Proper control arm preload

[67Twisty]

What's the best way to tighten the UCAs at the correct torque and with the appropriate preload? I used the angle measurement to the top hat (70 -81 mm) from the service manual and a proper torque wrench (Bentley says 50 nm), but now the bushings are starting to fail again. I only have about 10k on these and they're Lemforder replacements. Kind of pisses me off to have to do them again.

I can't see how you could reach these bolts to torque once mounted and with the wheels back on. Maybe I could get to them with a spanner wrench on ramps, but no way I can fit my torque wrench in there. Does removing the Jack stands and jacking up the hub work any better? I'm mildly lowered but not to the point of needing adjustable control arms.

[aluthman]

Before I jacked up the car and pulled the wheels off, I measured from the top of the hub to the fender arch. When getting ready to tighten the bolts after replacing the arms, I jacked the hub up with a bottle jack until the top of the hub was the same distance to the fender arch. My FCP Euro arms/bushings are still doing great nearly 30k miles later. As for tightening the bolts, I just hulked on them with a wrench until I felt they were tight enough (calibrated arm hehe).

[67Twisty]

Do you need to let the weight of the car rest on the jacking point before tightening? I assume it's just the correct ride height angle, but does the weight/load make a difference?

[aluthman]

You need to tighten the bolt that runs through the bushing when the arm is at the angle it will be at when the car is at rest. This allows movement in each direction once tight without tearing the bushing. Thats all that matters.

[vvenom800tt]

Or just get PowerFlex bushings and don't worry about preload

[rocket1420]

Do you need to let the weight of the car rest on the jacking point before tightening? I assume it's just the correct ride height angle, but does the weight/load make a difference?

Put the car on jack stands. Jack up the knuckle until it barely starts to lift the car. That's the correct angle/preload.

[seanf86]

Put the car on jack stands. Jack up the knuckle until it barely starts to lift the car. That's the correct angle/preload.

This^^ I can't get a torque wrench in there either, I just use 2 16mm wrenches and tighten the crap out of it.

[APR_Fast]

Torque spec is 50 Nm + 1/4 turn so try to get a "gauge" for what the "feels" like...a lot easier said than done.