Sanity check on setting TA vs Pinion *
03-28-2006, 12:33 AM
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Sanity check on setting TA vs Pinion * Ok attached is the best I could do to draw it out, tried reading the way to do this and confused me (damn simple mind 
).
On the left is supposed to be the trans, and the angle is 2.5* tail down from centerline. On the right, the pinion is 1.5* down from centerline. That should give me 4* or 1*? Thats the part that gets me. I have seen where some articles suggest there be a straight line from tail to pinion, but I think the way I have it now, I only have 1* of pinion angle dialed in, which this would lead to my answer why my 60' are so shitty and recently felt a little wheel hop. I need to get this dialed in before friday so I can attempt to be the first LSx in the 9's. Please help. Thanks.
Charlie
FWIW, I will be running 28" 10.5 15" slicks, BADZ Rod ended LCA's, QA1/HAL Shocks, Spohn rod ended TA, TH350, 4,000 stall.
).On the left is supposed to be the trans, and the angle is 2.5* tail down from centerline. On the right, the pinion is 1.5* down from centerline. That should give me 4* or 1*? Thats the part that gets me. I have seen where some articles suggest there be a straight line from tail to pinion, but I think the way I have it now, I only have 1* of pinion angle dialed in, which this would lead to my answer why my 60' are so shitty and recently felt a little wheel hop. I need to get this dialed in before friday so I can attempt to be the first LSx in the 9's. Please help. Thanks.
Charlie
FWIW, I will be running 28" 10.5 15" slicks, BADZ Rod ended LCA's, QA1/HAL Shocks, Spohn rod ended TA, TH350, 4,000 stall.
03-28-2006, 05:32 AM
#2
The trans mission has nothing to do with pinion angle. What you are measuring is driveline angle.
To set your pinion angle get the car like it sits at the starting line. Place your angle finder on the pinion yoke. Set your pinion at -2 degrees. The ground is your constant.
To set your pinion angle get the car like it sits at the starting line. Place your angle finder on the pinion yoke. Set your pinion at -2 degrees. The ground is your constant.
03-28-2006, 11:30 AM
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Originally Posted by MADMAN
The trans mission has nothing to do with pinion angle. What you are measuring is driveline angle.
To set your pinion angle get the car like it sits at the starting line. Place your angle finder on the pinion yoke. Set your pinion at -2 degrees. The ground is your constant.
To set your pinion angle get the car like it sits at the starting line. Place your angle finder on the pinion yoke. Set your pinion at -2 degrees. The ground is your constant.
Jay stresses how the transmission IS the basis and not the ground.
How can two top suspension gurus disagree on something this important?
03-28-2006, 11:46 AM
#6
Explain this car to me then.
You have a car that the crankshaft and trans output shaft are 10 inches from the ground. The pinion yoke is 13 inches from the ground. This has the driveshaft running up hill to the rear end. How would you measure pinion angle and how much would you have??
You have a car that the crankshaft and trans output shaft are 10 inches from the ground. The pinion yoke is 13 inches from the ground. This has the driveshaft running up hill to the rear end. How would you measure pinion angle and how much would you have??
03-28-2006, 12:15 PM
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Originally Posted by MADMAN
Explain this car to me then.
You have a car that the crankshaft and trans output shaft are 10 inches from the ground. The pinion yoke is 13 inches from the ground. This has the driveshaft running up hill to the rear end. How would you measure pinion angle and how much would you have??
You have a car that the crankshaft and trans output shaft are 10 inches from the ground. The pinion yoke is 13 inches from the ground. This has the driveshaft running up hill to the rear end. How would you measure pinion angle and how much would you have??
I have also seen diagrams where the measurements are related to the transmission center line, but IIRC it was referring to driveshaft angles and its effects. That being, an excessive angle will wear out the joint quicker than a straighter angle. I would think optimally you would want the the driveshaft to be the centerline from Trans to Pinion during launch, but not to exceed the (putting the pinion nose up). So, setting my pinion down 2* and the trans is 3* down, during launch the driveshaft will have 1* of deliniation, sounds acceptable, but then again I am rambling on with only what I think of the relationship.
No disrespect to Jay at all, but I have got nothing but good advice from Brian and obviously his track results speak loudly for his knowledge. I will reset the angle thursday when I put the new shaft in. Thanks Brian. -2* is referring to Nose down? Dont want to make any assumptions and be wrong.
Brian, what are the effects, other than loss of traction, of having too much or too little PA? I would think too little would increase the propensity to wheel hop, as the axle is rotated and the pinion goes nose up too far? And too little would give a good initial bite but not be able to maintain, therefore spinning shortly after launch?
