Hi Chaps,

I'm taking the plunge and planning to replace the air struts in my 2003 x350 XJR with BC Racing coilovers. The feedback on here seems positive, as does feedback on them from other makes (including the e39 M5 Community). I'm looking for a sportier ride (If JLR had made an XJR-R I'd have bought that one!) and, yes, I'm also to avoid the expense & pain of playing find the air suspension fault!

Any thoughts/comments/feedback on BC racing coilovers would be really welcome, but specifically, I'd really like to know:

As mine is a very early car (2003), forum research says I can avoid throwing a suspension code by just unplugging the control module under the back seat, can I just remove the modules fuse instead?

Suggestions for baseline settings?

I'd like to lower the car a bit (handling and looks) does anyone have a view on (with 19" wheels) what a usable drop would be (I'm guessing an inch is fairly safe as the air suspension drops that much at speed anyway? I'm in the UK so we do have fairly bumpy country roads!

I'm assuming that the springs will settle a bit in the first few hundred miles, any guesses by how much (eg should I set ride height as stock, expecting it drop an inch when it settles?)

If I only drop the ride height an inch, will I need to get the cars tracking/toe in etc reset?

Many thanks.

 

Greetings,

I had the BC Racing coilovers on my 05 XJR I just recently sold and I highly recommend them. Aside from the height being adjustable, the dampening can be adjusted easily as well. I had mine set in the middle, it wasn't as much of a cloud-like feeling like on the air suspension, but not so stiff it would cause your teeth to fall out. They don't settle too much; maybe a 1/4-1/2 inch if that. You should be safe to lower it as you please. I had mine pretty low with staggered 20" wheels and it was fine.

The quality is outstanding. In the 6 years I had them, I never had an issue with them and they never made any weird squeaks or other noises. I believe 05 and older X350s had the capability to just unplug the module behind the rear seat and the "air suspension fault" message would disappear. 06 and up needed something to plug into the harness, so you should be fine on yours just by removing or unplugging the module.

Being that you can set the height to stock or lower and have it as stiff or soft as you'd like, I'd say you cant go wrong with this set for the money. I loved the original air ride, but did not want to pay high dollar to fix it and end up having to do it again a few years later. Just make sure you get a proper laser alignment any time you adjust the height or change the geometry of the suspension in general. If you don't, your tires could wear unevenly fairly quick.

 

You sold! What now? I just hijacked the thread

 

This is the answer I was really hoping to get!!!

I really appreciate the reply & the info - just what I was after

 

Just to close off the thread - I fitted BC racing coilovers and am deliriously happy with them.

A definite performance upgrade, at soft setting it feels the virtually identical to stock (allbeit that it doesn't change damping) ... but at mid setting feels like an XJR-R. Its removed body roll, removed the feeling of needing an LSD, given me control back over low speed speed humps etc.

I'm not now spending hours of garage time playing find the fault... and its all at the cost of a single OEM strut.

Bargain. Cant recommend the swap highly enough.

 

I saw the YouTube that showed their product being installed.

My question to you is, did you get or need a module so the air suspension and car too low faults don't show up in the center message at the speedometer?

Arnott is the only one I have found that gives a module to turn those alerts off.

 

For x356 and x358 cars I believe a plug in module is needed... its a ten minute job to fit behind the rear seats. Or use airbag resistors in the sensor ends to fool it into seeing the correct voltage reading. I think you'll then need to use an OBD tool to trick it into thinking its at the right height front and rear and then its sorted forever. (You'll have to google this...I cant remember the info I'm afraid).

For x350 cars you can just disconnect the battery and remove the relevant fuses... the car then doesn't realise that anything is missing. You'll have to go digging on here for which fuses it is though... dead simple to do though.

 

I think the boundary for that is 2004 and '05. 2006 and up will throw the code, even with the air suspension module unpowered, as CATS goes through other stuff in the newer cars.

I think.

 

I believe you are correct wfooshee.
X356 models saw the introduction of the later series electronics package that continued into X358 production.

I think you can just get away with inserting a 1K ohm (1000 ohm) resistor in place of each missing shock absorber pressure sensor and the suspension control module should be satisfied. Resistor mod might be less prone to disturbance if done at the module behind the rear set rather than at the shock end of the wiring.
Worst case scenario you might also need to trick the ride level sensor lines with some fixed resistor values so it doesn't think there is any ride height alteration required if your replacement shocks result in a different ride height outcome from originals.

