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Driveshaft angles, here we go

Ronald Weishaar

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Trying to get all the angles right. Starting with Engine,Trans down angle if car is level. What is the range from good to bad and ideal?
 
You only need a couple of degrees of angle to make the U joint "work". 2 or 3 degrees at each end is enough. My 2 cents! ruffcut
 
It is very confusing but Spicer has a calculator and basic rules on the web. It also has a show diagrams button. Still got to get your head around UP or DOWN but if you remember their rules it does make it easier.
General accepted angles for the motor/trans and rear axle is 1 to 3 degrees.
Follow the Spicer rules and get the operating angles of the universals within one degree of each other and all should be good. If one end of the driveshaft is say 5 degrees and the other end is 1 degree it will shake at some point.
For some reason some cars are pretty forgiving with regards to angles some are not and shake like ****.
 
2 down and 1.5 up with full tank of gas for measure.
My Dart has Super Stock springs, would the 2* down at the trans and 1.5 * up at the pinion still apply? Or does anyone have the same set up that might know their Trans, Driveshaft and Pinion angles?
 
The angles are right but every car is different so you need to measure yours and then enter the figures in the Spicer calculator and adjust if necessary.
The engine/trans and the rear axle need to operate in the same plane. This will mean the universals operating angle is the same at each end of the driveshaft.
Knowing someone else's angles will not help you.
 
The angles are right but every car is different so you need to measure yours and then enter the figures in the Spicer calculator and adjust if necessary.
The engine/trans and the rear axle need to operate in the same plane. This will mean the universals operating angle is the same at each end of the driveshaft.
Knowing someone else's angles will not help you.
Thank you, that's kind of what I thought, never hurts to ask! Thanks all for your input. Ron
 
I have a digital angle finder with a bubble on it that I find really handy.
One thing you need to get right is are the angles rising or falling with regards to the front to rear of the vehicle. You need to double check your measurements or you get all screwed up.
Once you get your head around this the calculator makes the rest easy.
 
For what it's worth, a had to use angle shims to get the nose of the rearend down to where I wanted it, with superstock springs.
I wanna say 3° shim, but it may be 1 1/2 or 2, I don't remember. The goal was 5° down static.
 
I have a digital angle finder with a bubble on it that I find really handy.
One thing you need to get right is are the angles rising or falling with regards to the front to rear of the vehicle. You need to double check your measurements or you get all screwed up.
Once you get your head around this the calculator makes the rest easy.
Thanks
 
There is a ton of confusion with driveline vibrations and angles. Even the calculators can be confusing. Some say the driveshaft angle does not come into play. Only the transmission angle and pinion angle but I have found that to not always be true. Basically, if you have shudder under load and goes away when you let up, your pinion needs to go down. If it gets worse when you let up, the pinion needs to be raised. In my case, the calculations showed everything was good but I still had some vibration. I swapped in a pair of Hotchkis shackles with 4" spacing in place of the 3.5" raising the rear up just 1/2" and my vibration went away.
 
There is a ton of confusion with driveline vibrations and angles. Even the calculators can be confusing. Some say the driveshaft angle does not come into play. Only the transmission angle and pinion angle but I have found that to not always be true. Basically, if you have shudder under load and goes away when you let up, your pinion needs to go down. If it gets worse when you let up, the pinion needs to be raised. In my case, the calculations showed everything was good but I still had some vibration. I swapped in a pair of Hotchkis shackles with 4" spacing in place of the 3.5" raising the rear up just 1/2" and my vibration went away.
Yeah, It's confusing, I've been reading, watching video and seems like what they're saying is that the angles need to be parallel. But super stock springs need to be down at the front yoke 3*to 5* to work. Figuring that on a hard pull the angle comes up to parallel. I think it's one of those deals that it's either a race car or a cruiser.
 
Follow the Spicer rules as I suggested before and you cannot go wrong.
They actually make universals so makes good sense to follow their recommendations.
 
So I spent YEARS trying to get my vibration out of my 73 Road Runner.

Here is what I learned: The "rule" says that engine and transmission should be down about 3*. Then the pinion should be parallel to the engine/trans, meaning up about 3*. But this only works if the pinion doesn't move. BUT IT DOES. (There is a good reason Mopar put pinion snubbers on our cars!)

For a leaf spring car like ours, the engine and transmission should be down about 3*, but the pinion must also be down about 3* (these measurements with the car level and with the weight of the car on the wheels). This gives a difference of 6*, but is needed so when the pinion raises under load, it all works. This is what finally worked for me.

Good luck!
 
This post (from "another" site) from Cass/Dr.Diff sums it up nicely...though his statement about welding the perches only applies if you can't get there with shims while still keeping the spring locating pin in safe contact.

Screenshot 2022-10-08 at 13-14-05 How do you adjust pinion angle.png
 
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And the Best place to buy shims is ? I need some 3*er's for my project...
 
That is good info for sure from DR Diff.
With my car all set up at ride height etc.
My GTX was 1 degree pinion down from flat if you get my meaning. The car had a mild shake over 75 mph that stayed up to 100 mph. Never went over that speed but the shake was noticeable but not severe. At 60 mph it was fine.
I raised the pinion up to 2 degrees above flat and it cured the vibration in my car anyway.
I believe if you have a really powerful motor or really beat on it you may find you need the pinion a little flatter.
I just cruise along generally. Under hard acceleration in first or second gear the car is vibration free.
 
Super stock springs, 3° shims, 5° total down. Strip/street car. Probably shoot for 3° down for a pure street car.

20191124_100126.jpg


20191124_100112.jpg
 
Anther point to consider is - if your springs allow the rear axle to "wrap up" or your engine is very powerful you might need to adjust the angle the pinion is on for that combination.
What works on one car for one driver may not work for another situation.
 
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