Pinion Angle Question

[Pilot20]

I have a 57 Chevy that I am installing Air-Ride suspension on all corners. On the back I am also installing the 4-link AirBar system. My motor and transmission are setting at 3.5 degrees at ride height. I was planning on setting the pinion angle (front up) also at 3.5 degrees. Is this correct? Because of the low ride height, the back of the drive shaft will actually be a little higher then the front. Does this sound right? Thanks for the help.

[Vegas69]

Make sure and read the directions. I have the G bar which is the sister of the air bar. The instructions said to install it with 1 degree less angle than the drivline angle for pinioin angle change under hard acceleration. I went with .5 less since mine is driven on the street 95% of the time. So you would be at 3.5 driveline sloping down towards the rear of the car and 3.0 pinion sloping up towards the front of the car. \\ My driveshaft also slope up due to the low ride height. It's fine if your angles are correct.

[chicane]

Yes... that is fine.

Follow the linky... http://www.markwilliams.com/driveshafttech.aspx

[PRRC]

Yep, You will be fine. A Lot of the cars we set up the rear end is a little higher than the trans.

[Pilot20]

Thanks. I just wanted to make sure before welding everything up.

[The WidowMaker]

ive got to disagree again. if your pinion is higher, you want to point it down. you cant go off of what you have at your tranny, without measuring all of your working angles. if you have 3.5* down at the tranny, and now your DS points up towards the rear, you now have a WA of greater than 3.5*. check the specs on your u-joints, but most want an angle as close to 1* as possible (without going below), and no more than .5* difference btwn WA's.

for YEARS!!! its been common to match the pinion to the tranny ( \-\ ), but especially with your pinion being higher, you need to be like this ( \_/ ).

you could also raise the rear of you tranny to make its angle less. this would also lower your WA's.

check out this site. it lists the commonly accepted driveline configurations, and (third down) lists your up, down, up configuration as one of the unacceptable.

http://www.vibratesoftware.com/html_help/html/Diagnosis/Reference/Powertrain_Angle_Configurations.htm

Tim

[chicane]

Uhm...gee. I dont know about that. Agree to disagree then. My fourty+ year old F-body was shipped from the factory with a -4* powertrain and a +4* pinion... creating the null that cancels the working angle and maintains the "equal and opposite" theory that you dispute.

Just looking at that site and it's intripritation of any and all "one piece" prop shaft configurations basically it states that all of the OEM manufacturers for the last... uhmm I dont know, 60+ years... are wrong ??

Transmission Angle Propshaft Angle Rear Pinion Angle
UP UP UP
UP UP DOWN
UP DOWN UP
UP DOWN DOWN
DOWN UP UP
DOWN UP DOWN
DOWN DOWN UP
DOWN DOWN DOWN


I dont think so.



There is a general misunderstanding about "dropping the pinion down" several degrees. This is a practice that could be applied only to leaf spring cars without any traction control devices where springs can “wrap” and change pinion angle. This practice would not apply to 4-link, ladder bar or torque arm or high rate leaf spring equipped cars that have the ability to control the IC. Failure to maintain matched and minimum operating angles increase erratic non-uniform output velocity from the drive shaft to the differential.

[BBC69Camaro]

I'm certainly just a beginner, but what I was taught in my Suspension class was that you didn't want the driveshaft perfectly straight (0deg working angle). That was because the needle bearings inside the bearing cap need some force to rotate. Without rotation they can exert a constant force in one spot and cause damage to the bearing journal.

Least that is what I have in my notes. Is this not a valid concern? (trying to learn here).

[LateNight72]

Least that is what I have in my notes. Is this not a valid concern? (trying to learn here).
Yes it is a concern. And why drive shafts are never designed to be perfectly straight.

[Vegas69]

The driveshaft can be level but you must have a working angle at both joints. (The driveshaft can't be on the same plane as the pinion or output shaft)

[chicane]

I'm certainly just a beginner, but what I was taught in my Suspension class was that you didn't want the driveshaft perfectly straight (0deg working angle). That was because the needle bearings inside the bearing cap need some force to rotate. Without rotation they can exert a constant force in one spot and cause damage to the bearing journal.

Least that is what I have in my notes. Is this not a valid concern? (trying to learn here).

Your understanding is corret sir. All of what you have stated is true.

