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Re: How do you adjust pinion angle?
[Re: B G Racing]
#1254297
06/22/12 06:53 PM
06/22/12 06:53 PM
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Joined: Jan 2003
Posts: 8,016
Polson, MT
DoctorDiff
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Posts: 8,016
Polson, MT
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This is not a side line. I deal with pinion angle "in the real world" on a daily basis.
In addition to constantly answering phone calls and E-mails on the subject (including customers of chassis/drivetrain shops), I set pinion angle on everything from street cars, to drag cars to circle track cars to lifted 4 x 4 trucks. Once, I even corrected the pinion angle on a hydraulic low rider.
The only thing these vehicles have in common is that ideally, under operating conditions, the front U-joint should run as close to parallel (parallel, not necessarily "pointing" at each other) with the rear U-joint as possible.
Once again, regardless of the method used to get there, this is how 2 joint driveshafts are designed to run. I'm more concerned with the relationship between the transmission and the pinion, than the angle of the U-joints, as this varies with ride-height/power-train height.
BTW, if the driveshaft angle is so severe it binds the U-joints, I adjust the slope of the transmission to flatten the bend. This is not usually necessary except for vehicles such as short wheel base lifted 4 x 4s.
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Re: How do you adjust pinion angle?
[Re: StealthWedge67]
#1254299
06/23/12 02:13 AM
06/23/12 02:13 AM
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Joined: Jan 2005
Posts: 3,699
Newport, Mi
Evil Spirit
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Joined: Jan 2005
Posts: 3,699
Newport, Mi
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There are 2 different sets of angles that need to be addressed - PINION ANGLE and U-JOINT OPERATING ANGLE . Pinion angle is the relationship between the engine/trans centerline and pinion gear and addresses vibration. U-joint operating angle is the angle between the engine/trans centerline to the driveshaft in the front and the pinion gear to the driveshaft in the rear, and addresses wear (until it gets over 10*, then CAN start to cause vibration). While the Rossler chart is helpful in showing the relationships between the individual parts (1) it isn't intended to be a guide for leaf spring cars (2) it is technicially incorrect since it doesn't address u-joint operating angle. In other words, you can have your centerlines parallel, but if you don't have any, or you have too much operating angle, IT'S STILL WRONG! You may actually have to adjust your engine/trans centerline to get the desired 1-2* OPERATING ANGLE on the front u-joint, then set the PINION ANGLE after that.
Now, all that being said, leaf spring cars are a crapshoot on how much pinion angle they need, since the amount of spring wrap-up varies greatly. Low horsepower-poor traction (tires) probably only need 3* pinion angle; high H/P, high tracton cars may need 5-7* pinion angle so that the angle is correct under power. But if you are deflecting the springs that much you probably should be looking at ways to control spring wrap-up.
And lastly, again I see another mention of pinion angle changing or not changing 60' times - I've challenged many times for someone to show me in mechanical theory how pinion angle changes traction - IT DOES NOT . The means you use to change pinion angle changes other things that may change traction - I/C, ride height, wheelbase, etc.
Free advice and worth every penny...
Factory trained Slinky rewinder.........
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Re: How do you adjust pinion angle?
[Re: Evil Spirit]
#1254300
06/23/12 07:14 AM
06/23/12 07:14 AM
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Joined: Jan 2003
Posts: 10,011
Frostbitefalls MN (Rocky&Bullw...
gregsdart
I Live Here
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I Live Here
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Frostbitefalls MN (Rocky&Bullw...
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"I'm with you Cab... the rear end is constantly moving so how can the 2 U-joints be equal at all times.. granted when I build a chassis I line the centerline of the engine/trans up with the centerline of the pinion with it at zero to the driveline then I roll the pinion down X dergees for the style of rear suspension.... I hate to get involved in this question... there are the 2 theories to it and no one agrees with the other"  Exactly. This subject has been argued several times without much give from those that are wrong.  After my experience with severe pinion angle due to axle housing tube slippage, I can understand why folks aren't willing to change their minds. Damage didn't occur till pinion angle was off by 20 to 25 degrees up. But then it took out the trans. If you think about it, Chrysler was able to recommend as much as 7 degrees down during coast for leaf spring cars. That would lead me to think there is at least a 7 degree window the other way where it may not be close but damage wouldn't show itself for an extremely long time.
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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Re: How do you adjust pinion angle?
