Powerhouse UK markets an increased diameter rear sway (anti roll) bar for the X308. They describe their bar as being 35% stiffer than the stock X308 XJR/Sport rear bar.

I'm curious if anyone has any experience with the Powerhouse UK bar and can provide a review of the quality and how it changed the handling of the car.

From the basics of how a sway bar works, if one increases the diameter of the rear then the car oversteers more. However, if the car was already biased to understeer too much, this increased rear bar may help balance the handling of the car. But if not well matched, this could increase the chance of the rear sliding out too easily.

I'd like to know if in theory, or by experience, the Powerhouse bar would be beneficial to balance/improve the handling, or instead unbalance the X308?


The Powerhouse bar was briefly mentioned in the thread below:

https://www.jaguarforums.com/forum/x...ntures-164794/


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I experimented with this a bit last summer. At the moment i'm running a rear sway bar with a torsional rigidity increase of just under 200% with prothane urethane bushings on the OEM steel links. A good increase in tail wagging abilities, but I more so try to avoid bigger bumps or pot holes because it doesn't help with that, I noticed this with more time driving. In the aftermarket "tuner" world a 200% increase in rigidity of a sway bar isn't really too aggressive, but in the X308 world I suppose its significant. IMO 35% would prob be well suited for a daily driver that likes to have a little bit more fun, shouldn't add any harshness to the ride quality. Here's a little about what I had to say.

https://www.jaguarforums.com/forum/x...ntures-164794/

 

I am adding Mina Gallery springs to my car, and have ordered the Powerhouse rear sway bar as well. I hope to have everything installed soon. I will report on results when I get the work completed.

 

Can't offer any advice here, only know a little bit when it comes to fast forward ;-).

Maybe worth to know is, that the XKR (steel body) had a Sport Suspension upgrade (only for cpe), and that included (amongst others) a slightly thicker front sway bar, and a thinner rear sway bar. The thinner sway bar could have been chosen to allow better contact with the road for the inner tire, as with an open diff it would otherwise spin to easily.

 

Thanks Dan, I'll be very interested to hear how the quality of the Powerhouse bar looks, how the install goes and of course how it affects handling.

If you have a chance to install the sway bar first and alone before the springs, that would provide the best opportunity to gauge its impact.

And although it may not be clear, I'm considering installing this on my X300 XJR. The rear sway bar part number for the later VIN X300 XJR and X308 are the same.

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New owner here. Hello!

I'm also looking for larger anti-roll bars. The roll control is pretty soft compared to what I prefer. I think 35% stiffer would get the car closer to a Sport Package equipped BMW. Has anyone found a larger front bar also? It is likely ~40-50% stiffer on both front and rear would still be absorbed fine by the chassis. I haven't checked rear suspension travel but I assume there is enough that lifting a wheel won't be an issue. Are there any carry over parts that can be interchanged across years?

 

I can't see having a problem with rear wheel lift issue in a long heavy sedan such as an XJ. I'm at 200% increase and none of the sort.

If your looking to increase rigidity up front, first I recommend you remove or take a closer look at your present front bar and see what your dealing with. The front XJR bars are already over 30mm OD and have to weigh in at 15-25lbs! They are very large and ridid! I experimented with making a larger or reinforcing the front, but after digging into it I found the effort pointless. I upgraded to practically solid urethane bushings and it made quite a difference for me and matched my setup. If you find a front bar on the aftermarket it will not be cheap, I can guarantee that. Another easy option to stiffen up front a bit is upgraded upper shock bushings, don't forget those

 

You do have a LSD, that's a significant difference. There isn't that much difference in weight, ie my car is already 1820 kg. Nevertheless, I take it that jaguar knew what they where doing when it comes to handling when they created the sports pack. The XKR and XJR are obviously different cars to which I agree , and all depends on what you ask from it, ie like does it need to be fast? Or do you just want less body roll? Great that you went this far and share your experiences though!

 

Good point.

Depending on a million variables, stiffer and flatter doesn't always = faster.

Most people prefer flatter even if it means some sacrifices elsewhere. Everything is a compromise.

Cheers
DD

 

I think a reduction in body roll will not hurt the car's handling or ride. I am willing to bet it will help. I'm not looking for a race car but I would prefer more body control. I really need to ride in a stock car without worn dampers but that was my initial assessment based on the stock anti-roll bars.

 

Considering the age of our cars, if an owner wants to improve the ride and handling characteristics the first place to start is with are all of the ball joints and bushings that have worn out over the years, then start looking into changing actual hardware. I have replaced the front sway bar bushings and links, front shocks (stock XJR B4 Bilsteins) and associated bushings, tie rod ends, control arm ball joints, engine mounts, and vee mounts. (The control arm bushings remain to be replaced.)

I always hated how loose/sloppy the front end of my car felt, but after these changes it is so much tighter and more solid, transforming the car into a real joy to drive. The unique Jaguar feel presents itself really well, and I now have a stable platform upon which to tweak the handling to my liking.

On that subject, I prefer a slightly firmer ride with less rebound from hills/valleys in the road, and a flatter roll around corners. My plan is to replace the rear shocks with stock XJR B4 Bilsteins, Powerhouse rear sway bar, and Mina lowering springs.

 

I agree Dan, first thing to do before anyone upgrades their X308 suspension/steering is to do a full suspension/steering overhaul or at least target the normal suspects. These cars feel extra wonky with worn parts, front or rear. Then the upgrades and the R&D can happen. Make/buy a part....test...nope....make again.....test....nope....make again....test....yup thats it!

 

Edit (delete) double posted somehow sorry

 

On point exactly, all depends on what your going for. I went for stiffer/flatter/faster when all out flogging the car (not just going straight) and it worked. Lucky for me the car is still comfortable and a joy to drive....but of course!
I raced my XJR on a 1.3mi road course yesterday, could have drove the Porsche, should have drove the MG, but watching peoples jaws drop when they see the now surprising handling and the unforeseen times the Jag puts down makes the trip in the old girl worth it Preparing an X100 XKR for a similar race event over the next couple weeks

 

Agree, but the car doesn't feel like it's wondering from worn joints or bushings. It just feels soft, both for roll control and damping. I'll get under the car another weekend after a steam cleaning and do a survey.

Are there any well known, high execution Jag tuners? The best I have found is Arden. There is close to 0 aftermarket support for these cars it seems.

 

I had already renewed my shocks, and I keep all of my bushings fresh, so only thing still stock where my springs to which I compare now.

I went for stiffer springs and stiffer CATs shocks, which made a very good improvement in handing. Although I normally don’t push it on normal twisty roads, there are a couple of relatively sharp highway ramps I usually took at let’s just say highway speeds.

There the body roll and bouncing (caused by unevenness of the road), was pretty scary at the speeds I wanted causing me to temper it. Changing to stiffer springs and the stiffer cats shocks has made a big impact allowing me much higher speeds. For my type of driving its fine now as it is, so still comfortable enough with retaining the CATS shocks, yet way better handling.

 

I installed the Powerhouse sway bar (without changing springs). I have not noticed a negative impact on the ride, but the car does feel flatter. I look forward to getting the Mina springs and rear Bilsteins installed next week, then seeing how the whole package feels.

 

After another day with the new bar, I am noticing that the back end does not hike up when going around a corner (regardless of speed), and the back of the car feels "tighter". All good things in my book!