I have a wavy concrete garage floor.

Has anyone ever carefully measured and leveled the tub (independent of the floor) so that you know the chasis is straight, only to measure your fender arches from the floor and find what looks like a twist?

I'm feeling very paranoid because I've finished the structural repairs on the driver's side and am about to begin on the passenger's side. For curiosity, I took some measurements from the floor to the centers of the arches and here's what I found:

Click to view attachment

My measurements from the floor to the flanges on the rear suspension consoles are identical. At the front, the rear of the DS T-tube is 3/16" higher than the same measurement on the PS. I can shim that on the jack stand but I don't think that's going to bring the rear PS fender arch down or even out the fronts.

I'm trying to borrow an 8' spirit level from a friend so that I can level both sides of the car and make sure they are parallel.

***What are good index points for establishing "parallel"?

***And also, back to the original question: can the frame be true and the arches not be, presuming that there hasn't been previous crash damage that required replacement of a panel?

My best advise is to use plum bobs from the ceiling and use a level on all 4 sides. Elevate the car and make it "level" and start from here. The truest measurements come from the suspension attachment points... This is because that is where the factory held them in the jig. This is no different to today's manufacturing.

The fender arches can be different! Like I said the truest readings will come from the suspension attach points. Not to say there should be much difference since the panels came out of the same dies but I wouldn't use them as my reference point.

Thomas

See if you know some one with a rotary laser, perfect for this kind of work.

You need to measure off the suspension points. Rear control arm ears, front cross member attachment. You may want to jack up all four corners and use a self leveling laser level that sweeps 180degrees. Drop plumbobs from each suspension point then raise or lower each corner until you are happy with what you are trying to achieve.

The friend I'm borrowing the level from also has a rotary laser. I thought of that but how do you level a car most easily with one? Would you fire the beam close to the foor and measure UP to the bottoms of the mounting points?

Are the tops of the strut towers any good for index points?

Have you seen the chassis dimension diagrams? Click on 914 Info at the very very top of this page.

Nice thing about the rotary laser, doesn't matter where you put it, you just measure from the beam to whatever point you want. The one I had even had a receiver unit on a scale, would measure to 1/8" at 150 ft. I guess that was called a rotary laser transit. Get it from your friend, you will figure out how to use it in 5 minutes.

You can easily make a level using a bucket of water, a length of clear tubing and a yardstick. In the place where you will park the car. Place a bucket of water in the middle on a stool. Insert the tubing in the water and siphon the water so there are no air bubbles in the tube. Tape the tubing to the yardstick and place the end of the yardstick at each point where the wheels will sit and read the water level. This will tell you the difference at each point. You can then use wood or some material to make all 4 points the same.

Excuse me but if I may interupte at this point. Having put in an Engman interior long kit and doing corner weighting more times than I would like to admit. Getting the tub level is the most important thing. Keeping the longs parallel is the only thing that keeps the tub from twisting. I shim the floor to the tub under the jack stands making sure the longs are level fore and aft and side to side. Once you have it there you can track your progress and check your work. You can tell when you have done something wrong before it gets out of hand. Because the tub will be setting on 3 jackstands instead of 4. I use Stabila levels because after 40 years of carpentery I find them more accurte (easyer to read) than lasers. If you would like to see my set-up I would be happy to take a pic of it.

i've just been through this with my current project.
Body lines will never be perfect so better off checking the hard mounts such as suspension, engine and trans mounts.
I used a plumbbob from each point and measured then used the laser to check for a difference between the points marked on the floor to get a final measurement.
Good luck

Thank you, EVERYBODY, for your feedback and suggestions. I did come home with a rotary laser last night but it was too late to play with it. Hoping maybe this afternoon I can set it up and see where things stand.

Do you guys support the rear of trans a bit when doing this? Seems to me like when the car's on the ground the weight is supported by the rear shock towers vs somewhere mid-car when on stands (in my case the engine bar because both rear jackpoint were gone). With the weight back there unsupported, it was opening the tops of my rear door gaps.