 

The air suspension module itself is actually disconnected from power, so level sensors are irrelevant. The air suspension module (2006+) does monitor the CATS system, and if it doesn't answer (because it's powered off,) you get the dash message. The module from Arnott connects to two or three of the wires on the connector outside the air suspension module. No idea what's in the Arnott piece, if it's just resistors or something a bit more.

 

hi SWB1
I think its been a couple of years since you fitted the BC coilovers to your XJ. I'm currently debating whether to do the same. Do you still have them on your car and would you still recommend them?
I have an XJ8 sport with 20 inch wheels so im guessing the ride isnt as soft as other (SE) models, but i wouldnt want it too much firmer.
all the best, Nerf.

 

Note that he said "at ... setting"

So those ones are among the adjustable tribe of coilovers?

Cheaper ones might still offer adjustable spring take-up point if-even that much, others also add ride-height.. with lowering, not raising, their target.. if you live where all roads and carparks are "speed-bump" starved. Few do.

.

 

they are indeed adjustable. for height and dampening. Not overly concerned with ride height to be honest but like the idea i can soften the ride.

 

Adjustable damping is a nice feature. Even the ECATS original Bilsteins while "highly" dynamic, didn't give the driver the ability to select when, how, how much, nor set a different 'average' .. unless maybe by re-programing a module... and risking a weird FUBAR if or when parameters got into a conflict!

 

I had the MaXXPeedingRods coilovers installed on the 2006 XJR. It throws an air suspension fault and CAT fault. Been erasing the with reset button.
Planned on measuring my two Arnott air struts to see what resistance the car was seeing. I did this on a 2008 Suburban LTZ. They only were about 25 ohms.
Think having the air compressor power unplugged is an issue. Will see.
Have the 24 position dampening control in middle and am lower than normal XJR. Definitely tighter than new Arnott air springs. Another world compared to 18 year old Jaguar air struts.
Set front on 12 and rear on 14. Stiffer rear helps tame body roll.

 

Thanks for that.

MaXX Pee ding-rods have more than one coilover.

My set of four (the cheapest ones AFAIK?) are black, yellow, black coils, goldish anodized top disk. They have adjustable length & spring perch take-up point - ergo ride height...

... but I don't think these cheap ones (under $300 the set of four) have adjustable damping?

At the price, I might even be advised to expect "self adjustment" as they wear-out faster than more expensive ones?



As to getting the nagging minder-box to shut up and cease throwing errors:

Confirming earlier work already published on-forum by others, I found the Jaguar's WABCO-packaged Bilstein OEM system is looking into about a 5.7 Ohm DC resistance per front strut, perhaps identical for each and every strut (same solenoid coil used, even if valving differs).

CAVEAT: "small sample size", as I have only measured ONE, right front, so far ....

.. and just an RCH under 11 milliHenry's of inductance, measured on an also-cheap-**** ($32) 'Proster' BM4070 digital LCR tester.

Cheap or not, the meter nailed the factory label inductances of Lenze and Coilcraft inductors I had handy, DC smoothing to high RF, so that seems a reasonable value.

Up to me **** in Alligators this week, but I'll be looking to see if the "quick and dirty" "cheat" can work with a HIGHER DC resistance than 5.7 Ohms, such that there is less current draw on the upstream brain box @ its 400 Hz signal.

Inductive reactance as it is on de-facto AC signals ("pushback" so to speak) , 20 or more Ohms, per your GMC experience, just might do that as a decent substitute per-each Bilstein removed.

Higher resistance = lower current, less heat, lower wattage, lower cost, and easier to mount smaller physical size needed.

I have 100 Watt (and larger) wirewound rheostats lying about, so "dialing-in" a workable value just needs time & patience, not money.

FWIW-not-much the solenoid that modulates the OEM dampers is a closer cousin to a "voice coil", as it is optimized for very fast movement, low inertia or latency, and constant duty working without need of cool-down rest periods.

I have no inside knowledge as to whom it is that Bilstein buy theirs from, but with a strong presence in Germany of long years, Japan's EKK Eagle is a possible candidate:

https://www.ekkeagle.com/en/product/...solenoid-valve

Similar goods are also produced in the Nederlands.

