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Re: Pinion angle again
[Re: RV2]
#1819099
05/05/15 12:28 AM
05/05/15 12:28 AM
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Joined: Dec 2005
Posts: 12,628
Fulton County, PA
CMcAllister
Mr. Helpful
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Mr. Helpful
Joined: Dec 2005
Posts: 12,628
Fulton County, PA
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Who's right? Depends. If you can achieve the desired pinion angle AND the desired equal and opposite operating angles of the front and rear u-joints at the same time, congratulations. To do so requires the engine/ trans assembly and the rear end to be at the correct heights, angles, and distance apart. Usually only achieved on a car built from scratch. For example, if the tail shaft is angled down from front to rear and the front u-joint is lower than the rear u-joint, you can't make the pinion and the tail shaft parallel without having the pinion angle go positive which is never ok. Pinion angle is most important and can't be made wrong in order to get the pinion parallel with the engine/transmission.
If the results don't match the theory, change the theory.
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Re: Pinion angle again
[Re: Sport440]
#1819113
05/05/15 12:48 AM
05/05/15 12:48 AM
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Joined: Jul 2004
Posts: 19,318
State of confusion
Thumperdart
I Live Here
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I Live Here
Joined: Jul 2004
Posts: 19,318
State of confusion
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I'm almost positive Larry Morgans chassis book showed a straight line at 0 degrees from the tail shaft on the trans back to the rear then so many degrees down according to rear suspension type and that's how I do mine.
72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
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Re: Pinion angle again
[Re: RV2]
#1819305
05/05/15 12:08 PM
05/05/15 12:08 PM
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Joined: Nov 2004
Posts: 6,890
North Alabama
Monte_Smith
master
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master
Joined: Nov 2004
Posts: 6,890
North Alabama
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Wolfe's picture SHOWS the driveshaft at a down angle and he doesn't even mention trans angle, because it DOESN'T matter in a RACE CAR. It is what it is and is for the most part not adjustable. As usual, guys confuse pinion angle and driveline angle. And one more time, if you do manage to achieve perfect driveline angle in a static condition, or set it where you THINK it will be perfect under power, it will NOT be so going down the track, as it goes through a big range of movement. And as McAllister said, it should NEVER go positive, regardless of what is perceived to be "right".
And yes Sport, I totally understand drive angles as well as how a driveshaft works............do you? Shame on Wolfe huh?, Yep, he is just some scrub chassis builder that has no idea what he is doing and should be slapped around. Guess Bob George is the same, as I believe he agreed as well. So tell me this, Mr driveline expert. If the front yoke happens to be closer to the ground than the pinion yoke, which frequently happens, because of engine angles, ride heights, tire sizes, etc, that you still think it would be RIGHT to achieve proper and equal joint angles, even though that would put the pinion in a positive condition, as compared to shaft..............Is that what you are saying. Must be, as the proper operating angle seems to be the only thing you care about.
Monte
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Re: Pinion angle again
[Re: Monte_Smith]
#1819316
05/05/15 12:32 PM
05/05/15 12:32 PM
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Joined: Jan 2003
Posts: 4,825
Moved to N.E. Tennessee
GomangoCuda
master
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master
Joined: Jan 2003
Posts: 4,825
Moved to N.E. Tennessee
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Pinion angle posts are the most entertaining thing on Moparts.   That's why we do it so often.  What happens to the driveline angles in a leaf spring bracket or street car is totally different from what happens in a promod car. Your going to set it up differently regardless of what the popular standard theory says. Never forget: "If it's wrong but it works then it's not wrong". Does anybody stress this much over what happens to the pinion angle when your standing on the brakes?
Last edited by GomangoCuda; 05/05/15 12:39 PM.
In theory, there is no difference between theory and practice. In practice, there is.
