XJ XJ6 / XJR6 ( X300 ) 1995-1997

Unstable at high speed

 
  #21  
Old 06-16-2017, 04:09 PM
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Originally Posted by countyjag View Post
I have been following this thread with interest, and on the one hand can see that you have been offered much well intentioned and good advice, but on the receiving end it might all be a bit confusing and depressing!
Before throwing in the towel and handing the car off to someone else to "fix' i wonder whether it might be worth another attempt to more accurately diagnose the problem.
You say that everything is fine up to 60mph, which I would take to mean no knocks, rattles, vibrations or waywardness in the steering. You have not mentioned any knocking or rattling over bumps. At face value, this is good, and starts to point the finger away from the dreaded topic of bushes!
You mention that an upper ball joint is worn. I would replace it without delay, as it is cheap and fairly straightforward to do. If it isnt causing a problem up to 60, I doubt that it is the culprit, but it needs fixed, and is a distraction.
You mention that by 100mph, the problem is fully apparent. Do you have any recollection of how it was at 70? 80? 90?. I am not advocating that you drive it at these speeds again, as it all sounds rather dangerous, but if the problem came on progressively, I would start to think of the variable assistance aspect of the steering rack. In short, the amount of assistance is intended to vary with speed, the faster you go, the less assistance you get. If there was something sticking in your steering, you might be able to turn the wheel through it with power assistance, but not without. So when you reach a high enough speed for the power assistance to diminish sufficiently, the steering becomes sticky to turn. If you can jack the car up with both front wheels off the ground, you could try moving the steering from lock to lock with the engine off, to establish whether there is full range of movement and it is smooth.
Another thought might be to put the car in for whatever for of government inspection you have. I sometimes put a car in for an MoT test here, as it is a cheap way to get the brakes, ball joints and bushes etc checked over by an expert
That's a very well thought through reply and a very appreciated one. I have already received the new ball joint and bushes for the upper wishbone but the job is a little bit more advanced than my previous repairs so I'm a bit reluctant to start.
The car already passed it's MOT some months ago and they didn't comment on any of this even though they were thourogh. Had some issues with high Co reading but that is fixed and another story.

A friend of mine has some experience and I'll probably try to sort this with his help. Hopefully soon.
I did btw notice that the famous edd China from the BBC program wheeler dealers has now married a girl from Norway, so maybe I can lure him here to come and restore this British icon, now rolling through the streets of norway😂😅😊.
 
  #22  
Old 06-21-2017, 03:19 PM
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We just changed the ball joint and the upper wishbone bushes . It definitely helped and totally removed a clunking sensation at the steering wheel. Do I need a new alignment now? We did rearrange the shims to match the illustration from the technical drawing though as they were placed in different order.

One new in position here..It feels better now but the steering is still vague at high speeds. It does not drift as easily but small corrections on the steering wheel aren't always noticed until it suddenly changes direction just a bit too much.
I think I will once again try and fit that nylon shims kit I purchased for the steering rack..

Drove it to work and tried to race the train as well.. I lost 😅

 
  #23  
Old 06-22-2017, 02:33 AM
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Good job! If you were careful to replace the shims as you found them, I wouldn't be rushing to get the alignment checked just yet.
Did you try turning the steering from lock to lock with both wheels off the ground and the engine off ( i.e. No power assistance)?
It would be useful to establish that your steering has free and smooth operation from lock to lock without assistance from the pump.
 
  #24  
Old 06-22-2017, 02:41 AM
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Yes you should get the alignment checked.

The shims that you moved are for adjusting the Caster angle of the front wheels.
 
  #25  
Old 06-22-2017, 03:32 AM
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Ok thanks!

Didn't have time to check the steering but I will do that very soon. And a new alignment is coming up soon. Just wondering if I should do the same thing on the other side as well now..
 
  #26  
Old 06-22-2017, 07:31 AM
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I would definitely do both sides of the car with any suspension items! Even if the bush appears in ok condition, the rubber will have deteriorated since new and will behave differently to the replacement part.
On my XJR, have three shims in front of and one behind the top ball joint. I have a slight vagueness in the steering despite having replaced all the bushes and ball joints and correctly adjusting the wheel bearings. I plan to fit the steering rack shims this weekend in the hope of sorting it.
I know that my rear toe needs setting, does anyone know what it should be?
 
