I inquired here a few years ago this very issue but never got to the bottom of it so I try again: About 10 years ago I brought my XJS to my indie mechanic and he told me my rear shocks were completely gone. He replaced them with Boge OEM and since then I feel the ride is really harsh during low speed, city driving. Each pothole make me almost bounce in my seat. I checked that the Boges had the correct part number. I also do not feel that the harshness has increased since. So before I am going to replace them, can someone please tell me what - if any - other components could contribute to the ride comfort of the rear end? Although I do not think that individual bushings could cause this I checked all and found them in good condition. Thanks!!
Tires and inflation have dramatic effects on ride. Is it harshness accompanied by noise? If so, loose shock mounts, loose pivot points, or loose items on vehicle could contribute.
Also, if a rubber suspension bushing is tightened in the unladen position, it can add resistance to compression in the suspension- front only in the case of a Jaguar…
On my other non-Jag car, I had tried the original soft Boge shocks. And I noticed they were smooth, except for potholes. I switched to a stiffer shock, Konis. They were not as bad on potholes, but you could feel little bumps in the road more (manhole covers, etc)
So my theory, the soft shocks do a lot of absorbing of the little stuff for comfort, but for potholes, they just move too much and actually crash into the bump stops on rebound, so you really feel it.
The stiffer shocks don’t move as much over the potholes, and so can absorb the rebound more without crashing. But now you feel all the little stuff more.
It is almost impossible to find middle ground. I tend to go for the stiffer shocks because I get used to the little bumps in the road, and prefer the handling.
OK Greg so what you are saying is that what I experience is kind of the normal ride quality? Indeed, I can feel every groove in the pavement…Hard to believe for a “Grand Tourer”…
Robert: I understand the tire issue and I reduced pressure to 28 lb. Minor or no effect. No noise.
Boge (SACHS) should be providing for a very smooth ride.
I have a later convertible and chose to go the Bilstein route. They are supposed to be much firmer than stock, yet, the “plushness” is still present.
Something else is amiss.
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
7
I agree – but I wonder what. Is it possible that all four Boges were somehow defective? Doesn’t seem likely. So, is it something the installer did? Doesn’t seem likely either! What could possibly have happened back there to cause a harsh ride?
If a person became accustomed to worn out shocks then new Boge…or possibly any other brand…would feel quite firm. I recently experienced this. I replaced worn out KYBs (came with the car years ago) with new Boge…and it felt quite firm.
Thank you for all your input. Yes I agree “Something else is amiss”. I guess I will take the shocks and springs out to closely inspect them. What else than springs and shocks could cause a harsh ride? Subframe mounting bushes?
Many many moons ago I bought some new Boge shocks from a fellow Jag-lover who said they were too stiff and removed them from his car after only a few days. I installed them and they were indeed quite hard.
I remember researching the part number and, as I recall, I discovered that at one time Boge offered a HD variant of the Jag shocks…and that’s what these shock were. Neither the seller nor I realized it at the time; he didn’t intentionally order the HD variant.
This was 15-18 years ago. In more recent years I’ve looked and saw no such offering in the Boge listings. I might have made some references to the experience here on J-L. I’ll search the archives. My memory is vague on the matter.
It’s a stretch but maybe you unknowingly have the HD variant?
Doug, the shocks are Boge 30D 85A. Not sure if they are identical to the 36-XXX you referred to. Are you familiar with these or do you know if there is a difference?
Don’t have a lot of time at the moment but some quick Googling revealed virtually nothing about that particular part number…other than it fits Jaguars.
From time to time, we should think “function”.
It is the springs that carry the load. Stiff or soft.
there is the ride. As the old Buicks. soft ride but wallow like a whale.
Th old sock test bounce the front or rear vigourously down / Recover in one move up or bounce down again… The difference is the shock absorber. Actually more of a regulation function
Stiff shocks can make the spring move slowly or in extreme cases almost not at all. No real suspension. Just solid.
Shocks that cam be charged with air act as over lods for what ever the sprig capacity is.
Adjustable shocks seem the ideal. Control the bounce and jounce as one desires. Soft and willowy, hard and stiff or between…
And after a lot of driving with poor shocks, a new functional set will seem abnormaly stiff.
Cuz, they are stiffer!!!
Doug: Yes, that’s how far I got on the internet as well. I also did a quick search for the BOGE 36-303-0 which I found people recommended in the archive but these seem not so popular with the usual parts stores online.
Kirbert
(Author of the Book, former owner of an '83 XJ-S H.E.)
16
Update: So after quite some reading in the archive I decided to purchase Woodhead shocks. Installation was pretty simple and the ride quality has significantly improved. I was more looking for a “Grand Tourer” style ride rather than a sports car firmness. Very happy with the ride - I should have done that much earlier!
Thanks for all your suggestions and input.
