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Discussion Starter · #21 ·
Ok today after work I went out in the shop and rechecked the harmonic balancer and it was 2.4deg down
So I set the pinion angle to 2.4 up
And drive line is still .1 deg up
I put the angle finder on the bearing caps at the yolk and rearend on the drive line the working angles was about 1 deg.
I thank I did it right sound tell bearing cap was down then measured.
I didn’t get to drive it tonight hopefully tomorrow after work. And report back more thank you every one for all the help I pray this fixed the vibration problem
 

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Here's a great guide to setting this up.

Power Train Set-Up Guide (iedls.com)

Make sure you're measuring all of this with "weight on wheels".
You obviously need to jack your car (which looks f-ing awesome BTW!), so first measure the frame angle sitting on the ground, then jack it up so that the frame is at the same angle, so that you're simulating it sitting on the ground.
Obviously, the jackstands will be supporting the rear axle so that the springs are compressed...

They have another PDF that covers much more information, especially when setting up a custom hot rod chassis from scratch.

Power Train Setup.pdf (iedls.com)
 

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I forget now, but if the driveline is all in the same plane. Zero degrees. The uni-joints don't rotate completely and wear in one spot. Early failure. I'm ready to be corrected.
 

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'23 T-Bucket Pickup
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I forget now, but if the driveline is all in the same plane. Zero degrees. The uni-joints don't rotate completely and wear in one spot. Early failure. I'm ready to be corrected.
The transmission and pinion need to be in parallel planes.
 

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Discussion Starter · #27 ·
I got out to drive the coupe today it was nice out it wasn’t raining.
it was a pain to be able to get it up to speed in rush hour traffic but I finally got to a spot where traffic was light and to it up to 90 part of the vibration that I had was gone.
i didn’t get much of a chance to keep steady at the speeds I needed.
I was reving the car and around 1100 to 1500 ish there is a rumble and seems to smooth out some what at higher rpm.
 

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Hates: Liver. Loves: Diesel
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I just want to make sure I’m setting the pinion up right in this pic my rear end is frount up like the lower pic that’s correct right ?
Both of those pictures show possible correct configurations. The top one might be in a Jeep or a pickup, the bottom one might be in a cadillac. As long as the output shaft and pinion shaft are parallel (but not on the same plane so that you have 1-4 degrees of u-joint angle) you're good.

Picture a complete driveline that is one single line. The transmission, driveshaft, and pinion are dead-straight aligned with each other. The only thing bad about that setup is that you have no u-joint angle to cancel out harmonics. There are two equally valid and perfectly normal solutions: 1) shim the trans up 1 degree and the pinion down 1 degree, 2) do the opposite... drop the trans 1 degree and raise the pinion 1 degree. Both are perfectly acceptable solutions for the happiness of the driveline.

Some would argue that dropping the trans and raising the pinion is a smarter solution for engine operation - oiling, coolant bleeding, fuel slosh in the carburetor, but 1 degree either way won't really affect much.
 

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Hates: Liver. Loves: Diesel
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Having some angle at he u-joint has nothing to do with early wear or keeping the grease moving. It has to do with harmonics. Think about it... if you have 1 degree of u-joint angle, the cups aren't turning more than a couple degrees, so it wouldn't change how it wears. I would follow that logic if it was spinning 90 degrees or something, but it doesn't.

Have you ever given a yank on a spool of rope and it started jumping on the spindle, or spun the wheel of a small caster and it started vibrating on the axle? That's what u-joint angle prevents. It adds predictable resistance. With a zero u-joint angle, any harmonics (a bit of dirt, pulses from the combustion events in the engine, transmission shifting, etc) that make their way to the driveshaft have nothing to cancel them out.

Think about rubbing your finger over the rim of a wine glass. It takes a while to get it singing, but once it starts you don't have to change anything with your finger for it to get louder and louder. That's harmonics. It's a cumulative input of vibrational energy and self-amplifiying. How do you stop the glass from singing? Touch the side of the glass. The lightest touch defeats the vibrations at one tiny spot and the whole thing stops instantly.

u-joint angles. They're important
 

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Race it, Don't rice it!
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Sort of….A U-Joint speeds up and slows down twice on every revolution. The more angle, the more it speeds up and slows down per revolution. The yolk ends of a DS are indexed or phased 90’ to help cancel out the speeding up and slowing down.
if the DS is perfectly straight, you don’t get the speed increase or the rotation of the cross in the cups. It increases wear but not dramatically.
Equal and opposite angles cancel the speeding up and slowing down. That’s where the FS harmonics come from.
see example.
 
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