Adjustable Rear Upper Control Arms
 

My LeMans has what I believe to be a driveline vibration above 2500 rpm and more noticeable when going through the gears. It has a Ford 9” rear and my angles are as follows:

trans output shaft 3.3 degrees down

driveshaft 2 degrees down

Pinion 1 degree down

Are the control arms the same length for 64-67 A bodies? Some of the application charts don’t include 1964, only 65-67

The upper control arms are the same for 1964 - 1967.

The upper bushings in the 1964 rear end housing are a smaller diameter than 1965 and later but that doesn’t affect the upper control arms. Your Ford 9” won’t have the smaller bushings.

Shouldn't the pinion angle be closer to the transmission angle, but up instead of down?

That’s what I’m interpreting based on what I’ve researched- need longer uppers

Thank you!

Agree with that. Up on the rear axle pinion.

Tom V.

Grivera, if your numbers are correct, and the angles all slope the same direction, your operating angles are within 0.3 degrees. Rule of thumb is to have operating angles within 0.5 degrees, so you should be ok. If you raise the trans by 0.3 you would have both operating angles at 1 degree. Again, this is if all the angles are sloping down from front to rear.
https://spicerparts.com/en-emea/calc...gle-calculator

Thanks- that calculator is interesting and confusing. See link below which is indicates that ideally the trans tailshaft and pinion should be at equal but opposing angles - so in my case I used the adjustable a-arms to move the rear up to 3.1 degrees positive - any more and the coil springs rub the shocks. https://youtu.be/SDjBHT5-u_4

The “equal bit opposite” gets tossed around a lot and I believe confuses many unnecessarily. Parallel should be used instead. Also confusing is when someone says pinion up, when what they are describing is pinion down, like the guy in the video. In the attached pic below both the trans output shaft and the pinion shaft are sloping down toward the rear of the car, (rear of car, not the rearend). The entire pinion gear is a short shaft, (yoke, shaft,gear), and is sloping down to the rear, looking left to right, just like the trans shaft, parallel. Some would describe that as pinion up, but when calculating driveline angles, or using that spicer calculator, that would be wrong.

I think we’re on the same page - before I adjusted the angle, the pinion was “up”, meaning the rear of the differential was facing up but the pinion yoke was facing down. Now, the pinion yoke is close to parallel (3.1 degrees) with the the trans tailshaft - pinion yoke facing up, back of differential facing down. This is clearer with the Tremec app which says to take all measurements from the same side. I didn’t use the app other than instructions because it’s difficult to get a steady reading. I do have a small square digital angle finder with a magnetic base.