[The WidowMaker]

Uhm...gee. I dont know about that. Agree to disagree then. My fourty+ year old F-body was shipped from the factory with a -4* powertrain and a +4* pinion... creating the null that cancels the working angle and maintains the "equal and opposite" theory that you dispute.

i never intended to dispute your theory for all applications, just for an example like his. lets just say for instance that in your example, your tranny pointed down towards the rear 4*, your drive shaft down towards the rear 3* and your rear pointed up 4*. your driveline would meet all the criteria since your working angles are as close to 1* as possible, and they differ by no more than .5*. you have the PERFECT setup.

but, if he points his pinion up, he is increasing his working angles. that point cannot be disputed.... period. therefore, by pointing it down, he is decreasing his angles and can still cancel them out, but with lower working angles.

The driveshaft can be level but you must have a working angle at both joints. (The driveshaft can't be on the same plane as the pinion or output shaft) that working angle can be the result of the pinion and output shaft on the tranny being on different horizontal planes. not suggesting it since it would be harder to measure, but i found it interesting while reading.

Just looking at that site and it's intripritation of any and all "one piece" prop shaft configurations basically it states that all of the OEM manufacturers for the last... uhmm I dont know, 60+ years... are wrong ??


Quote:
Transmission Angle Propshaft Angle Rear Pinion Angle
UP UP UP
UP UP DOWN
UP DOWN UP
UP DOWN DOWN
DOWN UP UP
DOWN UP DOWN
DOWN DOWN UP
DOWN DOWN DOWN


you need to read what up and down refers to on that site. it threw me off at first as well. down on the tranny refers to the tranny actually pointing down towards the front. ive never see that in any oem application, therefore he is correct.


last quote i promise.....

Failure to maintain matched and minimum operating angles increase erratic non-uniform output velocity from the drive shaft to the differential.

matched would be the stated max of .5* difference, and minimum would be the 1* as stated. he states on the site that 4* is the max working angle you want for a shaft spinning like ours. but, i also talked to him on the phone and confirmed that 1* would not cause any issues and would lead to longer wear life on the joints. this echoed what spicer says.

with the OP having an angle of 3.5* on the tranny and the DS pointing up, he may be well out of the 4* spec, and hes way off the best case scenario of 1*.

Tim

[chicane]

I see what... you... are saying Tim. But the disconnection with how the others try to explain it leaves a reader astray.

Although... your example above... -4*/-3*/+4*... describes a truck... not a lowered street car. This cannot be applied to the example. Beside's... (-4)+(-3)+(+4) does not equal less than 1 or close to it. -3* is still outside of the 1* maximum. I hate to think that you are looking at this from a shaft angle 'point of view'.

The reality is... it would be better for the individual chassis to be measured, loaded, at ride height and make an adjustment from there.

In Pilot20's example... and with the relative suspension articulation associated with the peticular suspension being used... the pinion centerline and the transmission centerline need to be parallel and within 0.500*. With the associated suspension movement the operating angle will increase, but should not exceed 15 degrees. If he runs -3.5* power train and +3.5* pinion... he is well within the 0.500* tolerance... at a given ride height. It will change if/when the suspension is lowered and/or raised. But if he were to set it at -3.5*/+3.5* at static ride height... I dont believe that he will obtain the 15* maximum with the suspension lowered.

Anyway... we are :beathorse

[The WidowMaker]

Although... your example above... -4*/-3*/+4*... describes a truck... not a lowered street car. This cannot be applied to the example. Beside's... (-4)+(-3)+(+4) does not equal less than 1 or close to it. -3* is still outside of the 1* maximum. I hate to think that you are looking at this from a shaft angle 'point of view'.


not sure what the shaft angle point of view is???? but, i think you may be missing the pt of the working angle(WA). you dont take into account all three pieces, just the joint at each end. each joint has its own working angle. these angles can be completely different than each other, hence the requirement that they stay within .5* of each other. since in the example, all pieces point up towards the front the math would be the same for both joints;

(+4)-(+3)=1*..... so both WA's are 1*...... not (-4)+(-3)+(+4)=-3 ??????

I see what... you... are saying Tim. But the disconnection with how the others try to explain it leaves a reader astray.


i totally agree. there needs to be a common way of describing the angles. i acutally like the way he puts it since all the pieces are looked at the same way.

[chicane]

No... I get the working angle mechanics. I have built a few hundred drive shafts in my time. I stop doing the math long ago (and its shows)... right about the time of commercial lasers. That... is obvious, from the math above. It should read -3 vice that of -4.

Anyway... semantics.

What is actually more important here is that 'we' are missing the prop shaft angle measurement from Pilot20. Without that specific bit of information... we are pretty much grasping at straws to ultimately provide a correct asessment.