  #27  
Old 06-22-2017, 11:02 PM
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Please be aware that these shims you are discussing are of different thicknesses, namely 0.8mm, 1.2mm & 1.6mm. Castor adjustment is obtained by swapping them around appropriately back & front to get required total thickness back or front & thus obtain required castor adjustment.
The Toe adjustment for the rear is +4.36mm to -0.6mm.
I have successfully carried out my own front wheel alignment using a "Longacre" camber/castor tool & "Trackace" laser toe alignment tool & consider my steering to be spot on with no issues at all.

John Herbert
(1996 Jaguar XJR)
 
  #28  
Old 06-23-2017, 12:29 AM
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I see.. that's very useful information John. Will probably do the same procedure on the other side as well. Regret I didn't order that at the same time. I've been a good customer for DHL and fedex the last year..
 
  #29  
Old 06-23-2017, 06:52 AM
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Thanks for the info John, do the toe settings in mm refer to the difference in the separation of the wheels at the front and rear edges of the rims?
 
  #30  
Old 06-23-2017, 07:02 AM
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Also, when I rebuilt my front end a couple of years ago I bought new castor shims but only saw one part number listed - I did not know the other thicknesses where available. Interesting if finer adjustment is needed.
 
  #31  
Old 06-23-2017, 07:37 AM
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At least three thicknesses were offered...all show NLA from Jaguar at the moment. I suspect there are other suppliers

https://www.jaguarclassicparts.com/u...pper-and-lower

The shims serve two purposes-- to allow caster adjustment and to maintain correct spacing between the ball joint and the control arms.

Seems to me that the total thickness of the shim stack should be measured and maintained. You can use shims of different thickness and place them on either side of the BJ, obviously, but the overall thickness of the stack should be maintained.

Cheers
DD
 
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  #32  
Old 06-23-2017, 11:43 PM
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John XJR6 yes the mm refers to the total difference (Total toe) between the rear & front of the wheel measurement, not each individual wheel. Plus refers to Toe In & Minus refers to Toe Out.
Doug I have attached details on shims & adjusting Caster.
I did fail to mention earlier that you will also require (most important & essential actually) a pair of turntables, rather expensive unfortunately.
I have made a pair myself from suitable ply using the largest lazy Suzanne turntable I could purchase & marked them with the required angles etc.
They work fine & material cost very cheap. ( Photo attached)
My own car originally pulled slightly to the left & to correct I eventually ended up with the following adjustment which gave me approx. 5 degree positive caster each side (with in specs & giving good straightline stability)
LEFT WHEEL Total shim thickness
Front of Ball joint 4mm
Rear of Ball joint 0.8mm
RIGHT WHEEL
Front of Ball joint 0.0mm
Rear of Ball joint 4.8mm

Yes, right wheel required no shims at the front at all, you have to juggle the 4 shims to obtain appropriate thickness, and cannot use more or less than the 4 shims as indicated in the extract from a Technical bulletin.
Caster is the main adjustment that effects vehicle pulling either left or right & has a big impact on straightline stability, especially if it is biased towards the positive.
Also Dough I did take the plunge & fitted 225/55R17 Bridgestone tyres to my XJR with great results, absolutely no tramlining, slightly better ground clearance & tyre fitters commented they looked fine on vehicle. Much better suited to our Aussie roads overall.

John Herbert
(1996 Jaguar XJR)

John Herbert
 
Attached Thumbnails Unstable at high speed-wheel-alignment-turntable-medium-.jpg  
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File Type: pdf
Caster adjustment.pdf (1.05 MB, 44 views)
  #33  
Old 07-10-2017, 02:44 PM
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I'm baffled and utterly surprised now.
Returned to the garage and rented it for an hour. The steering turned smooth from lock to lock without any issues so that's all good. I brought with me the steering rack stiffening bushes again and decided to give it another go.
These nylon shims were quite flexible.. fortunately.
i thought to myself again that these could not possibly fit. And when I turned the wheel there wasn't any change in the gap.
Anyway, I decided to go for it, so I cursed and wrestled them into position more or less with some force and determination. I could not believe they would possibly do any difference at all so I just didn't care if they broke or didn't fit perfectly.