[Re: gregsdart]
#1254301
06/23/12 02:15 PM
06/23/12 02:15 PM
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Joined: Jul 2006
Posts: 4,319
Puyallup, WA
StealthWedge67
OP
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Posts: 4,319
Puyallup, WA
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we have gone over general settings for SS springs, ladder bars, and 4-links. The O.P. asks about split mono-leafs with Cal-Trac bars. 4-7 degrees here also????
LemonWedge - Street heavy / Strip ready - 11.07 @ 120
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Re: How do you adjust pinion angle?
[Re: DoctorDiff]
#1254303
02/18/14 09:45 PM
02/18/14 09:45 PM
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Joined: Jun 2013
Posts: 16
Orlando, FL
98 SNAKE EATER
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Orlando, FL
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Hate to bring up such an old thread, but Google brought me here and it seems I've run into the same debate everywhere else I go  I have a 69 Road Runner with OEM replacement springs and I recently installed a pair of helper springs to adjust ride height. Put her up on my flat lift a couple days ago and came up with these readings on my angle meter. (All readings taken from the driver's side) Output Shaft -1* (trans pointed down towards rear of car) Drive Shaft -1* (drive shaft pointed down towards rear of car) Pinion +2* (pinion pointed down towards front of car) It's a street/strip car that normally rides on skinny G15 red lines for daily driving, but wears huge 29x12.5 meats on the weekends. Trying to decide on what shims I should use, but I keep getting conflicting opinions  Some say 5* down for a street car and 7* down for a track car. Here are a couple of videos showing what kind of spring wrap I'm dealing with... https://www.youtube.com/watch?v=xlBh3DgIaMghttps://www.youtube.com/watch?v=o_SMZMKFEAQWhat shims would you suggest?
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Re: How do you adjust pinion angle?
[Re: Thumperdart]
#1254307
02/18/14 11:05 PM
02/18/14 11:05 PM
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Joined: Jun 2013
Posts: 16
Orlando, FL
98 SNAKE EATER
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Orlando, FL
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Quote:
If you`re on multi leafs you want more like 5-7 nose down............ 
Yes, OEM replacement leafs + 1 helper leaf per side.
So unless I'm reading it wrong, going from what I measured, I should currently be at 3* down, correct?
Since most suggest between 5*-7*, lets say I go with 6* since it's a street/strip car.
Then 3* shims are what I need to install to get me there, correct?
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Re: How do you adjust pinion angle?
[Re: Thumperdart]
#1254309
02/19/14 12:04 AM
02/19/14 12:04 AM
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Joined: Jun 2013
Posts: 16
Orlando, FL
98 SNAKE EATER
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Orlando, FL
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Quote:
Quote:
Quote:
If you`re on multi leafs you want more like 5-7 nose down............
Yes, OEM replacement leafs + 1 helper leaf per side.
So unless I'm reading it wrong, going from what I measured, I should currently be at 3* down, correct?
Since most suggest between 5*-7*, lets say I go with 6* since it's a street/strip car.
Then 3* shims are what I need to install to get me there, correct?
In your video it looks almost like 0 then goes UP not good. Throw a 4 degree shim in there and redo a vid and post it.
When you say "0", are you referring the relation between the pinion and the output shaft or the pinion and the drive shaft?
This part really confuses me
From what I've read in all the angle guides, for me to get an actual parallel line between the pinion and the output shaft under load, the pinion would have to rise above the line of the drive shaft.
Here's an old video I made a while back using 6 degree shims
https://www.youtube.com/watch?v=wNr0q5MI6LI
The pinion seems to line up fine with the drive shaft under load, but not too long after using the 6* shims, I took a good chunk out of the ring gear 
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Re: How do you adjust pinion angle?
[Re: Thumperdart]
#1254311
02/19/14 12:32 AM
02/19/14 12:32 AM
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Joined: Jan 2003
Posts: 27,421
Balt. Md
383man
Too Many Posts
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Balt. Md
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I agree with DR Diff. Look at this link I posted as the first few paragraphs in the orange shows and tells you about pinion angle very well. The rear is always lower then the trans on a stock muscle car. What I like to do is set the trans centerline at 0 first if it is not. Then roll the rear to 0 and then move it down from 2 to 7 degrees depending on whay you use the car for. The reason the rear is always lower then the trans is as Dr Diff said you dont want the rear and trans running the same paralell line pointing at each other. The drive shaft has to have some angle so the U-joints will lube. You just want the trans centerline and the pinion centerline the same as paralell to each other but the pionon centerline lower then the trans centerline. Once they are paralell just roll the pinion the degrees down you want. Ron http://www.moparts.org/Tech/Archive/axle/8.html
Last edited by 383man; 02/19/14 12:33 AM.