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Re: Pinion angle again
[Re: Quicktree]
#1819342
05/05/15 01:17 PM
05/05/15 01:17 PM
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Joined: Nov 2004
Posts: 6,890
North Alabama
Monte_Smith
master
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master
Joined: Nov 2004
Posts: 6,890
North Alabama
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Monte you know i respect you as one of the most knowledgeable guys on the board or anywhere as far as that goes. is there any negative to setting off the tail ? What if that is the lowest joint and the tail points down........whatcha gonna do then. Would you go positive, if the angles dictated you do that to make it RIGHT in your thoughts, even though positive pinion angle is NEVER desired in a performance car. That's the only question that needs to be answered. What would YOU do in above scenario. Your car, his car, that car..........doesn't matter whos car. If the rule is the rule, what are gonna do if the trans is pointing down and the driveshaft runs uphill. Think about that and then ask "does it hurt" to measure off the tail. Most big tire cars, with stock floor pans(backhalf cars) that have the motor in the stock location and angle........if the car sits anything resembling low and has a long trans, like a 727......the front joint is almost always lower than the rear. That's why there is always SO MUCH question on this stuff. They slide under there, start looking and measuring. Try to do it like the internet "experts" say and then look at it and say "that can't be right"............And they are correct, it's NOT right. If you want your car to ride down the road 100,000 miles, be smooth as glass and never have a problem, yes sir, concern yourself with overall driveline angle. Because YES, opposite angles are the smoothest in THAT scenario. But in a RACE CAR, it just flat doesn't matter, PINION ANGLE matters and the two are NOT the same. In a ten second car, you are worrying yourself to death over something that MIGHT be in the condition you deem ideal for about 3 seconds. Other than that, it is all over the place. Just put a go-pro under your car and WATCH the angle and see how long it stays static..........So, you want to measure off the trans, knock yourself out........but it is a TOTAL waste of time. Now I don't CARE what you do. But the fact that you and others think that you have to convince the whole world that it is the ONLY RIGHT way to set one up.........well, that I have a problem with, because in EVERY scenario, it is NOT right.
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Re: Pinion angle again
[Re: RV2]
#1819394
05/05/15 02:26 PM
05/05/15 02:26 PM
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Joined: Dec 2005
Posts: 12,628
Fulton County, PA
CMcAllister
Mr. Helpful
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Mr. Helpful
Joined: Dec 2005
Posts: 12,628
Fulton County, PA
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A 9" Ford with a 32" tire has the pinion about 13" off the ground. Danas and 12 bolts will be higher. In a stock front end backhalf car, that has likely been lowered and with the engine and trans in the original location, the front u-joint will likely be lower than the rear. Typically in the stock location, the engine/trans will angle down front to rear about 2 or 3 degrees. In this situation which is very common, in order to make the pinion and tailshaft parallel requires the pinion angle to go positive which you just don't do. It is not unusual in these cars to end up with what is called the "broken back" configuration. Not the optimum set up, but many times you have to compromise and do the best you can with what you have. The alternative is to relocate the engine/trans mounts. If you are building a car ground up, these things are taken into account and positioned correctly, but in a stock bodied, back half car, you usually don't have the luxury of everything being in exactly the right place.
I'm not saying the parallel tailshaft and pinion configuration is wrong, because it is the most correct way to set the driveline up. I'm just saying that sometimes you can't get there and you can't set-up the pinion angle incorrectly to make it happen.
Last edited by CMcAllister; 05/05/15 04:19 PM.
If the results don't match the theory, change the theory.
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Re: Pinion angle again
[Re: justinp61]
#1819416
05/05/15 02:53 PM
05/05/15 02:53 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Most of the big tire cars around here are four link and ladder bars. Does the pinion angle really change that much on them? I can't see them rotating near as much as a leaf spring car. Still matters.... you just dont want it going positive ... but the 4-link and ladder bar move about 1* to 2* where a leaf car moves about 6* EDIT I should say... you would like it to line up straight under full power 
Last edited by MR_P_BODY; 05/05/15 02:59 PM.
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Re: Pinion angle again
[Re: justinp61]
#1819476
05/05/15 04:10 PM
05/05/15 04:10 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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I understand it still matters, as I said I don't think they'll rotate as much as a leaf spring car. Your correct.. they move way less.. pinion angle on a 4-link is 1* or less but not zero.. and the ladder bar is 1 1/2* to 2*
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Re: Pinion angle again
[Re: CMcAllister]
#1819538
05/05/15 05:58 PM
05/05/15 05:58 PM
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Joined: Jan 2003
Posts: 32,394
Quicktree
I Win
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I Win
Joined: Jan 2003
Posts: 32,394
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A 9" Ford with a 32" tire has the pinion about 13" off the ground. Danas and 12 bolts will be higher. In a stock front end backhalf car, that has likely been lowered and with the engine and trans in the original location, the front u-joint will likely be lower than the rear. Typically in the stock location, the engine/trans will angle down front to rear about 2 or 3 degrees. In this situation which is very common, in order to make the pinion and tailshaft parallel requires the pinion angle to go positive which you just don't do. It is not unusual in these cars to end up with what is called the "broken back" configuration. Not the optimum set up, but many times you have to compromise and do the best you can with what you have. The alternative is to relocate the engine/trans mounts. If you are building a car ground up, these things are taken into account and positioned correctly, but in a stock bodied, back half car, you usually don't have the luxury of everything being in exactly the right place.
