So, after finally getting my vehicle back from the body shop, I replaced the front upper shock mounts, both sides, as well as both shocks. Now I am having an issues primarily at highway speeds 60-110mph where the wheel starts to vibrate on some road surfaces, and actually shake on other road surfaces, and sometimes nothing. Has anyone ever had this happen?
If I am driving on asphalt (black top) roads that are in fair condition it's typically fine, but on actual concrete bits of the highway, I get a shake in the wheel sometimes it's just a slight vibration (not visibly moving) and on other road surfaces it sometimes shakes as if I have a wheel badly out of balance. Shop checked all four wheels and all are in good order. Tire pressure is currently at 36f/38r.
I do a lot of highway driving and this is very annoying. If anyone has any suggestions as to what could be causing this it is much appreciated!
Thanks all!

 

Any additional vibration from brake (warped rotors?)?

I forget when was last wheel balance?

 

If I am driving and it starts happening, and I slow down there is no change.
I had all 4 wheels balanced about 2 months ago, but just a few days ago I took them to the shop to have it checked, since that was my first thought.

 

First try reducing your tire pressures to 32 psi front and 29 psi rear. For my 19" tires that is the sweet spot for ride quality. The higher pressures are making your suspension work harder than it needs to.

When you replaced the shocks and mounts did you do alignment after?

Have you changed any of these yet? If not then try replacing them in the order listed.

1. anti-roll (sway) bar bushings
2. anti-roll (sway) bar links
3. steering rack mounts
4. tie rod ends (requires realignment)
5. upper control arm bushings (requires realignment)
6. lower control arm bushings, ball joints, wheel bearings (requires realignment)

 

^^ As pointed out above, your tire pressures are much too high....

You may have other issues as well but I would reduce the tire pressures as a first step....

 

New links last year and new upper bushings on the driver's side as well. Has not bee Aligned since I put the new shocks and upper strut mounts. But I do see it needs it. Going to do ball joints, tie rods, and lower bushes all at one time. I'll reduce tire pressure and see what happens. They were low and inflation did help reduce the issue. My rear tires were at about 30 and looked like they were "cupping"/ the middle rib of the tire looked lower than the outer bits. I'll try the anti roll bar bushes. Has anyone had any luck with the "universal" poly bushes carried at most auto stores?

 

you had them balanced, was that a road force balance check that actually measures the "roundness of the tire wheel assembly? I can balance a brick but how would that ride? A high road force is a not very round assembly and you WILL feel it. The higher the number the more out of round. this does not matter if new tires or not. I have had new tires with high road force and you just will not get a smooth ride no matter how balanced the tires are. You can measure the high spot on the tire and the low spot of the rim then spin the tire on the rim to match these 2 points together creating a lower road force number. (26 or lower is passenger car spec) but many times the machine will recommend the tire or the rim be repair or replaced depending n the issue.
Past that one of the biggest complaints on these older XKs is that they can feel Skittish on the road. They were that way when new.

 

They used a hunter road force balancing machine. Don't have the numbers. I can live with it being skittish, but the wheel shaking gets pretty annoying. Haha, I know there was a slight shake prior to all this between 75 and 77mph then it went away above that speed. Not sure if it's related or out of the ordinary since my XJ did it as well, but the vehicle also like to move with any bumps in the road. Uneven roads will push me all over. I've just chalked that up to tramlining.
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Ok. Well everything vibrates at different frequencies or in this case mph. I have 1 from my slightly bent right side wheels(thankyou potholes) at 70mph which is where i normally set the cruise control on my 76 mile round trip to work.
so i just set a little faster until the day i cn send them off and repaired back to round again.

 

You really need to get it aligned. If you drive it much without realignment your tires will suffer the consequences and never recover from the uneven wear. I found a shop that offered a one time fee = lifetime alignments. That allows me to gradually change parts and get a quick free realign whenever I need it.

You only replaced the upper control arm bushings on one side? That seems like it should be corrected. Perhaps do the other side then realign.

Worn upper control arm bushings and tie rod ends can cause a tram lining effect.

I recommend using OEM rubber bushings since you want optimal ride quality like me. Poly will cost you some ride quality but they will last longer.

How many miles on this car?

Is the vibration feedback only in the steering wheel?

Does the steering wheel feel solid (you can't move it in any direction by pushing)? I have noticed on some XK8s the column can get to a point where it can be moved. Running the column all the way up/down/back to position usually fixes that looseness.

Do you feel it in the seat at all?
Does the feedback in the steering wheel oscillate left/right?
Or is it more like it is telegraphing the road impacts up through the column?

 

I replaced only the driver side since they were loose, and yes. OEM is the way to go! I used some el cheapo RockAuto bushes and they are junk. The car just ticked over 69k miles, the vibration seems only to be in the wheel itself, interesting development, when the wheel does its little shake-y bit I do notice that if I turn the wheel slightly in either direction the vibration in the wheel is more noticeable on the side of the turning direction. I.E if I turn the wheel to the right it seems that I feel the shaking more on the right side of the wheel than the left. This could all just be in my head too. I haven't noticed any play in the column really.
I have noticed once or twice that the whole car felt to vibrate, however it was a particularly uneven stretch of roadway.
As far as oscillating right or left, I am not sure I understand what that'd be referring to; if you mean does it seem more noticeable on one side, yes. When the wheel is turned. If I keep the wheel centred the vibration is equal on each side. I do plan to replace antiroll bar bushes as well as rack bushings ASAP,

 

Hi Barry,
Did you ever master this problem as I have the same issue.

If it were all the time the solution would be to work through the things which could be out of balance but it is intermittent. I did 300 miles yesterday and at times the ride was smooth and at others I could feel a definite vibration - centred on 50mph bt not confined to 50 by any means - and at times it felt like the car was going to shake itself to pieces. I tried to see if the brakes were binding but couldn't detect with any certainty, I'm not quite at a loss and I will work through the out of balance possibilities like tyres and wheels but I can't see what would be OK for 30 miles and then badly vibrating for two or three miles with different intensities - and then clear itself again.
Peter