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Post Info TOPIC: Driveline angles
Ben


- RAMBO -Mill Creek, WASite Administrator

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Driveline angles
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Been reading and trying to understand the DL & pinon angle stuff to understand how much i need to (if at all) adjust my new adjustable arms to eliminate my wheel hopping issue.

 

The car is on ramps in front and jackstands under the axle in back, weight on all 4 corners. Here are the measurements i took:

-1.5 engine centerline (measured at flat rear of the scattershield)

-2.5 Driveline

-4.8 Rear end (taken off the rear flange of diff housing)

 

I'm reading this as:

-4* trans/DL 

-7.3* pinion angle

Which works out to be a 3.3* operating angle?

 

Does that sound right?

And from what I saw that operating angle should be 2* or less?

 

Thanks for any input-

 



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Ben R.

1968 Chevelle 300 - 454 / 4spd



- Durand -

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Nope.
Here ya go.

www.quickperformance.com/Pinion-Angle-Measurement_ep_45.html

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Ben


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LaVelle wrote:

Nope.
Here ya go.

www.quickperformance.com/Pinion-Angle-Measurement_ep_45.html


 

 

 2111999?AWSAccessKeyId=1XXJBWHKN0QBQS6TG






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Ben R.

1968 Chevelle 300 - 454 / 4spd

Ben


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Ok... Found this page...
spicerparts.com/calculators/driveline-operating-angle-calculator

4* front angle (upward sloped F->R)
7.3* rear angle (upward sloped F->R)

So that means I need to lengthen the rear arms to take about 3* out of the rear angle?


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Ben R.

1968 Chevelle 300 - 454 / 4spd




- Mike -
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That page is confusing at a glance.

Imagine the engine/trans and rearend are parallel but at different heights(rear lower). The Driveline is between 3 and 4 degrees angled to connect the 2.

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- Durand -

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The calculator is pretty cool, you just have to pay attention to the up and down slope direction.
The front angle is pretty much set unless you want to change the ride height,
I just measure the degrees that the driveshaft and pinion are off level or plumb (depending on how you measure) and add them together.

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- Erik -
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Ben wrote:

Ok... Found this page...
spicerparts.com/calculators/driveline-operating-angle-calculator

4* front angle (upward sloped F->R)
7.3* rear angle (upward sloped F->R)

So that means I need to lengthen the rear arms to take about 3* out of the rear angle?


 You need to shorten the upper arms to rotate the pinion angle down, to get it closer to the 4° angle of the engine/trans angle.  You need a couple of degrees of working angle on the U-joints so that the roller bearing inside of the U-joint caps, roll around.

Sometimes, for launch, you can angle the pinion down a couple of degrees, so that when you hit it and the frame and bushings flex, you get near perfect alignment as the pinion tries to rotate upward in reaction to your tires spinning the opposite direction.

 

And, I may be reading you wrong on what you are saying...your engine/transmission is at a 4° slant?  Your Pinion is at a 7.3° slant?  Or you are calculating the working angle of the front and rear U-Joint?



-- Edited by ehjorten on Tuesday 9th of January 2018 08:14:26 AM

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Ben


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ehjorten wrote:
Ben wrote:

Ok... Found this page...
spicerparts.com/calculators/driveline-operating-angle-calculator

4* front angle (upward sloped F->R)
7.3* rear angle (upward sloped F->R)

So that means I need to lengthen the rear arms to take about 3* out of the rear angle?


 You need to shorten the upper arms to rotate the pinion angle down, to get it closer to the 4° angle of the engine/trans angle.  You need a couple of degrees of working angle on the U-joints so that the roller bearing inside of the U-joint caps, roll around.

Sometimes, for launch, you can angle the pinion down a couple of degrees, so that when you hit it and the frame and bushings flex, you get near perfect alignment as the pinion tries to rotate upward in reaction to your tires spinning the opposite direction.

 

And, I may be reading you wrong on what you are saying...your engine/transmission is at a 4° slant?  Your Pinion is at a 7.3° slant?  Or you are calculating the working angle of the front and rear U-Joint?



-- Edited by ehjorten on Tuesday 9th of January 2018 08:14:26 AM


I'm having a hard time understanding what I'm reading on the various pages, but i think what you said is correct.

The working angle of the engine/trans & driveline is 4* and the working angle of the pinion & driveline is 7.3*

-------------

The rear end is already nose down a TON- so much so that the rear springs have to be PULLED backwards hard to catch the frame spring perches at the top when jacking the rear back up- i'm pretty sure that is and has been the issue from the beginning (new upper arms are set to the factory 68-72 length).

The engine/trans is tilted upwards just slightly so the end of trans is close to the trans tunnel.

The rear is nose down, enough that it is visually obvious that its pointing down.

 

 

 

 



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1968 Chevelle 300 - 454 / 4spd




- Erik -
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OHHH!!!! Your Pinion is nose down! In that case, then you need to lengthen the upper arms. I try to refrain from saying rearend on this website!

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- Mike -
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Postition the rear pinion angle closer to 2.5* down and take all your measurements again.

http://www.wolferacecraft.com/pinionangle.aspx



-- Edited by 66SSFan on Tuesday 9th of January 2018 01:21:49 PM

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- wondah whooooaman-
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66SSFan wrote:

Postition the rear pinion angle closer to 2.5* down and take all your measurements again.

http://www.wolferacecraft.com/pinionangle.aspx



-- Edited by 66SSFan on Tuesday 9th of January 2018 01:21:49 PM


 This page is correct.  There is a flat space that machined into the rear end on either side of the differential cover that you can use to measure the angle of the pinion.  Measure the angle on the drive shaft as shown.  Don't over think it.Pinion angle is the difference between the driveshaft angle and the pinion angle on the  differentiPinion angle is the difference between the driveshaft angle and the pinion angle on the  differential. 



