Hello All.

Super grateful for this site. Beyond words.

2002 Jag XK8 Convert. I've replaced both upper control arm bushings, then had my worked checked by a local mechanic. Had him visually inspect other areas of the suspension & to check and tighten my hand tightened main upper bolt with air tools. All seems in place there. I suspected uppers needing replacement due to visible wear AND that when I drove, over say 50-60 mph and touched the brake in any way, I'd get what I consider an unacceptable (unsafe) shake/vibration/shimmy accompanied by a slight noise in the cabin coming front end. And yes, a slight (I'll describe it as slight) vibration in the steering wheel... At slower speed not so much or at all but braking at higher speeds, braking only, it was obvious something wasn't right.

Post replacement - Same shaking and vibration with only slight improvement but still unacceptable to point of not feeling safe... All said, not much change. I DO expect to bring the car for an alignment of course but don't feel this will solve all that's wrong.

Other points:

-Depressing brake is responsive and "normal". There is no vibration in the peddle.
-Inner and outer tie rods are tight with car off the ground, boot covers are intact.
-Driving at low speeds and up to 80-90 mph (haven't gotten her over 90 yet, lol) without braking - smooth and no unusual sounds or vibrations.
-Pads are new-ish and rotors seem fine BUT are not that polished silver in appearance. Slight discoloration from when the car sat.
-Taking my hands off the wheel when driving,,, car doesn't drift and alignment seems ok.

Is there a way to test for uneven pressure being applied to individual front rotors when braking?

I'm unsure where to go from here.

Any help suggestion or advice would be greatly appreciated.

Thanks in advance

 

Jay, I once read an article in that great jaguar periodical , the one that comes out big monthly from the UK, darn I forget it's name. Anyway, the article explains step by step how to pull the lower control arm to replace it's bushings.

The reason I am posting this is because the stated that this bush will produce the pulse you described when worn. I remember this because I too experienced the same thing hours before I read the article.

Jay, this is brainstorming to help you out. Let's see what the experts on the forum think of this or other possibilities.

I think I lost track of that darn magazine,but I'll look around. It'll help me with an upcoming job too.

John

 

Were the tires rotated to the back to check for a wheel/tire issue?
The brakes should be uniform polished silver after even a short drive from surface rusty red. If not, a caliper is hanging up.

 

I had a similar issue with high speed braking wobble. I replaced all this and the wobble is completely gone. This stuff is all cheap and easy DIY.

I would keep replacing in the order below until problem is resolved.

Front rotors and pads
Upper control arm bushings
Sway bar bushings
Sway bar links
Outer tie rod ends (+realignment)
Steering rack bushings
Lower shock bushings

I had already replaced my rotors and pads once but this time I used Brembo rotors that are thicker. Further explanation is here

I can't say enough about how important both front and rear sway bar bushings seem to be on these cars. I plan to change mine out every two years or 15K miles max.

My tie rod ends and sway bar links felt tight but once I had them off they were a lot looser than the new ones and would flop around on their pivots while the new ones only moved when forced.

My steering rack bushings were hardened from age and while the rack was not loose I do think some vibrations were telegraphing to the steering wheel.

My DIY notes and pics are here

If after you do the above you still have an issue then the lower control arm bushings and ball joints would be next. I have not done mine yet but only have 70K miles on the car.

Here is a link to the magazine article I scanned and posted a while back that shows how to do those.

 

Brake pad deposition on the rotors can cause uneven friction and the type of shaking you experience from longer/harder braking at higher speed. Remove the rotors and give them a light sanding or fine lathe turn. I also had a car with floating calipers that shook like hell under braking. It turned out to be a frozen caliper guide pin. I freed that up and lubed and the shaking was gone.

 

On the tie rod end check, make sure you jack up the lower wish bone to approximate the tie rod angle during normal driving.


