VERY easy way to check pinion angle - Chevelle Tech
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post #1 of 18 (permalink) Old May 31st, 12, 11:57 PM Thread Starter
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VERY easy way to check pinion angle

I have found a very easy way to check pinion angle with little to no chance of making a mistake.The fiirst thing we all do to check pinion angle is jack the car up,so why not jack it up to where the drive shaft is level, 0 degrees! now check your pinion,it is what it is,no adding no subracting, just make your necessary adjustments if any and your done.

Last edited by qtrn10; May 31st, 12 at 11:57 PM. Reason: spelling
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post #2 of 18 (permalink) Old Jun 1st, 12, 12:46 AM
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Re: VERY easy way to check pinion angle

Suspension loaded or unloaded?
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post #3 of 18 (permalink) Old Jun 1st, 12, 12:47 AM
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Re: VERY easy way to check pinion angle

I'm missing something here. pinion angle is the relation to the transmission axial angle to the pinion axial angle and the drive shaft angle is a different animal. pinion angle should be anything from a few degree to almost 0 degrees but never 0 degrees and the drive shaft angle is the angle the drive shaft sits connecting the transmission and rear end which can be over 14 degrees without affecting ujoint performance.
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post #4 of 18 (permalink) Old Jun 1st, 12, 1:18 AM
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Re: VERY easy way to check pinion angle

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Originally Posted by qtrn10 View Post
I have found a very easy way to check pinion angle with little to no chance of making a mistake.The fiirst thing we all do to check pinion angle is jack the car up,so why not jack it up to where the drive shaft is level, 0 degrees! now check your pinion,it is what it is,no adding no subracting, just make your necessary adjustments if any and your done.

That's not entirely true. You don't want to jack the car up as you need to check it on level ground at ride height with suspension loaded with driver. There should be no need to add/multiply/subtract/divide etc...it helps to have the back of the driveshaft disconnected from the yoke, and use an angle finder on the flats of the pinion yoke. Whatever angle that is, that is what the pinion angle is. At that time, if you have a girdle diff cover with a flat spot on the back, check that angle and see if it is the same or if it is off, note how much it is off by so you can check it from there instead of having to crawl under the car and disconnect the shaft everytime. Angle of the driveshaft means nothing. What negative angle you start with depends on the setup. Stock type suspension can be anywhere from -6 to -2, ladder bar and 4-links can be anywhere from -2 to 0 as they do not move. There is no mathematical formula to know how much it will move, so you get a starting point depending on what parts are used, and creep up on it. We also make sure the engine has just enough of an angle for proper oil drain back, but no more than 3-3.5 degrees. Knowing where the driveshaft is and adding and dividing by 2 or whatever people do, does nothing, the rear influences the driveshaft on launch, not the other way around. Optimally, you want the rear inline with the driveshaft and transmission on launch. There is no formula to know where that will be because you won't know how much it moves, other than track performance so adding and dividing doesn't do much nor will it give you a number to be at that will make it "inline" when launching the car. If you don't have enough negative angle, the pinion will go into positive, meaning past that center, or "inline" and will not run as good, also leading to broken u-joints. If you need a baseline on where to start, fill us in on what parts are used, but doing it that way won't help you much. 2cents

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post #5 of 18 (permalink) Old Jun 1st, 12, 10:31 AM
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Re: VERY easy way to check pinion angle

Quote:
Originally Posted by Vengeance Race Engines View Post
That's not entirely true. You don't want to jack the car up as you need to check it on level ground at ride height with suspension loaded with driver. There should be no need to add/multiply/subtract/divide etc...it helps to have the back of the driveshaft disconnected from the yoke, and use an angle finder on the flats of the pinion yoke. Whatever angle that is, that is what the pinion angle is. At that time, if you have a girdle diff cover with a flat spot on the back, check that angle and see if it is the same or if it is off, note how much it is off by so you can check it from there instead of having to crawl under the car and disconnect the shaft everytime. Angle of the driveshaft means nothing. What negative angle you start with depends on the setup. Stock type suspension can be anywhere from -6 to -2, ladder bar and 4-links can be anywhere from -2 to 0 as they do not move. There is no mathematical formula to know how much it will move, so you get a starting point depending on what parts are used, and creep up on it. We also make sure the engine has just enough of an angle for proper oil drain back, but no more than 3-3.5 degrees. Knowing where the driveshaft is and adding and dividing by 2 or whatever people do, does nothing, the rear influences the driveshaft on launch, not the other way around. Optimally, you want the rear inline with the driveshaft and transmission on launch. There is no formula to know where that will be because you won't know how much it moves, other than track performance so adding and dividing doesn't do much nor will it give you a number to be at that will make it "inline" when launching the car. If you don't have enough negative angle, the pinion will go into positive, meaning past that center, or "inline" and will not run as good, also leading to broken u-joints. If you need a baseline on where to start, fill us in on what parts are used, but doing it that way won't help you much. 2cents
Beware of what people post on the internet, kids.....

