[marculan]

Hi,

Starting a pro touring build with a 68 and concerned that maybe the unibody isn't straight. You can see it is resting comfortably on 3 jack stands while the 4th hangs out on its own. The jacks are adjusted equally and the garage floor is pretty straight and even. Is there a way that I can tell if it is bent without bringing it to a shop with a frame machine? Someone did work on the car before I bought it, and the panels were all aligned very nicely before I took it apart. Doors, trunk, fenders, hood, all had close, even gaps, but not sure if that is a reliable indicator.

Thanks,
Marc

 

[X-77 keith]

Metal has memory. These cars do flex. A jig on a perfectly level floor would tell better. How are your door gaps at this moment? It's possible that bolting the frame back on with good mounts may pull it back in line if it's out. Have you checked your subframe for not being true? What you have it sitting on could be plumb, but actual measurements from the exact same area with the stands in the exact same area would help tell some info. Are you 100% the stands are true? The stands themselves could be tweaked. This is why I mentioned the jig. You have alot of variables going on right now and by just that picture, your question can't with certainty be answered. Looking at the picture, your front jack stands are not in the same location on both sides. Reset your stands and see what you get. You don't have to be a professional, or do collision work everyday to do these measurements. You just need to be consistent and rule out all of the variables. It's probably not as bad as it looks in the picture.

 

[jimsl78]

Are you sure about the floor? If you pour water on the floor where would it flow and possibly puddle?

 

[DOUG G]

Thats a pretty good amount. 1"+ (check the floor also ?)

Maybe use a 6' level and check front to back, side to side, and diagonally at the same points on both sides ?

 

[Sauron67MM]

I only have decades of frame machine experience so don't trust me. All our frame machines were set up properly and
measurements are taken on the rack .

I don't understand why people who have zero daily experience in frame machine work will lead someone over a cliff. The subframe will not correct your issue even if there is one. The unibody will not flex that much.

Make sure your shop floor is flawless, just like the racks we use. Call me if you have any questions. I've rebuilt cars that other shops have hacked.

I'm sure others on this site who do this everyday have done the same. It's common sense. The first frame I needed pulled as a customer the shop owner told me where the the frame machine tools were and I spent the afternoon figuring it out. Yanked my own frame at his shop in the 90's. Try working on an old 50's frame machine when you have to move the heavy towers by hand.

 

[jimsl78]

If there is some body twist, that's the side that lifts under torque. If your unsure, a shop with a good frame rack would be your best bet.

 

[bilodeaulynn]

Scott offered to help. You should take him up on that.

As has been pointed out, you need to make certain the floor is absolutely level. They rarely are.

Next, make sure each jack stand is exactly the same height.

Otherwise, it is just a guessing game.

 

[srode]

I would call Scott and take him up on the offer. But like other's, I can guarantee your floor is not level. A large level is good but over the span you are talking it can be off a fair amount.

My suggestion is go buy a 15 foot section of clear tubing and make a water level to check it at home. Very easy to use with 2 people and VERY accurate. We used to use those for setting coping height on in ground pools when I built pools for a few years before going back to school.

 

[X-77 keith]

The floor may be perfect, but the right side jack stand is farther back than the left side. Change that first. He may not have a problem at all. I'm sure if Scott saw that he would point that out . No frame machine or body experience needed to know that will throw the measurements off.

 

[DOUG G]

The floor may be perfect, but the right side jack stand is farther back than the left side. Change that first. He may not have a problem at all. I'm sure if Scott saw that he would point that out . No frame machine or body experience needed to know that will throw the measurements off.

Good eye... could very well be the body is on an uphill slant... 1/16" over a few feet adds up quickly.

 

[SOA-Nova]

Maybe look at doing something like this that is used in woodworking:

Better Winding Sticks | Popular Woodworking

Winding sticks are very useful for gauging twist in a board, but they’re difficult to read. My improved version of these time-tested helpers makes the twist stand out. I start with a pair of straight…

www.popularwoodworking.com

I had a friend from years back with a first generation Camaro and we set up even height blocks off of the trunk floor and then placed a straight board across those two spots. We then did the same off of the firewall and we could see one left to right board was not even with the other one which told us we had a twist issue.

Jim

 

[stamatisg1977]

Plus to me that drivers side jack stand doesnt look like its under the car lol

 

[jimsl78]

A few good recommendations here, but it looks like the OP has left the building.

 

[Worn Out Welder]

A construction laser with a self leveling function could possibly help. That would depend on your understanding of how to create a benchmark and use the laser as a reference. That may seem a bit extreme but it’s just a thought….I’m just a welder so take me very lightly

 

[marculan]

Hi, no the OP was just busy with actual work and not the fun car work. Thank you all for the replies, and Scott, I will definitely give you a call if I can't figure this out. I'm going to setup the scales that I use to corner balance a race car I run. I have levelers and can make them level all the way around. From there I can put a jack stand on each scale and see how it sites on the stands. If it rests on all four stands evenly then I'm guessing all is ok. If not, then I'll call Scott!

Don't know why I didn't think of this to begin with. Let me know if this doesn't sound like a good next step. The doors and body panels were aligned very nicely before I took things apart, so I have no reason to believe that it would be bent. Just want to make sure before I spend a ton of time massaging the unibody.

Thanks again, and I'll reply back to the thread once I have a chance to setup the scales and check.

 

[X-77 keith]

If the door gaps were fine before, how are they now compared to before? The scales are not a bad idea. Placing the jack stands in exactly the same place is a better idea. If your gaps are the same now, it's probably just the placement of the stands making it worse than it actually is. My car was twisted over 3" and was able to get it within a 16th of an inch. On the first day of pulling. It's dead on now . I don't own a frame machine, but have access to one, and like to do my own work. I'm not a professional body guy, but if you take your time you can figure most of it out.

 

[tp_smith]

I really don't think your car is tweaked. The front jack stands have to be in the same location on the rockers to make contact. It looks like you have one or two inches of gap between the driver side rocker and the floor jack. If your car was bent that bad, the doors and fenders would not fit.

If you want to check the alignment, use the Fisher body measurements shown in the photos below:

The first thing is to elevate the body so the rockers are level.

After leveling the rockers, I bet all the jack stands will be supporting the car.

I removed my subframe from the car and had to reinstall it. This required me to realign the subframe. My reproduction fenders did not fit so I also checked the Fisher body measurements to a datum line. These are the measurements with the small letters. Example a = 11 15/16", b = 13". My datum line was just a long piece of square tubing.

I used to have a build thread that described how I made these measurements. Here is the link below. It starts on post #232. You have to click on the links to see the photos.

1969 firebird convertible without photos

 

[scblucam]

Most garage floors are sloped for drainage, probably sloped in two directions. laser level and rod can prove that. measure your floor first. Harder with car in the way. You will have to move the laser to get all four elevations and must be at exactly the same elevation.

 

[marculan]

tp_smith, thank you so much, that is excellent info. I'm going to read through your build thread, because it looks like you've done what I am planning to do. Thanks for the measurements and the excellent pics!
Marc