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Re: How do you adjust pinion angle?
[Re: Thumperdart]
#1254312
02/19/14 12:49 AM
02/19/14 12:49 AM
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Joined: Jun 2013
Posts: 16
Orlando, FL
98 SNAKE EATER
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Orlando, FL
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Quote:
Can`t see the trans angle but the diff goes up past 0 under load. Put it back in the air, measure trans angle, figure what shims needed to get 5 down and go from there.
When you say "0", what do you mean?
Like inline with the drive shaft?
What I have measured is what I posted previously
Sitting on a flat, level lift with a full tank and a trunk full of junk, I got these readings...
-1* on the output shaft (output shaft pointing down toward rear of car)
-1* on the drive shaft (drive shaft pointing down towards rear of car)
+2* on the pinion (pinion nose down towards front of car)
Taking the drive shaft measurement out of the equation and just focusing on the output shaft and pinion, I'm looking at a 3* difference.
So I take it this means that I have 3* nose down?
From the charts I've read, the suggested setting for a leaf sprung car is 5* for a street car and 7* nose down for a track car.
So lets just say for the sake of argument that since my car is both street and strip, I go for 6* nose down by adding 3* shims (am I on the right track here?)
Even with those shims, the pinion would still have to rise above the center line of the drive shaft in order to be parallel with the output shaft of the tranny 
Like the bottom diagram in this image...
On a side note, my car has a rather level low stance and isn't jacked up in the rear, which would likely make a difference in how the pinion lines up with the output shaft on a parallel plane
https://www.youtube.com/watch?v=EcenVVInpms
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Re: How do you adjust pinion angle?
[Re: 98 SNAKE EATER]
#1254313
02/19/14 01:40 AM
02/19/14 01:40 AM
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Joined: Jan 2003
Posts: 27,421
Balt. Md
383man
Too Many Posts
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Too Many Posts
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Balt. Md
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No the top pic that says "Correct pinion angle" is correct. You want the trans and pinion centerline level at the same angle but paralell each other like the top pic as they should not be the same line. Once you get both the trans and pinion at a level 0 degree angle then you nose the pinion down the amount of downward pinion angle you want (2 to 7) so that way when you hit the gas and the diff wraps upward you will have both lines basically about paralell to each other as in the top pic that says Correct pinion angle. They build the cars with the rear lower then the trans and you need some angle in the driveshaft to make the U-joints work and stay lubed. If the shaft was dead straight the U-joints would not work and they would not keep lubing. Ron
Last edited by 383man; 02/19/14 04:26 PM.
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Re: How do you adjust pinion angle?
[Re: Thumperdart]
#1254315
02/19/14 11:28 AM
02/19/14 11:28 AM
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Joined: Jun 2013
Posts: 16
Orlando, FL
98 SNAKE EATER
member
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Posts: 16
Orlando, FL
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Quote:
No the top pic that says "Correct pinion angle" is correct. You want the trans and pinion centerline level at the same angle but paralell each other like the top pic as they should not be the same line. Once you get both the trans and pinion at a level 0 degree angle then you nose the pinion down the amount of downward pinion algle you want (2 to 7) so that way when you hit the gas and the diff wraps upward you will have both lines basically about paralell to each other as in the top pic that says Correct pinion angle. They build the cars with the rear lower then the trans and you need some angle in the driveshaft to make the U-joints work and stay lubed. If the shaft was dead straight the U-joints would not work and they would not keep lubing. Ron
This is the issue I'm having cause with my current readings, the trans is inline with the drive shaft, like this....
Taking the drive shaft out of the equation and just concentrating on getting the trans an pinion parallel using pinion shims, this is what my setup would look like...
Sorry for the crude diagrams.....I really suck at photoshop
When I had SS springs with the ass end jacked up to the sky and the front end in the weeds, the axle was lower than the trans and I was able to adjust pinon angle as you say...
But now that I have OEM leafs with the front end cranked up, it appears that the axle is now located higher, so the only way I can adjust the pinon to be parallel with the trans would be with the pinion center line above the trans
That's pretty much where I am at this point and still a bit confused
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