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[manny]

Under normal load the wishbone sits horizontal. As long as the bolts are tightened in that position i carnt see what difference it makes if the strut is attached or not.?

[feeutfo]

If you apply a jack or lift under the ball joints so the vehicle weight at the front is resting on this then the suspension will be compressed by the cars weight in the same way as if the wheels were fitted and sat on the ramp. 

I think this is the best explanation as to why it is ok to torque up by the wim method (especially for a techno retard like me!)

In addition when this is done the damper is not connected to the hub.

i think what we're interested in is weather the the wish bone bush is clamped in the subframe at the same position as when assembled and on the road.

i cant see how thats achieved with the shock removed from the hub ?

I will draw some pics and do some WIM reading tomorrow so I can get the theory straight in my mind.[/quote]
indeed, i've read the roll centre piece a couple of times and dont yet see the link between matching the ride hight of the wishbone to the clamped position of the bush.

...i.probably need the pictures.

and whats up with these quotes?

[Marks DTM Calib]

Under normal load the wishbone sits horizontal. As long as the bolts are tightened in that position i carnt see what difference it makes if the strut is attached or not.?

Thats the thing, it doesn't, it differs from model to model dependent on engine fitted and suspension setup.

Mv6 is close to level....others are angled downwards (as you would expect with a ride 30mm higher)

[feeutfo]

Under normal load the wishbone sits horizontal. As long as the bolts are tightened in that position i carnt see what difference it makes if the strut is attached or not.?

does it sit level though? exactly level? bit splitting hairs to be fair, but say the cars been lowered(i know wim always ask that but as an e.g.) or has brand new shocks and springs or old tired worn out suspension. Will the chassis, and hence the wishbone angle, ride at the same hight in all three senarios? I dont think so.

It will be far closer than wheels hanging of course. But we want zero stress in the bush or as close as possible. They'll last longer.

[manny]

Under normal load the wishbone sits horizontal. As long as the bolts are tightened in that position i carnt see what difference it makes if the strut is attached or not.?

Thats the thing, it doesn't, it differs from model to model dependent on engine fitted and suspension setup.

Mv6 is close to level....others are angled downwards (as you would expect with a ride 30mm higher)

I agree with you on that one .Before strip down its would be a good idea to note angle of wishbone on the car being worked on and then set it to the same when bolts are tightened. But i still dont think its a problem cranking bolts up with strut not attatched. personally i would do it with wheels on car on the ground but thats a no go due to ground clearance. Bets on a ramp if you can. When i done mine i used trolley jack under strut and lifted it up to the load angle then tightened bolts.

[feeutfo]

Under normal load the wishbone sits horizontal. As long as the bolts are tightened in that position i carnt see what difference it makes if the strut is attached or not.?

Thats the thing, it doesn't, it differs from model to model dependent on engine fitted and suspension setup.

Mv6 is close to level....others are angled downwards (as you would expect with a ride 30mm higher)

I agree with you on that one .Before strip down its would be a good idea to note angle of wishbone on the car being worked on and then set it to the same when bolts are tightened. But i still dont think its a problem cranking bolts up with strut not attatched. personally i would do it with wheels on car on the ground but thats a no go due to ground clearance. Bets on a ramp if you can. When i done mine i used trolley jack under strut and lifted it up to the load angle then tightened bolts.

or, put it another way, when i fit new mv6 lowered sport chassis shocks and springs next week i'll need to undo the wishbone bolts to let the bush sit unstressed at the new wishbone angle, because those components let the chassis sit 15 mill lower.