Technical Another pinion angle question

Ok the terminology confuses me. I found this chart and circled how my transmission and pinion angle are at. I have a triangulated 4 link with rubber bushings. My transmission is roughly 1 1/2" higher than my rearend if that plays any part.

Anyhow my transmission is 4 degrees (per chart) and I have no way to (lift) up and decrease the angle. Pretty damn close to trans tunnel.

My pinion per the chart is at 3 degrees, if trying to tilt up and achieve a matching 4 degrees I may not have the floor clearance.

Anyhow I am asking if this will work being 1 degree out? Or will i get premature wear on the u joints?

Also I am confused on the bottom half of the chart. Why is center diagram on upper and lower sections completely different on the pinion side? Is that based on if the rearend sits higher than the transmission?

Yes I noticed the chart says 4 link and ladder bar.

Thanks in advance

 

View attachment 4821220

 

3 down (trans) 3 up (pinion) is pretty good for a street car. 4 is no big deal. Don't sweat it.

 

I didnt think 1 degree would matter. Everything I have been reading states 1 degree is acceptable.

Just overthinking I suppose.

So what is the bottom half of the chart referring to? The pinion is opposite of what i have circled. Meaning why is the pinion down not up?

Thanks again

 

You can try this app for your smart phone: https://www.hotrod.com/articles/tremec-driveline-angle-finder-app/
It actually works.
(I realize that a smart phone is not HAMB friendly so if it makes you feel better just drag your corded Princess phone out to the garage and use that.)

 

Haha, yes I found that yesterday. According to the app its says acceptable. Well all green anyways.

 

Bottom of chart shows pinion down since engine is up, no different then what you have just opposite direction. The driveline doesn't know the difference.

Remember, you are just setting the baseline, when driving or racing, the angle is constantly changing and will be all over the place angle wise. One or even two degrees over or under the " ideal angles " will not hurt a thing, just be sure you setting up with the full " as driven " weight on the axles, that includes driver and passenger weights.

 

This is the diagram I was referring to. I do understand when the engine is tilted (front) the opposite goes for pinion. But these I have circled both arrows are down.

 

If I get your question correctly, what you are seeing in your chart is a slight preload to counteract the rise in the pinion under acceleration. I didn’t know it differed between 4-link and ladder bars.

 

I kept an earlier copy of the Spicer driveshaft installation information. This is a link to the SPicer instructions that is a PDF so a person can save it. It is an easy read.
https://www.waterousco.com/media/wysiwyg/pdfs/content/J3311-1-DSSP.pdf

 

That makes sense. Just didnt realize it would change. know with leaf springs its totally different as well.

 

Thanks, down loaded and saved.

 

Think of it like this. You DO NOT want the trans mission angle and the rear pinion to be in a direct line (even if trans is down and pinion is up). Generally about 3 degrees down for the trans and 3 degrees up for the pinion BUT in different planes. Most of the time the pinion will be in a lower location, so if you extended the line out from the pinion it would pass below where the front u-joint is located......but be close to parallel with a line from the trans u joint.
Basically parallel planes on similar angles.
Now with leaf springs moving up and down thats going to vary some when driving, and thats good. Also if you accelerate hard, the springs will tend to let the rear end rotate and change the pinion angle a little (lot). For that reason its good to actually keep the pinion on slightly less than the 3 degree angle....more parallel to the ground. Then the normal reaction of the rear end as torque is applied for general driving is to rotate the pinion up to the desired 3 degrees. You can't check it very easily, so you just go a degree or two down and it will rotate slightly upward as you drive. Thats when using leaf springs.
If you use a four link, the rear end pinion can move up and down when the car is in motion, but it can't rotate like it can with leaf springs.
This video isn't exactly applicable, but you get the idea of whats happening.

 

Hey thanks to who ever posted that Spicer thread info. Ive had some trouble sorting out a 2 piece shaft ongoing issue. That info helped to make it more understandable.

 

I’ve got that vibration On my Ranchero that the Hot Rod article mentions, someone swapped in an 8.8 rear, guess I need to check those angles.

How do you adjust the pinion angle on a transverse leaf rear end? Need to check my 40 as well...

 

Just focus on the left and middle columns. Ignore the right column unless you have a 4-link or ladder bar.
I repeat; Pay no attention to the right columns. Don't circle anything there. Don't look at it. It's not for you.
One degree difference is not too bad in your circumstance. At least the slope at each end is going the same way. U-joints can speed up and slow down in a single rotation so having the slope the same keeps them in phase and not fighting against each other by each end trying to speed up at different points in a rotation.

 

I just picked up an 8.8. Did you ever find out if that was it ?


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