70 series control arm loading question

[SonicAdventure]

I am about to replace lower control arm on my 98V70 n/a, and I have a question about "loading the suspension prior to final torque.

In RSPI's video on YouTube, it looks like he jacks the ball joint end of the arm to be about parallel to the frame rail that the other end of the arm is attached to. It looks like he leaves the sway bar link attached while he does this.

In FCP's video on YouTube, Ben removes the top sway bar link nut from the strut tower, and it looks like he jacks the ball joint end as far as it will go, to a point where the ball joint is way higher than the frame rail before setting the frame bolts to proper torque.

Is there a set rule on how to do this? Both of these video providers have considerable knowledge of the cars, yet they are doing it differently. Is there a right or wrong here?

[RussB]

I connect everything (like sway bars) and drive up on ramps, then tighten the control arm bushings

[tryingbe]

I connect everything (like sway bars) and drive up on ramps, then tighten the control arm bushings

That's also how I do mine on all my cars.

[dosbricks]

On both my cars, I jacked it up until the arm was level as per rspi's video and other DIYs. No problems. I did pad the ball joint with a piece of soft wood while jacking it up. If the sway bar link is connected, the other side probably should be together and the tire on the ground. I did mine with both sides dissembled and the links disconnected at the top because I was doing a full suspension rebuild. So just depends on how you approach the job.

Anyway, if I tried to jack the arm higher than level it would start to raise the whole car off the jack stand on that side.

[cn90]

1+,

However...

1. If you loosely attach the bolts, drive up the ramps and tighten them, there will be much less room to play with the wrench. It is doable but tight.

2. The other "proper" way is to measure things before the job.
In most stock P80 cars, the distance from fender to center of axle is about 15 inches.
So when you tighten the control arm bolts, just follow this...

PS: You simply cannot "overdo" this, once you jack it up to about 15", no matter what you do the car will keep going up in the air!
In other words, you cannot get it to 13" or 12".

[Ozark Lee]

I just jack it up from under the ball joint as high as it will go before it starts to lift the car off of the jack stands. That puts the center of the hub about even with the bottom door seam. Driving it up on ramps I suppose will work but it is a bear to get in there with a big torque wrench with the wheel on.

What you don't want to do is torque it down with the control arm dropped all the way down.

...Lee

[SonicAdventure]

Thanks for the feedback everyone.


I have to knock this repair out by the end of next week. I feel more confident now. Have a good one

[Clemens]

@ OzarkLee:
Why is that again you don´t want to torque it down with the arm dropped all the way down? Will it seriously unscrew the bolt?
I raised my control arm a few inches before torquing it down, but I thought a jack failure would be ugly with suspension components under load involved. This was like 2 months ago and the bolts are still in there.

[Ozark Lee]

@ OzarkLee:
Why is that again you don´t want to torque it down with the arm dropped all the way down? Will it seriously unscrew the bolt?

It isn't the bolts that are the issue, it is the bushings. This is only relevant to the FWD versions but the bushing should be at, more or less, its relaxed state at the cars normal ride height. If you torque them down with the controls dropped down the bushings are constantly loaded torsionally and it tears the rubber up quickly.

On the AWD cars the bushing preload is baked into the cake so to speak since they bolt to the subframe rather than through the ears off of the subframe.

...Lee

[Clemens]

Thanks, I got the impression it was because of the nut unbolting from watching the fcp video.