Charlie
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03-28-2006, 01:15 PM
#10
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Originally Posted by MADMAN
Too little will allow the pinion to over rotate. -2* is down yes. Usually I run -2* on a t/a car. Leaf spring cars I run as much as -7*. I havent found the need for more than -2* on any T/A cars. I havent seen them pick up any with more angle.
Reason I ask is, from a "u joint" perspective (from the manufacturers) they want to parallel the pinion yoke angle to the transmission mainshaft angle to phase the ujoints. So if the trans shaft angle is 1.5 degrees down, they want the pinion to be set 1.5 degrees UP. Just to keep the angles phased for cruising, etc....not for a drag launch where the diff trys to rotate.
So in your above example you would want the trans shaft angle 0 or + (up) some degree so the pinion could be turned down - to parallel it the same degree. (For the ujoint manufacturers)..........
For drag racing traction, Madman's real world experience rules.
My driveshaft is currently zero phased with a 1.5 degree UP pinion angle...I'm going to try the 2 degree down angle for traction.
Thanks for the comments Madman.
03-28-2006, 01:19 PM
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Originally Posted by MADMAN
The trans mission has nothing to do with pinion angle. What you are measuring is driveline angle.
To set your pinion angle get the car like it sits at the starting line. Place your angle finder on the pinion yoke. Set your pinion at -2 degrees. The ground is your constant.
To set your pinion angle get the car like it sits at the starting line. Place your angle finder on the pinion yoke. Set your pinion at -2 degrees. The ground is your constant.
03-28-2006, 01:49 PM
#13
Originally Posted by MADMAN
Explain this car to me then.
You have a car that the crankshaft and trans output shaft are 10 inches from the ground. The pinion yoke is 13 inches from the ground. This has the driveshaft running up hill to the rear end. How would you measure pinion angle and how much would you have??
You have a car that the crankshaft and trans output shaft are 10 inches from the ground. The pinion yoke is 13 inches from the ground. This has the driveshaft running up hill to the rear end. How would you measure pinion angle and how much would you have??
Well, what if it's the opposite and the crank/trans centerline is 30" above the ground and the pinion is 13"? Now you have a difference of about 22* between the pinion and driveshaft......
03-28-2006, 02:08 PM
#14
Originally Posted by 1fastWS6
Well, what if it's the opposite and the crank/trans centerline is 30" above the ground and the pinion is 13"? Now you have a difference of about 22* between the pinion and driveshaft......
True but we are working on a race car not a monster truck.
03-28-2006, 02:43 PM
#15
Originally Posted by MADMAN
True but we are working on a race car not a monster truck.
It was just an extreme example. My point was that you are trying to acheive a straight line between the pinion and driveshaft under load, right? So how does the ground even come into the equation?
03-28-2006, 03:15 PM
#16
Im not trying to get a straightline from the trans. I am trying to use the pinion to provide lift on the front of the car. The pinion is naturally trying to climb the ring gear. All I am trying to accomplish is keep the pinion from going over center.
Just for your info I just set pinion my way at -2*s. I then measured the other way and it comes to drivelineangle at -1.2*.
Just for your info I just set pinion my way at -2*s. I then measured the other way and it comes to drivelineangle at -1.2*.
03-28-2006, 03:54 PM
#18
How can you use the ground as a constant? Going by your method, pinion angle will change with front vs. rear ride height. By lowering my spring pressure on my QA1's up front, the front comes down, therefor changing my pinion angle. Obviously this is wrong. On the same theory, if I was to raise the back of my car (or run taller tires), this would also change the pinion angle. In a situation where a guy has lets say 30" slicks and has the front end slammed, setting the pinion angle your way will have the driveline at such a bad angle that you'll kill U joints and have the pinion over center.
With your method I think you're assuming a near level car, which isn't always the case.
Not trying to argue, I highly respect the knowledge you have, but I just don't understand how your method can work all the time?
With your method I think you're assuming a near level car, which isn't always the case.
Not trying to argue, I highly respect the knowledge you have, but I just don't understand how your method can work all the time?
03-28-2006, 04:37 PM
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Well, I guess I will be loading up the 28" Slicks for the rear and the 26" ET Front Runners, unloading the **** in the car, loading up the heap of **** driving the car (Me), get the suspension to settle from the unloaded to loaded extension of the shocks, and then set the pinion angle that way.
I appreicate the info tremendously.
I appreicate the info tremendously.