The angle of the driveshaft is CRITICAL!!! The pinion angle is not just the pinion angle, as stated above. The angle of the pinion in relationship to the ground, or earth, or gravity is completely irrelevant. What is critical is the relationship of the tranmission output shaft, the driveshaft, and the pinion gear.

When setting up the driveline, the critical measurements are the working, or sometimes called, the operating angles of the front and rear u-joints. The front working angle is defined as the angle between the transmission output shaft and the driveshaft, while the rear working angle is defined as the angle between the pinion gear and the driveshaft. The front and rear working angle need to be equal, but opposite, and for smooth operation, they need to be as small as possible (preferable under 2 degrees), without being zero, under load. Here is a good diagram:



So the OP is correct, if you don't want to do any math, then position the car, with the suspension loaded, so that the driveshaft is level with respect to gravity, earth, aka "level." Then you can measure the pinion angle and the transmission angle, and those will be your working angles, because the driveshaft angle is zero.

Alternatively, you can have the car in any position, with the suspension loaded, and do some simple math, and arrive at the same results.

Andrew
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post #6 of 18 (permalink) Old Jun 1st, 12, 11:26 AM
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Re: VERY easy way to check pinion angle

Quote:
Originally Posted by andrewb70 View Post
Beware of what people post on the internet, kids.....

The angle of the driveshaft is CRITICAL!!! The pinion angle is not just the pinion angle, as stated above. The angle of the pinion in relationship to the ground, or earth, or gravity is completely irrelevant. What is critical is the relationship of the tranmission output shaft, the driveshaft, and the pinion gear.

When setting up the driveline, the critical measurements are the working, or sometimes called, the operating angles of the front and rear u-joints. The front working angle is defined as the angle between the transmission output shaft and the driveshaft, while the rear working angle is defined as the angle between the pinion gear and the driveshaft. The front and rear working angle need to be equal, but opposite, and for smooth operation, they need to be as small as possible (preferable under 2 degrees), without being zero, under load. Here is a good diagram:



So the OP is correct, if you don't want to do any math, then position the car, with the suspension loaded, so that the driveshaft is level with respect to gravity, earth, aka "level." Then you can measure the pinion angle and the transmission angle, and those will be your working angles, because the driveshaft angle is zero.

Alternatively, you can have the car in any position, with the suspension loaded, and do some simple math, and arrive at the same results.

Andrew
Very good. I have a '70 Coupe with boxed lowers and adjustables uppers. I had them done and just expected the angles to be adjusted properly. I'm now going to check using your thread as a guide.

One more thing, since the trans angle can't really be adjusted the adjustment should come from the rear pinion angle, suspension under body weight with driver, drive shaft level, and adjustment should match the trans angle but the oppisite direction. Thanks.

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post #7 of 18 (permalink) Old Jun 1st, 12, 7:01 PM
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Re: VERY easy way to check pinion angle

Quote:
Originally Posted by tom6870 View Post
.....

One more thing, since the trans angle can't really be adjusted the adjustment should come from the rear pinion angle, suspension under body weight with driver, drive shaft level, and adjustment should match the trans angle but the oppisite direction. Thanks.

Tom6870
You are right Tom, there is not a lot of adjustment in the transmission position, but there is a little. In most cases, if a car is lowered from the stock ride height it is beneficial to raise the transmission as high as possible. This make the working angles less, but may not be enough.

Andrew

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post #8 of 18 (permalink) Old Jun 1st, 12, 7:57 PM Thread Starter
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Re: VERY easy way to check pinion angle

Thanks Andrew, I forgot to mention the obvious,yes by all meens load the suspension
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post #9 of 18 (permalink) Old Jun 1st, 12, 10:00 PM
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Re: VERY easy way to check pinion angle

Quote:
Originally Posted by andrewb70 View Post
Beware of what people post on the internet, kids.....

The angle of the driveshaft is CRITICAL!!! The pinion angle is not just the pinion angle, as stated above. The angle of the pinion in relationship to the ground, or earth, or gravity is completely irrelevant. What is critical is the relationship of the tranmission output shaft, the driveshaft, and the pinion gear.

When setting up the driveline, the critical measurements are the working, or sometimes called, the operating angles of the front and rear u-joints. The front working angle is defined as the angle between the transmission output shaft and the driveshaft, while the rear working angle is defined as the angle between the pinion gear and the driveshaft. The front and rear working angle need to be equal, but opposite, and for smooth operation, they need to be as small as possible (preferable under 2 degrees), without being zero, under load. Here is a good diagram:



So the OP is correct, if you don't want to do any math, then position the car, with the suspension loaded, so that the driveshaft is level with respect to gravity, earth, aka "level." Then you can measure the pinion angle and the transmission angle, and those will be your working angles, because the driveshaft angle is zero.

