Sorry for being long winded in this write up. Like many on this forum, I have been experiencing a vague and difficult to describe steering issue with my XK8. In general, the steering feels ok when on a flat/smooth straight road with a consistent crown, and on the highway at speed. Yet around town, if the road is bumpy, irregular, and or when the crown in the road changes significantly, or even when crossing a painted line (lane lines) going in the same direction of the car, the steering feels lose, sometimes even like someone is pulling on the wheel (this is particularly noticed with significant and sudden crown changes). This “pulling” of the wheel though isn’t like a toe issue, it is more like something is lose, and the pull stays there, and I have to keep slight pressure in the opposite direction on the wheel, and it stays like this for a bit, then it just goes away and all is normal again. I would not describe the issue really as the feeling I would get if the alignment (toe) is out, as that generally is more of a “wandering” feel in my experience, and none of this seems to happen when the road is smooth and consistent.

I have had an alignment done twice; the car did this with the old tires, and new ones I put on. I had the shock top mounts replaced with Jaguar parts, as the shock mounts were very worn. The new mounts seemed to help a little, for a while. All bushings and ball joints seem ok. Again, like many on the forum, all suspension components on the car seem ok and no one can really pinpoint any cause.

Even though I had the top shock mounts replaced, which clearly were worn, I have suspected that the cause of the problem was related to the mounts anyhow. Clearly when pushing on the car sideways and bouncing the car up and down, the top of the shock rod that comes up through the top of the mount can be seen moving around up and down and side to side. I have suspected that the top of the shock moves around in the mount while driving, and especially with road irregularities, resulting in “steering angles” changing somewhere within the suspension. This is of course only my theory and there is no science in this conclusion.

Based on this theory, I fabricated a top shock plate for each front shock to help stiffen up the mount. The plate sits on top of the shock tower. I simply removed the 3 nuts (and pulled up the brace that’s also attached to the firewall), installed another nut onto the shock rod (to allow the plate to push down onto the shock once the plate is installed), dropped the plate on top, reinstalled the brace and the nuts. When tightening the nuts, the plate conformed somewhat, and clearly pushed down onto the shock mount and pushed the top of the shock down. I did this with the front wheels off the ground.

I can say that without a doubt this has made a HUGE improvement, and frankly, I can’t really feel any of this vagueness I have tried to describe above. There is no doubt that the steering wheel doesn’t “give” at slow speeds (20-30 mph) when on a curve and I hit a small bump such as a man-hole cover. There is no doubt that the ride feels more controlled, and clearly gone is this pull that happens particularly when the crown in the road changes. Overall, the car drives differently; I am no longer fighting or having to pay attention to the steering and wondering when I will have to correct the wheel.

I would guess there are some that are reading this that may think this is not possible based on the way the suspension and steering is designed. I get it, and I probably would be skeptical too. I am sure also that some may think this could just be masking a worn part somewhere, and maybe that is true, but that is ok with me if true, since I don’t know what is (or may be) worn. And since the issue is resolved, all is good as far as I am concerned.
I have attached the technical drawing for the part I made, and a photo of the plate installed on drivers side. Of course, I have installed one on the passenger side as well; I just didn’t feel another photo was needed.

 

Years ago, Ford had this problem with their big cars. turns out the steering rack was pulling and to fix the problem they rplaced the steering rack. |something about internal pressure leaks that caused it to pull.

Hope this helps. I can't remember how they tested the rack for the internal leak.

Opps, did not read to the end. sounds like I spoke to soon, yoou had it under control Congrats on the fix.

 

I wonder if this addresses my earlier post about XKR front suspension and steering are not fundamentally jiggley.

How do I go about having this made for my 2002 XKR? I want to have it installed and see if that improves things.
NICE JOB!!

 

I have felt that "looseness" when going over uneven pavement on a freeway or at freeway speeds, it feels like the steering rack is loose and bouncing around. I'd love to try a pair myself. Good job.

 

Better to be long winded than incomplete

Your solution is almost certainly the first to take the described approach on JF. It certainly seems sensible.

