I did search through the archives and read through just about all of the “hits”’ but none seem quite the same or no resolution listed. Ive been having a shake that affects the whole car. Basically I can feel it in the steering wheel and in the seat. It “feels” like it goes more into the seat sometimes and others it’s pretty balanced between everything. I’ve had my tires balanced a total of 5 times, the last 2 times they were road force balanced. I have noticed that the shake seems worse at around 14-1500rpm, but is still there at higher rpm, and when put in neutral coasting, although less of a shake, and the higher the rpm the less of a shake. So basically cruising in 5th at about 50 the rpm is around 14-1500 and it shakes throughout, drop through the gears and the rpm increases and the vibe seems less. I’m wondering about the flex jurid on the driveshaft, but it was replaced by one of the previous owners when the trans was replaced. Has anyone had this personally and resolved it? It’s more annoying than anything.
In would check that the Jurid was replaced in the correct orientation the webs have thick and thin sections, the thick sections should be under compression when driving.
Hey Robin,
Don’t know if this will help, but mine sits in a controlled environment facility for somewhat longer periods of time. My dealer had once told me to get used to the shaking wheel,
as it is typical to our brand. Me, not believing this, I began the sidewall warm up they do on race tracks. Now this worked! I currently am using Dunlap tires with turning
tires in front and larger traction tires (per manual instructions) in back. I am fortunate enough to have a straight line and level road to do this on, with not much traffic and
do the slow warm up swerves to the stop sign about a third of a mile. That works for me, and, its a five time North American, First in Class auto, with only one Second in
Class for wheel curb rash on some wheels and other slight wheel blemishes. All fixed for whenever we are able to have a Concours d’ Elegance again.
Bob
GR8 XK8
Bob Allen
kabob@wavecable.com
Interesting idea to say the least! Maybe I’ll give it a shot on the way to work this morning! Hopefully won’t get pulled over for being drunk! Although, I guess I could just say “now officer you may not believe this!” Of course that may make me sound more drunk! Lol!
Welp sidewall warm up didn’t seem to make any difference. Oh well
Right , has the car a centre support on the prop shaft? The other possibility is a slight imbalance of the prop shaft. I had an annoying shake on my ‘92 ‘40 that only went away when I wrecked another one and changed the prop shaft over. BTW it was already off the road before I stripped it for parts so don’t judge me 
Hi again,
One more thing on the tires, usually a last resort considering the other options given you. You’ve balance tires, etc.
Last resort is to have tires shaved to pure round. Do this with only a VERY trusted tire shop. I have done this only
once many years ago. It worked, but todays high end tires should not need this. Good luck!
Bob
Bob Allen
kabob@wavecable.com
I kinda thought that with the road force balance they might have told me if the tires were out of round, bjt who knows anymore smh
Have you inspected all the u-joints?
I did the ones on the rear, but not the one on the prop shaft. And by that, I looked at them and turned the wheels on each side back and forth looking and listening for any noise or visual slop.
Hi Jason, I had this same problem for years…spent a fortune on wheels, bearings, tyres, drive shaft do nuts etc… quite by accident I removed the X frame under the engine and refitted it… I did this with car on a hoist so the engine weight was “hanging” on the front of the car. Did the frame up tight… all problems gone… suggest look at that frame. cheers and good luck. Chris
Gotcha! Ill have to give that a shot! Yeah mines still there. Smh
Mine was vibrating, and found one of the engine mounts was gone, as well as the transmission mount. The trans mount looked OK, but as soon as I raised the engine up, it was apparent that it was in two pieces. Hard to tell when compressed in the car.
I changed out my trans mount a little while ago, and have considered just changing the engine mounts too
If you have a bad engine mount, it can lead to the trans mount breaking again. If you open the bonnet, engine running in neutral, and have someone blip the throttle up to about 2500, the engine should not move much. If it rotates up a couple of inches, then then one of the motor mounts is bad. You may have to shift to drive or reverse, with the brake on, to do this test- if in gear, don’t rev too high- just a little blip.
You can also inspect the mounts to see if there is any leakage of fluid, another sign of failure. Harder to see if you don’t have a lift.
Yep no lift and most of my working on stuff is on the stone driveway. Lol. Oh and dont forget im a decently large guy lol. So that doesn’t help either. Smh
Jason how old are the tires……
What brand…
Droning and shifting is real common because of the weight of the car
The v12 s camber was such that you would eat through tires around 12,000 miles tops
That carried over to xk8 and Aston db7 and db9
All the same basic platform
Tires 9 out of 10
I joint or prop shaft next
Even though you have a 4.0
Tires are about 2 or so years old possibly 2 and a half. They are falken tires. Im wondering about the flex joint in the driveshaft. Im surprised there arent more solid alternatives to put in place of the rubber one.
If the Jurat keeps failing, look to the other end of the drive shaft. I had an XJ 40 that ate up Jurats like desert. Finally replaced the mid-shaft bearing and no more failed Jurats and the vibration I thought was tires disappeared. I don’t remember if the XK8 has a mid-shaft hanger on the prop shaft but if not, try looking at the bearing on the transmission end.
The Jurat has to be flexible to tale out any vibration or flexing in the drive line.
The Jurid also has to be in the correct orientation there are thick and thin webs, the thick webs should be the ones in compression when the car is going forward.