[CJman77]

I did some research, maybe I am missing a thread but I am trying to find what the powertrain angle should be? I am install a 350 (already has previous 350 engine mounts) SM465, D300. What angle should all this be on when its mounted? I will have to build some kind of mount so the stock skid plate works, I just want to make sure I do this right.

Also will I need to change the degree the front spring perches are mounted at? I have heard degree shims in the front are bad. I have seen the post with all the pictures, etc. I understand some of it, but I don't understand how to determine what mine is and what is desired.

This will all be on a 4 inch skyjacker lift.


Thanks Very Much and Happy New Year!

[jeepdaddy2000]

Engines are generally mounted horizontal to the frame. You will want to insure the fan is centered in the shroud. The only time the t case is lowered is to either make room for something or relieve the driveline angle. The latter can be adjusted after everything is installed by inserting shims between the crossmember/skidplate and the frame rail.
As for the front axle. Install the lift(which usually doesn't change the existing angles much), then take it to a reputable front end shop to have the caster/camber angles checked. If they are off, you can adjust the angles a number of ways. Feel free to ask your front end guy what he recommends.

[CJman77]

Originally Posted by jeepdaddy2000

Engines are generally mounted horizontal to the frame. You will want to insure the fan is centered in the shroud. The only time the t case is lowered is to either make room for something or relieve the driveline angle. The latter can be adjusted after everything is installed by inserting shims between the crossmember/skidplate and the frame rail.
As for the front axle. Install the lift(which usually doesn't change the existing angles much), then take it to a reputable front end shop to have the caster/camber angles checked. If they are off, you can adjust the angles a number of ways. Feel free to ask your front end guy what he recommends.

How will I determine whether or not I need to lower the case to be lowered?

(Maybe this all will be easier to determine when I start mounting everything)

I still need to figure out the skid plate and whether it will work with the 465.

[jeepdaddy2000]

The simplest way is to install the drivetrain, lift and driveline. raise the Jeep till the tires are off the ground then try to rotate the driveline by hand. If it binds, then you will need to shim. You will also have to drive it. Excessive angle can cause vibration. A double Cardin joint installed on your driveline can also help with the angle.

[gojeepin]

Originally Posted by jeepdaddy2000

The simplest way is to install the drivetrain, lift and driveline. raise the Jeep till the tires are off the ground then try to rotate the driveline by hand. If it binds, then you will need to shim. You will also have to drive it. Excessive angle can cause vibration. A double Cardin joint installed on your driveline can also help with the angle.

If your driveline binds you need a driveshaft the offers more clearance for the universal joints... or you have to change the angles on both the output yoke and the axle pinion yoke to make them match. You can't really do that until everything is assembled and the vehicle is at its normal ride height.

On a side note... A perfectly straight driveline is constant velocity regardless of driveshaft type. With a single cardan driveshaft you're driveshaft has two "phase" changes per revolution if the driveshaft deflects from the rotational centerline. These become greater as the deflection angle increases.

Excessive (deflection) angle doesn't cause driveline vibration but it could cause the yokes to make contact. Excessive deflection angle just means driveshaft "phasing" speed differences will be greater and you've got very little room for mismatched angles. Mismatched deflection angles on the ends of your driveshaft cause vibration since they change speed at different rates and velocity.

[CJman77]

Originally Posted by gojeepin

If your driveline binds you need a driveshaft the offers more clearance for the universal joints... or you have to change the angles on both the output yoke and the axle pinion yoke to make them match. You can't really do that until everything is assembled and the vehicle is at its normal ride height.

On a side note... A perfectly straight driveline is constant velocity regardless of driveshaft type. With a single cardan driveshaft you're driveshaft has two "phase" changes per revolution if the driveshaft deflects from the rotational centerline. These become greater as the deflection angle increases.

Excessive (deflection) angle doesn't cause driveline vibration but it could cause the yokes to make contact. Excessive deflection angle just means driveshaft "phasing" speed differences will be greater and you've got very little room for mismatched angles. Mismatched deflection angles on the ends of your driveshaft cause vibration since they change speed at different rates and velocity.

