GM front-wheel-drive engines come out the bottom by lowering the cradle with the engine and transmission on it. Without a hoist you have to lift the body off the cradle. It may be possible to sneak the engine out the top but I've only seen it done that way once and it wasn't pretty.
Be aware that removing the cradle can lead to a very miserably handling car. Before you start, look for dust around the three nuts holding each strut to the body right by the rear corners of the hood. That dust will show you where to slide the struts to put them in the exact same spot later. Use spray paint to mark them if there's no dust.
Use spray paint around the four bolts holding the cradle to the body, then use those marks to line the cradle up when you reassemble it. If that cradle is reinstalled to either side, that will bring the lower control arms to the side too which pulls the bottoms of the struts, and the lower ball joints to the side. The tops of the struts stay put so this causes the struts and the wheels to tip. One strut will stand up a little straighter and one will lean over more than normal. On the alignment computer that change results in a change in "camber". That is the inward or outward tilt of the wheel as viewed from in front. Camber must be correct for proper tire wear, and it must be nearly equal on both sides because tires want to roll in the direction they're leaning, and when camber is equal the two pulls offset each other. Camber can be adjusted on the alignment computer but that will not solve the terrible handling.
The pivot points for the steering are the lower ball joint and the upper strut mount. The imaginary line drawn through them, viewed from in front, is called "steering axis inclination" (SAI). It is extremely important that SAI is the same on both sides. There is never a spec given for SAI. All that is important is it is the same on both sides within 0.2 degrees. A typical value is 28 to 32 degrees so you can see that 0.2 degrees isn't very much, but just wait until you try to drive one of these cars with unequal SAI.
Experienced alignment mechanics know that when they see incorrect camber on both sides of a GM car and there's no other explanation for it, they have to look at SAI. That shows up on the alignment computer but we rarely look at it unless we're looking for the cause of an unusual problem. On other car brands, the cradle is held in it's proper orientation by the mounting bolts or it is welded to the body and is not removable. If SAI is unequal on those cars, something is seriously bent.
If you end up not getting the cradle back in the right spot, you'll have to have the car aligned. Be sure to tell them the cradle was removed so they don't overlook SAI. If the car was in good alignment before the cradle was removed, readjusting the cradle will likely be all that's needed. That's not hard to do. What IS hard is readjusting camber on both wheels, then adjusting "toe" on both of them, test-driving the car, and then finding out SAI has to be adjusted and camber and toe has to be done all over again. That wastes a lot of time and aggravation.
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Wednesday, October 31st, 2012 AT 9:27 AM