Alternatively, you can have the car in any position, with the suspension loaded, and do some simple math, and arrive at the same results.

Andrew

No disrespect to you Andrew, as I don't get involved with the pissin matches or posts about me not knowing what I am talking about, but Judging by that diagram, it is obvious you don't want the transmission lower than the rear, which in most cases it is not. But please explain how you think knowing all these angles has anything to do with how much the rear moves getting that "0" angle or directly inline for optimum power without swinging the driveshaft into positive numbers? There is no math that can tell you where it will wind up. You never want the driveshaft at a positive angle, or angles up towards the rear so if that is where you feel the angle matters, then I agree. As long as it is pointing down towards the rear yoke. As for engine/trans placement, you can put it anywhere you want. Taking a drivehft angle number and adding or dividing the yoke and all that nonsense to derrive at what you think the pinion is still doesn't tell you how much that rear will move on launch or what angle will be make the rear directly inline of the driveshaft on launch. Sorry, not gonna happen.. This where a lot of people get confused by throwing numbers out there and why I usually do it the way I explained from experience, to make the cars that get tuned on paper go faster lol...so yes kids, beware of what you read on the internet. I have been telling people that for years and this is why. Ofcourse, I would never TELL you that you are wrong, as you have every right to do what works for you. And I will continue to post and backup everything I advise to people from experience because it works my friend. If you have a driveshaft angles up like the diagram then there are other issues. Nothing to do with the earths gravitational pull or anything you described lol..You simply set the actual angle at the pinion, with everything else on pint in the car mind you, and tighten that angle until performance drops, like with anything you tune on a car. No need to reinvent the wheel with it. Doing it too long with results to even think math has anything to do with it, matching all angles and putting things where they look good in a diagram or on paper will not net any results but the assumption that it's right, when it isn't...

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post #10 of 18 (permalink) Old Jun 1st, 12, 11:37 PM
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Re: VERY easy way to check pinion angle

Beware of anyone who posts in all upper case and uses multiple exclamation points. Angles A and B have to be equal, duh.

As far as the OP's suggestion, the driveshaft angle is easiest to measure, but dependent on the relation of the trans and diff centerlines. Sorry, I'm not a mech engineer so if this is BS slap me!
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post #11 of 18 (permalink) Old Jun 2nd, 12, 2:54 AM
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Re: VERY easy way to check pinion angle

Man, this topic is a can of worms.. I think the drag race guys idea of optimum angle tends to clash with the guy who drives primarily a street car that is looking for as little vibration as possible at all speeds. The equal and opposite angles makes sense and I can confirm that my driveshaft ran uphill to the rearend in my Chevelle until I replaced the worn out springs.
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post #12 of 18 (permalink) Old Jun 2nd, 12, 11:59 PM
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Re: VERY easy way to check pinion angle

A country boy way to do this is use a drive on lift. I found a base hobby shop unit, which happened to be dead level.

Five minutes with a protractor did it.

And my 66 has the rear end higher than the trans output with new rear springs. That was a surprise.

You want two things:

Equal or nearly equal working angles at each end of the shaft, at 1 1/2 or 2 deg or less.

A static setting that will result in the above under launch and acceleration. A little preload if you will.

A set of UMI upper arms got my 66 pretty close.
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post #13 of 18 (permalink) Old Feb 16th, 17, 11:22 PM
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Re: VERY easy way to check pinion angle

Quote:
Originally Posted by rkd View Post
A country boy way to do this is use a drive on lift. I found a base hobby shop unit, which happened to be dead level.

Five minutes with a protractor did it.

And my 66 has the rear end higher than the trans output with new rear springs. That was a surprise.

You want two things:

Equal or nearly equal working angles at each end of the shaft, at 1 1/2 or 2 deg or less.

A static setting that will result in the above under launch and acceleration. A little preload if you will.

A set of UMI upper arms got my 66 pretty close.
andrews picture looks backwards to me. I cant recall looking at a driveline where the pinion is higher than the transmission.
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post #14 of 18 (permalink) Old Feb 16th, 17, 11:52 PM
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Re: VERY easy way to check pinion angle

this topic is allways made into an overcomplicated mess. the diagram above is good. its like this ;the front and rear ujoint angles need to be equal and opposite under load so depending on what suspension the rear pinion sngle needs to be set 2 to 6 degrees down at ride hieght .also,its very important to have the actual u joint to drive shaft angle 2 degrees or less.the more angle here the less rpm the driveshaft will tolerate. you want a little angle however otherwise the needle bearings will wear on one spot of the joint and shorten ujoint life
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post #15 of 18 (permalink) Old Feb 17th, 17, 10:20 AM
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Re: VERY easy way to check pinion angle

Quote:
Originally Posted by supertrucker View Post
andrews picture looks backwards to me. I cant recall looking at a driveline where the pinion is higher than the transmission.
It happens alot. Especially when you get into a car that is lowered or a backhalf car with 31 -33 inch tires.
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