I have a small but annoying issue with my XJ8, there is occasionaly a slight shake of the steering when braking, not like brake judder (brakes are new any way) and also a front end vibration at high speeds (above 110mph) I suspect the front lower arms but the bushes seem fine, there is a small amount of play which appears to be in the left wheel bearing but I don't realy think this is the cause, he car has new tyres and they are all well balanced (same problem on old ones) i didn't bother doing anything until I'd ruled out the horrible Pirelli tyres, but the issue still persists, any thoughts? Could it still be the bottom arm bushes, how bad are bad ones? mine you can twist the arm a bit bit I wouldn't say there was any real play there,

 

Rear brakes can cause vibration, as I found out when rears were replaced and problem went away.

Apropos front end vibration over 110 mph !! What size wheels ? 20" are notorious for accentuating the smallest tyre or wheel defect.

 

Standard 18" wheels, i've been doing a few runs and now I think I can feel the vibrations throughthe wheel most of the time, just slight side to side feeling through the wheel worsening at higher speeds and during braking, as there is play in one wheel bearing I will replace that anyway, if that doesn't improve thinghs then i'll look closer at bushes etc. but hinestly they all look and feel ok to me.

 

If the front lower arms are bad, you can see the wheel moving fore and aft if you walk alongside and have somebody roll slowly, applying and releasing the brakes. It is normal for the links to move a good bit if you pull them up and down at the middle curved portion. I doubt these are you problem. I also doubt it's wheel bearings or bushings. These items will give you more of a scary drifting feel at speed...not a shake, more of an "Oh S#%!" sensation.

I would still lean towards tire balancing. Tire machines are not designed to balance above 100 mph. Sometimes they get the balance close enough, other times they don't. Other most likely things to check are a warped rim, out of round tire, and tire delamination. Just because tires are new does not always mean they are good. Try swapping front to rear and see if the shake leaves the wheel.

 

I have tried all the wheel swapping stuff, no matter which tyre the problem still appears exactly the same, i fitted and balanced the new ones myself as am trained and have the kit (not a tyre fitter by trade though) there is also a slight feeling through the wheel at most speeds, a slight harshness with a side to side movement, sometimes under braking it can develop into a judder although braking hard is pretty smooth and certainly acceptable.

 

I've had more than one set of tires that I fought shimmys with...only to find later that they were defective internally. A small delamination of the chords can seem to balance on the machine, but ballon out on the car and cause an imbalance.

 

Yes I appreciate the issues with tyres, not helped if the car is stood for a few days also, any way the bearing has some play and is noisy also if you spin it with no disc, I'll change this first and post the result, hopefully a massive improvement that will see the car driving with the refinement I would expect.

 

A bad bearing usually sounds like a rumble as you drive. If it continues to fail, so you get play in the wheel, the car will occasionally dart, just enough to unnerve you while driving. I had a car that a PO actually put front bearings on that were larger than the spindles, so they had several degrees of play when I shook the wheel. In general, the car drove fine, but occasionally would just seem loose.

The point being, bearings and bushings don't cause shake. Something warped or out of balance causes shake.

 

I tend to agree the bearings usually cause noise, however I have experienced wobbles and vibrations from worn bushes and joints, namely track rod ends, roll bars and top shock mounts, and there lies the problem, the wheels are true, the discs are true the joints and bushes all appear tight, even with the air pressure released there is no detectable play in the suspension, the wobble is only there sometimes, it can appear under braking, or sometimes not, it can appear in a straight line or sometimes not, warped discs are very uncommon in my experience, brake judder usually caused by uneven coefficient of friction on the disc, this can be caused by stopping when pad and discs are very hot and causing brake pad material to be unevenly distributed on the disc or by corrossion caused by the vehicle being left to stand, my theory (not that I need one) is that the bearing is noisy and has some play, this can cause the wheel to move around independently of the rest of the suspension and more so of the brake caliper, thus causing the slight loose feeling when driving at any speed and when braking the wheel the disc can move around on the worn bearing giving the same effect of being out of true, anyway the bearing has to be replaced and is turning up today. I just hope it cures it, cause it is a bit annoying.

 

Changed the bearing today, had to remove the vertical link and press the old assembly out as it was firmly stuck in, I expect this would be the same on all cars with this set up, anyway the judder and shake under braking has dissappeared, I still feel there may be a bit of vibration above 110, but difficult to say what it might be, maybe a rear tyre, prop or something or it maybe the suspension just stiffening up and lowering (not sure at what speed this occurs) and it's tyre/road noise/feel. anyhow it's not too bad and I rarely drive this fast!

 

Sweeper, it's a long shot after 8 years but can you tell me what exact bearing you replaced?

 

I am not sweeper. But he was referring to front wheel bearings. These do fail. They are ball bearing hubs. Most every Auto has roller bearings now.
These are very cheap from China. Less than a 100.00 a pair. Includes a speed sensor too. In US Detroit Axle is a reputable supplier. Now sure about Europe but there has to be suppliers. The dealer price on these is very high. May be made in China also.
I have them on mine. Don has installed some for customers. Seem solid.
The shake on our cars may be anywhere. But get a good alignment. Alignment will not fix shimmy, but if there is wear the adjustments will jump around indicating play on the alignment machine. Should be able to find the worn parts.
I have heard European Jaguars do not have problems with the boots and bushings disintegrating. Will we were so lucky in the US. Mine were all totally kaput in 2015, nine year old car. I thought someone had been treating them with gasoline to eat up the rubber.

 

the original supplier is Koyo. tons of vag cars still use ball bearings

detroit axle is notorious for selling the worst stuff on planet earth but even a broken clock is right twice a day