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I posted this in the Galaxie pages, but I thought someone here could learn from it as well. This style of pullbar could be adapted to any leaf or coil spring style rear suspension.

I was experiencing severe wheel hop on my Nascar styled '64 Custom because of some 2" lowering blocks and the long stock leaf springs. I built my own version of the C/E Slide-A-Links which worked well but they would hang up on everything as the car is very low. I thought about building a torque arm, but the Frankland quickchange made it very hard to package. I finally settled on a circle track style spring equipped pull rod to control the axle wrap, as well as to help plant the rear tires. This is a very common type of traction device in C/T racing. I used progressive rate AFCO spring that goes from 250 pounds to 800 pounds in 2 1/2" of travel. This type of pull bar is usually the upper bar of a three link coil spring rear suspension, but I have successfully used it on leaf spring suspended cars.

The first thing I had to do was build a rear crossmember for the front of the pull bar to attach to. The driveshaft also had to pass through the crossmember. I used some .083 wall x 1 5/8" chrome moly for the side pieces, and .058 x 1 1/4" chrome moly for the hoop portion. The front of the pull bar attaches at the same height as the front of the leaf spring eye so that there are not two competing instant centers that could cause a bind in the suspension. The 4 1/4" aluminum driveshaft was found in the dumpster at a local Ford dealership, I took it home and shortened it to fit and it spins vibration free and the cost was nothing.


The front bracket attaches the front of the pull bar in double shear.


The rear of the bar attaches to a 3/8" bracket that is welded to the housing tube.


Here is a view from the bottom of the car. The spring is pre-load adjustable in case you want it to hit the tires faster and harder.



This is a side view, the bar angles down to the same height and distance as the front leaf spring eye. The traction is awesome with the pullbar now!! You can definately feel it lifting on the chassis when you mash the gas pedal , and there are no clearance issues. The feel is totally different than with under-rider style traction bars, as it really plants the tires hard.







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<font size=-1>[ This Message was edited by: F15Falcon on 4/4/06 10:32am ]</font>
 

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Well done. I think the guys at Cobra Automotive use a similar setup on some of the GT-350s and Mustangs they prep for vintage racing.

cheers
Ed N.
 

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Awesome work! Man that sure is purdee under there!


Would you know what the driveshaft came from?
 

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Discussion Starter #8
I believe it is off of a Super Duty pickup. I get all kids of throw aways from the local Ford dealership. I actually arc welded the driveshaft back together after I cut it to length with some A/C aluminum rod as my TIG welder was down at the time. I also have a smaller diameter aluminum driveshaft out of the trash bin in my '66 Falcon that was out of a Crown Vic police car that fit with no cutting.
 

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Great idea, Tom!...
I've got a Lefthander spring loaded 3rd link from my last asphalt stocker and had considerd a similar install on my '64 when I finally put some horses under the hood. You just confirmed for me that this wasn't one of my crackpot ideas...


Jan
 

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couple questions...I'm trying to understand how an undamped spring helps prevent wheelhop- if it works well, great, I just dont understand HOW it helps wheelhop...my 06 needs something, it can get hopping bad if t/c off... another Q- any idea how much compression travel the spring actually uses on a hard launch? looks like just a couple inches radius from axle centerline, wouldnt expect more than a few degrees windup in the housing- or am i misunderstanding, and the preload comes in as the rearend squats from weight transfer? and explanation appreciated, as Ive never seen anything like this before. Oh yeah- how does it affect ride in a street car? very curious here
 

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Discussion Starter #11
The ride in un affected with the pull bar. The leaf springs are still doing some of the lifting on the car, except that now they have some help with the addition of the pull bar. I might install a 90/10 shock next to the pull bar, but it is so that the spring does not un-load all at once on braking. The shock will extend out easily to allow the spring to compress, but it will go in very hard to keep the pull bar loaded longer. The shock is not needed for dampening. The bracket on top of the axle is small because of two things, one of them is the amount of room under the car, and the other is because the leaf springs are still planting some of the weight. If the pull bar were on a coil spring car with trailing arms, the top bracket would be about 12" tall to get alot of compression on the spring. The spring compresses about 1 1/4" on this car, it also depends on which gear ratio is in the car, with the 3.88's, it is about 1 1/4", with the 3.06's, it is about 3/4". The spring does get progressively stiffer as the car accelerates. Trust me, the wheel hop is now gone.
 
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