XJ ( X351 ) 2009 - Onwards

Bumpy ride

 
  #1  
Old 03-12-2019, 10:27 PM
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Default Bumpy ride

Hi all,

My ride quality is pretty bumpy at the moment. Trying to figure out the cause. I took it to a tire shop and had two of my rims restraightened and two tires replaced. Still bumpy.

I have some to-do items in my que including supercharger isolator spring service and addressing a brake booster/ vacuum pump issue, but I canít see how that would be related to my ride quality. I think it may have started after I disconnected and reconnected the battery to reset my EPB. But not really sure.

My indie confirmed my air suspension is working fine. Thinking the adaptive suspension module may need resetting (if that is even a thing), but that is a wild guess. Any thoughts? Thanks.

BTW I only have a Blue Driver OBDII reader. Not sure which reader would list suspension issues.
 
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Old 03-12-2019, 11:42 PM
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Nedoerr, what size rim are you running? In addition, what pressure are you running in your tires? The larger the rim you are running, the less the tire can flex to absorb the imperfections in the road and therefore results in more bumps inside the cabin. The same is true for running higher pressures in the tires. The higher the pressure, the less the tire can flex. Most people find that keeping the tires at say 38 psi front/35 psi rear is a pretty good spot to sit to keep the tire at a high enough pressure to get good tire wear but be soft enough for a nice ride.

I have noticed that sometimes I will get a suspension worning if I start the car when it is parked on an uneven surface. This will force the car into dynamic mode and stiffen up the suspension. Grnated, I normally get a light on the dash when this happens.
 
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Old 03-13-2019, 12:29 AM
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Thanks for the reply. I have the 20Ē stock rims with the 380mm brakes in the front. I inflate to 32 PSI, as indicated on my door frame. I havenít changed the rear tires yet, so that remains a possibility.

Not sure how much bumpiness is normal, but it feels more than I expect. Donít remember it being this bumpy when I first bought it. No warning lights illuminate.

If tires and rims are the most likely, I could take them back in to make sure they were straightened properly the first time.


 
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Old 03-13-2019, 09:47 AM
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Question, is your ride bumpy or bouncy?
 
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Old 03-13-2019, 11:11 AM
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Does the current XJ still have CATS ? When there are any faults recorded that could affect handling or braking, CATS will default to 'Hard' thus giving a harder ride than normal.
 
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Old 03-13-2019, 01:30 PM
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The ride is bumpy (firmer) not bouncy (softer).

I think it has the adaptive damping system as opposed to the CATS system. But maybe it also defaults to hard/dynamic mode if there is a fault. Is there any way to check what mode itís in?

Thanks
 
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Old 03-13-2019, 06:34 PM
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OK, so this may sound weird, but had the same issue once after a car wash. It fixed itself after I did the same maneuver that race car drivers do to heat up their tires by turning the steering wheel abruptly left and right and swerving the car, but in a tight line. This rocked the car and after that the suspension "softened up". Call me crazy but it worked for me.
 
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Old 03-14-2019, 10:56 AM
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Originally Posted by XJsss View Post
OK, so this may sound weird, but had the same issue once after a car wash. It fixed itself after I did the same maneuver that race car drivers do to heat up their tires by turning the steering wheel abruptly left and right and swerving the car, but in a tight line. This rocked the car and after that the suspension "softened up". Call me crazy but it worked for me.
Thanks, worth a try. I will have to wait till itís safe to do so (perhaps a late night drive on a toll road). Iíll report back either way. Thanks again.
 
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Old 03-14-2019, 01:13 PM
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You do not need to be driving fast. I did it @35mph within my lane on a local street outside my neighborhood
 
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Old 03-15-2019, 09:24 AM
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CATS is an adaptive suspension. Computer Active Technology Suspension.
Not sure if they still call it that on the current XJ or not?
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Old 03-16-2019, 08:36 PM
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I read somewhere that the CATS name went away for our X351 model.
 
