'77 911 DIY Home Alignment Question

[tonyduc]

All
Preparing to do my own alignment and I find that the height of the car on a level floor is about 1/4 - 3/8" higher on the drivers side both F & R (just a preliminary measurement using a tape measure to the fender well, but will double check using factory method). But my basic question is does anyone do this while the wheels and weight of the car are resting on a table type platform ? I've seen some do this while wheels are resting on a platform, others with the wheels suspended which then requires lowering and rolling the car around to settle the suspension each time. Also, does keeping the weight on the wheels make it tough to turn the eccentric bolt near the TB on the spring plate ?

Thanks
Tony

[stownsen914]

1/4" is a pretty normal difference L to R in my opinion, and I wouldn't worry about it. In fact, put some simulated weight in the driver's seat, and it might wind up level.

As for the platform, that's a fine approach if you have one, but any leveled floor is fine. Do make sure it's level though. Left to right level is more significant for setting up a car. Use a level to check, and you can shim the low side with vinyl/linoleum floor tiles like you get at Home Depot. It's common for a floor to have a 1 degree or more slant - barely noticeable, but obviously impactful to properly aligning a car.

Note that floors often have a "wave" i.e. not a simple slant in one direction. So you might need to put a different number shims under front vs. rear.

Best to unload the suspension to make adjustments in the rear. Though as you note that does mean settling it after each adjustment.

[dannobee]

Most alignment machines have plates with plastic ball bearings that allow the suspension to settle without rolling the car around.

Similar results can be obtained by using sheets of waxed paper under and between floor tiles. You'll also need a brake pedal depressor if you're checking caster. And something to keep the steering wheel centered when setting the front toe.

And yes, the floor should be flat or corrected to flat by using the same floor tiles under the tires. If you plan on doing more than one alignment, mark the floor where the tiles were level so that you can quickly get back to square one.

[brianlay]

I would be more concerned with wheel weights than side to side height differences.
I believe the factory spec is 5mm difference side to side, so you’re close.
In my experience a corner balanced car will rarely have heights matching side to side.
Without scales you’re really just guessing.

[dannobee]

You can corner balance and still achieve correct ride heights. It just takes a little bit of work, and of course knowing what you're doing.

[tonyduc]

Thanks all for the advice, gonna invest in a laser level to make sure the floor is level again, and maybe put some weight in driver's side to test the height again.