How to Torque Suspension with the Weight on the Car?

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Sep 19, 2021 | 09:48 AM
  #1  
My first ever suspension work is replacing the front struts on my 07 XKR. Going to replace those nasty shredded boots too.

Now the Jaguar service manual says CAUTION: Nuts and bolts must be tightened with the weight of the vehicle on the suspension.

How is this possible? I have 4 post lifts so getting under the car isn't an issue, but there's no way my torque wrench would be able to reach some of these bolts with the wheel on.
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Sep 19, 2021 | 10:12 AM
  #2  
well, assuming you have worked out the right distance to raise each assembly, what's wrong with using the brake disc as a lift point with an additional floor jack? you just need a reference point you can measure with the wheel on and again with the wheel off, no?
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Sep 19, 2021 | 10:27 AM
  #3  
I am on a 4 post lift with a bridge jack holding up the front wheels, so no getting a trolley jack on there. Maybe I can pick up a small bottle jack and use that to put weight there?
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Sep 19, 2021 | 04:13 PM
  #4  
Don’t know what the clearance issue is that you have, but sometimes you’ve got to get a bit creative, like use a claw-foot instead of a socket on the torque wrench, or stick the handle of the torque in a pipe to give extra length. Would using the spare tire instead of the regular tire give you more room? Don’t think I’d lift by the rotor, but under the knuckle instead. If a bottle jack will fit, go for it. Or just partially tighten stuff, come down off the 4 poster and use your floor jack (not sure if with the bottle jack or floor jack you can get correct ride height though).
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Sep 19, 2021 | 04:14 PM
  #5  
It really is the upper control arm bolt on the ball joint that has no clearance and I can't figure out. I can access the lower bolts to torque OK.
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Sep 19, 2021 | 06:03 PM
  #6  
i see the predicament. i wonder whether you can tighten just that one to spec without the weight of the vehicle on the system, so you don't have to come back to it later.
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Sep 19, 2021 | 07:20 PM
  #7  
Lose the lift and use jack stands on the front end, then pull the wheel. Then use the dolly to lift under the ball joint. Should be 15 1/2 inches from the top of the wheel arch to the center of the hub. Other choice is to have the tech torque it when you take it for an alignment check, but the torque must be done with the correct wheel height. I asked the tech to check mine last alignment check and he did them all at no cost. I gave him the specs and watched him double check me.

A note on crows feet on a torque wrench or any extension - Torque wrenches are calibrated using the center of the drive 3/8 or 1/2 inch to the center of the handle grip. Adding a cheater bar, though helpful, changes the torque spec. Same thing happens when you add a wobbly head or anything that gets the head beyond center point. So if using a crows foot, torque will be correct @ 90 degrees but will change as the wrench rotates. This probably explains it better than I am:

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Sep 20, 2021 | 04:04 AM
  #8  

it’s not that complicated, easier on stands.

the workshop manual is from fantasy land so don’t take it too seriously
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Sep 20, 2021 | 09:29 PM
  #9  
Quote: Lose the lift and use jack stands on the front end, then pull the wheel. Then use the dolly to lift under the ball joint. Should be 15 1/2 inches from the top of the wheel arch to the center of the hub. Other choice is to have the tech torque it when you take it for an alignment check, but the torque must be done with the correct wheel height. I asked the tech to check mine last alignment check and he did them all at no cost. I gave him the specs and watched him double check me.

A note on crows feet on a torque wrench or any extension - Torque wrenches are calibrated using the center of the drive 3/8 or 1/2 inch to the center of the handle grip. Adding a cheater bar, though helpful, changes the torque spec. Same thing happens when you add a wobbly head or anything that gets the head beyond center point. So if using a crows foot, torque will be correct @ 90 degrees but will change as the wrench rotates. This probably explains it better than I am:
Is it OK to use Jack and jack stands on the x150? I know I can't on my X351 XJ, because of the possibility of twisting the aluminum frame.
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Sep 20, 2021 | 09:56 PM
  #10  
Quote: Is it OK to use Jack and jack stands on the x150? I know I can't on my X351 XJ, because of the possibility of twisting the aluminum frame.
ignore all of the warnings nothing will happen nobody has ever bent their car jacking it up on one side
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