Option for Pinion Angle - Chevelle Tech
Transmission & Driveline Transmissions and Differentials

 
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post #1 of 7 (permalink) Old Jul 13th, 20, 9:02 PM Thread Starter
 
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Option for Pinion Angle

I have a 67 chevelle with a 496 Vortec pro that is lowered two inches and I just installed a 4l80E transmission. The Angles were to steep so I cut the tunnel and now I'm able to raise the transmission. I have a few options below and I wanted to know which you think is the best for a Strong street car with street slicks. I have SPC adjustable rear control arms with delran sockets so I'm thinking it should only need an additional 1 or 2 degrees of negative rear Pinion angle to account for the rear pinion moving upward during hard acceleration. I have put three examples setting the transmission at -1.7 and three examples for the transmission at -2.4 degrees accounting for additional negative pinion angle.

transmission tailshaft -1.7 , driveshaft -3.1, rear pinion +1.7 Goal during hard acceleration
transmission tailshaft -1.7, driveshaft -3.7, rear pinion + .7 1 degree down for acceleration
transmission tailshaft -1.7, driveshaft -4.4, rear pinion + 0 1.7 degree down for acceleration


transmission tailshaft -2.4 , driveshaft -2.8, rear pinion +2.4 Goal during hard acceleration
transmission tailshaft -2.4, driveshaft -3.0, rear pinion +1.4 1 degree down for acceleration
transmission tailshaft -2.4, driveshaft -3.3, rear pinion + .5 1.9 degree down for acceleration

So how much additional negative rear pinion would you think I need? 1 or 2 degrees?
Which example would you think would work best?

Thanks in advance for any input!
Tom
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post #2 of 7 (permalink) Old Jul 14th, 20, 7:09 AM Thread Starter
 
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Re: Option for Pinion Angle

sorry my numbers got condensed in the above post.

transmission tailshaft -1.7 , driveshaft -3.1, rear pinion +1.7 ....................Goal during hard acceleration
transmission tailshaft -1.7, driveshaft -3.7, rear pinion + .7 ...................1 degree down for acceleration
transmission tailshaft -1.7, driveshaft -4.4, rear pinion + 0 ...................1.7 degree down for acceleration


transmission tailshaft -2.4 , driveshaft -2.8, rear pinion +2.4 ....................Goal during hard acceleration
transmission tailshaft -2.4, driveshaft -3.0, rear pinion +1.4 .................. 1 degree down for acceleration
transmission tailshaft -2.4, driveshaft -3.3, rear pinion + .5 ....................1.9 degree down for acceleration
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post #3 of 7 (permalink) Old Jul 14th, 20, 10:17 AM
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David Estes
 
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Re: Option for Pinion Angle

Download the Tremec app on your phone. It works great.

Have you ever stopped to think and forgot to start again??
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post #4 of 7 (permalink) Old Jul 14th, 20, 10:44 AM
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Troy
 
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Re: Option for Pinion Angle

I'm into drag racing, so just curious.

Do you need to allow for pinion gain in the four link style rear ends as opposed to a leaf spring car that allows the differential to rotate when power is applied?

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post #5 of 7 (permalink) Old Jul 14th, 20, 11:07 AM Thread Starter
 
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Re: Option for Pinion Angle

from what I have read you should allow 1 or 2 degrees for a 4-link.
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post #6 of 7 (permalink) Old Jul 14th, 20, 11:18 AM
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Troy
 
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Re: Option for Pinion Angle

Quote:
Originally Posted by tomsheaffer View Post
from what I have read you should allow 1 or 2 degrees for a 4-link.
I wonder if that changes with solid delrin style bushings vs factory style rubber bushings.

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post #7 of 7 (permalink) Old Jul 15th, 20, 2:01 PM
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Re: Option for Pinion Angle

The '91 Fox body Mustang in the picture has a 4 link with solid bushings. I set 1% down and it worked great. In a 4 link rubber bushings will compress under hard acceleration. Prior to the 1% down it had wheel hop.

Chas

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