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What does it take to twist a 65/66 Mustang

5K views 9 replies 10 participants last post by  Beoweolf 
#1 ·
The idea for this post came from Blstangs post about subframe connectors.

I installed weld-in sub frames back in the 80's because of the horror stories that you would hear from time to time. Problem is I have never actually seen this happen first hand.

I imagine some of you must have first hand experience. Please tell the rest of us slow pokes how much power it takes to tweak one of these early Mustangs when you don't have a full cage, and what starts distorting first?
 
#3 ·
Stuff started coming unglued on my car when I hit the 11's. The motor started yanking the spot welds loose in the shock tower to motor mount bracket area. I also found some sheet metal buckling inside the car around the rear fender wells. I don't have subframe connectors installed(yet). I don't have a cage either. Something else that I have noticed is that the driver side door makes a kathunk sound for a day or 2 after I race.
 
#4 ·
What year was your car Hottarod? You were exceptionally lucky if it was an early model. Either that or you were running a small block, and thus were subjecting it to less torque. The 11's was where my small block 67 started twisting up as well. Somewhere around 400hp, with a 4spd, 3.89's and 3000rpm + launches (both with slicks and without). With a big block or a stroker, the problem increases exponentially.

Cris
 
#5 ·
I first noticed my problems in the rear quarter panels. The paint started to spiderweb and show some craking in the underlying bondo. This was with the 289 running 8.25's in the 1/8th and slicks.
 
#6 ·
Power? How about just putting a floor jack under one front control arm. Two of the early Mustang's we've had would deform enough to cause the opposite side door to rub the jam somewhere.
 
#8 ·
On 2006-03-06 14:40, ckelly wrote:
Power? How about just putting a floor jack under one front control arm. Two of the early Mustang's we've had would deform enough to cause the opposite side door to rub the jam somewhere.
It was a pain to open and close the doors on my '65 fastback when the front was jacked up before subframe connectors.
 
#9 ·
Relative to 65/66 Mustang Coupes - Take a look at the top of the quarter panel right where the drip rail ends. Is it cracked? Then, you can see evidence that the unibody is flexing. That's a fatigue failure of a highly stressed point in the unibody structure. Fix that crack. Then, install some sub-frame connectors. Viola! No more crack...ever.

<font color="blue">On edit: The title of this post is "What does is take to twist a 65/66 Mustang". Actually, about 2300 ft-lbs per degree of twist for a coupe. A strong car (not a stock 65/66 mustang, mind you) will take 10,000 ft-lbs per degree of twist. I'm going for ~5000 ft-lbs per degree of twist on a highly modified "Project Hard Way".</font>

Robert

_________________

Beegshot
65 1/2 'stang, Hard Way
79 F100 SuperCab, parts hauler
03 Expedition, grocery getter, kid hauler
Henry Ford said, "If you find you need a tool, you have already paid for it."

<font size=-1>[ This Message was edited by: beegshot on 3/7/06 7:39am ]</font>
 
#10 ·
I've seen where the subframe attaches to the unibody is nearly ripped loose from the floor pan. The guy was still thinking about "waiting" until after he finished his motor, before fixing it. As someone mention in another thread...his windshield was cracking at the cowl, rust had taken out most of the bottom of the plenum. The car has zero structural integrity.

Face it guys, first generation Mustangs were never meant to last more than 10, maybe 15 years at the most. Instead of bragging about early Mustang sales, Ford should be apolizing for all the short cuts they took, back then.
 
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