rear shackle location

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ratvon

ratvon

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I just started research on moving my leaf springs inward on my 68 barracuda and I see a couple people said to use the existing hole in the frame to relocate the rear shackles. this hole is forward and was wondering if that would cause any problems. also the car is completely stripped down no motor trans nothin i took a reading on my pinion off the yoke where the ujoint clamps bolt with a digital inclimeter and it read 5 degrees up with the tires on the ground, is this an accurate reading to set my new rear end at? Is this a factory setting I always thought the pinion should be pointing down 5 degrees.

Thanks any info would be appreciated
 
At ride height you want the shackle angled with the lower part farther back. If it's straight up and down or leaning forward it won't work. When you hit bumps the spring flattens out and becomes longer, thus the reason the shackle has to be angled back.

The pinion angle is measured relative to the driveshaft, not the ground. You actually measure the transmission to driveshaft angle first then the driveshaft to rearend yoke to find you working angle. The working angle should be close to zero under a full load (wide open throttle on take off). The type of suspension and power level dictates how much negative pinion angle you need. If your running springs with no traction aid 5-8 degrees negative is correct.

Here's a link to an article on setting pinion angle

http://www.carcraft.com/howto/91758/
 
thanks how about the front shackles? they are nowhere close to being square from the factory do I use them as guides or square them up with the torsion mounts
 
sorry, let me clarify, as for the pinion I wanted to know a way of getting a factory setting without the trans installed there has to be an acurate way because the factory did it. i was just wondering what was the most acurate places to measure from but I probably will wait on the trans to be sure. As for the front spring hanger when i compared them to each other they re not in line. I used a dowl through the bolt holes from one side to the other. The drivers side is more forward than the passengers side. and they both angle in.
 
I'd say how the factory came up with the pinion angle is by building a model, working out the measurements it took to achieve what they wanted then made a set of blueprints and built all the cars to those measurements. Here's what I'd do if I were in your shoes. I know by experience that the trans. angle is generally around 0-1 degrees positive. You want the rear to be exactly opposite that under a load. The type of rear suspension, any traction aids, power level and driving style (cruising or racing), are all factors in figuring how much negative pinion angle you need. If you have stock leaf springs and it's a moderately to high powered vehicle that you run hard or race you generally shoot for 5-6 degrees negative angle so when it's under a load it's cancels out. If it's a stock 318 you don't need that much negative angle.

Are you sure your front spring mounts are for an A-body Barracuda? I have a 68 Cuda and they are not like that. Both are equal length and straight. If I remember right E-body Cuda's have angled springs. I don't know for sure if it's due to the frame design or the front spring brackets are different but if they are maybe someone has put E-body spring hangers on it.
 
thanks for the info. everything you said is what i figured i just wanted to be sure, except for the front hangers, I dont whats goin on there but they are in line now thanks again
rob
 
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