Pinion angle?

[Budneeds2beers]

Ok so ive ordered a truss kit for my truck.
https://www.ballisticfabrication.com/products/aam-11-5-rear-axle-truss
So my question is when i go to weld the kit do i match the pinion angle or weld at 0*? Im going to lift the truck and maybe later on in its life link it.... not sure yet but who knows. I guess what determines pinion angle?

 

[KyleC4]

pinion angle is determined by driveline angles. More so your driveline working angles. So, there's an angle formed by the intersecting line from your trans/transfer case output shaft and the driveshaft. Then, there's another angle formed by your pinion and driveshaft. You'll have to measure your front driveline working angle. A general rule of thumb is a working angle that doesn't exceed 4 degrees. Measure output shaft angle and then driveshaft angle. Subtract them from each other to get working angle. Then do same for rear pinion and driveshaft. And also, you don't want any angle to be 0 degrees. That'll cause u-joint failure. And in the end you want the difference between your front driveline working angle and the rear driveline working angle to be between 1/4 to 1 degree.

sorry for late response and let me know if all that jibber jabber from me made sense

 

[lts1ow]

I have my camaro set for -1 at normal setting. So rear end is pointing down a degree, theory being that a hard launch twists it up to neutral.

 

[Chevy1925]

Ok so ive ordered a truss kit for my truck.
https://www.ballisticfabrication.com/products/aam-11-5-rear-axle-truss
So my question is when i go to weld the kit do i match the pinion angle or weld at 0*? Im going to lift the truck and maybe later on in its life link it.... not sure yet but who knows. I guess what determines pinion angle?

there is no set position for pinion angle that will work on both a leaf sprung truck and linked truck (specifically a triangulated 4 link like you will be after for off road play).

put the truss on so it runs parallel with the diff cover mounting flange. its position will not determine pinion angle, the link bars you build or the shims you add to the leaf perches will determine the pinion angle. if you put blocks in the rear ALWAY get tapered blocks, even if they are 2".

the ONLY time the pinion working angle can be 0 is if you are running a DC joint at the t-case output, you then want the working angle to be 0.

 

[2004LB7]

if you put blocks in the rear ALWAY get tapered blocks, even if they are 2".

Are you sure about this? I always was under the impression that both u joints on each end of the drive shaft had to be at the same angle. If you put blocks on the rear and push the axle straight down the angles should match. If the blocks are tapered then the two joints may be at different angles. I thought the only time you wanted tapered was to compensate for angles that didn't match.

On my truck, I only have 2" blocks and they are straight. Runs smoothly

 

[bmc1025]

When you raise the truck you will want the pinion and the output shaft to be on the same plane. Having the pinion slightly lower is a good starting point.

 

[Chevy1925]

Are you sure about this? I always was under the impression that both u joints on each end of the drive shaft had to be at the same angle. If you put blocks on the rear and push the axle straight down the angles should match. If the blocks are tapered then the two joints may be at different angles. I thought the only time you wanted tapered was to compensate for angles that didn't match.

On my truck, I only have 2" blocks and they are straight. Runs smoothly

the u-bolts not being at the same level from a tapered block wont hurt a thing. its not that one bolt has each side at a different angle, that would be an issue. its all a matter of making sure they are tight. just about EVERY lifted truck running 4" + lift blocks is running a tapered block. 2" lift blocks can be either way. some have no issues with vibs, some do. i have not checked the pinion angle on every truck but some are more sensitive than others. axle wrap, power level and shackle choice are also factors in how much vib you will feel too. i prefer the 2" tapered block as it keeps the pinion angle stock and doesnt push the axle back slightly. If you notice how steep the leaf spring angle is on these trucks (front is lower than the rear even on a stock shackle), the taller the block becomes, the farther back the axle goes and the worse the working angle becomes due to this.

