I installed my coil over kit about a month ago now. Don't get me wrong, it still drives great. Its a Jag. I have noticed some issues, one of coarse is now the suspension is not a active suspension. The suspension no longer has control of the squatting of the car upon hard acceleration, and it does roll more in corners now. These issues I can get past since I don't have any real urge to race the girl. One issue I am having that is really, REALLY, bothering me is that for some reason, when, at certain speeds, when I hit hard bumps in the road and large speed bumps, I am getting a VERY large banging sound in the front of my XJ. Just for the record, it is a 04 x350. I have examined the suspension, checking the torque specs on "all" the suspension hardware, checking my ball joints, control arms, tie rod ends, and sway bar links. The boots for the majority of my ball joints have broken down and are for the most part gone. I took my car into the local Jag dealership for a recall and they did a vehicle inspection and all my suspension parts were in specs to them as well. They told me that all my ball joints/tie rod ends are tight and have minimal play in them, suggesting that they are still serviceable (other than the boots). They didn't even try to sell me new ones to fix the worn boot problem. I then got home and did my own inspection and noticed a very small scrape on my right upper control arm, right at the edge of the ball joint. My concern is, since there is more suspension travel now with the coil overs (a more bouncy ride) is it possible that my upper control arm is slamming into my wheel well? Any thoughts on this matter or suggestions?

 

A scrape on the upper wishbone should be matched by a similar scrape somewhere else, but surely the inside of the wheel rim covers the end of it ? Putting the wheel back after fitting the coilovers could have resulted in the wheel banging on the front of the wishbone, so nothing serious, I would have thought.

There should be a bump stop somewhere; on the air springs it was internal I think, but probably you no longer have one on your car.

BTW I get a loud bang from the REAR when I go over similar bumps, but so far nothing found ! Mine is still on air springs

 

I would find some way to "cycle" the suspension.. back when I was in the 4 wheeler world we use to "flex" out the vehicle to find where suspension parts rubbed or came apart..

Basically you want to jack up opposite corners of the vehicle to fully "cycle" the various suspension parts.. you may need to disconnect any sway bars to allow for full travel.

 

Great advise so far. On the note of the bump stops. There are none to speak of. I did not remove any bump stops either. I understand that the air struts most likely had a built in unit. I feel as if I should start there and install something, perhaps aftermarket stops. I need to fix this before something ends up badly damaged. Where would stock bump stops be located on the front. In the rear, there are rubber stops of some sort and on both sides my e-brake cable run trough them. Are they similar to the rear stops?

 

I just had a look at my Jaguar X350 Technical Notes, (there is a picture of the air spring internals), and can confirm that the bump stop is inside the unit just below the top mount. The air piston/shock rod goes through it and the air piston is what contacts it and eases out the bump impact. It is a circular cone-shaped rubber with a central hole for the piston rod.

I would have thought Arnot would have made sure something similar was installed, as these coil-over things are essentially the same as McPherson Struts used in thousands, even millions of cars, and they will all need bump stops

 

FWIW, it looks like the units for the non-air suspension on the armoured X350 had some sort of bump stop incorporated in to them as well.

 

Remember MK82 and his famous thread on his coilover conversion? I remember over there that there were those of us expressing concerns on an untested, dramatic departure from the OEM setup. There are SO MANY unintended consequences that are scarcely imagined when tackling such an engineering challenge. Does Arnott have the resources to exhaustively test their solution in the real world? No. They are using "us" as the test subjects.

Tell you what: Arnott will be fortunate if they don't end up with damage claims against them. I hope for their sake, and their customers', that they have robust liability coverage.

 

I called Arnott this morning to inform them of the issue I am having with my struts and asked them about the bump stops. The gentleman I was talking to from their technical help department informed me that yellow bump stops are installed on the top of the strut assy. underneath the rubber "skirt" that is under the coil. The people of Arnott's tech help department were intrigued with the issue that I am having and are going to do some investigating, possibly sending me two new front strut units for perhaps there is a manufacturing fault with the units I received. I am waiting on their phone call. I will post their results.

 

So, I got word back from Arnott, apparently there is a now known issue with the front coil over struts that they have on the market. I was not the only individual with the same problem. They have recalled all the front coilover struts and are sending out new ones to all who purchased the kit. From what I was told, the front struts are lower than they are supposed to be and cause either the suspension or the whole front of the vehicle to bottom out. They found the weak link and fixed them and are as I said giving everyone who purchased the kit the new struts, no charge. I am glad that they are standing behind their products. I receive my new struts on Tuesday, I will post the results on whether the problem is fixed or not. Wish me and the cat luck. Good day.

 

So...........

As the motto of the old BSA company used to run (maybe !!)

"Every customer is a tester"

 

And are they rebating the installation costs as well for those that paid out of pocket and not skinned knuckles?

Arnott has a bad rap at eh Lincoln Mark 8 site...

 

Well, they did not mention anything about that to me. Give em a call.

 

Has anyone found out whether or not they are going to rebate the cost of labor too?

 

I doubt they or many companies would rebate labor costs, but at least they are sending a corrected unit without jumping through hoops.

 

I wonder if Arnott should come up with a network of authorized installers such as TireRack has. For those such as myself who are too busy/lazy/clueless to do the work themselves. Granted administering such a network would be a chore. OTOH Arnott does apply these products to several different automobiles; the market could be considerable.