XJ40/X300 half shafts, complete with hub carriers, X300
outboard vented brakes, and some spacers approximately the same
thickness as the discs you are removing to make up the length.
or have the disc bit cut off the center bit;)
Getting
the handbrake working is a bit more tricky but doable - but you probably
don’t need to bother if it’s a track only car.
I’ve had a discussion with a chap about the various XJ40/X300 rear
brakes: he claims that using pre-89 (Girling) would produce too
little stopping power and only the later (Teves) should be used? I
have plenty of both so I don’t care either way. IMHO a vented rear
disc would border on overkill, seeing that many people have managed
for years with the original setup? Still, if you have a set lying
about…
I took some pictures at the Stoneleigh event last year of a modified
IRS. Here they are: http://www.jag-lovers.org/v.htm?1166264813--
Arnoud
iMac, therefore I am
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Arnoud wrote:
Getting
the handbrake working is a bit more tricky but doable - but you probably
don’t need to bother if it’s a track only car.I’ve had a discussion with a chap about the various XJ40/X300 rear
brakes: he claims that using pre-89 (Girling) would produce too little
stopping power and only the later (Teves) should be used?
It’s worse than that. The early XJ40 rear brakes (11in solid discs) have
no problem with stopping power, but with longevity under race conditions
when on the back of an XJS. I found that the life expectancy of the pads
was 8 laps / 12 minutes - from brand new. To make things worse, when the
brakes gave up, they gave up without any warning. Finding that your
brakes aren’t working (fluid boiled, pedal hits the bulkhead) when
you’re trying to stop for the chicane from 160mph is not what you want.
It leads to pain and embarrasment.
Later XJ40 type brakes (11.5in solid discs), however, seem to be fine.
But for preference, go for the 12in X300 vented discs. You can never
have too much brakes.
Gordan
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Hi Gordan et all,
It’s worse than that. The early XJ40 rear brakes (11in solid discs) have
no problem with stopping power, but with longevity under race conditions
when on the back of an XJS.
I can see that, but can you venture a guess about simple everyday traffic?
(snip)
Later XJ40 type brakes (11.5in solid discs), however, seem to be fine.
But for preference, go for the 12in X300 vented discs. You can never
have too much brakes.
One detail I wondered about: the fulcrum bearings are a different
size on the '40. Which ones did you use and did you modify anything
there?
cheers,–
Arnoud
iMac, therefore I am
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Arnoud wrote:
Later XJ40 type brakes (11.5in solid discs), however, seem to be fine.
But for preference, go for the 12in X300 vented discs. You can never
have too much brakes.One detail I wondered about: the fulcrum bearings are a different size
on the '40. Which ones did you use and did you modify anything there?
If you’re talking about the bearings where the hub carrier attaches to
the whishbone, I’ve used the bearings that come with the hub carrier
(i.e. XJ40) and the pin that was already on the car (i.e. XJS). All fits
together just fine.
Gordan
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In reply to a message from Gordan Bobic sent Mon 18 Dec 2006:
A very interesting thread.
What about brake bias control? Race cars would have this, but what
about us street-car guys? Would this mod result in a lot of spins?
I recall from other list discussion ( e-type rear caliper upgrade,
or using S3 XJ6 calipers on S1 ) that this is a concideration.
I hope to try this mod someday. I just love how interchangeable Jag
parts are, and you are able to upgrade something by 30 years!–
The original message included these comments:
Later XJ40 type brakes (11.5in solid discs), however, seem to be fine.
But for preference, go for the 12in X300 vented discs. You can never
have too much brakes.
–
Robert, S1 XJ6, '88 XJ40, '94 XJ40
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FWIW, I’ve never used bias control on my race cars and never really had
a problem. If I brake too hard, the front always seems to lock up first.
Yet most people with bias valves seem to wind them all the way forward,
which I personally think is counter-productive. Maybe this is because
they are running huge after-market brakes - I don’t know.
Gordan
Robert Laughton wrote:
A very interesting thread.
What about brake bias control? Race cars would have this, but what
about us street-car guys? Would this mod result in a lot of spins?
I recall from other list discussion ( e-type rear caliper upgrade,
or using S3 XJ6 calipers on S1 ) that this is a concideration.I hope to try this mod someday. I just love how interchangeable Jag
parts are, and you are able to upgrade something by 30 years!The original message included these comments:
Later XJ40 type brakes (11.5in solid discs), however, seem to be fine.
But for preference, go for the 12in X300 vented discs. You can never
have too much brakes.
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In reply to a message from Gordan Bobic sent Fri 5 Jan 2007:
For several years I used the stock brake set up for autocross, they
worked pretty good. I then cross drilled the front discs, this mod
really worked for me. The standard stop box and track proved that
for sure, I had to retrain my brain to brake later than before, as
I stopped too soon in the box, I could however lock up the fronts
if not carefull, the backs were not cutting it. I then installed a
brake proportioning valve in the more powerfull front brake line
and reduced the front line pressure, this gave more rear brake and
after a lonf Summer of slaloms I dialled the valve in to give rapid
stops to include the rear brakes and with no front lock up, the
pedal was also harder to push. This system worked untill I hit the
road race circuit… I am now still experimenting, I have
installed 13 inch Vette rotors and JFZ alluminium race callipers
with hand forged mount brackets. I am very pleased with that part
of the system now, we are getting closer but the rears can use
improvement and I do not wish to burn the seals outa the rear
end … If you have too much rear bias you could easy spin on a
damp track, even worse on a wet track, be carefull out there…Art–
The original message included these comments:
What about brake bias control? Race cars would have this, but what
about us street-car guys? Would this mod result in a lot of spins?
–
Pacific Jaguar Enthusiasts Group 44, Canada.
Pitt Meadows, BC, Canada
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