 

[THEFERMANATOR]

Pinion angle depends on MANY factors. Will it still have single cardan's at each end, or will you be going with a double cardan CV type at the transfer case. If you run a single cardan at each end, then each u joint needs to have roughly the same angle as the other within +/- 3 degrees max to keep the driveline semi smooth, but +/-1 degree is optimal. Angled blocks are if you drop the transfer case down to try and maintain lesser angle on your u-joints. If you drop the transfer case you lessen the angle at the transfer case to shaft connection, so you need to go an equal amount at the diff to driveshaft connection. If you don't drop the transfer case, then in most cases you do NOT want to run an angled block. Now if you go with a double cardan CV type joint at the transfer case side, then you want to run the driveshaft at the diff side down 1-3 degrees from level so that under hard torque, the driveshaft will go straight. HARD launching drag cars will often times run 3-6 degrees of down angle because under hard launches, it will torque that far even with all solid connections(ran 4 degrees down on our car, but it weighed around 1950lbs and did 1.06 60 footers tripping the beams with the rear tires).

Heres a basic breakdown of a single cardan type shaft.
http://www.youtube.com/watch?v=gmV4qwLfOMY

 

[Chevy1925]

Pinion angle depends on MANY factors. Will it still have single cardan's at each end, or will you be going with a double cardan CV type at the transfer case. If you run a single cardan at each end, then each u joint needs to have roughly the same angle as the other within +/- 3 degrees max to keep the driveline semi smooth, but +/-1 degree is optimal. Angled blocks are if you drop the transfer case down to try and maintain lesser angle on your u-joints. If you drop the transfer case you lessen the angle at the transfer case to shaft connection, so you need to go an equal amount at the diff to driveshaft connection. If you don't drop the transfer case, then in most cases you do NOT want to run an angled block. Now if you go with a double cardan CV type joint at the transfer case side, then you want to run the driveshaft at the diff side down 1-3 degrees from level so that under hard torque, the driveshaft will go straight. HARD launching drag cars will often times run 3-6 degrees of down angle because under hard launches, it will torque that far even with all solid connections(ran 4 degrees down on our car, but it weighed around 1950lbs and did 1.06 60 footers tripping the beams with the rear tires).

Heres a basic breakdown of a single cardan type shaft.
http://www.youtube.com/watch?v=gmV4qwLfOMY

i completely disagree on when an angled block is needed Ferm. my own testing over the years has proved otherwise. simply putting an angle finder on the pinion and t-case with a angled vs flat block will show you this.

 

[bmc1025]

My findings with these trucks 01-10 have been the same as James. Straight blocks might work for some but I haven't been able to get away with it.

Running airbags only without lift blocks to gain 2 inches has even worse driveline vibrations under hard acceleration than straight 2" blocks.

 

[THEFERMANATOR]

i completely disagree on when an angled block is needed Ferm. my own testing over the years has proved otherwise. simply putting an angle finder on the pinion and t-case with a angled vs flat block will show you this.

Put a gauge on it and see what it needs. I've seen many instances where they came with them, people put them in, and I ended up putting shims in to smooth out the driveline(this was on JEEPS as that is what I used to do). I don't use blanket statements, but instead do the math, and correct as neccesary. The math doesn't lie. So long as you don't exceed 7 or 8 degrees of angle, you need both joints to have the same angle on them. As the video shows, if you get the angles off, then you CREATED a vibration. You can't fool physics. If you have a 8 degree at the case, and a 3 at the diff, it's going to vibrate.

 

[Chevy1925]

Put a gauge on it and see what it needs. I've seen many instances where they came with them, people put them in, and I ended up putting shims in to smooth out the driveline(this was on JEEPS as that is what I used to do). I don't use blanket statements, but instead do the math, and correct as neccesary. The math doesn't lie. So long as you don't exceed 7 or 8 degrees of angle, you need both joints to have the same angle on them. As the video shows, if you get the angles off, then you CREATED a vibration. You can't fool physics. If you have a 8 degree at the case, and a 3 at the diff, it's going to vibrate.

this is nothing i didnt know already and nothing i dont agree with, i simply stated i disagree on using non tapered blocks for our trucks and my previous statement to that explains why. This thread is about our trucks, not jeeps, not toyotas, not fords, just our rigs. So my information pertains to that. you change to a different vehicle and what i stated will not move with it depending on how the leaf spring is set up. Jeeps use a relatively flat plane on where the eyes of the springs sit (very close to parallel to the horizon), a flat block is needed there if you didnt drop the t-case and shackle length was not messed with.





For another tech point, a 2" flat block in these trucks in the borderline point. if you run axle wrap bars, you are much more likely to notice the vibration over someone who does not since axle wrap wont take place to point the pinion up and help correct the pinion angle.