Yeah I figured it would have to be built first. But a plain old 4 inch lift shouldn't be too bad right?

I also was planning a double cardon shaft to deal with angles etc.

[JeepHammer]

Engine & Drive train tilt is called 'Cant'.

The easiest way to determine proper 'Cant' is to put a level on the intake where the carb bolts down. When you reach 'Level' at that point, you are correct in the frame.

The 'Cant' is usually about 3 to 5 degrees... Transmission DOWN angle.

For axles...
If you are using a standard drive shaft, then your outlet from the transfer case and pinion angle should be the (roughly) the same, just reversed.
If your output for the transfer case is 3 degrees DOWN,
Then your pinion angle should be 3 degrees UP,

NEVER, EVER install a drive shaft in a straight line.
(Much more common in race car & street rod builds than Jeep installs)

When a drive shaft is straight, the needle bearings in the U Joints do NOT rotate, and you hammer on the same bearings all the time... Causing VERY premature failure!

With some off set Up/Down or Side to Side the needle bearings rotate with use, and the U joint lives.

The closer your output and pinion are to 'Same But Reversed' the less vibration you will have during operation.
3 degrees up/down, and 3 degrees sideways on BOTH ends will keep the needle bearings rotating and you will not have the drive line vibration that some experience.

Most of us have MUCH MORE than 3 degrees in the drive line angles, but the closer you keep those angles to 'Even' from one end to the other the less vibration you will have.
-------------------------

If you have 'Double U Joint'
(Some times called a Cardian Joint)
In the transfer side of your drive shaft,
Then you want the differential pointing directly at the transfer case output.

(When people say 'Double Cardan' it's like saying 'Double-Double Cardan... All cardan joints have TWO U Joints, so there is no point in saying 'Double'...
Just 'Cardan' joint is plenty!)
-----------------------------------------

The old chassis builders trick is to take a piece of brake line or stiff wire and center in the pinion center,
Then bend up towards the transfer case output at the point where the U joint will go...
When you get up to the transfer case, do the same there.
This will tell you the EXACT length between U joints for axle length,
And it will give you EXACT angles to measure instead of using a protractor type inclinometer and tape measure which can lead you down the wrong road.

Don't get me wrong, I double check with inclinometer and tape measurer,
The wire/tubing gives you something you can lay on the work bench and work with that DOESN'T change as your memory plays tricks or measurements get wiped off the work bench or lost on note pads.

We keep the mock up tubes/wires hanging on the wall so we can order new drive shafts for the race cars even when the vehicle is out of town... Handy thing to have and doesn't cost much!
--------------------------------------

Most guys like to point the pinion UP a few degrees, which is generally the wrong direction in my experience.

When the pinion loads the rear differential,
The pinion gear tries to CLIMB the ring gear, so the pinion angle moves UP as you load the differential.

So if you point the pinion DOWN a degree or two,
When you load the drive line, the pinion angle comes into proper alignment and you have less vibration and other 'Issues'...

Any, or all of this is subject to interpretation, so if you want to do something different,
Or someone gives you an explanation that makes more sense,
Then by all means do what YOU THINK IS 'Correct'...

[CJman77]

Originally Posted by JeepHammer

Engine & Drive train tilt is called 'Cant'.

The easiest way to determine proper 'Cant' is to put a level on the intake where the carb bolts down. When you reach 'Level' at that point, you are correct in the frame.

The 'Cant' is usually about 3 to 5 degrees... Transmission DOWN angle.

For axles...
If you are using a standard drive shaft, then your outlet from the transfer case and pinion angle should be the (roughly) the same, just reversed.
If your output for the transfer case is 3 degrees DOWN,
Then your pinion angle should be 3 degrees UP,

NEVER, EVER install a drive shaft in a straight line.
(Much more common in race car & street rod builds than Jeep installs)

When a drive shaft is straight, the needle bearings in the U Joints do NOT rotate, and you hammer on the same bearings all the time... Causing VERY premature failure!

