Underbody Dimensions

[Don C]

I decided to post a couple of underbody dimension diagrams here so they would be easier to find. I know that some of them have been posted before, but are buried in hard to find threads.

The first one is for 1971s, and is from my 1971 Shop Manual (figure 12), the other one (figure 13) is from a 1972 or 1973, maybe someone can verify from their shop manuals. Most of the dimensions are the same, some are just a few hundredths different, some are more. One I noticed is the rear of the 71s is shown about 2.5 inches lower while the front is about 1/2" higher.

Underbody dimensions-2.pdf

EDIT, added images

 

[Paul113]

I decided to post a couple of underbody dimension diagrams here so they would be easier to find. I know that some of them have been posted before, but are buried in hard to find threads.

The first one is for 1971s, and is from my 1971 Shop Manual (figure 12), the other one (figure 13) is from a 1972 or 1973, maybe someone can verify from their shop manuals. Most of the dimensions are the same, some are just a few hundredths different, some are more. One I noticed is the rear of the 71s is shown about 2.5 inches lower while the front is about 1/2" higher.

Thanks Don!!

 

[Paul113]

So I completed the replacement and it was a relative breeze. except for the cleanup prior to installing the new one. I used a sawzall with long metal cutting blades and removed the crossmember leaving the welded flanges only. Then i used a combination of sawzall, grinders, chisels and brute force to remove the remaining flanges. the dynacorn cross member went in perfectly. After drilling holes for welding, simulating the factory spot welds, I used .30 wire, played with my welder settings and went for it. Looks great! and bummer for the next guy who needs to remove this thing. I took many measurements before and after removing the original and I had no deflection at all after I cut it out. The car was level, with the engine in it and on jack stands. Thanks for your advice.

 

[Don C]

That's great! You went at it the right way. :bravo:

 

[dfayette]

So I completed the replacement and it was a relative breeze. except for the cleanup prior to installing the new one. I used a sawzall with long metal cutting blades and removed the crossmember leaving the welded flanges only. Then i used a combination of sawzall, grinders, chisels and brute force to remove the remaining flanges. the dynacorn cross member went in perfectly. After drilling holes for welding, simulating the factory spot welds, I used .30 wire, played with my welder settings and went for it. Looks great! and bummer for the next guy who needs to remove this thing. I took many measurements before and after removing the original and I had no deflection at all after I cut it out. The car was level, with the engine in it and on jack stands. Thanks for your advice.

How did you get your upper dimensions correct for your hood opening?  Measurements across the aprons, mainly across at the radiator support.

 

[Carolina_Mountain_Mustangs]

I took some measurements for a member once under the hood for inner fenders and radiator support. I have attached again. These are not Ford numbers just some reference dims. from a pretty rust free California car.

I did search the net for more dimensions but there does not seem to be any out there.

Every stamping in the unibody has locator holes, tooling holes, that were used to stamp the parts, check the parts and also used in the weld fixtures to locate the parts. A lot of time you can do cross measurement to see if something is square from one tooling hole to another.

 

[Don C]

Thanks for adding this, David.

 

[92GTS-R]

I need some help with these measurements and am a complete novice.

I have to replace the front  chassis cross member and work out why one inner RH  wheel is almost touching the rear bump stop but the left inner wheel is a good 1 inch away from the LH rear bump stop.

Can these measurements be taken without stripping down the car?  IE : removal of engine, trans and rear Axle?

My car has been in accident at some point in its life and I can tell the chassis was never properly repaired or aligned!

RHS REAR WHEEL

LHS REAR WHEEL

FRONT CROSS MEMBER!

 

[Carolina_Mountain_Mustangs]

.Don that is not the dimensions I was talking about. The assembly line drawings have the suspension and everything in them. The give dimension from axle to frame if I remember right in the assembly line info. The ones you posted are what you should have before you start to replace panels. I always say first place you need to go is frame shop they bend so easily. 

 

[Hemikiller]

David, you posted this one a while back

View attachment 73chassisheight.pdf

@92GTS-R, the rear can be caused by many things. A failed bushing, bent shackle, misaligned axle on the springs, stuff like that. It could also be production line tolerances. 

If you want to be absolutely certain the chassis is square before you replace the front crossmember, have it put on a frame machine and square the chassis. 

 

[351cleveland-performance]

Hi everyone, I'm back at the restoration of my Fastback. At the moment I am working on the trunk area, quarter panels and so on. So my question is, could someone measure the following two masses of the "standing sheets" from the trunk floor as marked in the picture? Thanks a lot. Best wishes from Switzerland.

 

[baz70]

I took some measurements for a member once under the hood for inner fenders and radiator support. I have attached again. These are not Ford numbers just some reference dims. from a pretty rust free California car.

I did search the net for more dimensions but there does not seem to be any out there.

Every stamping in the unibody has locator holes, tooling holes, that were used to stamp the parts, check the parts and also used in the weld fixtures to locate the parts. A lot of time you can do cross measurement to see if something is square from one tooling hole to another.

hi David

do you still have these measurements, I dont see the attachment ? I have some mis-alignment on my front chassis area that I am trying to get to the root cause of.  It seems to emanate in the rear crossmember, front crossmember and radiator support gaps. thanks. 

 

[Don C]

I believe this is the one he was referencing, last post in this thread:

How to check if your unibody is straight - Exterior, Body, Chassis & Paint - 7173Mustangs.com

 

[baz70]

thanks both. this will be a great starting point for my investigation.