How is the noise transmission?


++

 

Thanks for this, I have that same vague not entirely connected to the road feeling sometimes.. If you ever get time a step by step for this would be amazing! Nice work!

 

Steve,

Kudos to your ingenuity and willingness to think and act outside the box....

Are you interested in fabricating and selling pairs of your top shock plate design to interested forum members?

 

Steve, Awesome! And WOW, thanks for the detailed dimensions on the PDF!

 

I have also felt this "looseness" in the steering. Did you make these plates yourself or did you have them made? I'm interested in performing this fix on my car and it looks like several others are as well. Perhaps you could get a number of sets of these plates made up? I would be more than happy to pay you a reasonable price. Thanks for sharing your solution.

Mark

 

I have noticed no change in road or suspension noise at all.

 

Thanks to everyone for your comments. I spent all day today driving around town doing errands, shopping, etc and I can't explain how much more enjoyable the car has been to drive. As I said in my first post here, I don't know why, from a technical perspective, this has made such a difference, I have my theory only as described in my first post... and so I can't tell anyone here if it will make a difference in your car, but I sure am curious.

As far as me having some made and selling them, I am not really interested in that. I provided the PDF drawing which is all any machine shop will need to fabricate these. The shop I used really doesn't normally do small jobs, but they are local, and I think they charged me more than what others probably would. I paid $238 for the pair. I don't mind anyone else using the drawings and having some made and resell, it's all free to anyone to use. I know that many of you could probably make them up yourselves if you have a bandsaw with a metal cutting blade.

I will write up some more detailed install instructions, at least provide my opinion on how best to install, and some options you have.

Steve

 

Interesting solution Steve, something I might have to consider...
My 1998 XK8 also suffers from what I perceive as excess wandering on uneven roads. It almost feels as if it is toed out, as the car will follow almost any imperfection in the road surface. I checked out my top shock mounts and they are in good condition. I replaced the top suspension bushings (they were worn and needed replacement) but with no discernible improvement in steering. All other ball joints and bushings appear to be in good condition.
I had the steering realigned a year ago and when I reviewed the sheet from the alignment shop I noticed the Caster angles were a little low. Specs call for 5.9-7.3 deg left front, 6.6-8.0 deg right front. Mine were 5.9 deg left front, 5.2 deg right front.
I took a look through the forum and reviewed the alignment sheets reproduced in the threads and noticed all the XK8’s seem to have minimum caster angels similar to mine. It occurred to me that increasing the caster angle would help stabilize the steering. I ordered new shims and installed them so as to maximize the caster angle without doing anything else to the suspension. I noticed a definite improvement during a test drive, but it still does not quite track like my Audi’s do.
As I said it still feels as if it’s toed out so I’m having that checked again, and will ask the shop to align it with a greater toe in than the current set up. Specs allow 0.04-0.21 deg for both fronts, mine are 0.12 deg left front and 0.14 right front, I will ask them to adjust it closer to 0.20 deg both sides. I had intended to take it to the alignment shop yesterday, but the threat of freezing rain put an end to that plan. I will be taking it in on Monday,
I should know my new Caster angles by Monday evening, and if anyone is interested a subjective report on improved steering (if there is any improvement!).
Regards,
White Bear.

 

Step by step install

Once I had my plates in hand, I rustoeum primed then painted them and let the dry.
The next day installed them. Some things to understand first, which you will need to know when installing.

- look at your shock tower from the top. Remove the plastic cover if you have them. The top surface of the shock tower is flat, but there is a raised ridge or lip around the edge of the hole where you see the top of the shock rod and nut that holds the shock to the factory shock mount. This ridge is not an issue (I had once thought about machining my plates with a groove for the ridge but decided against, it isn't needed with 1/8 inch sheet steel, as you will understand below).

- Now look at the nut that secures the shock to the factory mount. The top surface of this nut may or may not be at the same level is the lip or ridge around the hole. If your shock mounts are very worn these may be at the same height. For me, the nut was about 3mm lower that this ridge.

