My 2005 XK8 (60,000 mi) has a noticeable oversteer to the left, noticeable on most roads and surfaces, often when changing lanes, and without increasing power. This is not a question of rear/front unloading. Movements to the right are normal. I have a clunk when going over bumps / potholes, and attributed that to upper damper bushings, the driver's side assy of which I have rebuilt and getting ready to install. Haven't started on PS yet. Thoughts on this would be appreciated, along with any test methods I can use whilst the damper struts are out. (Thanks to Sam and his You Tube work for guidance on that!)

 

Hi Atlastajag1,

Could you maybe say a bit more? I'm not exactly sure what your question is and I don't want to assume anything.

Please define "oversteer" as the driver (IOW, what are you seeing happen? what should happen?). Please tell us what the difference (driver experience wise) is between left and right turning.

When you mention test methods, could you tell us more about what you want to test, or test for?

When you say "damper struts" I'm not exactly sure what you are referring to. Maybe I know it by a different name?

I hope this doesn't land the wrong way my friend. I just don't want to assume anything. Sometimes things that are so obvious to you as the driver they are not detailed in your question or background description. But it may not be something we think of.

I look forward to your updates, hope we can help.

John

 

Thanks JonKen.
"Oversteer" meaning that the car's steering is over-responsive when, say, driving into a curve or avoiding a hazard. At a high enough speed, oversteer can unexpectedly induce a rear-end breakaway. Typically, a car might be criticized by, say, Road & Track as having either oversteer (or understeer), but (presumably) that would be an inherent feature of the car's design, not correctable by front end and / or rear end alignment, and would affect both left and right turns equally. In my case, the car makes right hand turns / direction changes in a perfectly predictable and comfortable manner. I know exactly how much steering wheel movement is needed. When making a left lane change however, the same amount of movement produces a much more noticeable effect. It feels the same as coming up on a car whose driver failed to use signals when stopping to enter a driveway, and having to make an abrupt lane change to the left. Except that there is no urgency; I just need to move gently to the left lane, but it feels like I have turned the wheel more abruptly.
I use the word 'damper' because I am both a Brit and an engineer, and the telescoping device in the middle of the spring is for damping spring movement, not for absorbing 'shocks'. Shocks are the more casual term, particularly in the US. My apologies for not writing more plainly. The strut is (to me) a term implying a structural component, such as a Macpherson Strut. Dampers / shock absorbers do not have to be structural, and although the XK8's 'coil-over' arrangement looks like a strut, I think the presence of upper and lower control arms (wishbones) mean that it isn't really a strut. Just my opinion. Regardless, that coil-over damper arrangement comes off the car in a unit, just like a Macpherson strut does.
I should also have mentioned that there is no observable tire wear on any of the tires. Also, the car does not wander off course on a straightaway; I don't have to make unusual corrections. The suspension does have a clunk that appears to be on both sides, and which is the reason I am working on the 'shock' bushings.
The 'test methods' question referred to - once having more of a clue than I do at this point as to the cause of the left oversteer - what physical tests / examinations I can perform whilst the car is having its coil-over assembly upper and lower bushings changed. I don't want to take the car for an alignment check - all four, no doubt - if I have a worn (fill in the blank) component that needs to be replaced. The question is, then, once I 'know' the cause(s) of one sided oversteer, then how can I locate that defect. I hope that all better explains the situation.

 

The symptom sounds like a worn tie rod end ball joint. When you steer left the rack is pushing the joint and when the wheel begins to turn the tire moves left and then rapidly takes up the small amount of wear and it feels like you turned to hard.
Have someone move the steering wheel gently back and forth while you observe the tie rod. Do you detect a slight amount of rack movement with no tire movement?

 

How many miles over what road conditions, and any replacements in service history are all relevant, but no amount of guesswork will avoid hoisting the car and testing every part of the PS rack, suspension, dampers and wheel bearings.

Only then can you budget your expenses and priorities.

Cheers,

Ken

 

Reminds me of when my son race stock cars when he was young. For an overseer, loose condition, I would take cross weight out of the car or go down on the track bar. Since we don't have those adjustments in our car then you have a suspension component that is bad.

I'm not by any means a suspension expert here are my ideas on trying to figure out the problem.

With the car parked and engine on turn the steering wheel to the left and right to see if you feel any play in the steering, or in the body of the car?
From the outside of the car push on the front of the car sideways from both the left and right side of the car. See if you can feel any movement in the suspension. Repeat for the rear of the car to see if could possibly be the rear of the car. If you feel movement in the suspension you might need a friend to find where the movement is while you are pushing sideways on the car.
It possible that you upper shock mount is warned that it not only is giving you up and down movement causing the clunking, it could be giving you left to right movement giving you the feeling of oversteer.

I repeat I'm not a suspension expert but these are some of the things I do when trying to diagnose a suspension problem. Not a guarantee it will find the problem but it doesn't cost anything to try.

 

Many thanks to all for replies, and apologies for delay (due to trip). Will be back on it Wednesday, and will advise as to findings. Current plan is to fully test the mechnical parts of the drivers side, as possible before replacing the coil assy. Then doing some heave-Ho with the wheel in place, before moving over to the PS, where the problem is thought to lie. I'll do the Heave-Ho before pulling the spring/damper this time. Stay tuned!

 

. . . and not just the heavy handed heave-ho . . . although that and judicious use of a jemmy bar (pry bar, crow bar?) is a good aid too. Remember to use a firm but gentle (?) rocking of each suspended wheel while listening for clicks, groans and knocks . . . 6 & 12 o'clock for wheel bearings . . . then 3 & 9 o'clock for steering linkages.

I suggest you pay special attention to the top mounts for springs & dampers - well known here as points of failures - also known for premature failures if installed incorrectly.

Finally, please report back your findings. You have done a fine job in reporting the symptoms & prevailing conditions (as distinct from "torque steer" which usually points to rear suspension) so marrying your findings & fix to the symptoms & conditions is valuable data for us all.

Best wishes,

Ken