Jaguar XJS Racing
2014 ended with a to-do list. Some of it was maintenance,
some was improvement. Realistically, the starting point had to be maintenance.
There is no point advancing the pace again if the car cannot cope with the pace
it can already generate. In this regard we’re encountering one of the great
unspoken secrets of racing. It’s not so much that going faster is all that
hard, it’s surviving it, and to squeeze that extra one mph out of the car has
all kinds of hidden costs.
Lessons from last year included the seat being inadequate.
Fine for a 240bhp car on road tyres, no use if you top 300bhp and add grip, it
didn’t support the driver, and I was hanging onto the wheel. Pulling at the
controls exhausts the pilot, and reduces the control available. Fatigue was not
an issue at the time, the penalty was being paid the day after in sore muscle, but
addressing it was clearly necessary.
My belts are also out of date for 2015, and any halfwit has
seen in advance that HANS is on the verge of becoming mandatory. Might as well
get out in front of that now, and buy the full kit together, so that seat,
belts, and HANS all work together. It means a new helmet too. It’s a big bill,
and the trip to Demon Tweeks in person is a ballache, but it means we won’t
have the problem of buying one item and discovering that it doesn’t interact
It also means we got to try on every seat in the shop until
I found one that fitted, and gave the right sort of support in the right
places. Amazingly, so many of them do not. We believe the there will be speed
in the improved interface between driver and car. Arse-feel, if you will.
Installing a new seat is rarely as simple as just bolting it
in. The move from a base-mounted seat with runners to a side-mount that won’t
have any means a lot of messing about re-drilling holes. In the process I shifted
the seat forward a little, to get a bit more muscle to the steering wheel and
edge the clutch pedal that bit closer, but increased the layback on the seat a
little to help with the odd HANS-induced sensation of being pushed off the back
of the seat. It hasn’t improved helmet-to-cage clearance any, sadly. Movement
with the HANS on is not restricted, but does feel more deliberate. It’s the
noise of the tethers slithering through as you move your head, makes you feel
like a kid pretending to be a robot.
HANS requires you to be a little more careful about your
belts too. Looping them round the cage is fine and all, but they do have a
habit of slipping laterally, and they have to stay within certain tolerances.
Setting them to the right angle in the workshop, and then the simple expedient
of adding a couple of strips of self-adhesive foam to the cage stops the belts
sliding. There is no need to get complicated, but there is also no sense paying
for HANS if you’re not going to get the benefit because your belts were in the
Basic maintenance also meant a new extinguisher, my existing
unit well out of date in every possible interpretation of both service date and
bottle life. Whoops. Naturally the new extinguisher did not fit the old
bracket. Well, why would a manufacturer use a standard size when replacing
their own product?
Next up, the less than stellar hot oil pressure. Not
low, but not as high as we’d hope. Bigger oil cooler, or is this more
fundamental, like the oil pump? It hasn’t deteriorated with engine use, it was
like this from the first day of running. Doesn’t mean the pump was great to
begin with. A smart man would pull the engine and swap it. We’re smart. Sort
of. Engine out. The box is coming off anyway, so why not
Engine inverted, pump swapped. Whilst we’re upside down, the
issue of the oil leak from Brands. The cam cover holes are therefore helicoiled
to give us some actual thread, and new top hat seals fitted. You can’t keep
missing half of quali with oil leaks. The engine gains an additional breather
whilst we’re here, for the fun of it.
The head gasket munching issue from Silverstone last year is
addressed in more conservative fashion, by simply “lifing” the gasket, until
the more permanent solution is machined into the second head, but that is a
longer-term fix. For now we simply avoid road use and keep note of the miles
Gearbox swapped. The oil that came out was very dark for its
age, and there was a lot of far too-large debris on the drain plug. Our
conclusion that it was dying appears correct. The replacement is another
standard box, again whilst an improved solution is found, but once more with a
price-tag applied. We appear to be at the tipping point between “could just
cope” and “can’t quite cope” with the equipment we were running. You can’t
blame the gearboxes, each one is 25+ years old, and is now thrashing along at
internal speeds it’s never before had to consider. Full synthetic oil now
replaces the ATF we have used for so long.
Clutch has no issues. The flywheel teeth look a bit worn
already, the answer there lies in a starter that has eaten its bush. Bow chicka
bow wow. Off for repair for that then.
Reassemble, and chuck it all back in the hole. It’s actually
quite therapeutic, so much easier working on your own machinery with all the
tweaks and techniques that evolve from doing this a couple of dozen times.
Annoyingly, we’re running out of ways to make it faster or easier.
The rear hub failure deposited me in the grit at Brands.