30 minutes later they were both in place, but they sat so damn tight I didn't even bother trying to attach the steel wire that came with the shims.
Not my photo but it looked a bit like this, minus the steel wire.
So, I left the garage, headed for the highway to get home, and MY God there was actually a big difference now in the responsiveness in the steering. More precise, sharper and less of that tramlining sensation. I almost believe now that I've cured this issue. I still haven't gotten a new alignment after I changed the ball joint and the upper wishbone bushes, but I guess after that it will be 100%

Very happy about this.
 

Last edited by Tcasmarcus; 07-10-2017 at 03:49 PM.
  #34  
Old 07-10-2017, 11:33 PM
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So it was really the rack moving side to side within it's mounts. That's a fairly common thing with Series III and XJS, where the rack is mounted in rubber bushes that degrade over time. I didn't know X300 had spacers too.
 
  #35  
Old 09-09-2017, 03:30 PM
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Originally Posted by Tcasmarcus View Post
I'm baffled and utterly surprised now.
Returned to the garage and rented it for an hour. The steering turned smooth from lock to lock without any issues so that's all good. I brought with me the steering rack stiffening bushes again and decided to give it another go.
These nylon shims were quite flexible.. fortunately.
i thought to myself again that these could not possibly fit. And when I turned the wheel there wasn't any change in the gap.
Anyway, I decided to go for it, so I cursed and wrestled them into position more or less with some force and determination. I could not believe they would possibly do any difference at all so I just didn't care if they broke or didn't fit perfectly.

30 minutes later they were both in place, but they sat so damn tight I didn't even bother trying to attach the steel wire that came with the shims.
Not my photo but it looked a bit like this, minus the steel wire.
So, I left the garage, headed for the highway to get home, and MY God there was actually a big difference now in the responsiveness in the steering. More precise, sharper and less of that tramlining sensation. I almost believe now that I've cured this issue. I still haven't gotten a new alignment after I changed the ball joint and the upper wishbone bushes, but I guess after that it will be 100%

Very happy about this.
hi canni ask where you buy these spacerscas mine is really badly tram lining
 
  #36  
Old 09-09-2017, 04:01 PM
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  #37  
Old 09-09-2017, 04:20 PM
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.

I thought I had mentioned the 1059 spacers but looking back it must have been someone else . Thanks for the source for Lady P has quite the gap and I knew it had to be an issue with mine . I was going to make them myself . The trick is to turn the wheel so the assembly walks from side to side in the mounts ?

Working on the Stereo LED messed up digits now
 

Last edited by Lady Penelope; 09-09-2017 at 04:36 PM.
  #38  
Old 08-14-2018, 03:26 PM
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just an update. the nylon shims greatly improved the ride. I still have a bit of a vague steering sensation because i guess the rack is worn. I now have also changed all 4 shocks and the rear spring isolators and that completely removed the feeling of an unstable car at high speeds. I guess some speeding tickets are now coming up..

Next up are all the front suspension bushings and the balljoints etc.
 
  #39  
Old 09-22-2018, 07:10 AM
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Finally started to change all bushes and bits in the front suspension. Looking forward to the next drive





 
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  #40  
Old 09-23-2018, 07:39 AM
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Quick and dirty steering rack spacer. Jack up one side of the front. Put a stand under the car. Key on but dont start. have someone crank the wheel one direction and one side will open up. (You might see if your spacers fit at this point!) I used a few plastic wire ties in the gap. Crank the wheel the other day....more wire ties. (or your spacer).

Makes a big difference.

Also check your tie rods. (Shop probably did when they did alignment but who knows?)

Look at you upper front wishbones...you will see spacer between the ball joints and the arms. Moving the spacers forward moves the ball joint aft and increases caster. Caster increases self centering feel. Usually you will find one side has all the spacers up front and the other side set to match the one that is out of adjustment. but if you find one spacer on each side the same thickness that is in the back position and you can move it to front postion and add camber easy.


Originally Posted by AL NZ View Post
which has made me wonder how a Daimler would go with XJR shocks but retaining it's standard softer springs...
Me too... (95 VDP) New rear soft bilsteins still seem way to soft in rebound. I may just swap rears.

I have a set of XJR sways I have yet to install too.
 
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