If you check the tie rods in full suspension droop, you may not detect the worn spot in the ball/socket. My inners seemed tight in full droop, but when I jacked up the suspension, the tire could be towed in and out and the driver side inner flopped around like a fish when separated.

 

Bent Rim? Mine had the shakes at about 70 and above. i was told a rim was bent and fixing it would take care of shake.

 

Hello All. I didnt forget the amazing advice, time and energy folks had put into my OP, it just took me some time (and money) to get busy. For all the offerings in these posts,,,, a deep bow and sincere thank you.

It was/is winter here, although mild, not having a garage, it took me some time to get to things. More, full time work full time school but I was able to roll up sleeves and do some things recently which didn't solve the problem immediately but, all of the work leading up to discovering the problem, needed doing anyways.

So, after upper & lower control arm bushings, steering rack bushings, tie rod ends, and trying to replace upper shock mounts (at which I gave up on for now due to not wanting to undo upper control arms on this venture) I got in the car and took it for a spin and,,,,, SHAKE , lol...

Brought it right back home, pulled calipers, pulled rotors which all came off easy enough, and BAM...! The inner face of both calipers (out of sight) - completely un-uniform surface, wavy sort of uneven wear and color (I wish I'd taken pictures), obviously the problem & where pads were hanging up.......Ordered a set of slotted, drilled rotors and ceramic pads, put them on and smooth as silk with noticeable braking improvements.

Again, I appreciate all of the suggestions and attention!

Thank goodness for an early Spring or,,,, global warming, lol

p.s. this coming Sun, Mon, Tues... Full tensioner replacement and attempt to reset drivers side intake CAM to retarded position, hopefully ridding myself of a p1396 code & CEL I've had since replacing drivers side cylinder head in the fall, and trying get rid of the damn SRS light which is haunting me.

p.s.s. *ROTHWELL* thank you for the amaaazing link and write UP!

 

My 2003 XK8 has 38000 miles.
It has a similar problem. Mechanic replaced the steering rack, struts, strut mounts , disks and pads.
The car had a wheel alignment afterwards.
The shimmy occurs on the driver's side wheel between 30-40 mph and then goes away.
The tires are almost new with about 2000 miles on them.
I thought it might be tire balance but wouldn't that occur at all speeds?
I also thought maybe a bent wheel.
Any help would be appreciated.
This is my 1st Jaguar so I am at a loss.
I am a 60-70 Chevy guy.
Thanks in advance.

 

Hey Ron...

Did they do all that work chasing the shimmy??? I would say be very careful with mechanics and shops unless you can send them in a specific direction or know them very very well. In a tough economy everyone is working to make up the bucks somewhere...

A lot of times with a shimmy like that you can jack up the tire in question, sit on your ***, prevent sliding back with hands behind ya,,, and kick the tire fairly hard at all four quadrants... Best, have someone do this while you look and listen for a wobble, movement, shake etc. Try to pinpoint and area or component... Its possible.

It sounds they checked and replaced a lot of things that I might have checked - but later... I think I updated this string to say that it ended up being rotors - a simple fix. These cars can be strangely sensitive... For the mech to have replaced all of those things (which I think are important but a little further away from direct suspension) as opposed to ball joints upper and lower, upper and lower control arm bushings, tie rods and tie rod ends, sway bar links and the like,,,, is a little peculiar... That's just me.

Another thing I can think of that might also allow a shimmy or a shake at a specific speed "might" (and I really really want to stress might as I don't want to be the one responsible for you going out and spending a ton of cash) be Subframe Mounts. I have an engine with 35-37k miles I am about to put in mine and while the engine is out I will change mounts. They do wear thin...

Please let us know the results when you find out more...
~ J

 

Thanks for the reply. The new parts were not due to the shimmy. The car sat for a very long time before I bought it and the strut bushings were bad along with seal leaks. Horst Autoworks has a good reputation around here so I don't think he did any unnecessary work.
I'll try your test and see what happens.
Thanks, Ron.