My thoughts are you are chasing your tail.  Mark where the stands will sit on the floor.  Roll the car out of the garage.  Use the longest level you have (ideally a 6').  You can also put the level atop a longer, rigid straight edge (piece of square metal tube, or a really straight 2x4 (very had to find nowadays)).  Check level side to side, front to back, and diagonally.  Find the highest spot.  That stand sits on the floor.  Then level each stand starting at the next highest point.  With each stand check level to the highest point stand and do not move on until it is perfect.  You can take measurements from the level to the ground to see what thickness shims you need.  Plywood comes in 1/4"-3/4" thicknesses, and you can use metal if you need a thinner shim.  For thicker than 3/4" you can use a short section of an LVL (local building site dumpster or lumber yard scrap pile).  They are typically 1-3/4" or 1-7/8" thick.  You can also use 2X lumber.

You have to constantly reference back to the highest point only when leveling.  I learned this years ago setting cabinets.  I built four stands from wood to hold my '89GT 4' off the ground with the weight on the tires so I could work underneath it.  They are all perfectly level, and I've marked the floor and numbered the stands so they can go back in those spots in the future. 
 

TKOPerformance wrote:

.   I built four stands from wood to hold my '89GT 4' off the ground with the weight on the tires so I could work underneath it.  
 

HOW....did you get the 89 up 4' to put it on the stands?  And then back down on the ground afterwards?
Not being ugly............just curious........
6sally6
 

One problem ill have is if i place stands under the rear rails my jig  wouldnt be able to slide under the car. Also have to isue now of the rearend being to low and hits the top of my jig. Other wise I could slide it freely underneath.  Hmm so im thinking I may need to level the rear rails later once the jig is slid underneath the car. Then after the jig is checked and leveled. Then I was going to fabricate my vertical attachment fixtures that will be welded to my jig. Im thinking I should do also as instructed and buy aome lumber and build some stand bases. This way I can get my car also a little higher. Any reconmendations for stand base top material? OSB or MDF? Then also use some 2x4s shim as needed. I would like the car higher to also be able to get it on a rotisserie. I was thinking I would like to fabricate a vertical up right for my chassis jig at some point to be able to rotate my car and make my jig more universal. I was thinking of using a 4 lug rear axle that would be my main rotating device I would weld the axle tube to the chassis jig vertical post. Then with the axle shaft installed i would be able to roatate the brake hub assembly. I would use the hub assembly to mount the vertical post and rotisserie arms. To rotate the axle shaft i saw in a thread a guy used worm gear trailer winch or jack that was welded to the axle shaft. Dunno if thats a good idea or not. I was debating on using a weld on pipe flange that has holes predrilled for a locking hub for the rotisserie but then I saw the thread with the rearend and worm gear winch being used. I though id ask the experts HERE.

True74yamaha wrote:

One problem ill have is if i place stands under the rear rails my jig wouldnt be able to slide under the car. Also have to isue now of the rearend being to low and hits the top of my jig. Other wise I could slide it freely underneath. Hmm so im thinking I may need to level the rear rails later once the jig is slid underneath the car. Then after the jig is checked and leveled. Then I was going to fabricate my vertical attachment fixtures that will be welded to my jig. Im thinking I should do also as instructed and buy aome lumber and build some stand bases. This way I can get my car also a little higher. Any reconmendations for stand base top material? OSB or MDF? Then also use some 2x4s shim as needed. I would like the car higher to also be able to get it on a rotisserie. I was thinking I would like to fabricate a vertical up right for my chassis jig at some point to be able to rotate my car and make my jig more universal. I was thinking of using a 4 lug rear axle that would be my main rotating device I would weld the axle tube to the chassis jig vertical post. Then with the axle shaft installed i would be able to roatate the brake hub assembly. I would use the hub assembly to mount the vertical post and rotisserie arms. To rotate the axle shaft i saw in a thread a guy used worm gear trailer winch or jack that was welded to the axle shaft. Dunno if thats a good idea or not. I was debating on using a weld on pipe flange that has holes predrilled for a locking hub for the rotisserie but then I saw the thread with the rearend and worm gear winch being used. I though id ask the experts HERE.

2x4s are plenty strong if you load them properly.  For flat material I would not use anything other than 3/4" (23/32") CDX plywood.  MDF will fail from moisture and has no strength in flexion or tension, and OSB is more likely to fail from water/fluid interaction.  For my stands I built the tops at 18"x18", framed rings of 2x4s for the top (with 2 "joists equally spaced inside the ring) and bottom, then ran vertical 2x4s at each corner.  I added cross bracing as well.  I used structural grade 3" screws at all connections.  3/4" CDX for the tops secured with 1-5/8" screws and glue.  When I set the car on them nothing so much as creaked.  I left the bottom rings a slip fit until I had each stand level based on the method given above.  This allowed me to trim the bottoms of the vertical 2x4s and then secure the ring.  I'll see if I can get a pic to load.
 

I have an alternative:  
A length of clear tubing when set in a U shape and almost filled with water will have the water levels at each end the same height.  Then use that to find the highest stand.  Then still using the tube adjust the other stands to the same height.   That's how my contractor levels framing over long spreads.

You may need a buddy to do this.

I did buy my self a cross be laser level. I just now need to buy myself a short tripod for it.

Last edited by True74yamaha (9/24/2022 12:58 PM)

I have taken four jack stands 6 ton stands work easier to get the car higher up.  to put the car on a rotisserie. I have used a 4x4 under the rocker before r
With a jack underneath to raise the car up. This enabled me to mount one car on a rotisserie id just do the same method to get my car high enough. With my car on the jig it would alreadt be pretty high to begin with. I would just have to raise the car up off the body mounts.