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Transmission, Rear End... Talk & Q&A! Tranny, rear end, drivetrain related stuff... shift it... grind it... pop da clutch!

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  #1  
Old 09-17-2018, 08:27 PM
Oldboy Oldboy is offline
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Default Pinion angle woes

Hello,
I may have posted this before, but i have not resolved this and could use some help.
46 Plymouth, V8, auto trans. Ford posi.
Cannot seem to get my pinion angles right. I am using an angle finder on the trans yoke. Think i may pull the driveshaft and take my angle from the flat of the trans where the yoke would be. I seem to have 5 1/2 degrees down from the trans. Now the diff pinion needs to be 5 1/2 up? But this cannot be because then the pinion is pointed up and I thought that was wrong .
Please weigh in this is driving me nuts. Thanks
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  #2  
Old 09-17-2018, 10:44 PM
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Dr Crankenstein Dr Crankenstein is offline
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You're not wrong. The old rule of thumb is crankshaft/output shaft 3° down, pinion shaft 3° up. (Your 5.5° seems excessive.)

You want equal and opposite angles without exceeding the u-joint's working angle. (Crankshaft and pinion shaft must be parallel to each other.)

Flip through this document, ignore the multi-shaft arrangements and note the offset chart which may apply to your Ford diff...

http://media.spicerparts.com/cfs/fil...store=original

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Old 09-17-2018, 11:52 PM
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First... you didn't say what type of rear suspension you're using. Rear ends using parallel leaf springs are usually set up at 3-5 degrees because they flex more. 4-link's are a lil more stable & are typically set at 2-3 degrees.

I like to set mine up at 6 degrees total. Engine down 3 degrees with rear end up 3 degrees. Also... I measure the engine's 3 degrees off the intake manifold where the carb sets.

Hope this helps!

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Old 09-18-2018, 08:48 AM
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Blue Eyed Devil Blue Eyed Devil is offline
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5 1/2 degrees is way too much - 3 down 3 up.

Like Billy Dee says - Works every time...
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Old 09-18-2018, 09:07 AM
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Old Iron Old Iron is offline
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Doc, the Spicer page is great for someone trying to wrap their head around this process.
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Old 09-18-2018, 12:17 PM
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I've read the Spicer pages too, and formed an opinion. It seems to me that the working angles of each U-joint is more important than the slant of your transmission and rear-end, [as long as they are parallel]. Hopefully, some of the off-road guys will chime in here, with their really slanty driveshafts.
My opinion is not to be trusted completely because I'm in the middle of healing up a driveline vibration on my '36. I have just lined up my motor and transmission to be parallel to the pinion, on a horizontal basis. We all worry about the vertical driveline angles but I'm telling you to remember the horizontal ones too. I have not test driven my latest driveline change, so have no answers, only opinions.
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Old 09-19-2018, 08:16 PM
Oldboy Oldboy is offline
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Hello,
Yes the rear is leaf spring.
I am thinking i will raise the trans crossmember, or at least bring the angle closer to 3 degrees with spacers. I may have to trim the trans tunnel a bit but am ok with this. Then at least i will have some flexibility with pulling the pinion down a bit. Will strive for 3 degrees each.
Not sure about looking down from the top view, but think they are pretty much in line that way.
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Old 09-22-2018, 07:40 AM
Oldboy Oldboy is offline
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Ok,
Well i clearanced the trans tunnel slightly, raised the tail up about 1”.
Readings with the spicer app resulted in all “green” after entering the 3 measurments. So i locked it down and will hopefully drive the car later.
Post w result.
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  #9  
Old 09-22-2018, 07:46 AM
Oldboy Oldboy is offline
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After using the Spicer app I got all “green “in the results,
locked everything down putting it back together hopefully take for a ride later and post with results
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Old 09-27-2018, 08:43 PM
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Quote:
Originally Posted by Blue Eyed Devil View Post
5 1/2 degrees is way too much - 3 down 3 up.

Like Billy Dee says - Works every time...

Yep, been doing that for years, never a problem with vibration or anything.
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