I have seen a number of times in these forums, and I've done it myself more than once, most recently over in the XJS section, various Jags stored for various lengths of time on jack stands placed properly under the jacking points.

Having been under my car more than once (as have we all), both front and rear, and having observed the relatively flimsy way in which the suspensions are attached (especially the rear), my question is, What kind of tension stresses does the practice of Long Term storage in this manner put on the rubber-bonded V-mounts both front and rear? How long before the rubber fatigue sets in (as they're designed for Compression and not Tension) and cracks begin to propagate unseen to the naked eye?

I'm sure the owners are concerned about flattening their tires and sidewall cracking, but I wonder if it wouldn't be a better idea to place stands under spring pans of shock absorber (damper) mounts if the car will be suspended for some months.

I'm certainly giving this some Serious thought for the next time I have Nix jacked up for extended storage (which I do hope isn't anytime soon!).
(';')

 

The front subframe has safety bolts in the V mounts (the rear mounts of the front subframe) and the front two are the six shot rubbers. Therefore the rear mounts are not having the rubber stressed as the safety bolts take the weight. The 6 shot mounts are probably no more stressed (albeit in the opposite direction) than when the car is on its wheels, as the weight of the chassis goes through them when the car is on its wheels, while the weight of the engine/gearbox is on them when the car is on axle stands under the jacking points.
The rear is something different; the four subframe mounts are not designed to take tension, and unlike the front subframe V mounts, have no safety bolt though the rubber to the metal outers. So when the car is on its rear jacking points the entire weight of the rear axle assembly is being held in place by about 24 square inches of rubber bonding (6 sq ins per mount)!
So it is very important, at least at the rear, to place axle stands under the lower wishbone as far outboard as you can. There have been cases of the rear axle falling out of the chassis whilst the car is on a 2 post lift. Some garages always place a wood beam vertically under the rear subframe when the car is on a 2 poster. What i do (having foresworn the cruise on retirement in favour of a 2 post lift - he said smugly!) is to place the rear arms of the lift under the radius arm big end, slightly rear of centre, as this then does much to support the cage.
In your place (guessing no lift, LnR?) either use stands under the suspension front and rear, or just pump 45 psi into the tyres, which will prevent flatspots and is much easier!

 

Elinor:


Makes a lot of sense to me. As best as I can remeber, I have never put jack stands under the jack points.

And only on occasion used them to jack up the car. I use the front cross member/ And, not quite kosher, the center of the rear cage.. Adding jhack stands as needed at the corners.

When feasible, I like my ramps !

Off topic!!!!

I won the months long printer war. My new Canon TS 3520 is on line and works!!!!

Nw to shuffle stuff around in my "office" to make room for it. going to grit my teeth and dump some stuff. An ancient no worig printer nd a leaking ancient FAX machine. The latter about 20 yeqars old.

 

I *Knew* that!
I can only plead momentary stupidity and caffeine deprivation for forgetting that little detail!

Thank you, Greg (she said sheepishly). I doubtless will remember all this.

I hope our good weather holds so I can get a few hundred more miles before I have to jack it up again.
(';')

 

Rubber is really poor at taking stress in tension, so I certainly would not let my suspension hang by the mounts alone. I either inflate the tires, or for very long term storage see if you can find a set of old wheels and tires that would be used just to hold the car for storage, not for being driven on.

 

Greg
thats very interesting. Are you saying to put the rear jack arms of a 2 poster on the axle suspension area?
Can you show a diagram where exactly perhaps.

Regards
peter

 

In the photo you can see where the arms are placed, just a bit rearwards of the large bush on the radius arm.

This helps support the rear axle assembly. If the car is to be supported on axle stands, then I would place these under the rear lower suspension arms. Hope this helps!

 

That has to be the cleanest underside of a Jaguar ever!

 

That is a photo taken at the end of my 2 year rebuild in 2011. It isn't so clean now!

 

There are some Jaguar shops, such as David Marks in Nottingham, who would say never put one of our cars on a 2-post lift or anything that leaves the irs unsupported. And, if you do, then don't go under the rear of the car or any where near!

I'd do like Greg, put the stands under the front wishbones/spring pans and as far out as possible under the rear 'wishbone.' If the car is sitting for a long time, it's best for suspension bushes etc to be as close to their normal, on the ground position as possible.