Damage was limited to rubber smears in the wheelarch and a hole punched in the
boot floor, but it is to be avoided if possible. The answer is an engineering
solution that is simply too expensive. The other alternative is the improved
XKR hub, but hen’s teeth found in rocking-horse shit are more common than
those. There is a third way, which is to buy brand new hubs.
Like the gearboxes, you have to consider the age of the
parts we’re using. V8 hubs are 12-15 years old, X300 up to 20, XJ40 could be
25. Nothing goes forever. How many failures are actually caused by sheer age
fatigue, rather than a single moment of stress? Well, we will find out, by fitting
brand new hubs, and seeing if they break in the course of a single, full,
They are £115 each, plus the VAT. That’s expensive, but cheaper than the
cost of sitting in the gravel. If you throw one away every year, but you never
break another hub, you still come out ahead. Of course then the forking supplier couldn't actually supply them. Morons. Analysis of failed units suggests
that they don’t just break in one single bite either, the initial fracture
would probably be detectable if you pulled the hubs regularly as part of basic
maintenance. The problem with that is the cost of the once-only hub nuts. It
may be time to drill the driveshafts for castellated nuts and split pins.
Rear subframe dropped and dismantled to check the diff,
reassembled and reinstalled. Just like that. A plan to improve location failed
after a number of hours’ investment, but may later seed results. Design rarely
seems to work first time.
Of course none of this happens in isolation in life. You can
guarantee that as your deadline approaches and you have a nice, quiet, relaxed
schedule planned out to complete it all, that will be when work goes mad and demands
your late night attention. Could that GP practice not have kept the fridge
switched on and therefore not caused 515 kids to be re-vaccinated, please? I
mean, I like having work and all that, but did it have to be this week? Fitting
work and racing into life does tend to mean little time is left over for, you
know, life. And sleep. But grimly hammering away into the small hours has a
certain satisfying masochistic determination about it. Commitment reaps rewards.
Next up, the brakes. I was learning to brake at Brands.
Braking has been my weakest area for years, in fact I can tell you the race
that caused me to turn into a big girl on the middle pedal, but at Brands I was
starting to believe the car might stop. It’s all a learning curve, this
transition into modified territory I think should always be slow, and I don’t
regard this process as even halfway complete yet.
So, there you have it. A couple of weeks of evenings and
weekends, what you would probably call a major service. In total I blew a month's salary on kit
and a car many would say is already fast enough. It might have been, but only briefly.
This ought to make it swifter, and safer, for longer. Consolidate what you have before you
make another jump. Many could learn from this approach.
Many who are prepared to spend this sort of money would have
spent it on camshafts, but in my never-humble estimation, they would have been
wrong to do so. I have seen too many people show up with massive, expensive,
extensive modifications to their car aimed at a quantum leap in performance,
and then fail miserably when not only does that not work, but the rest of the
car breaks in the process.
I think that a slow process of inexorable changes is the way
forward. A small jump in performance, then consolidate it by letting everything
catch up to allow you to survive the new capabilities. Then do it again. When
the car can stand what it is currently being asked to do, then we will think
about more power, but not until.That’s my theory. Does it work? We’ll find out
at Silverstone next week.
In trying to stop later, we found flaws in the brakes. The
EBC pad could not cope with what we were asking, so a move to something much
more expensive, both ends, if we can get it. The hydraulic system itself was
getting too hot. Fixing this means re-routing some brake lines, adding heat
shields, and venting the bonnet. I usually fit louvres, but instead this time
we’re trying simple slots cut into the composite.
Vented rear discs for the first time, and V8 rear calipers,
rather than X300 items. Salvaged and resealed calipers, naturally, no new
stuff. I would go as far as a pedalbox at this stage, but it’s hard to match
the mechanical advantage without a servo, and I’m not convinced by the various
solutions yet proposed. No bias adjustment means the smaller piston rear
calipers from the V8, they’re to hopefully avoid over-braking the rear. The
vented discs should get the heat down. A little extra cooling ducting is also
Lastly, what of that accursed understeer? Well, a couple of
small changes. Nothing major, actually, just a small tweak, see if it helps at
all. If so, that’s the direction to go further with.
You can just whistle, and this jumps straight out now. After a winter of road cars, this was a joy to work on.
There may have been a slight spillage incident caused by a holed drip tray. Oops.
Rear subframe was removed, dismantled, and the diff internals inspected, just to be sure. The diff was fine, but I found other niggles. Which is why we do it.
In the traditional pre-race stance, no wheels and many parts removed. Yes, that is still a steel bootlid.
Kneeling in brambles to salvage V8 calipers is not the most glamorous aspect of motorsport. But it is cheap.
The vented rear discs are something I bought in 2010 and never needed. I can't claim this to be forward planning, I forgot I had them. Bear knew. Bears are handy.
Silverstone ho! What did you call me?
And we're calling that ready. 2 whole days before we have to depart for Silverstone. A new record.