first test drive results after MOT and repairs.

So, finally it happened. I made a small testdrive last weekend. First thing I did was driving to the gasstation for a wash and a fill up. On the way I already noticed a strange feeling in the steering like it was pulling on it and occassionly also a vibration and a weird wobble effect on the wheels at higher speeds. 

My gut feel said something was not good. But first I had it washed.

And next fill it up. My son was accompying me and drove along with the 400. In fact we made a small tour beforehand as I had not used it for a while.What a great combo and totally a different car in looks and handling but both true GTs. I did post this photo in the 400 FB group and some owners responded to it and mentioned they had the same pair in their garage. 

The first thing I noticed is the fuel gauge was stalling and still remained at 20% or so. Sigh! It´s an item I had fixed ages ago, see this blogpost:

https://erwinxjs.blogspot.com/2016/09/eureka-fuel-gauge-repair.html

In any case, I drove back via a different route and went via a small section on the highway. But above 80 kmh the XJS became very shaky and bumpy. It almost felt the frontwheels were falling off. I was shocked, it never had behaved like this before. What happened?

I feared something was still wrong with the new gearbox spring seat rubber which was done last year:

https://erwinxjs.blogspot.com/2025/12/gearbox-spring-seat-rubber-mot.html

Perhaps the new rubber made it all worse and thats why it was missing in the first place? Then again, the knocking noise was gone - although it was now nearly impossible to detetct due to this new issue. Then I figured it might have been the steering rack or powersteering pump playing up. I recall the mechanic mentioned he had cleaned up oil dirt and filled it up. Maybe it had to much oil fluid? Perhaps thats why the steering felt strange. As said, it felt like the steeringwheel was pulling a little and at higher speed it became uncontrolable as the front suspension and frontwheels became shaky and bumpy. 

So I had checked the fluid level first but it was spot on. I checked the wheel nuts but these were firm as well. I still suspected the gearbox mounting somehow. Perhaps it was not fitted correctly or the spring broke somehow. Hard to believe though. So I parked it and kept wondering about it.

Could it have been something with the front suspenion, stalling brakes or a shockabsorbers? Again, hard to believe as I had tackled the front suspension and frontbrakes, ie the ball joints:

https://erwinxjs.blogspot.com/2017/03/upper-and-lower-ball-joints-replacement.html

Also the shockabsorbers are solid and functionality as I could test on various road speed bumps. 

Then I figured it might be the propshaft u-joint. I had looked into this before but never carried out this job. See these blogs:

https://erwinxjs.blogspot.com/2017/04/u-joint-diagnostics-propshaft-xjs.html

http://erwinxjs.blogspot.nl/2017/04/u-joints-propshaft-replacement-attempt.html

Then again, if this was really the case I would not expect this would have such dramatic effect on the front suspension as I was having now. 

Over a good night off sleep I potentially figured out another candidate for this problem. I remembered I had removed the adhesive wheel weights. Again, a long time ago I bought a spare set of rims with the aim to have these refurbished. See this older blog:

https://erwinxjs.blogspot.com/2017/12/new-used-starfish-rims-and-tyres.html

It's another job I parked and was planning to do once the car is technical sound and reliable. And a few weeks back I made a little effort to inspect the rims and clean them a little. This as the car is now finally getting into the desired state. And I had to sort out new tyres a as well if I now was going to drive it more frequently. The front wheels had back then new "Vredestein Sprint" tyres in 2015 done by the previous owner. The car more or less has not been actually driven since. Meaning the profile is almost as new but at least 10 years old. In the Neterlands there is no limit on tyre age, only on remaining surface. So am still in doubt what to do. The Vredestein Sprint classics are pretty expensive. For one pair you could buy a full new set of four instead. I also found out that Pirelli has been an official supplier for XJS tyres, so I consider that cool as well: 

https://erwinxjs.blogspot.com/2021/03/longstone-classic-tyres-advert-pirelli.html

I need to give this a little more thought on what do with these tyres.

In any case I was annoyed by the large amount of balance weights they had put on the outside on all wheels. Who are these people who do this? It's not the first time I have seen this. 

So yesterday, I had both front wheels taken off and brought them to the garage to have them rebalanced. As I had not made a photo when I removed these weights, you can see on this one the large black spot of its location

And with the new balance weight on the inside. Quite a lot, the other wheel did require less weights.
Yes, I know the wheel is very dirty but for now that's the least of my worry:

And afterwards I made a new test drive. And you guess it, it was a smooth flying carpet ride. Yes, that was the culprit. Never thought these balance weights would have such massive impact on the handling / suspension of the car. 

Another issue that became apparent is the idling is now to high, hopefully I can have that easily adjusted.

I need to souce airco filling adapters, so it's compatible for modern airco gas fill up. 

And I need to fix the fuel gauge again.

Watch this space but don't hold up your breath.