I just learned side wall strength is a function of the speed rating. I had H ratings on my 98 XJ8. This may explain my front end vibrations and maybe I have damaged my car due to a combo of ignorance and dearth of $'s. I have been over looking this speed rating/side wall strength for 35years.


It had a RH front end vibration since when I bought it at 56k. I hope the V rated I am putting on today will solve my issue.


However, while it was on the lift and wheels un-sprung both front tires move some when the top/bottom and front/back of the tire is pushed/pulled perpendicularly and horizontally and no steering wheel movement. Rear wheels not movement in these axis/planes. My manual does not indicate if this is acceptable.


The ball joint connecting pieces do not move when pulled/pushed on although the RF lower BJ looks worn. I have 100k on this one.


It looks like I can change these lower BJ's pretty easy. The rest of the connections look plenty difficult.


Does anyone have some thoughts on this matter?

 

If a tire is damaged it can (and almost certainly will) cause a vibration. And, if so, then replacing a damaged tire will solve the vibration. But, if your H-rated tires are in good condition there is no reason for them to cause a vibration. IOW, going to a lower speed rating won't, in-and-of itself, cause a vibration. People do it all the time.

Speed rating isn't that big of a deal to American drivers as we seldom drive fast. Load rating, however, is a different matter....and isn't something you want to mess around with very much, as far as safety goes.



You might be getting closer to the cause of your vibration



Cheers
DD

 

Thanks Doug. I most surely noticed an increase in handing as these V rated tires are stronger and don't want to give laterally. This car is plenty heavy and wants to go straight.


The vibration is still present but much better after discarding the worn out H rated A/S P 01 Sumitomo's. They lasted the 40k miles as advertised.


I replace with Sumitomo V rated LS V's. My first impression is noticeable better handling but noisier. They are mine for the next 65kmiles so I will live with it.


Back to vibration/steering: I never knew the amount of play in the steering wheel. I thought is speed sensitive or just normal. Now I sense something awry.


Any body have an idea where I should stop with regard to the joints? I figure if I get into it, all joints should be changed while I am there. What about the wheel bearings?


I failed to describe the un-sprung wheel movement I posted earlier adequately: 12-6 o'clock - movement 0.25", 3&9 the same.

 

That's excessive for sure. Could be a 'stack up' of worn parts. Could be very badly worn bearings.

Have a helper move the wheel while you observe from below and/or behind the wheel to see what is actually moving.

Cheers
DD

 

At 100K miles, many front end components are past their prime, but with that much movement it is highly likely that your wheel bearings need to be replaced.

The inner and outer tie rod ends are also worth inspecting for any noticeable play.

Any of the good independent Jag parts specialists can supply the ball joints, bearings, etc. at reasonable prices. Check with our forum sponsors Coventry West (just east of you in Lithonia), SNG Barratt, Jagbits, and Welsh Enterprises, and RockAuto is now carrying a lot of Jag OEM parts. The one thing I can't recall is whether the X308 lower ball joint can be replaced separately or if the entire lower control arm must be replaced.

If you can replace just the ball joint, the original joints were probably made by Lemfoerder and that's the brand I would personally seek out.

The original wheel bearings were probably made by SKF, Timken or Koyo, and those are all very high quality and inexpensive if you shop around.

Cheers,

Don

 

Before I bought my 2005 XJ8L in 2009 I did some research on it the day earlier. I deduced that the one I was looking at used to be a limo some 200 miles away. The lower left side ball joint had given way and dropped the chassis to the ground, scored the undercarriage and thereby ended it's usefulness as a limo. This would be a major concern of mine as I believe you have to replace the entire arm to replace the ball joint (unless you have the know how and a source for a new ball joint).

 

Disregard

 

and be careful of Ebay! I bought Two supposed Timken bearings. Same box but different stickers. One bearing was stamped SKF and the other had no markings. So I returned it and got another SKF