With the power train at -4.5*... and the pinion at +4.5*... this is merely thought of as good... as you can only go so far in suspension travel to actually worry about the propshaft angle. Normally... having equal and opposite will suffice for a street driven chassis. Although... if we had the propshaft angle... and specific ride height information... we could actually provide direction with the emperical data from just that.

Working Angle Calculation:
1. If both angles are upward, subtract the smaller angle from the larger angle to obtain the working angle.
2. If both angles are downward, subtract the smaller angle from the larger angle to obtain the working angle.
3. If one angle is upward and the other angle is downward, add the two angles together to obtain the working angle.

Not subtract.

I gave up on the hit and miss, manual angle theory since the introduction of "True Laser Alignment's" driveline tool. I fell it's better to do thing right the first time... and gain the 12-18 HP from doing it right.

[The WidowMaker]

trust me on this; your reputation regarding facts and knowledge makes it difficult for me to disagree.

i guess all im stating is that his angles could be better, much better. whether he will suffer from vibrations with 3.5+* angles is yet to be found. but, im just stating that he would be better pointing his pinion down ~3.5* which would lower both the front and rear WA's. it is a little more difficult than that, but a little math and a little time will dial in the perfect combo.

all my experience comes from my current chevelle. not only does my pinion sit higher than the tranny, but im running into clearance issues where the pinion passes through a crossmember. running the pinion down not only improves the clearance, but it was enough to dial in the numbers.

btw..... if hes not comfortable running the pinion down, he can raise the rear of the tranny to decrease its angle, and therefore decrease both WA's.

Tim

[chicane]

I agree... I like to keep the angles no more than 2.5* respectively.

Good to point out the trans angle adjustment. I too feel that a little less angle will be a benifit, not only to reduce the angle... but because it falls within the 1 to 2.5* that I believe high power/performance builds should be set up with. With a larger angle... and power being appied... it will open up the working angles and quite possibly induce vibration from just that.

[Pilot20]

Thanks for all the information, I'm trying to follow. Below is a little more information.

As previously stated, the transmission is pointing down towards the rear at 3.5 degress and I have the pinion pointing up at 3.5 degress. With this setup at ride height, the driveshaft is at 0.5 degrees with the back higher than the front.

I downloaded the trail version of the vibration software that WidowMaker provided a link for and entered the above information. The software shows it is OK since the working angles are not over 4 degrees which it claims is the maximum allowed for a "high speed" driveshaft.

What do you guys think?

[Vegas69]

Go with it and forget everything these over analytical fellers ever said. :rofl: Seriously....you will be fine. These guys are talking about pulling every last fragment of horsepower out of a race car. Your main focus is to get your u joints in harmony on a street car. That will allow the longevity you need and reliability. There just isn't much pinion wrap on a 4 link. I still like .5 degrees less pinion angle than drivline personally. I originally thought much like widow maker on the donward pinion angle and actually tried it. I can't say I noticed a driveline vibration but when I set it up in on the same plane I immediately noticed less driveline resistance and I think my chassis dyno proves it.

[chicane]

Thanks for all the information, I'm trying to follow. Below is a little more information.

As previously stated, the transmission is pointing down towards the rear at 3.5 degress and I have the pinion pointing up at 3.5 degress. With this setup at ride height, the driveshaft is at 0.5 degrees with the back higher than the front.

I downloaded the trail version of the vibration software that WidowMaker provided a link for and entered the above information. The software shows it is OK since the working angles are not over 4 degrees which it claims is the maximum allowed for a "high speed" driveshaft.

What do you guys think?

As I stated in my first post... I think you will be just fine.

[MickyT]

Im installing a Moser rearend behind a 406 SBC with Turbo 350 with a GV overdrive unit and a shortened drive shaft and have 3.5 down measuring from the starter on the engine which I read is an acceptable place to measure from for trans and the rear is -2 measuring using the vertical pinion yoke. This is on a lowered 67 Camaro. Reading this thread I need to shim rearend 5.5 degrees up to be correct. Is this correct and do I need to be concerned re working angles? Thanks for any assistance

[Vegas69]

Yes, but I would take advantage of all the tunnel clearance you have. If you can achieve 2-3 degrees of drivetrain angle you are better off as long as you working angles are ok.

[MickyT]

Thanks, do u think the measurement from the bottom of the starter is ok for transmission angle or would it be better or possibly different from the tailshaft housing of the GV?

[Vegas69]

You're better off using the harmonic balancer, oil pan rail, or better yet ujoint at the transmission yoke. You just need to make sure its at 90 degrees to the floor. Then you can use a socket that fits and is flush on the ujoint cap.