With some off set Up/Down or Side to Side the needle bearings rotate with use, and the U joint lives.

The closer your output and pinion are to 'Same But Reversed' the less vibration you will have during operation.
3 degrees up/down, and 3 degrees sideways on BOTH ends will keep the needle bearings rotating and you will not have the drive line vibration that some experience.

Most of us have MUCH MORE than 3 degrees in the drive line angles, but the closer you keep those angles to 'Even' from one end to the other the less vibration you will have.
-------------------------

If you have 'Double U Joint'
(Some times called a Cardian Joint)
In the transfer side of your drive shaft,
Then you want the differential pointing directly at the transfer case output.

(When people say 'Double Cardan' it's like saying 'Double-Double Cardan... All cardan joints have TWO U Joints, so there is no point in saying 'Double'...
Just 'Cardan' joint is plenty!)
-----------------------------------------

The old chassis builders trick is to take a piece of brake line or stiff wire and center in the pinion center,
Then bend up towards the transfer case output at the point where the U joint will go...
When you get up to the transfer case, do the same there.
This will tell you the EXACT length between U joints for axle length,
And it will give you EXACT angles to measure instead of using a protractor type inclinometer and tape measure which can lead you down the wrong road.

Don't get me wrong, I double check with inclinometer and tape measurer,
The wire/tubing gives you something you can lay on the work bench and work with that DOESN'T change as your memory plays tricks or measurements get wiped off the work bench or lost on note pads.

We keep the mock up tubes/wires hanging on the wall so we can order new drive shafts for the race cars even when the vehicle is out of town... Handy thing to have and doesn't cost much!
--------------------------------------

Most guys like to point the pinion UP a few degrees, which is generally the wrong direction in my experience.

When the pinion loads the rear differential,
The pinion gear tries to CLIMB the ring gear, so the pinion angle moves UP as you load the differential.

So if you point the pinion DOWN a degree or two,
When you load the drive line, the pinion angle comes into proper alignment and you have less vibration and other 'Issues'...

Any, or all of this is subject to interpretation, so if you want to do something different,
Or someone gives you an explanation that makes more sense,
Then by all means do what YOU THINK IS 'Correct'...

Good Info Hammer.

So do I want to do away with this degree shim on the rear springs?

[JeepHammer]

Originally Posted by CJman77

Good Info Hammer.

So do I want to do away with this degree shim on the rear springs?

Depends on the lift you have.
If you have more than an inch or two lift, then axle angle shims will decrease the loading on the U Joints somewhat.
Doesn't do much for vibration, but it will decrease the load slightly.

If you have a lot of lift, generally more than about 3", a cardan drive shaft with the pinion pointing at the output of the transfer is a good idea.

[gojeepin]

Thanks JeepHammer for clarifying the straight driveline issues. You're right. You don't want a completely straight driveline for the wear and stress reasons you described. I used it to illustrate how driveline deflection affects driveline speed.

I was writing as much as I could before boarding an airplane.

To the OP, if you use a double cardan driveshaft, aim the pinion about 2 degrees below the rotation centerline. You want it to point directly at the (CV) double cardan joint. Under normal operation, your pinion will turn upward during acceleration and remain while maintaining a constant speed.

[CJman77]

Originally Posted by gojeepin

Thanks JeepHammer for clarifying the straight driveline issues. You're right. You don't want a completely straight driveline for the wear and stress reasons you described. I used it to illustrate how driveline deflection affects driveline speed.

I was writing as much as I could before boarding an airplane.

To the OP, if you use a double cardan driveshaft, aim the pinion about 2 degrees below the rotation centerline. You want it to point directly at the (CV) double cardan joint. Under normal operation, your pinion will turn upward during acceleration and remain while maintaining a constant speed.

What are the best ways to adjust the pinion up and down where it points? Degree shims? Changing spring perch locations?