- Imagine the top plate sitting on top of the ridge, not fastened with the nuts. There likely is a space between the top of the shock nut and the bottom of the new plate. If so, the new plate does nothing. A spacer is needed to take up this space, and when the new top plate is secured, it will push down, pushing the top of the shock downward toward the ground, and thus, the entire factory shock mount is also pushed down, which is the intent of the new plates. For me, the spacer I used was another nut on top of the nut that secures the shock to the factory shock mount.

- Once the correct thickness spacer is determined, the new top shock plate cannot just be placed on and secured, because it would be too difficult to tighten the nuts holding the plate down because of the weight of the car. So what I did was:
- remove the 3 nuts holding the factory shock mount to the shock tower. The brace to the firewall on one of the studs just popped up for me without difficulty.
- place the spacer that was decided was best, then place the new plate on the studs. It will not sit flush on that ridge around the hole if the correct spacer is there.
- next I used a hydraulic jack to slowly lift the front of the car up until the new plate rested level on the ridge. As the car is lifted slowly, the shock and spring assy will lower accordingly. Don't just lift the front wheel off the ground, as I suppose the shock/spring assembly could come out and that's not good. Just lift the car a little bit until the new plate rests level on the hole. Now secure the new top plate onto the studs with the nuts removed earlier. Tighten to whatever factory torque is recommend, I don't know what that is. Don't over tighten and break the studs. Slowly lower the car and remove the jack. Re check the nuts to be sure they are tight. Do the other side.

When the new top plate is secured in place, the shape will conform somewhat around that ridge or lip around the hole, this is ok and expected, it no longer is completely flat due to that ridge around the hole.

I had my plates made with a center hole. The shock rod doesn't protrude through the hole, it is just under the hole. I made the hole for 2 reasons: to see where the top of the shock rod is; and in some applications I can imagine the shock rod may protrude, but, it really shouldn't if the correct spacer is used.

 

May we have the name of the shop that made them for you? Perhaps they'd be game to make more of these as I'll bet there are at least 5 of us who'd like to buy them.

 

Certainly, here is the link.

Machining and Manufacturing | Sohacki Industries - Saint Augustine, Florida

They don't deal with the public much, so I had to create a po number and paid by check only, no credit card capability. PM me and I will provide contact info at the machine shop

 

Count me in and I'd wouldn't mind spending $250. It would save me trying to find a machine shop in my home town.

Mark

 

Very well explained, Steve. I will pick up some plate and make a pair. The best part is, if I don't notice a difference I can remove them and no big loss.

 

I may give this a try also. I think I know a machine shop that will do this custom request. .

 

might as well be stainless

 

Now that I fully explained the install process and there has been time to digest what is going on, one can see that this pushes the entire factory shock mount down - toward the ground. If my thinking is correct, there are a couple of things happening here, one, I think the ride height could be raised a bit, as I think it acts the same as if a spacer was installed on top of the factory mount between it and the underside of the shock tower, or, as if a new factory shock mount were installed to replace worn mounts. new mounts are thicker than worn mounts and from what I have read they do restore ride height. Again if my thinking is right, such a spacer would not only raise the ride height, but correct camber issues caused by worn shock mounts or worn springs. My idea with the new top shock plate is to "in effect", install that spacer from the top, without disassembly of the suspension. In my installation steps, I explain that a suitable spacer is needed between the new top plate and the top of the shock mount, and that I simply used an additional nut on the top of the shock rod for that spacer. Because the fist nut secures the shock to the factory mount, pushing down on the top of the shock rod does push down on the factory mounting plate too. With all of that said, we also know that the factory shock mount is rubber, therefore compressible. So, the installation of my new top plate must also squish or compress that rubber, therefore stiffening it up and making it less flexible. Less flex may be a factor to improved handling as well. In theory, if the spacer used under the new plate is thick enough, it would also push down enough to correct camber and Restore ride height. Therefore, different thickness of spacers should produce adjustable results. I suggest trying out different spacers, and checking ride height before and after installation.