pinion angle advice

[stubbygda]

i have a 68 charger 383 with tko 5speed conversion from silver sport. i am trying to adjust pinion angle. i have read everything on the forum and lots on internet about it. i think i 1/2 understand it. my output shaft is 2.2 deg down and the pinion is about 2 deg down clearly not ideal ending up with a drive angle of close to zero so not good. there is no easy way to get output shaft up so i was thinking i could use 2 or 3 deg shim in rear to rotate up so that they would be close in opposite directions. i was thinking of using 3 degree so that would be 2.5 and 1 giving drive angle of 1.5 and some room for rotation up in acceleration. or maybe i should do 2 deg to get 2.5 drive angle but more room for upward acceleration. i currently have standard 5 leaf in rear but an looking at replacing with espo 6 leaf.

with the tko the output shaft is actually about an inch lower than the pinion, if i measured right and the drive shaft itself is level. opposite of what i am use to i guess. anyway i just finished car with rebuilt engine, new tko, new driveshaft, and new pumpkin. i have only had it up to about 50 mph and didn’t notice any vibration in either acceleration or deceleration but clearly a drive angle close to zero results in premature wear.
any advice/correction appreciated, sorry about having to post another pinion angle thread lol.

 

[PurpleBeeper]

The simple way I think of it is that if you viewed the driveshaft and rear end pinion from the side of the car, it should make a “V”, not a teepee.

 

[dvw]

You have 3.8 pinion angle right now. With leaf springs that isn't very far off. If it doesn't vibrate at higher speeds you could run it. You could also experiment with a 1-2 degree shim. That would get you 2.8-1.8 pinion angle. With only 1.8 and leaf spring it's very possible under hard load it'll go past center. To much pinion agle will always show up as a vibration on decell.
Doug

 

[snakeoil24]

Engine should be down 2-3 degrees pinion up 2-3 degrees

 

[Bird 426]

I was never good at math. Pinion angle advice leaves me more confused than educated.

 

[R/T Boy 67]

The center picture is what you want under load. For drag racing you want it to look like the top picture, at rest, so it looks like the center picture under power.

 

[threewood]

I think you will be fine. Under hard acceleration the pinion will wrap up 2-3° maybe even a touch more. You need it to wrap up 4.2° to get to zero.

2.2 up on the pinion + 2.2° down on the tailshaft = 0

 

[stubbygda]

You have 3.8 pinion angle right now. With leaf springs that isn't very far off. If it doesn't vibrate at higher speeds you could run it. You could also experiment with a 1-2 degree shim. That would get you 2.8-1.8 pinion angle. With only 1.8 and leaf spring it's very possible under hard load it'll go past center. To much pinion agle will always show up as a vibration on decell.
Doug

ok i lied i don’t think i understand it at all lol. can you show me how ya got 3.8 pinion angle? i thought pinion angle was angle relative to ground or level in my case about 2 deg. i don’t doubt your right i just want to understand it.

 

[stubbygda]

I think you will be fine. Under hard acceleration the pinion will wrap up 2-3° maybe even a touch more. You need it to wrap up 4.2° to get to zero.

2.2 up on the pinion + 2.2° down on the tailshaft = 0

ok that makes sense i was thinking the 2 angles needed to be opposite and the same with weight on car not under acceleration. so if i was really worried i could raise the pinion 1 deg or so making the wrap up a little more reasonable. the car is street driven only with occasional spirited driving.

 

[bm02tj]

All your angles need to be in relation to the drive shaft not the car body

 

[Sixpactogo]

i have a 68 charger 383 with tko 5speed conversion from silver sport. i am trying to adjust pinion angle. i have read everything on the forum and lots on internet about it. i think i 1/2 understand it. my output shaft is 2.2 deg down and the pinion is about 2 deg down clearly not ideal ending up with a drive angle of close to zero so not good. there is no easy way to get output shaft up so i was thinking i could use 2 or 3 deg shim in rear to rotate up so that they would be close in opposite directions. i was thinking of using 3 degree so that would be 2.5 and 1 giving drive angle of 1.5 and some room for rotation up in acceleration. or maybe i should do 2 deg to get 2.5 drive angle but more room for upward acceleration. i currently have standard 5 leaf in rear but an looking at replacing with espo 6 leaf.

with the tko the output shaft is actually about an inch lower than the pinion, if i measured right and the drive shaft itself is level. opposite of what i am use to i guess. anyway i just finished car with rebuilt engine, new tko, new driveshaft, and new pumpkin. i have only had it up to about 50 mph and didn’t notice any vibration in either acceleration or deceleration but clearly a drive angle close to zero results in premature wear.
any advice/correction appreciated, sorry about having to post another pinion angle thread lol.

Why do you say "No easy way to get the output shaft up"? Is the transmission hitting the tunnel or something? A quarter inch shim under the rear mount would be much easier than adding shims to the pinion. You should expect to get about 2-3 degrees axle windup under normal load. I know some of the info out there says 5-6 degrees with leaf springs but I know my 68 Charger with stock springs gets no more than 2 degrees. I think you are ok the way you are though if you have no vibration

 

[steve340]

Google search - spicer driveline angle calculator.
It tells you how to measure the angles properly and gives specification limits.