I'm not saying the parallel tailshaft and pinion configuration is wrong, because it is the most correct way to set the driveline up. I'm just saying that sometimes you can't get there and you can't set-up the pinion angle incorrectly to make it happen. ok when you say the tail is lower, give me an angle on the trans? is the tail pointing up? how many degrees?
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Re: Pinion angle again
[Re: Monte_Smith]
#1819542
05/05/15 06:02 PM
05/05/15 06:02 PM
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Joined: Jan 2003
Posts: 32,394
Quicktree
I Win
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I Win
Joined: Jan 2003
Posts: 32,394
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Monte you know i respect you as one of the most knowledgeable guys on the board or anywhere as far as that goes. is there any negative to setting off the tail ? What if that is the lowest joint and the tail points down........whatcha gonna do then. Would you go positive, if the angles dictated you do that to make it RIGHT in your thoughts, even though positive pinion angle is NEVER desired in a performance car. That's the only question that needs to be answered. What would YOU do in above scenario. Your car, his car, that car..........doesn't matter whos car. If the rule is the rule, what are gonna do if the trans is pointing down and the driveshaft runs uphill. Think about that and then ask "does it hurt" to measure off the tail. Most big tire cars, with stock floor pans(backhalf cars) that have the motor in the stock location and angle........if the car sits anything resembling low and has a long trans, like a 727......the front joint is almost always lower than the rear. That's why there is always SO MUCH question on this stuff. They slide under there, start looking and measuring. Try to do it like the internet "experts" say and then look at it and say "that can't be right"............And they are correct, it's NOT right. If you want your car to ride down the road 100,000 miles, be smooth as glass and never have a problem, yes sir, concern yourself with overall driveline angle. Because YES, opposite angles are the smoothest in THAT scenario. But in a RACE CAR, it just flat doesn't matter, PINION ANGLE matters and the two are NOT the same. In a ten second car, you are worrying yourself to death over something that MIGHT be in the condition you deem ideal for about 3 seconds. Other than that, it is all over the place. Just put a go-pro under your car and WATCH the angle and see how long it stays static..........So, you want to measure off the trans, knock yourself out........but it is a TOTAL waste of time. Now I don't CARE what you do. But the fact that you and others think that you have to convince the whole world that it is the ONLY RIGHT way to set one up.........well, that I have a problem with, because in EVERY scenario, it is NOT right. lol I am not trying to convince anyone about anything. I have never run into a situation where the angle is so much that it puts the rear in a positive mode. if the tranny is low and points up the rear has to point down to get to zero. then you have to roll down from there to what ever you want.
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Re: Pinion angle again
[Re: Monte_Smith]
#1819647
05/05/15 08:26 PM
05/05/15 08:26 PM
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Joined: Jan 2003
Posts: 13,081
Benton, IL.
DaveRS23
Master of nothing...
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Master of nothing...
Joined: Jan 2003
Posts: 13,081
Benton, IL.
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Whats going to happen.......is that after 20 pages of arguing, showing some drawings, the "god" illustration from Rossler, there is still going to be two sides to who is right........LOL!!!........But I won't be one of them. My one and only post right here.......................................................
Monte
Just too much fun to resist, isn't it?
Master, again and still
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Re: Pinion angle again
[Re: DaveRS23]
#1819726
05/05/15 09:47 PM
05/05/15 09:47 PM
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Joined: Jan 2003
Posts: 32,394
Quicktree
I Win
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I Win
Joined: Jan 2003
Posts: 32,394
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Whats going to happen.......is that after 20 pages of arguing, showing some drawings, the "god" illustration from Rossler, there is still going to be two sides to who is right........LOL!!!........But I won't be one of them. My one and only post right here.......................................................
