pinion angle W/ adjustable torque arm?
11-06-2007, 04:29 PM
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pinion angle W/ adjustable torque arm? i just got an edelbrock adjustable torque arm and poly. torque arm mount. i took the rubber pieces off the top of the rear springs and wrapped them with heater hose(free mod) so its is about a 1/2 inch lower then stock in the rear. im not sure if that is enough to make a difference. i was wondering if anyone knows what i should set the pinion angle at.
11-06-2007, 06:14 PM
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my quick and dirty recommendations:
1/2 degree negative for a DD or weekend cruiser
1 to 1.5 degree negative for a car with slicks and sees frequent hard launches
2 to 3 degrees negative for a strip only car
1/2 degree negative for a DD or weekend cruiser
1 to 1.5 degree negative for a car with slicks and sees frequent hard launches
2 to 3 degrees negative for a strip only car
11-07-2007, 08:42 PM
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As was explained to me it would be the reverse of the above.
Stock suspension/bushing car would take more negavtive angle for the given flex when launching, and you would lessen the angle as the bushings/suspension got more taught.
Example:
Stock lightly modded suspension = -5 to -4 degrees
modded suspension = -3 to -2.5
Race suspension = -2 to -.5
Stock suspension/bushing car would take more negavtive angle for the given flex when launching, and you would lessen the angle as the bushings/suspension got more taught.
Example:
Stock lightly modded suspension = -5 to -4 degrees
modded suspension = -3 to -2.5
Race suspension = -2 to -.5
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11-08-2007, 12:29 PM
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you have to figure out whats going on.
THE ONLY REASON for a very negative pinion angle is when you launch hard, the torque wants to rotate the axle in the opposite direction that the wheels rotate in (think of a wheelie). So when you launch real, real hard, and if your torque arms is real weak, you can flex positive several degrees. If you have a weak torque arm set at 0 degrees and flex up 3 degrees under hard launch, you run the risk of failure.. positive 3 and strong forces. By setting the pinion angle to -3 you arrive at 0 in this scenario when forces are at their greatest (during launch) BUT this means you have to drive around with -3 the rest of the time which increases wear and often increases noise and vibration.
SO like I said..
If you have a car that never sees hard launches.. there is NO REASON WHATSOEVER to have a significantly negative pinion angle because you'll never see great enough torque to push the pinion angle positive and risk failure.
If you have a car that sees moderately hard launches but spends more time daily driving, a slight negative pinion angle is acceptable.. a little insurance during the launch (so you run a degree positive, not going to kill you on streetable power levels) and your pinion angle wont cause excessive wear
If you have a car that sees very hard launches and is actually likely that it will flex an aftermarket torque arm.. then maybe you'll want 3 or 4 degrees negative. We're talking 500 hp or more and slicks.
you've got to understand that your power, your tires, your launch and your driving habits and what kind of torque arm you have all determine what your pinion angle should be.. anybody that says something like "all auto's should have X" doesn't get it
Judging by your sig.. running nearly 13 seconds, I wouldn't set your pinion angle much more than 1.5 degrees negative.. but still it would be good if you shared what tires you have, what torque arm you have and how often you perform drag strip launches
THE ONLY REASON for a very negative pinion angle is when you launch hard, the torque wants to rotate the axle in the opposite direction that the wheels rotate in (think of a wheelie). So when you launch real, real hard, and if your torque arms is real weak, you can flex positive several degrees. If you have a weak torque arm set at 0 degrees and flex up 3 degrees under hard launch, you run the risk of failure.. positive 3 and strong forces. By setting the pinion angle to -3 you arrive at 0 in this scenario when forces are at their greatest (during launch) BUT this means you have to drive around with -3 the rest of the time which increases wear and often increases noise and vibration.
SO like I said..
If you have a car that never sees hard launches.. there is NO REASON WHATSOEVER to have a significantly negative pinion angle because you'll never see great enough torque to push the pinion angle positive and risk failure.
If you have a car that sees moderately hard launches but spends more time daily driving, a slight negative pinion angle is acceptable.. a little insurance during the launch (so you run a degree positive, not going to kill you on streetable power levels) and your pinion angle wont cause excessive wear
If you have a car that sees very hard launches and is actually likely that it will flex an aftermarket torque arm.. then maybe you'll want 3 or 4 degrees negative. We're talking 500 hp or more and slicks.
you've got to understand that your power, your tires, your launch and your driving habits and what kind of torque arm you have all determine what your pinion angle should be.. anybody that says something like "all auto's should have X" doesn't get it
Judging by your sig.. running nearly 13 seconds, I wouldn't set your pinion angle much more than 1.5 degrees negative.. but still it would be good if you shared what tires you have, what torque arm you have and how often you perform drag strip launches
Last edited by OldeSkool; 11-08-2007 at 12:36 PM.
