Ok, I have read pages of threads but just can't get the answer I want so I am counting on you HAMBers to help me out. On The wife's A I have a 9" rear with a 40 Ford transverse spring and I am using ladder bars. My rear is higher than my tranny. I am in the process of making my tranny mount and ladder bar mounts. With the tranny set at 3* down do I set the rear pinion at 3* up? I can easily go 2* would that be OK also or is 3* better?
Your rearend is fixed, so 3 up would be right. With parellel leafs in the rear the rear would be set at 0 or 1 and under normal driving the rear rotates up as the springs flex to be 3.
Here is a link to Inland Empire Driveline..... http://www.iedls.com/Education-Zone.asp click on the link "open printable document". Everything you'll ever want to know about setting up your driveline is there.
As a drag racer i hate to see the pinion 'up', car won't hook on velcro. What i'd try to do in the same situation is make the motor level - i know it depends a lot on what intake you plan to use - that would minimize the differences in angles so that your pinion could be 'down' a touch.
I respectfully disagree.......the rear end does tend to 'wrap up' a bit on initial acceleration but under 'normal driving', which to me means cruising at fairly steady speed, the suspension wrap would be minimal to non-existent. The reverse happens on deceleration.......so putting the angles the same on the trans and rear end is reasonable....... Ray
I don't understand how the pinion being 'up' would have any effect on hooking up on acceleration.......especially if there are ladder bars in place, as the OP states in his post. But even without traction bars, how does pinion angle affect traction?? Ray
I have a transverse spring, how would that wrap up under acceleration? I don't think it would with ladder bars. Anyhow my concern is that my rear is higher than my trans so do I lay the tranny down 3* and tilt the rear up 3*?
If the engine and trans are lower than the pinion, you need only set them at the same angle. You can even point the trans up and the pinion down. The only thing that matters is having them parallel. Ladder bars don't allow wrap up. Pinion angle has nothing to do with traction. The only thing you will affect is fuel level in your carb. An angle milled spacer will correct that. Rich pointed you in the right direction. Just so we don't start a debate that's been done on here so many times before, my resume looks something like this:
From what I understand the crank centerline and the pinion need to be parallel. The rear end can't tell whether or not it is higher or lower than the tranny.
My trans output yoke is lower than my pinion yoke w/ladders & coilovers. I read everything I could find & concluded the ladders keep wrapup @ 0, and the trans is 3 down & rear is 3 up with the DS running uphill front to back. Parallel with a slight offset. Good luck.
This is a good site with some simple diagrams http://www.streetrodderweb.com/tech/0203sr_drive_shaft_angles/index.html yea I know, streetrodder, but they actually have some pretty good tech here and there what I think people tend to do is focus on the driveshaft/pinion angle too much, what you're really trying to do is make the u-joints both spin relatively the same circle, you don't want one spinning differently than the other, or elliptical, thats what will give you vibration, and ultimately lead to u-joint failure(in the extreme end of things ,4x4's etc.) later down the road. Then again, dont take my word on it, thats just what I've put together in my brain from varying information sources.
Universal Joints were designed to be used where both angles, one from the trans and the other from the rear cannot be more than 4 degrees and the variance allowed 0-1/2* between them. For example; if the trans is set at 3* down the diff must be set to where operational angle is within 1/2* either + or - of the 3*. Meaning it can be from 2.5*-3.5* up to meet the same plane parallel to the trans down 3*. Anything more than that and a constant velocity joint will have to be used. I am not saying that having a leaf spring suspension at rest that the diff must be at the set angle, take into account for spring wrap caused by the pinion climbing the ring gear. I said OPERATIONAL angle or intended working angles.
yo man I'm finishing my model A build. I'm in the same boat. My 8" rear is actually above my trans. I'm running transverse spring in rear with radius arms. I just tilted the the rear up 3 degrees and the trans down 3 degrees. I've done a few short drives with it. No problems. Main thing is to make sure they are parallel.
I guess countless hours spent on the internet and the HAMB looking at tech stuff has finally paid off
a rearend with ladder bars and coilovers will still wrap.. thats why ladderbars work in the first place adding this: you get a torque wrap not spring wrap with ladderbars, thats why the pinion angle is less with ladderbars/radius rods
I think you are talking about the arc they sweep in from the ladder pivots and the drive shaft conflicting arc. Ladders pivot from their local on the frame and the drive line from its local on either the diff or the end of the trans. IF the length of the ladder can me made to pivot in the same location as the front u joint, there is no wrap. Most times this is not the case and they conflict and there is bind. not wrap and is translated as "torque wrap".
I knew this thread would turn into comedy hour.... Pinion angle does not affect traction. Mopar brought us the pinion snubber, a moderately effective way to limit axle wrap up on leaf spring cars. They still had to find the sweet spot where weight transfer, spring deformation and pinion snubber could all meet, then set the correct pinion angle at that position. Mopars like to howl on deceleration from the excessive downward angle on the pinion. The added traction found in these cars was the result of limiting axle wrap up, not a particular pinion angle. Ladder bars do not wrap up, they lift the car, adding weight to the rear tires. They use less nose down pinion angle than leafs because they don't wrap up. If you want traction without destroying u-joints, you must control suspension movement. That does not mean eliminate movement. It means making it move like you want it to. Once you have control of the suspension, you know what your pinion angle needs to be to provide the minimum degree of deflection in the u-joints. The strongest drive shaft is straight, like a torque tube. You want a u-joint to have as little angle as possible, except that they will try to lose their rotational center if you get too close to zero deflection. It is a compromise. You must have deflection for suspension travel and ride quality, so you must have a u-joint. Now you need to set it up as straight as you can without causing it to self destruct. Too much angle and the eliptical path that the bearing caps travel in will cause torsional stress on the shaft, resulting in vibration and eventual failure of the shaft. Too little angle and any imbalance at all (they all have some) will pull the shaft off it's rotational axis and create a steel jump rope, also resulting in vibration and eventual shaft failure. Keep it in the sweet spot and allow it out of bounds very rarely and a shaft will quietly do it's job.
The flux capciter is warped. So much nonsence. The engineering is well understood and available. Look up power transmission in engineering ref. books for some truth.
My 9" pinion is above the tail shaft in my A. I am running nice long radius arms. I put a fixed yoke on the trans and run a double-cardin drive shaft, with the articulated joint at the trans end. The pinion-line is pointed directly at the tail shaft. It is basically the upside-down arrangement you'd find on the front, and often rear of a Jeep off roader (since I build those too). This arrangement nicely accommodates the pinion angle change during suspension cycling. It is probably over-kill, but that is how I roll.
This link and the one I added to the beginning of this thread contain the correct, accurate information along with diagrams and thorough explanations of the theory.....
The Direct Connection chassis book suggests the pinion be nose down 2-5 degrees on a car with Super Stock springs. This is so that under load, when the pinion torques up, the angle will be close to correct and the u joints will live longer, and it will not vibrate due to different angles on the two u-joints. The pinion angle has nothing to do with how the car hooks.
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