 

[AR67GTX]

There is another driveline layout option to confuse matters even more - what they call the “W” configuration. Don’t ask me why a “W”. Looks more like a “U” to me. Mid-year Corvettes have this driveshaft alignment including my 66. Here is what it looks like after shimming the transmission higher to get the 2 angles within 1/2 degree of each other.

 

[stubbygda]

Why do you say "No easy way to get the output shaft up"? Is the transmission hitting the tunnel or something? A quarter inch shim under the rear mount would be much easier than adding shims to the pinion. You should expect to get about 2-3 degrees axle windup under normal load. I know some of the info out there says 5-6 degrees with leaf springs but I know my 68 Charger with stock springs gets no more than 2 degrees. I think you are ok the way you are though if you have no vibration

transmission is not hitting tunnel but is close. when i jack it up to shim it lifts car not transmission so something is maxed. also don’t want to stress engine mounts. i need to try and figure why it won’t raise. i agree easy to shim 1/4” if transmission moved. i need to figure out why it won’t shift up and see if i can overcome that limitation.

 

[dvw]

Pinion angle isn't hard when you do the math correctly. Which I didn't. 3.8 is incorrect. The correct current angle is 4.2 degrees Lets start with the engine trans C/L. Then the pinion C/L. Zero angle under under loaded acceleration is ideal. How do we get there? First what type of susspension? Leafs can use anywhere from 2-7 degrees dependending on use. Caltracs about 2 degrees. Ladder bars or 4 link about 1-1.5 degrees. In the original posters question. Eng/trans is 2.2 degrees down, pinion is 2 degrees down. To get the current angle the math is simple. How far does the pinion have to move to be up to be parallel with the eng/trans C/L? It needs to be the exact opposite which is 2.2 degrees up. so the math is 2.2+2 = 4.2 It's that simple. Don't look at car angle, driveshaft angle, or anything else. Now back to the type of suspension in the original question. It's leaf spring. Does 4.2 degrees fall into the 2-7 sweet spot zone? Yes. Now what is the intended porpuse of the car? Mostly street and not a pure track car? Then that range tightens up arouned 1.5-4 degrees. Thats why I suggested to see if it's smooth, Running very low pinion angle on a performance car with leaf springs can cause the angle to go over center on accell. My racacar is similar in that the eng/tans C/L is downward.

 

[stubbygda]

hey thanks for taking time to explain. i think i finally get it at least to some degree lol. i think i will get it out drive it a bit more to check for vibrations. then correct as necessary based on that.

thanks to all who replied.

 

[Sixpactogo]

All your angles need to be in relation to the drive shaft not the car body

I agree with this. You have to consider the drive shaft angle any time it is other than zero. If it is up or down 1 degree it will change how you need to set up pinion angle. If you disagree, just go to Driveline Angle Calculator
Put in your drive line angle and pinion angle. Then see what happens when you change the driveshaft angle even by .5 degree up or down.
You want your operating angles to be the same or within .5 degree

 

[dvw]

I agree with this. You have to consider the drive shaft angle any time it is other than zero. If it is up or down 1 degree it will change how you need to set up pinion angle. If you disagree, just go to Driveline Angle Calculator
Put in your drive line angle and pinion angle. Then see what happens when you change the driveshaft angle even by .5 degree up or down.
You want your operating angles to be the same or within .5 degree

That calcultor isn't what we see in the real world. A car deiveshaft doesn't stay in a static location. The angles are constantly changing. The rear axle housing holding the pinion not only rotates around the center of the axle, but moves up and down as well. If the operating angles are with-in .5 degree at static rest they will go over center under load. You would be surprised how much angle you can get away with and not cause a vibration that is felt in the car. Yes ideally they should be exact. But thats not posible with a car driveshaft unless the rear is IRS.
Doug

 

[Sixpactogo]

That calcultor isn't what we see in the real world. A car deiveshaft doesn't stay in a static location. The angles are constantly changing. The rear axle housing holding the pinion not only rotates around the center of the axle, but moves up and down as well. If the operating angles are with-in .5 degree at static rest they will go over center under load. You would be surprised how much angle you can get away with and not cause a vibration that is felt in the car. Yes ideally they should be exact. But thats not posible with a car driveshaft unless the rear is IRS.
Doug

True. However, you have to start out with the correct calculation or close to it. That way, when your axle and drive shaft are moving up and down, both angles cancel each other out. If you don't take the drive shaft angle into consideration to start with, it better be close to zero or you will get vibrations.

 

[steve340]

On a milder street car the torque is starting to taper off by the time the driveshaft really starts spinning at higher speeds in top gear.
I believe you are better off with the angles close to right at rest.
Most cars I have experienced driveline vibration was evident only when the RPM of the driveshaft got higher.
You need to get the operating angles of the front and rear universal as close as possible to the Spicer recommended angles.