Unfortunately very few aftermarket parts exist for Jaguars. I have not done the change since most of my driving is straight freeway drive, I can take up with the handling as it is. Also, I am leasing the XJL so I do not want to modify it.

Your best bet is to see what size rear bar the Supercharged model uses and see if that can be fitted to the XJL Portfolio. An other poster who changed his front sway bar, used the XJR's larger front bar. But, he stated that the XJR used the same rear bar and the Supercharged models. Now, I am not sure if those used a thicker bar than the Portfolio.

Also, even if the Supercharged bar is larger than the Portfolio's, find out exactly how much larger. A small increase in size will not make enough difference. As an example; my '05XK used a similar small rear bar. There, I had enough room to work with and installed a second stock rear sway bar in parallel with the original one, doubling the effective rear-bar rate. While it improved the handling very noticeably, the double bar still was not enough to produce the neutral handling that I was after. At the time I had a software calculator for swaybar stiffness and the calculated value for that particular bar was, like 125 lbs/inch. So, 2x that was not enough, the car needed more like 350 lbs/inch.

I would be comfortable to install something in the range of 3/4" - 7/8" for the XJL. I'd do it in a heartbeat on the XF that we have. BTW-I consider the stock XF the best handling Jaguar of the 4 that I have owned lately ('05XK, '08XK. '12XJL, '12XF). The XF has the agility that the much larger XJL just does not.

Please let us know if you find a larger rear bar anywhere.

Albert

 

Just to update since my original post and my findings/opinions after owning the car since Dec 13.

1. I retract my statement about the Bowers Wilkens system sounding like crap. The issue wasn't the sound systems, it was that extra bass/thump I'm used to. Easy fix. Had my Rockford Fosgate 12" enclosed sub and an amp in slim box added to trunk. But guess what? Goddamn Jaguar insulated the trunk so well from road noise getting into the car that I still wasn't getting the full bass. Mind you this same sub has been moved from at least 3 other cars (since I trade them for something else every 2 years or so). OK, so I added a second 12. Hated to lose the trunk space but these are slim boxes and I travel light anyway. If I need to haul stuff I'll take the Q7. Now when I crank the system with my two subs I get CRISP CLEAR bass and CRISP CLEAR sound (I'm not an audiophile, but I guess that would be mids and highs?) I've cranked it up to 42/45 and the system rocks wonderfully without distortion. Mind you I've faded out the factory sub, and turned up my aftermarket subs for the lows. Wonderful system.

2. The airbag light intermittently being on, seemed to go hand in hand with the battery low issue. Because I saw these forums, I knew there were some issues where battery would report low when just listening to the radio without the car being started. But literally mind would say it after 5 mins or so. The dealership found the battery was weak in general and replaced it. That seems to have resolved the intermittent airbag light and being only able to listen to the radio for 5 mins with the car off. Of course they made it a point to mention my amp and two subs. But they replaced the battery anyway. I can assure you this issue was happening before I introduced an aftermarket amp and sub.

3. I called the ride floaty. When I really meant it has more body roll in corners than I would prefer. But this is compared to German cars. This remains true. I just have to remind myself on corners, this is a big sexy XJL beast, it's not meant to hug corners at high speeds, it's meant to be seen in.

4. Power/Speed - JESUS! This big monster can haul for it's size. In fact my CL550 either had a couple more tourque or a couple more horsepower I can't remember. I just remember between the two cars one had one or two more horses while the other had one or two more torque. The problem with Mercedes, they're always HEAVY as hell. It's evident when I realize this Jag could probably beat my Benz (until we have to take a corner). I haven't been let down yet, I frequent dynamic mode on highways. And when I really want to get nasty "S" mode which is ridiculous. I would love to see what a SS version could do.

4. I've identified that I have the roof rattle. But it's not that noticeable. Not enough for me to risk them screwing something else up while repairing it. My Q7 was in the shop and I'm still pissed they dirtied up my roof liner with their hands. It's not that noticeable.

5. I haven't had one peep out of this car with respect to issues. Every time I get into it, I love it. Heads turn no matter where I go. I'm used to that having had a CL550 though. The back of the car is still love it or hate it. I'm in love with the front and how long it is, but the back sometimes from the side view is ugly. Head on standing in the back it looks much better. Either way I have the L makes me always want to ride in the back seat. Only problem is no one is allowed to touch my baby.

6. I love the valet mode. Why didn't anyone think of that sooner. Program a pin to enable, then pin to disable. Simple and easy! I still haven't figured out how to work valet mode in the Audi. Then again I also struggled to cut the air off in the Audi when I first got it. Audi does strange things.

7. For a car so big, more trunk space would have been nice.

8. I can't find a feature this car is missing.

All in all I'm still happy with the purchase.

 

I moved from a Mercedes CLS550 to a XJ-R 5.5, the suspension isn't soft. The car seems to handle breaking and turning much better than the CLS I had.

 

Hi derrickonline, I am the one who replaced my front sway bar on my 2013 SuperSport with the speed package with the 2014 XJR bar. The improvement was subtle as my old bar was 30mm and the XJRs is 31mm, but I now have flatter cornering and better turn in. According to a sheet that I have regarding the 2014 XJR the rear sway bar is also larger by one mm from 17 to 18mm. I do know that the sway bar sizes on the supercharged cars are larger than the non supercharged XJs, but do not know their sizes. Also, alignment in critical on the XJs and any total toe on the front or rear that is in excess of 20 (not sure what that is in measurements) will result in more body roll when turning. I love the car and am closing in on 30k. I have changed the rears 2 twice and the fronts once so far (I have the Dunlap SP Sport Maxx GTs fitted). My XJ came with the Meridian sound system and I think its the best I have ever had in a car and it has no rattles anywhere. The only mechanical problem I have had is one of the exhaust valve cam timing adjusters went bad and resulted in a rougher idle and not quite as much acceleration. Enjoy your ride.

 

Thank you for this post. I just loaded the trunk with beach chairs, umbrellas, and luggage for a stay at the ocean (210 miles away) with the family, so I won't be too critical of the entertainment system if it doesn't sound as excellent as usual.

 

Some of you drive your XJ very differently to us in the UK, having to consider our heavy speed camera population, give me a real traffic cop any day. However, I'll be off through France and Germany to Italy soon so will have the chance to evaluate the car better, so far only 48hrs and 160 miles done!