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- Mike -
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gotago wrote:
66SSFan wrote:

Postition the rear pinion angle closer to 2.5* down and take all your measurements again.

http://www.wolferacecraft.com/pinionangle.aspx



-- Edited by 66SSFan on Tuesday 9th of January 2018 01:21:49 PM


 This page is correct.  There is a flat space that machined into the rear end on either side of the differential cover that you can use to measure the angle of the pinion.  Measure the angle on the drive shaft as shown.  Don't over think it.Pinion angle is the difference between the driveshaft angle and the pinion angle on the  differentiPinion angle is the difference between the driveshaft angle and the pinion angle on the  differential. 


 I agree, that page is much easier for someone to understand by a glance.  Good examples of different bushings also.



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gotago wrote:
66SSFan wrote:

 

http://www.wolferacecraft.com/pinionangle.aspx



-- Edited by 66SSFan on Tuesday 9th of January 2018 01:21:49 PM


 This page is correct.  There is a flat space that machined into the rear end on either side of the differential cover that you can use to measure the angle of the pinion.  Measure the angle on the drive shaft as shown.  Don't over think it.Pinion angle is the difference between the driveshaft angle and the pinion angle on the  differentiPinion angle is the difference between the driveshaft angle and the pinion angle on the  differential. 


"Ditto"  My link is just a little more lengthy.



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- Erik -
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Maybe I have just lost it, or never even had it, but I do not get the Wolfe Racecraft pinion angle explanation! You can't just set your pinion angle without any consideration of the angle of your engine and transmission! Those two things ideally need to match so that the un-even accelerations in the 2 U-joints cancel each other out. If your engine is slanted back 1.5° then your pinion yoke should be at the same angle, which would make the yoke pointed up, 1.5°. Now depending on whether you have a leaf-spring suspension, or you have trailing arms and bushings, you will want to statically point the pinion yoke a few degrees downward to compensate for when you are on the go-pedal and the bushing flex, leaf-springs wrap-up, etc. and the pinion rotates upward. What you then check is the working angle of the U-joint to be sure it is within tolerance. U-joints normally will only survive with less than about 10° of working angle and they also won't survive if they are at 0°. They need a slight working angle to cause the needle roller bearings inside to rotate around. As driveline speeds go up, the limit of the working angle goes down.

Now if you are talking about a C-V driveshaft, then the theory of the Wolfe Racecraft article it true, because that u-joint on the pinion you want to be within 1° under power. If you are talking about a truck with a 2-piece driveshaft and 3 U-joints, the issue of proper phasing is even more tricky!

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- Mike -
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I measured both ends of mine which ended up the same angle without modifying the trans height even with added overdrive length. I just figured Ben would be smart enough to do that since he did it already. LOL.

As far as the page, if the u-joint fails, maybe people will learn to check both ends like a normal person would do.

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- Mike -
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I don’t think all that will matter much for Bens wheel hop issues. I believe it all lies with the rear pinion angle being so far off there’s too much stored engery. When it hooks, it’s already wanting to stuff the pinion upward. I bet you could eye-ball the adjustment to a slight downward angle and test drive it and be close. Of course, this is assuming your engine and trans aren’t at a crazy odd angle already?

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Ben


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66SSFan wrote:

I don’t think all that will matter much for Bens wheel hop issues. I believe it all lies with the rear pinion angle being so far off there’s too much stored engery. When it hooks, it’s already wanting to stuff the pinion upward. I bet you could eye-ball the adjustment to a slight downward angle and test drive it and be close. Of course, this is assuming your engine and trans aren’t at a crazy odd angle already?


 This is pretty much where i was at- I knew it was angled way too far nose down- but i wanted to be a little more accurate with adjusting it- would like to get it to its ideal angle if i'm going to do it.

 

I've got a new issue though- Apparently while i had the upper control arms off all last week, the pressure of the Driveline on the yoke has caused it to start leaking badly from the pinion bolt and dripping down the ujoint.

There was a little bit of fluid "spray" visible on the mufflers and the floor boards before, but never any drips visible on the floor.

But since Sunday its pissed out a couple cups worth of fluid, i finally put a bowl under it last night when i came home from work to keep it all off the floor.

Its not coming out the pinion shield, so not sure if that means that the pinion seal is still ok, or??

 

So i guess i need to pull the driveline and check the yoke/pinion shaft for play that might indicate a bad pinion bearing.

If no play, i guess i will take the yoke off and replace the pinion seal and hope it seals up.

 

 



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- Shane -
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it may be coming thru the spilnes for the yoke...easy fix if so..

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Ben


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leadfoot067 wrote:

it may be coming thru the spilnes for the yoke...easy fix if so..


I hope thats what it is... It is not coming out under the pinion shield, so it would make sense.

I I'll try that first before i screw with the seal. I read some posts on TC about both topics.. hopefully cleaning & re-sealing the splines will resolve it.

 

Busy with seat work this week, but next week i should be able to spend some time on this again.

 



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Ben R.

1968 Chevelle 300 - 454 / 4spd

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