Monte
Just too much fun to resist, isn't it? absolutely
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Re: Pinion angle again
[Re: Quicktree]
#1819938
05/06/15 01:08 AM
05/06/15 01:08 AM
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Joined: Dec 2005
Posts: 12,628
Fulton County, PA
CMcAllister
Mr. Helpful
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Mr. Helpful
Joined: Dec 2005
Posts: 12,628
Fulton County, PA
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A 9" Ford with a 32" tire has the pinion about 13" off the ground. Danas and 12 bolts will be higher. In a stock front end backhalf car, that has likely been lowered and with the engine and trans in the original location, the front u-joint will likely be lower than the rear. Typically in the stock location, the engine/trans will angle down front to rear about 2 or 3 degrees. In this situation which is very common, in order to make the pinion and tailshaft parallel requires the pinion angle to go positive which you just don't do. It is not unusual in these cars to end up with what is called the "broken back" configuration. Not the optimum set up, but many times you have to compromise and do the best you can with what you have. The alternative is to relocate the engine/trans mounts. If you are building a car ground up, these things are taken into account and positioned correctly, but in a stock bodied, back half car, you usually don't have the luxury of everything being in exactly the right place.
I'm not saying the parallel tailshaft and pinion configuration is wrong, because it is the most correct way to set the driveline up. I'm just saying that sometimes you can't get there and you can't set-up the pinion angle incorrectly to make it happen. ok when you say the tail is lower, give me an angle on the trans? is the tail pointing up? how many degrees? Typically on a backhalf car because of a taller tire and lowering of the car, the rear axle is higher in the car than original. Yes, typically the engine/trans (tailshaft) is 2-4 degrees down from front to rear on stock mounts. The OP says his is 4 degrees down. As a result of the rear being higher in the car, the front u-joint ends up lower than the rear u-joint. Often I find the driveshaft very close to level with the tailshaft down a couple of degrees and the pinion angle also down a couple of degrees as it should be. Total difference between the tailshaft and the pinion ends up being 4 or 5 degrees, maybe more. This is the "broken back" configuration. Lots of cars running like this and I see no problems as a result as long as it doesn't get to far out of whack. Raising the back of the trans on the mount can help, if there is room to do that.
If the results don't match the theory, change the theory.
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Re: Pinion angle again
[Re: Quicktree]
#1819960
05/06/15 02:03 AM
05/06/15 02:03 AM
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Joined: Nov 2004
Posts: 6,890
North Alabama
Monte_Smith
master
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master
Joined: Nov 2004
Posts: 6,890
North Alabama
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A 9" Ford with a 32" tire has the pinion about 13" off the ground. Danas and 12 bolts will be higher. In a stock front end backhalf car, that has likely been lowered and with the engine and trans in the original location, the front u-joint will likely be lower than the rear. Typically in the stock location, the engine/trans will angle down front to rear about 2 or 3 degrees. In this situation which is very common, in order to make the pinion and tailshaft parallel requires the pinion angle to go positive which you just don't do. It is not unusual in these cars to end up with what is called the "broken back" configuration. Not the optimum set up, but many times you have to compromise and do the best you can with what you have. The alternative is to relocate the engine/trans mounts. If you are building a car ground up, these things are taken into account and positioned correctly, but in a stock bodied, back half car, you usually don't have the luxury of everything being in exactly the right place.
I'm not saying the parallel tailshaft and pinion configuration is wrong, because it is the most correct way to set the driveline up. I'm just saying that sometimes you can't get there and you can't set-up the pinion angle incorrectly to make it happen. ok when you say the tail is lower, give me an angle on the trans? is the tail pointing up? how many degrees? I know of NO factory installed engine, that points the trans up in the rear. What he is saying is the same thing I said....which IS, if the FRONT joint is LOWER than the rear joint(which is common) the shaft is obviously running uphill. And even if the trans and pinion were dead level the shaft is STILL running uphill.......soooo, if you set it up to try and achieve parallel angles, the pinion is GOING to be positive angle.......that's a no-no. Bottom line, if the front joint is LOWER than the rear joint and the trans is either level, or down, the theory of "equal angles" goes right out the window.......So I ask again, in THAT scenario, how are YOU going to set the angle, if you maintain the angles must be even. And if your answer is that you have never seen a car like this............well then you haven't set up many cars, because this is a VERY COMMON scenario. Even my daily driver Challenger that sits low and has a 315 radial on the back, has the shaft running uphill in the rear. And we KNOW factory Mopars had an angle on the motors from the factory. Amazing that it doesn't toss driveshafts out on the road or rattle my teeth out I guess. Monte
Last edited by Monte_Smith; 05/06/15 02:18 AM.
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