Mustang Underbody Dimensions (long) - Ford Muscle Forums : Ford Muscle Cars Tech Forum
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post #1 of 7 (permalink) Old 03-13-2010, 04:07 PM Thread Starter
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Mustang Underbody Dimensions (long)

I have a '65 Fastback that needs new sheetmetal and a new rear framerail. I am leveling up the chassis according to the original underbody dimension ( I only have it on jackstands at this point, but adjusts the height front to back to get the measuring points lined up with the Baseline, which is my garage floor (it's pretty straight)). I will be building a frame jig for it later, but for now, the floor will work as a rough Baseline.

All 4 measuring points won't level up at once, I can get 2 to level up to the B-line, but not the other two. I can level up the front leafspring hole and the front bumper mounting hole, but then the rear leafspring hole and steeringbox/idler-arm holes are way off, as much as ca 1" at the rear.

If I level up both rear and front leafspring holes, then the rest of the car seems to point up in the sky, the rocker panels leaps upwards in the front, and the entire front-end is way off the B-line.

Sometimes in the '80s the entire frontend of the car, forward off the firewall was replaced with brand new sheetmetal, and it was done in an Autorobot according to documents included with the car. The car was never driven with after the repair, and I bought it from the original owner a couple of years ago in a disassembled state (it still is, awaiting new metal).

I have looked for signs of collision damage, and have found that the LH rear framerail have been pushed up and inwards. There are no other signs of damages, except the LH rocker panel which have followed along the raildamage. I know the rear portion of the rear framerails can sag over the years (also have a '65 HT and had a '66 HT), but it doesn't look like this one is sagging that much.

Is it normal for these cars to have been tweaked that much over the years, or have something else happened here? I cannot see why that left rear damage would tweak the entire car so much that it wont line up to the B-line on the opposite side?

Should I just leave the car the way it is (except for the LH rail), or should I correct the dimensions to it's original measurements?

And another question; If I ever get the car lined up to the original dimensions, should the rocker panels/floor lip be parallelle to the Baseline?

1965 Mustang HT / 306cid/5.0 roller / T5 / 3.80
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post #2 of 7 (permalink) Old 03-13-2010, 08:40 PM
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Re: Mustang Underbody Dimensions (long)

If you straighten out the LH rail it should bring the car back to straight. The car HAD to have been wrecked in the past or the FRONT of the dang car would NEVER have been replaced.

I've heard how they're soft or like to sag, but other than springs giving I've never seen a Mustang frame droop naturally. They are stouter than people believe.

Car was wrecked otherwise the front end would be original....
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post #3 of 7 (permalink) Old 03-13-2010, 08:45 PM
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Re: Mustang Underbody Dimensions (long)

Do you have the proper frame dimension drawings? The factory repair manual has them in the back chapters.

Here are the '67's so you can see what they look like. These ARE NOT exactly the same as your car but it will give you some idea of the dimensions from the datum line and hoew they are measured.

Maybe someone with a 65 manual can scan this diagram for you.

Good Luck!
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post #4 of 7 (permalink) Old 03-14-2010, 06:05 AM Thread Starter
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Re: Mustang Underbody Dimensions (long)

Yes I have the diagrams for the dimensions. I have the one in the shop manual where measuring points are from the CL of holes, but I also found one online where measurements are from the underside of frame rails.

1965 Mustang HT / 306cid/5.0 roller / T5 / 3.80
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post #5 of 7 (permalink) Old 03-14-2010, 06:58 PM
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Re: Mustang Underbody Dimensions (long)

Anybody got the assembly manuals in a pdf or word file for the 67. If not what assembly manual would be best for replacing/repairing sheetmetal?

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post #6 of 7 (permalink) Old 03-15-2010, 09:40 AM Thread Starter
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Re: Mustang Underbody Dimensions (long)

Originally Posted by billywatson View Post
Anybody got the assembly manuals in a pdf or word file for the 67. If not what assembly manual would be best for replacing/repairing sheetmetal?
Here is the frame dimensions for the '67

A great manual you should consider buying if replacing sheetmetal is the "Weld and Sealant Assembly Manual" from Jim Osborn Reproductions. It doesn't include any dimensions, but it's excellent in showing you where and how those panels are welded together. Very detailed exploded drawings. The PN# is L-34D (for the '67). NPD have them.

1965 Mustang HT / 306cid/5.0 roller / T5 / 3.80
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post #7 of 7 (permalink) Old 03-15-2010, 02:42 PM
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Re: Mustang Underbody Dimensions (long)

I went through this confussion with mine, tried checking it with the dimension sheet Capt V and others had. Used plumb bobs made from fishing wieghts and string.
It was tough, some would come out dead on, some wouldnt. If your not on the jig and have the "baseline" dimension, your guessing.

I located a frame shop that specialized in muscle cars, had it put on the jig. I figured the back of mine was square, I got enough dimensions to feel good about that. The front end, I knew for a fact had collision damage. Me being in the car for one, and prev indications. I couldnt figure out the dimensions either from the drawing.

The car was within 3MM of factory specs, the factory tolerance is +/- 5mm. Like FE said, they are tougher than you think, and that old 1/8 inch tolerance is bunk.

Looking at mine, and figuring it had been wrecked, I was pleasantly surprised to find it just fine, with some wrinkled sheet metal to fix. You can beat your head trying to figure out the measurements and base line, floor level etc.
Even if you do find its bent can you fix it? Take it to a pro if you have doubts, let them verify and tweak it if you need it.
I saw my guy pull a 68 Charger that had been front ended. When he was done, you couldnt tell it.

Also, the report or dimension sheet I got , my guy went over his and my factory spec sheet to show me how they did it. Well worth the 129 bucks.

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