Upward driveshaft angle?

[gfridland]

Can anyone lend advice for aligning a driveshaft? I am measuring for a driveshaft and and got the tranny face parallel to the 9" ford pinnion in two different planes, however, the driveshaft will have approximately 5 degree angle upward to the rear end ( rear pinnion is higher than the tranny output shaft by 3/4") Will this cause a problem? I have always seen the rear end lower than the tranny. I am installing a 390FE with tremek TKO and a for 9" rear end.

[Roscoe]

Here is an article on it:
http://www.drivetrain.com/driveline_angle_problem.html

Here's another:

http://www.2quicknovas.com/happypinions.html

Roscoe

[gfridland]

It seems that both article address the individual angles for pinion and tranny slip yoke, but my concern is the actual drivshaft orientation. Is it OK to have the driveshaft parallel to the frame when the engine driveline (crank) is on a 5 degree angle down toward the rear?

Am I missing something?

[Jon Miller]

I went through this a couple of years ago, and what I found out was that the most important thing was having both axis parallel.

In your case, with the engine 5 degrees nose up, the rear end should also be 5 degrees nose up.

What I don't know is how important that is with a live axle car, since the rear end may be moving around quite a bit with suspension travel.......

-Jon

[A Snake]

It is vitally important that that the u-joint angles match exactly on both ends of the driveline.

To illustrate, picture a letter Z lying down. It doesn't matter which is higher, the rear end or the engine as long as the angles match. So...if the engine is angled down 5 degrees, angle the pinion up 5 degrees. It doesn't matter if the driveline goes "uphill" to the rear end at all, as long as there's room under the car's floor pan or tunnel for it.

It is equally important that if there is an offset in the differential to one side of engine centerline, that these angles be equal also. It is hoped that this would be accounted for in the selection of rear axel asseblies. It is simple to determine. Simply measure from each axle face to center of pinion shaft, using a straightedge. The straight edge needs to be long enough to lie on the axle face and protrude past the backing plate. This allows a straight line for the tape measure. Unless you have really long arms, it takes two people.

If you don't match all of the angles exactly, you will have serious vibration and premature u-joint failure.

Use a protractor with an accurate spirit level. Since your engine is apparently already mounted, use the u-joint flange on the trans for reference measurement and duplicate by again using the protractor/level(already set) on the pinion flange. If you already have leaf spring perches welded on the housing, you will most likely need spring wedges to get the angle right. If you are using coil over and watts linkage, I can only hope you don't already have the mounts welded on. That needs to be done after the pinion angle is properly set.

Hope this helps.


Al

[gfridland]

Al, Thanks for your help, I have adjustment in the upper and lower bars to get the angle for the pinion, and the rear end is centered properly, will try to get angles to match the tranny within a degree or so.

Gene

[Coloradocobra]

For Midstates as well as a few others, the transmission and pinion angles are essentially opposite conventional wisdom. If you set up the pinion to be parallel to the transmission, the total angle at the u-joints will be too large creating vibration and potential failure.

The goal is to get the two centerlines to intersect at the center of the driveshaft - which requires that the pinion points DOWN at the front. It seem weird, but it works and every Midstates with a solid rear that I have seen uses this to success. The problem with this configuration is that is is very sensitive to rear position and you must set it up with weight in the car equalling a passenger, a driver, and some cargo. You may also want to set the pinion down a degree or two from "ideal" to allow for some wrap-up during acceleration.

If you don't believe me, contact Bob at Midstates to confirm this. On several of the web sites on driveshafts, they illustrate this setup although they concentrate on the parallel configuration. I set mine up parallel for the first drive and it shook so bad that I thought I had real problems. I went to the "nose down" and have not had to adjust it since.

Oh, one of the "Oh yeah, we do that all the time" things I learned after messing around with mine is that Midstates often places spacers above the transmission crossmember plates to raise the transmission up to get a better angle. I have 428/toploader and ended up with 3/4" spacers to improve the angles.

Good luck,

Gary

[gfridland]

Thanks Gary, I talked to Bob and he also confirmed that parallel would give me problems. Will set to opposite angle of tranny as you and he reccomends. I currently have 3.5 degree downward in the slip yoke, and will do the same for the pinion. This will also give a better angle for the driveshaft (slightly down).

Thanks for everybody's help.

Gene

[Wayne Maybury]

The fellow that made my driveshaft told me that I should try to keep the angles on both u-joints approximately the same and that they should be no more than about 5 degrees each. He said that u-joints that work at 10 degrees or more cannot be expected to last very long. He also told me that a u-joint that operates at exactly 0 degrees will also wear out more quickly than normal since the needle bearings are not moving around and they will pit the surfaces where they touch.

I used a magnetic angle finder to adjust the angles to about 3 degrees. Of course that is at normal ride height. The actual angles will change up and down as the car is being driven and the live axle moves.

Wayne

[gfridland]

An interesting explanation of driveshaft angles. According to this opposite angles should also work. Different from most other setups.


http://www.roddingroundtable.com/tec...driveline.html