11-08-2007, 03:30 PM
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stock is a rubber T/A bushing on a transmission on a rubber trans mount and an arm of questionable strength. much more likely to flex up under a launch, even on 245 street tires
an item i left off my last post:
an exact 0* angle is reportedly bad because it doesn't rotate the u-joint bearings properly. so everybody should have at least some negative pinion angle.
an item i left off my last post:
an exact 0* angle is reportedly bad because it doesn't rotate the u-joint bearings properly. so everybody should have at least some negative pinion angle.
11-08-2007, 06:36 PM
#15
My car runs 10.00 to 9.90 and ive changed my pinion angle 5 times still the same 60 ft times. I would set it for the least wear on the u-joints makes better sense for a street car.
11-08-2007, 07:21 PM
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you have to figure out whats going on.
THE ONLY REASON for a very negative pinion angle is when you launch hard, the torque wants to rotate the axle in the opposite direction that the wheels rotate in (think of a wheelie). So when you launch real, real hard, and if your torque arms is real weak, you can flex positive several degrees. If you have a weak torque arm set at 0 degrees and flex up 3 degrees under hard launch, you run the risk of failure.. positive 3 and strong forces. By setting the pinion angle to -3 you arrive at 0 in this scenario when forces are at their greatest (during launch) BUT this means you have to drive around with -3 the rest of the time which increases wear and often increases noise and vibration.
SO like I said..
If you have a car that never sees hard launches.. there is NO REASON WHATSOEVER to have a significantly negative pinion angle because you'll never see great enough torque to push the pinion angle positive and risk failure.
If you have a car that sees moderately hard launches but spends more time daily driving, a slight negative pinion angle is acceptable.. a little insurance during the launch (so you run a degree positive, not going to kill you on streetable power levels) and your pinion angle wont cause excessive wear
If you have a car that sees very hard launches and is actually likely that it will flex an aftermarket torque arm.. then maybe you'll want 3 or 4 degrees negative. We're talking 500 hp or more and slicks.
you've got to understand that your power, your tires, your launch and your driving habits and what kind of torque arm you have all determine what your pinion angle should be.. anybody that says something like "all auto's should have X" doesn't get it
Judging by your sig.. running nearly 13 seconds, I wouldn't set your pinion angle much more than 1.5 degrees negative.. but still it would be good if you shared what tires you have, what torque arm you have and how often you perform drag strip launches
THE ONLY REASON for a very negative pinion angle is when you launch hard, the torque wants to rotate the axle in the opposite direction that the wheels rotate in (think of a wheelie). So when you launch real, real hard, and if your torque arms is real weak, you can flex positive several degrees. If you have a weak torque arm set at 0 degrees and flex up 3 degrees under hard launch, you run the risk of failure.. positive 3 and strong forces. By setting the pinion angle to -3 you arrive at 0 in this scenario when forces are at their greatest (during launch) BUT this means you have to drive around with -3 the rest of the time which increases wear and often increases noise and vibration.
SO like I said..
If you have a car that never sees hard launches.. there is NO REASON WHATSOEVER to have a significantly negative pinion angle because you'll never see great enough torque to push the pinion angle positive and risk failure.
If you have a car that sees moderately hard launches but spends more time daily driving, a slight negative pinion angle is acceptable.. a little insurance during the launch (so you run a degree positive, not going to kill you on streetable power levels) and your pinion angle wont cause excessive wear
If you have a car that sees very hard launches and is actually likely that it will flex an aftermarket torque arm.. then maybe you'll want 3 or 4 degrees negative. We're talking 500 hp or more and slicks.
you've got to understand that your power, your tires, your launch and your driving habits and what kind of torque arm you have all determine what your pinion angle should be.. anybody that says something like "all auto's should have X" doesn't get it
Judging by your sig.. running nearly 13 seconds, I wouldn't set your pinion angle much more than 1.5 degrees negative.. but still it would be good if you shared what tires you have, what torque arm you have and how often you perform drag strip launches
i called edelbrock this morning and they said i should run -2 degrees for a daily driver with the edelbrock adjustable torque arm and -4 degrees for an all out race car. i set my angle at -2 degrees. do you think it will be ok, or should i change it? keep in mind that i "hot rod" my car everyday, do a lot of hard acceleration from stop lights, alot of burnouts, and take off on the highway alot. i am also going to the tulsa dragstrip this weekend. my tires are kuhmo ecsta supra 275/40/17 and they are not very sticky. it sounds like you have researched this alot and know what you are talking about so i trust your opinion. let me know what you think. thanks
11-09-2007, 07:24 AM
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ok, last night i drove it home for the first time in two weeks. from about 30mph and up i get a rotational noise. almost like a rotational grinding but not horrible. i put it on a lift at work and the u-joint is still tight, nothing is lose, and nothing is rubbing. im not sure if my new driveshaft is slighty out of balance or the pinion angle needs changed. do you think i should try changing it to -1.5 degrees or -1 degrees?