The XJ40 has a tendency to eat shock bushings, especially the top bushing on the left side of the car. Some people believe the heat from the coolant reservoir leads to the early demise of that upper bushing.

So a nice gent sent me (for free / I paid for shipping) some black rubber bushings. The kind you buy on the high performance online shops.

I have some of the yellow OEM bushings in hand, also the black ones. Which to use?

From my research, a harder bushing will not allow denting of the bushing and will transfer the efficiency dampening to the shock, allowing the shock to do what it is to do, control the movement.

The harder bushing will transfer more noise.

The softer bushing will indent more and some of the work load is transferred from the shock to the bushing. You'll have less transfer of noise.

If I use the black harder bushing will I even notice the increased noise?

I wonder how many people are driving their XJ40 with bushings that are already close to failure, crumbling into pieces.

Usually people don't notice until they hear the telltale clunk noise. How long where they driving without their shock obtaining the maximum control of the car?

I think it might be better to have a bushing that isn't going to prematurely die, a bushing that will transfer maximum work load to the shock.

Yesterday for fun I replaced the top yellow OEM upper bushings with the rubber black bushings. I installed the new yellow bushings last week so they are new bushings. I only did the top just to see if I would notice any difference in vibration transferring into the cabin. I didn't notice any difference in vibration.

My next test will be to go to the curvy country road and give it the pedal to see how it handles the curves.

Any ideas on this matter?