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Old 03-24-2019, 11:26 AM
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Tried the race-car maneuver, but the bumpiness remains. So I think I'll take it back to the wheel repair shop to make sure the wheels are properly balanced and circular. Perhaps I will need to entertain the idea of downgrading my rim size if the bumpiness persists.
 
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Old 06-25-2019, 04:06 AM
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This post is edited
I must have accidentally posted somehow.
This was the equivalent of a but dial only it was a post here.
 

Last edited by mcmism; 06-26-2019 at 03:32 AM.
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Old 06-26-2019, 09:29 AM
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I would get the wheels balanced on a Roadforce balancer. This actually measures runout under a simulated load, so is much better for detecting and compensating for wheels and tires that are out of round.

What kind of tires do you have? My experience with Pirelli P Zero All Seasons was terrible. Chronic balance issues that could never be totally fixed, and terrible for flat spotting when parked. The Dunlops on my new XJL also will flat spot, typically takes 5-10 miles on the highway to totally settle down.
 

Last edited by Mark SF; 06-26-2019 at 09:31 AM.
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Old 06-28-2019, 12:26 PM
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So it turns out I had another damaged rim (two cracks in the rear drivers side). Repaired it and now the car is much better. These rims are pretty pathetic IMHO.

Still would like to do a little more suspension work to get iĒeverything perfect. But Iím going to stay focused on the powertrain for now. Maybe next year Iíll revisit the suspension.

Thanks everyone.
 
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Old 06-28-2019, 02:56 PM
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Originally Posted by Nedoerr View Post
So it turns out I had another damaged rim (two cracks in the rear drivers side). Repaired it and now the car is much better. These rims are pretty pathetic IMHO.

Still would like to do a little more suspension work to get iĒeverything perfect. But Iím going to stay focused on the powertrain for now. Maybe next year Iíll revisit the suspension.

Thanks everyone.
Well I now have 4 Wheels sitting in storage for the same reason theyíre bent. I got new aftermarket ones installed. Jaguar uses cheap metals and their wheels suck.
 
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Old 06-28-2019, 03:28 PM
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Originally Posted by Supercharged Jag View Post
Well I now have 4 Wheels sitting in storage for the same reason theyíre bent. I got new aftermarket ones installed. Jaguar uses cheap metals and their wheels suck.
So far we might have established that Jaguar wheels can be damaged, what has not been established is that aftermarket ones cannot be damaged. So your statement might be a tad hasty.
 
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Old 06-28-2019, 05:15 PM
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Originally Posted by Mark SF View Post
So far we might have established that Jaguar wheels can be damaged, what has not been established is that aftermarket ones cannot be damaged. So your statement might be a tad hasty.
Sorry, i didnít mean to intend my statement in that way. And of course, Iím pretty sure all wheels can be damaged, but what I meant was that Jaguar wheels can be bent/damaged much easier than others. The aftermarket wheels I got are flow formed so they are a bit more durable than OEM. On my 09 XF SC the wheels are bent on it as well, but not my Porsche Cayenne that has a 21 inch rim. I shouldíve been clear sorry
 
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Old 06-29-2019, 08:43 AM
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I think it depends on what wheels you have?
I have 20" forged alloys (Farallon) on my XJR and never had any bending or cracking despite hitting several pretty big pot holes and all the normal road hazards.
I don't think the other 20" rims are forged?
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Old 06-29-2019, 10:46 AM
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Originally Posted by clubairth1 View Post
I think it depends on what wheels you have?
I have 20" forged alloys (Farallon) on my XJR and never had any bending or cracking despite hitting several pretty big pot holes and all the normal road hazards.
I don't think the other 20" rims are forged?
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Thanks for that info. Can you please post a picture of your rims? Thanks

I understand the 19Ē rims are also pretty resistant to bending. Maybe others with 19Ē rims can comment on this. Really all 20Ē rims should have been forged or something to prevent easy bending. Itís understandable to not do this on the 19Ē rims because they have more tire to absorb the road.
 

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