Matching the inductance and DC resistance is not on for commonly stocked goods. Typical under five bucks each 10 mlliHenry goods have less a tiny fraction of an Ohm DC resistance. Same inductance, higher DC resistance is an unusual winding for anything much smaller than your fist.

Closest one I have is an "orphaned" 1989 Lenze variable choke for DC power conditioning that is several times the size and mass of the OEM solenoid on the Bilstein. Also long years out of production, as the 'ultralinear" analog-mode DC power supply class it served is itself long-obsolete in favour of lighter and more efficient "switched mode" PSU's.

Read: Can't find this s**t cheaply these days, even if one didn't mind the size and ma$$.

Meamwhile, on snow and ice, clever Swedes, and not-only, have been "cheating" their similar-not-identical Scandihooligan dynamic suspensions for Donkey's Years by cutting out the coils and keeping them on-vehicle and in-circuit whilst using something else altogether for suspension.

Can't recommend that on our Bilsteins. Our ones are harder to get to, and under captive Nitrogen gas pressure, shock hyraulic chamber side.

BFBI resistors should do the do.

No need of one of Mynheer Bernard Tellegen's elegant "Gyrator" circuits - which may or may not be what is inside some other-people's cheater modules, op-amps having gone cheaper than they were on his watch... . several years before even the transistor had yet been invented!

https://en.wikipedia.org/wiki/Gyrator

N'er mind the math in that, down & dirty is that a tiny OP Amp, a resistor, a capacitor and a modest source of power can dynamically simulate a really massive but "passive" inductor.

NASA, for "civilian space shots", & harder-edged "warshot" missile-makers needed to save space and weight for other payload, so these became dirt-common items a very long time ago.

More on the "cheating game" - which applies just as much to "dumb" AKA unmodulated, third-party air struts (Suncore et al) as it does to coilovers - when we know more?

Or have gotten off our search-engine ***** and found that forum members who have already published on this, years ago, are larfing at we who re-invent the wheel ... as Bill Godbout once told me whilst altering an S100 board he made "all alone, and in the dark".

Alone, we are not.

Lazy, maybe?

Besides.. re-inventing wheels ... and other gnarly s**t ...can be a bit of FUN!

Seen what's on "Tee Vee" lately? Exit, stage left..... barfing ...

 

I purchased the Blue ones, CS said they are the Sport. Paid 450.00 USD delivered.
The active shocks in the Suburban had a dc resistance of around 12 ohms. But still threw codes. Doubling that value tricked system. Used high inductance wire wound resistors to add a little H to the mix. I am making probes to get down on the pins on top of the struts. Have Arnott with a filter for loading CATs and real Jaguar struts to see what the CAT’s really see.

 

"damned little" L !!! Cylindrical wirewounds are often counterwound to minimize L, have damned little to begin with at the Frequencies involved, here.

400 MHz not 400 Hz? Diff'rent bowl of electron stew.

Put one on an LCR meter and see.

Doubling the DC resistance sounds about right.

Might add a 400 Hz square-wave source if you are 'into it'? Trivial exercise.

I didn't see the point of any "micro-fab" for probes, as I've given up on Bilsteins.

Just left an inch of conductor, cut and spliced an OEM 'probe' to test leads to the LCR meter, pushed it back into the top of the Bilstein, captured the reading.

"Fakeout" resistors won't need nor use that connector anyway, so you salvage four ready-mades right off the first car converted for no more work than making a decent splice. "pin jacks" are good. Most meter probe tips will mate to those. They are meant to do.

 

Ok, let me pick your brain. I am thinking about buying either the BC racing adjustable coil overs or the Arnott conversion coil overs for my 05 Vanden Plas. I want a soft ride period. I want to glide over bumps. That is why I am looking at the BC Racing adjustable. Which has to softest best ride without bouncing around. I am trying to get ones as close to or better than the air suspension shocks to get the soft ride. Any suggestions on which to buy?

 

They have 24 position dampening adjustment. Started out at 12 on front and 14 for rear. Backed off the front to position 10.
Drives great, running car a little lower than the XJR are normally. Have not seen settling of coilovers.
The factory CAT system is not real active dampening. My A8 has real active system where dampening is adjusted by computer. The CAT system only has firm and off. Off is just the dampers in strut. When driving and cornering the CAT system set rear shocks to firm to reduce body roll and reduce under steer.
That is why I set rear coilovers dampening stiffer than front.