Length alert: This is my year for annoying Jag stuff. Has anyone seena potentially brake-related vibration through the frame as well as in the steering wheel with the brakes NOT applied, which then can become pronounced when braking from higher speeds with pedal pulsing?

Back story: 5 new Continental blah blah 54s installed a month ago at a well-regarded tire shop now in a local chain. It took four balancing efforts — each gradually reducing vibrations — including gratis “road force” balancing and shifting wheels about. It’s now there in the semi-background, annoying but not the end of the world. I read this to no avail: https://www.jaguarforums.com/forum/s...errerid=132355

The store manager insists the tires are round/properly balanced. I watched today as all were spun/driven while on a rack. There is no tread wobble of consequence, both rear original starburst wheels have near imperceptible off plane movement. There is no visual indication of out-of-round any of us can see. Wheel bearing 12/6 tests all negative. Drive shaft has a little side-to-side movement. We did not test motor mounts but I’ve seen no issue.

After the manager and his balancing guy came back from a drive he asked me to ride with him. He believes changing f/r pads and rotors will largely make this go away, that there’s likely some rotor movement off vertical that’s getting to the frame. Trying to remember how it was before, I do not recall any brake pulsing of consequence, but cannot recall how the old tires rode other than one tire/wheel combination was permanently consigned to a rear wheel as it could not be brought into the OK range on the road force gizmo. That wheel is out of the picture now on the spare.

My Indy all-brands shop said: Hey, just drive it; a tech at the Brit car shop said he’d not seen such while brakes are inactive but “bring it round and we’ll check.”

All this said, the Conti tire is pretty nice. Very quiet, civilized ride, corners well but I don’t flog it hard. AI suggests there have been rare balancing issues, but nothing beyond that. There’s a shop in this group over in MD that does a lot of high end cars and I could pay to have them doublecheck the balancing I suppose, but they have identical equipment.

So, apologies for taking up so much bandwidth, but the thought of spending $1200 to solve a problem evidenced by $1000 worth of tires seems a little counterintuitive.

Thoughts?
Sent from my iPad

Hey Eliot, ...if you haven't already, review this since you mention driveshaft play... https://www.jaguarforums.com/forum/x...g-info-188400/

Maybe new pads and rotors (or just a cut off the old rotors); but maybe wheel bearings; but maybe engine and transmission mounts are loose or going bad; and the drive shaft (end to end) as HH recommended.

If new pads, make sure they clean up the rotor to hub surfaces.

If they think it's rotor runout or hop it takes 10 mins in the air to check with a clamp on dial indicator... I'd hope they would actually measure things rather than guessing with a parts cannon.

If the driveshaft carrier bearing has play, it's worth replacing that before chasing down things like rotors. Fix the things you know, then find out what you don't. I'd also more closely look at bushings - those motor mounts can be deceptive, also things like vee, steering rack, and other subframe mounts.

Is the vibration only in the front/steering, or rear as well?

Yes...vibration is mentioned but not where the vibration us evident (steering wheel, trans shifter,
seat, floorboard) In my experience, where the vibration is felt, tells me a lot of what to look for.

.

Find some place near you that does Hunter road Force balancing and have them do everything the machine tells them to do on the wheels and tires, my XJR was extremely sensitive to tire balance issues and I had to do the hunter road force thing four times, four times because they didn't do everything the machine told them to do each time, worth the money.
Vector

Vector: thanks for your suggestion. You're right about Jags and horses!

To bring this thread up to date, I took the car to the parent company of the firm that put on the Continentals. The founder of the company immediately pronounced the left front tire out of round and gave it some counterweight to lessen the problem.The fault was clearly visible to the eye! It was late July 3 so I offered to come back the following week. Then, they pulled all the tires, did the road force thing, and he pronounced every one off the tires flawed with vertically offset joints between segments. He found the same issue on a set he had in storage and said none should ever have left the factory.

We swapped them for road force balanced Michelins and damn near all the issues went away. I now have the car booked into my local British car shop to run the last of the vibration to ground, whether it out of round rotors or hubs, or a driveline issue.

Thanks for checking in.

Continentals are usually pretty good tires. It just serves us as notice that
ANY brand can have a bad day. I have never had any problems with my
Generals....or my Tiger Paws...but we are glad you found what it was.

Randy: You're spot-on about good days and bad days at any manufacturer. Years ago I had Generals on my X300 and they were just fine. On the basis of that experience, I put them on my late, lamented X350 and it was a horrid experience. The tread grooves were dreadfully irregular and visibly wobbled back and forth and shook the car. I then switched to Continentals that were smooth as glass. That experience was what drove my initial decision on the current X308. Heck, maybe I should have gone back to Generals as they did so well on that basic Jag design! Anyway, off to the shop in mid-August to get this sorted out and put to rest.

Someone asked about where the remaining vibration is: it's coming both through the frame into the seat and roughly an equal amount into the steering wheel.

Good thing I'm retired and have nothing else of consequence on which to spend my kid's inheritance!