Well, surprisingly, I only had to add some 1/4" steel plate under the right rear jackstand in order to bring the suspension points parallel. I first measured all 4 points UP from the rotary laser beam with the unit sitting about mid-car, across the garage. I also verified my measurements with the laser sitting in front of the car and behind it.

Once I felt good about the car being structurally straight, I took measurements from the beam UP to the centers of each fender arch. My suspicions were confirmed again. My fender height's vary:

Click to view attachment

This is a bit distressing to me because when the car is finally on the ground, it will appear to have a twist--the right rear sitting high (or the right front sitting low)--all spring lengths and torsion-bars being adjusted equally.

I'm planning using adjustable perches on the rear eventually and the front's adjustable anyway. So whatcha think? Live with it? In all likelihood, I could probably average out the "twist" with suspension tweaks.

It it possible other cars have this kind of variance in them and people just don't have occasion to measure them???? This car has had body repairs in its former life. One of them I have yet to get to to correct yet but it did involve the front right corner (headlight box, etc).

Other 914 certainly have uneven fenders. Likely other cars as well.

Don't fret about it; the suspension pickup points are the important bits. The fenders are just a covering.

--DD

If you corner balance it the correct way (with your weight in the drivers seat) it'll look just a tad funky anyways if you're not in it.


As long as it doesn't look like the pic below *after* a good corner balancing, you're OK. If it does look similar to the pic below, you have a tweaked chassis.
http://www.914world.com/bbs2/index.php?showtopic=50515

I wouldn't use the fender lips as a point of reference. Once you have the check sets parallel (the four donuts under the chassis) Establish a datum line. You can hang flat bar across the under side of the car with tie wire off the donuts and use a string line to check the difference from one shock tower to the other.


http://www.914world.com/specs/bodydims.php

http://www.914world.com/specs/underdims.php

First of all the rotary level is a decent idea but not that accurate.The top of the laser light to the bottom can be 3/16 of a inch. I own several different ones and they are not always accurate. I have had them dropped and they become out of level. I have even had brand new ones from the factory that needed to be recalibrated.And these are not the cheap ones you get at Lowes or Home Depot. These cost several thousand dollars. The best and easiest way is to use a water level. The Stabila is a accurate tool but only as good as the guy using it

Back in the day we used centering gauges and a tram gauge. They work fine and it is likely you could purchase a used set on ebay.

http://www.moclamp.com/7400%20manual.pdf

Check page 10 of the attachment above to get an understanding of what a datum lin is and how to read it.

This is and East Coast car. I WISH it had donuts. It had 3 when it came to me and I removed one rotten one when I rebuilt tie driver's side wheelhouse. I did lift it by one of the 2 remaining ones this weekend and it was extremely soft. So THEY won't be my indexes!

I used the "pinch flanges" running horizontally on each of the outer suspension consoles as my rear points. Good? No? Somebody mentioned the suspension ears but the HE's prevent me from getting to their centers. Measuring only from their lowest points, they don't measure "level" off the beam when the flanges do. They probably differ by 5mm.

If there within 3mm from end to end they should be within spec. The rule of thumb is 3mm (three thicknesses of a dime) Pinch weld flanges are not the best gauge as they can be dented easily and give you a 2mm over reading. But if you have nothing else they are far better than nothing.

Is the front suspension still in? If so you could still level the car left to right and check the strut towers with a level left to right.

Next check the upper body, cross the targa to windsheild, door openings and cross the car from the right latch to the left hinge and visa versa. That will tell the end story.

Lots of ways to check the car. You'll get it.

Thanks, Rick.

The pinch flanges I was talking about are the ones where the outer suspension consoles' top and bottom halves are joined. Mine don't look they've ever been bent or dinked. The flange is straight. During the course of checking all this, I did notice that one side has a 5mm shim and the other has a 3mm, but that's all camber stuff. Just an interesting note.

Yes, the front suspension is still in and the crossbar between the T-bars is on two jack stands. That measured level when I shot the rotary beam from the side, front, and rear. I'll take your suggestion and check the front strut towers.

Thanks for all the tips and thanks, everybody else, for your advice and input.