I bought a 1999 about a month ago and have sorted out various problems and the car is running like a champ.
I have a vibration that happens about 75 MPH and then again about 85 MPH and above. The steering wheel doesn’t move and at lower speeds you don’t notice it. the tires are fairly new and show no unusual wear patterns. I had the tires road pressure balanced and it improved a little but still there. I am not getting any brake shimmy at any speeds.
I just read a thread about a dash rattle and their solution was to lower tire pressures is that a common problem or issue? I am running 32 PSI cold right now.
Have a check of the drive line.
When I had my XJ40, I had a vibration I thought was tire related, but turned out to be the driveshaft bearing. On the XJ40 and the X300 there is a bearing at the mid point of the drive shaft. I couldn’t figure out why I was going through so many flexible couplings (jurats) at the differential end till I discovered that the bearing had gone. Once it was replaced, the vibration that I’d thought was tire related was gone and the car was silent and smooth again.
Grahame,
I read your post then went to the parts breakdown and I can see the bearing you are talking about but there is no reference to it or part number. My car is up at the airfield in my hanger so I’ll make a trip up and look at it.
To check a bearing like that I’ll have to disconnect the drive shafts to feel the travel I suppose.
Mark
Check the jurat out also.
Let me know how things work out. I’m always interested and like to learn.
Grahame,
I had a few minutes to take a look but I will have to jack the car up to get at the hanger bearing and it was a bit cold today and I didn’t want to fire up the heaters. It’s going to be nice tomorrow so I plan on jacking the car up tomorrow and getting under the car and see what I can find. I am particularly interested in looking at the jurats piece to see if there is any deodorization or anomaly that would indicate irregular movement of the drive shaft.
I was also thinking I would be able to grasp the shafts on both sides of the hanger bearing and see if there was any movement like you described on your car. I also want to insure the balance weights on the drive shafts are intact as well. If one of the drive shafts becomes unbalanced that would cause the problem as well and eventually cause the bearing and the jurats to fail.
I am actually leaning to a flat spots on the tires since it sat for almost a year. I haven’t driven the car in warm weather for any distance but I did put about 20 miles on a test drive and I thought it was a little better when I exited the interstate near the airport. I take the V12 on a certain section of smooth asphalt that is great to feel any strange handling or steering problems. I think if I run it on a 50 mile run on warm asphalt that should give me a better idea though.
I will close this thread out with a conclusion or solution. That’s one of my pet peeves when folks just abandon a thread after help is solicited and no feedback is given. Especially when a successful solution is found. It benefits know one if you don’t come back and wrap it up.
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Are you a pilot? I’ve had my private license since my early 20’s, although I haven’t been very active of late.
Yes I am and a A&P as well. I fly a Premier IA for a Law Firm. Ive flown professionally for 35 years. Started in piston twins now Jets. Back in the ole piston days I did a lot of maintanece but the jets rarely fail so not much maintanece now a days.
Do you still fly? What are you flying?
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I just got my medical back a couple of years ago after letting it lapse because I wasn’t flying. I recently got some time on a C172 with a friend who is an instructor. I first started flying on a PA 12 Super Cruiser and finished my license on a C150. My preferred tail wheel is the Citabria. I’ve flown the single engine Cherokee line from 140 to Arrow to 6/300. I got my twin on an early Aztec. My preferred cross country machine is the Comanche B. Presently I hanger fly and hit the magazine stand.
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I used to own a Cherokee 6/260 and loved that old bird. You could carry everything including the kitchen sink.
Well I got under the XK today and there is no intermediate hanger bearing. I pulled the shield covering the drive shaft and it’s a one piece.
I did discover however my input seal on the differential is leaking! I just rebuilt the IRS on my XJS and changed the input seal and both output bearings. I also cleaned up the cage and completely reconditioned the brakes. I guess I’ll have do replace this seal too. I inspected the garat coupling and it looked good.
I’m going to put a 50 miler on it tomorrow via interstate and see if I can tell any difference. Stay tuned.
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Sorry for sending you on a wild goose chase. I’ve never been under my XK8, so didn’t know if the drive shaft had a mid shaft bearing or not.
I was struck by how similar your problem was to my own with my XJ40. I went through 3 jurats before discovering the bearing had gone out. After the replacement, I was pleased that a vibration, I had assumed was from tires, had disappeared.
Funny the parts diagram does show a hanger bearing but it is not referenced per part number. Well I did find my diff. seal leak.
Now back to the vibration. I am still pretty sure it’s tire related. My tires are one direction low profile tires so they tend to be more susceptible to flat spotting. My next step is to inflate the tires to the maximum allowed as posted on the sidewall and driving for at least 100 miles and see what that yields.
Good luck. I hope you find the solution.
Hi, dont know if this is fixed, but if the car is a convertible, I may have a suggestion. Mine is a 97 XK8 convertible and I had all sorts of vibration problems… tried tyres, new wheels, special balancing, shocks, tail shaft… all sorts of things.
Quite by accident I removed and refitted the cross brace under the front of the car…problem gone. turns out it was just a little loose. This may help you…if its a convertible with the brace.
cheers
Morro
Motto,
Interesting I’ll have to check it out tomorrow. I did find a little too much end play in the rear bearings so that’s on my list as well. Thanks.
Mark