Pinion angle?

[focusedontheprize]

Before I set the pinon angle on my truck, I had did quite a bit of research and everything I found recommended setting the trans angle at -3 degrees and the pinon angle at +3 degrees to get 0 degrees on the drive shaft.

I have a 1997 Ford Explorer 8.8 rear end in this also.

Here is an image of my angle with the truck on the ground (on just roll around tires, not the ones I will be running).

As I look at that angle of the driveline and my pinon, it doesn't look level at all. This weekend when I drive home to work on it, I am going to re-check the angle of the transmission and the pinon, but I am 99.99% sure the transmission is -3 and then pinon is +3 degrees.

This angle looks a little off to me, but I wanted to get your guy's feedback. Does it look okay?

[Coach529]

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[focusedontheprize]

Originally Posted by Coach529

Subscribed..........

Hahaha.

[mark '87 930]

Wouldn't the lentgh of the driveshaft also make a difference as to what angle to set it at? The shorter the driveshaft, the steeper the angle...

[butchp]

Is your pinion angle down, with leaf springs the pinion will climb up on hard acceleration. In the photo it looked to up. The torque on the wheel will make the pinion rise, perfect world it would rise to 0 degrees on hard acceleration.

[Speedbumpauto]

I think what you need is around 3 degrees static difference, the theory being the diff will rotate close to 3 degrees under acceleration which will make your angles correct or at least very close. Since "most" engine/trans assy's mount at about 2 1/2 to 3 degrees down (-) your static should be at or near 0 so your dynamic angle will be moving toward +3. Different suspension systems deflect different amounts, but unless you're making and using killer horsepower, I think this will get you close.

[focusedontheprize]

Originally Posted by butchp

Is your pinion angle down, with leaf springs the pinion will climb up on hard acceleration. In the photo it looked to up. The torque on the wheel will make the pinion rise, perfect world it would rise to 0 degrees on hard acceleration.

I understand what you are saying here, however in order to derive the 0 degree angle on the driveshaft, in order to to achieve that with a -3 degrees on the trans, the pinon has to be set to +3 degree which a lot of rod shops agreed with.

[NEWFISHER]

How are you measuring your engine trans? Where are you taking the degree measurments from? try other areas like valve cover, trans case not pan, end of trans output at the seal is the best way. I agree it looks weird in the pic.

[Kabwe]

Originally Posted by NEWFISHER

end of trans output at the seal is the best way. I agree it looks weird in the pic.

I agree.

[Coach529]

Originally Posted by Kabwe

I agree.

Great post thanks!!

[focusedontheprize]

Originally Posted by NEWFISHER

How are you measuring your engine trans? Where are you taking the degree measurments from? try other areas like valve cover, trans case not pan, end of trans output at the seal is the best way. I agree it looks weird in the pic.

I am putting the angle finder at the end of the trans output at the seal and on the flat face of the pinon on the rear end. I also did the harmonic balancer too just in case.

Originally Posted by Kabwe

I agree.

That was one of the diagrams I was referring to.

[focusedontheprize]

Is there any chance because I am using a Ford Explorer rear end (and it is offset to one side) this would affect the angle?

[NEWFISHER]

Originally Posted by focusedontheprize

Is there any chance because I am using a Ford Explorer rear end (and it is offset to one side) this would affect the angle?

No it should not. Pinion angle doesnt care how far left or right it is from center, how up or down the axle tube is in to relationship of frame etc. I would make sure the proper weight is on the truck, recheck the front trans as shown above and then recheck the pinion. report back

[focusedontheprize]

Originally Posted by NEWFISHER

No it should not. Pinion angle doesnt care how far left or right it is from center, how up or down the axle tube is in to relationship of frame etc. I would make sure the proper weight is on the truck, recheck the front trans as shown above and then recheck the pinion. report back

I will see what I get this weekend. Only weight not in the truck is glass, seat and a hood.

[thotfulspot]

I'm used to offroad applications, but I always use an angle finder on the transmission or transfer case and work to get it 90 degrees at the pinion and point the axle pinion a couple of degrees for torque on the rear axle. On the street you will only get a couple degrees or torque with leaf springs.

Once you get it mounted check it at full drop on a lift to make sure it doesn't bind. If you are using a 4 link or similar setup you don't have to worry about the torque. As long as there is no bind you can run it off center.
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[mechanixman]

This should help
http://jniolon.clubfte.com/driveline...nephasing.html

[1project2many]

When the trans is spinning at a constant speed, the driveshaft actually speeds up and slows down with each revolution. It's absolutely amazing to watch in action. It happens whenever power is transferred through a standard type U joint and the greater the angle between the parts on each side of the joint, the greater the change in speed. A two joint driveshaft is set up properly when the angle between trans and shaft cancels the angle between shaft and pinion. When done correctly, this allows natural speed changes in the shaft while maintaining constant speed at transmission and pinion. When done incorrectly the engine and axle fight each other and the result is vibration and increased wear.

Instructions linked above seem to miss some info. And so do many online articles as they assume your engine and axle are parallel to the frame and the mounting points are set so all you're doing is adjusting the angle in the horizontal plane.

You can measure angles at trans and axle, ok, but this doesn't give angle of driveshaft relative to these components. Imagine driveshaft angle if pinion were three feet to right of trans and only two feet back. Now how is measuring pinion / trans angles alone going to get that one right? You really need more information.

There's only a brief mention, but if you've swapped engine / trans and fabricated or custom made your mounts it's very important to ensure the engine and trans are parallel to centerline of the truck. With a frame that's straight front to rear you only need to measure distance from centerline of frame rail to centerline of balancer, then do same at trans output shaft. Any difference needs to be corrected before trying to get involved in building the driveshaft.

Next is a quick check to see if the differential is offset to one side more than the transmission. Any difference here will cause the driveshaft to be at an angle when viewed from the top of the vehicle. This angle is part of the operating angle of the universal joint and must be considered so you don't have vibration. You should already know if the transmission is offset from the truck centerline so the next step is measure the distance between the frame rails and the pinion. If the measurement doesn't match the measurement at the trans, you're going to need some math to figure the total angle. Record transmission offset from centerline, pinion offset from centerline, and distance from trans shaft to pinion.

Next is to determine the angles as viewed from the side. If you have a driveshaft that will fit into the truck this will be easy. You need the pinion and trans angles plus the angle of the shaft itself. Before going any further, note that you should have the pinion yoke below horizontal. This has been said several times but it appears above horizontal in those photos. To get the operating angles here, you'll measure trans and pinion angles as well as driveshaft angle in the horizontal plane. Finding the angle between both is a simple subtraction problem.

If you don't have a driveshaft you can still do it but you'll need to get the vertical offset between trans and pinion centerlines as well as the length between the two then do some calculations to figure the angles.

Finally, if the driveshaft will be at an angle when viewed from the top and from the side, you have compound angles and you need to do more figuring to determine the true operating angles of the joints.

This Spicer driveline book may seem complex but the instructions for checking / setting angles are exactly correct and they show you how to get true operating angles when working with compound angles. They also give you a good idea how much the pinion can be offset to the side before the angle gets too severe. http://65.170.161.218/~spicerpa/site...stallation.pdf Start at Page 8 to view driveshaft setup.

Also, there's a simple video that can help with figuring angles measured with the angle finder:

How to Measure & Calculate Drive Line Angles...

HTH
I've been involved with issues where very nicely built vehicles needed a bunch of work to solve vibration or U-joint durability problems and all of the work could have been avoided if the proper steps were followed at the right time.