Drive line angle

[Racer57]

I have a Tremec TKO500. As near as I can tell the angles are.......

Tranny is pointing down 3 degrees
Differential is pointing up 4.4 degrees using a 4 degree wedge under axle
Driveshaft is 2.0 degrees up at rear

At 75mph car has a very slight vibration and starts to increase. 90 is really faster than you should go.

There is 3/16, 1/4 and 1/2" spacers under the tranny mount and just to check things out I removed the 1/4 spacer and the car was smooth until 90, but my Shaker rubber seal was hitting the windshield wiper motor.

I know there's issues because of the Tremec not being high enough at the rear. Originally it vibrated at 65 and I tried a 2 degree wedge and it allowed 70, so I went to a 4 degree. Am I stuck where I am or can I fine tune it better somehow ? Is it possible to have the differential up/down too much ?

[bigblue73]

Here is a recommendation for you.  Down load the Tremec application for your smart phone and use it.  It's a very intuitive application that will verify the angles for you and tell you the results and correction if needed.  It's taken a lot of guess work out these questions.  I'm sure you've read all the other causes of vibrations as well so make sure those are ruled out.  You are close right now. 

[Racer57]

Thanks. I'll check it out.

[dodj]

You need a 3-4* down angle of the rear in relation to the driveshaft. So when you put the power down, the torque raises the rear closer to 0*. If the driveshaft is already pointing up in relation to the d-shaft, vibration will get worse, the more power you apply to the rear wheels.
If I understand you correctly, you will need to rotate your rear down in relation to the driveshaft.

When you say the rear id pointing up 4.4*.

4.4* in relation to what? Level? or the driveshaft?

[Racer57]

You need a 3-4* down angle of the rear in relation to the driveshaft. So when you put the power down, the torque raises the rear closer to 0*. If the driveshaft is already pointing up in relation to the d-shaft, vibration will get worse, the more power you apply to the rear wheels.
If I understand you correctly, you will need to rotate your rear down in relation to the driveshaft.

When you say the rear id pointing up 4.4*.

4.4* in relation to what? Level? or the driveshaft?

Placing a digital level on the yoke of the differential, shows it is pointing up 4.4 degrees.

The tranny yoke is pointing down and can't be changed. That's why I have the differential yoke pointing up, which is what I assumed is required.

Tranny is pointing down 3 degrees
Differential is pointing up 4.4 degrees using a 4 degree wedge under axle
Driveshaft is 2.0 degrees up at rear

[Chryco Psycho]

This should help http://www.cuda-challenger.com/cc/index.php?topic=93146.0

[Racer57]

This should help http://www.cuda-challenger.com/cc/index.php?topic=93146.0

I had watched that awhile back Thanks for making it a sticky.

[DocMel]

Before you get too involved on the angle side, get your ds balanced.    I have the same set up as you, (Tremec 500) ,only my vibration occurred at 65 and was pretty bad thru 70-80.   

I took the brand new shaft, cut by the vendor, and it was almost an ounce out of balance.  I couldnt beleive it.  The damn thing wasnt balanced from the vendor!

A balance is cheap, and I would do that to see if thats your prob before you start messing w/angles

[Racer57]

Before you get too involved on the angle side, get your ds balanced.    I have the same set up as you, (Tremec 500) ,only my vibration occurred at 65 and was pretty bad thru 70-80.   

I took the brand new shaft, cut by the vendor, and it was almost an ounce out of balance.  I couldnt beleive it.  The damn thing wasnt balanced from the vendor!

A balance is cheap, and I would do that to see if thats your prob before you start messing w/angles

The shop that originally installed the tranny suspected the shaft and sent it off to be balanced. It checked out ok.

[dodj]

Placing a digital level on the yoke of the differential, shows it is pointing up 4.4 degrees.

The tranny yoke is pointing down and can't be changed.

The tranny yoke angle CAN be changed.  There are spacers (or not) under the rear mount of the tranny that will change the angle of the tranny.
What is the angle of the differential yoke in relation to the drive shaft. It is important that when power is applied, the rear end yoke raises and gets the angle of the rear end close to a straight line with the drive shaft.

[Racer57]

The tranny yoke angle CAN be changed.  There are spacers (or not) under the rear mount of the tranny that will change the angle of the tranny.
What is the angle of the differential yoke in relation to the drive shaft. It is important that when power is applied, the rear end yoke raises and gets the angle of the rear end close to a straight line with the drive shaft.

If I lower mine enough to make a difference, then the shaker gets into the wiper motor.

[Chryco Psycho]

you must have a 2spd wiper system

[Racer57]

you must have a 2spd wiper system

yes