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Does my 1969 f-100 need a backbrace or is 550 horse and slicks not enough to hurt it ? thanks.
 

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The '69 F-100 pickups use a large bearing 9" housing, but it is not the big web housings like the later year pickups had. It is also really wide, so I wouls say that a back brace could only help you. Be careful when you weld it on, as the housing will distort very easily. Your best bet is to take it to someone who has a housing jig that will keep the housing straight.
 

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Even on the '69 to '72 there is a lot of difference in the housings. I found one that came with 31 spline axles
and it had bigger diameter housing tubes. It was a LOT
heavier than the one I was using. Mine was in a government issue pickup; but I would look for one from a four wheel drive. When you find one, you'll know just by looking at it.
 

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A backbrace is unnecessary at 550 HP, IMHO, especially with the heavy truck 9" housing.

It's not worth taking the chance on warping the housing by welding the brace on.

I am running a stock passenger car housing, and putting enough HP through it to go 1.5x 60 foot times with a 4100 lbs car. No bending of any kind, and no brace either.

Good luck,

Greg
 

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Discussion Starter · #8 ·
any idea how much a shop charges to do this ? i really dont wanna screw this up-
 

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Well, I ran a little over 800 hp thru a narrowed 9" (non reinforced/backbraced), 2500 pound car, 1.26 60 foots, and it twisted the absolute **** out of it!!!!!
Better safe than sorry. I thought that stuff only happened to REAL race cars, but it happened to me.
The next time (like this winter), when I totally rebuild/redo my ass end I'll for sure have the bracing (and whatever else can be done to a 9", done to mine!!!

Better safe than sorry. Plus that's alotta weight to be putting thru those tubes!

My .002
 

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On 2006-08-27 19:02, drag79stang wrote:
Well, I ran a little over 800 hp thru a narrowed 9" (non reinforced/backbraced), 2500 pound car, 1.26 60 foots, and it twisted the absolute **** out of it!!!!!
Better safe than sorry. I thought that stuff only happened to REAL race cars, but it happened to me.
The next time (like this winter), when I totally rebuild/redo my ass end I'll for sure have the bracing (and whatever else can be done to a 9", done to mine!!!

Better safe than sorry. Plus that's alotta weight to be putting thru those tubes!

My .002
If your 60's are 1.26, you DO have a real racecar! That's a serious short time, man!

Greg
 

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Probably overkill but if you have the $'s why not. I get some grief for overbuilding my car, but I'm not spitting parts on the track either.

I'm assuming you've boxed the spring perches already. If not, do that first.

don
 

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I'm assuming you've boxed the spring perches already. If not, do that first.


great advice.
 

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Wow. I am impressed that anybody could twist a housing. Is this caused by the rotation along the driveshaft (right rear lifting and left rear falling)? If so, would a rear anti-roll (sway) bar help? That might help keep the tires planted too.

(Just a thought from a guy with no real experience.)
 

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Torque.........pure and simple........LOTs and LOTS of torque. Weakest part twists. Mine twisted between the center section and the ladder bar mount on the drivers side. (over an inch diff side to side). Looked goofier'n hell coming back to the pits. Made another run like that too..........(just to see if I could wreck even more chit).....:&gt


(and I don't consider 1.26s that quick. I want teens!!!!!!!!!!!!!!)
 

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I'm still trying to understand. The rear sees torque along 2 axis. One is about the axles. The other is about the pinion. Seems we are discussing the rotation about the pinion. Correct?

Would a panhard rod mounted at the center section help?
 

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I think some of it has to do with spring wrap and the shock load to the perches/plates and housing.
I noticed 2 distinct cracks along my welded perches... had to re-weld them. Boxing them would be the best route.
 
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