Hantzum

iTrader: (13)

I just got my adj. torque arm installed on my 98 f-body, everything went in smoothly and all, however when I drive my car my enter body begins to shake, the faster I go the harder it shakes. So I figure my pinion angle must be wrong. I thought I had it at a -2 but it was also at + 1.8 degree slop when I was measuring it. The rear end was at a - 6.8 degrees minus the slop of + 1.8 gives me a -5 degrees on the rear end and the shaft was at a +5.8 minus the + 1.8 slop giving me a + 4 degree on the drive shaft. All in all - 5 + a + 4 gives me a - 1 degree on my pinion angle, well within the tolerances of what BMR suggest. Does this mean I just need to keep adjusting my pinion angleuntil the car stops shaking? Anybody with any suggestions please let me know.
Thanks

CW00BlackTA

iTrader: (31)

Not sure I followed exactly what you did but here's the way I do it. Measure the angle at the face of your crank pulley or the vertical flat at the rear of your transmission. Then set the angle of the pinion yoke to be the same. That puts you at zero. From there, adjust your TA to lower the pinion 1-2 degrees.


Why do it this way? The whole objective is to minimize drivetrain loss at WOT. To do that you want your pinion shaft, transmission shaft (and therefore crank shaft) roughly parallel at WOT to minimize u-joint angles. Setting those angles to be the same does that. That final adjustment down 1-2 degrees compensates for drivetrain load at WOT. If all you do is race, you might even try -3.

Hope that cures your shakes.

Hantzum

iTrader: (13)

I appreciate that suggestion, I'll give it a try, it seems to be a little more accurate as well. I'll post back at ya in the next day or two and let you know how it turns out.
Thanks

BMR Tech2

iTrader: (5)

Getting the pinion angle correct is easy but its also easy to get confused. I will post a link to our site. There is a video on how to correctly set the pinion angle on an f body. If you have any further questions please give us a call and we can step you through it. Our tech dept is open MON-FRI 8:30AM- 6:00PM.

http://www.bmrfabrication.com/

http://www.bmrtvonline.com/video_detail.php?mId=3788

03 BUSA

iTrader: (25)

Good video. Do all the torque arms come with the angle finder? Just curious.

Jimmard

iTrader: (12)

After watching that video, he takes the angle of the driveshaft and the angle of the pinion on the rear axle. I thought you had to take the angle of the output shaft of the transmission and the angle of the pinion on the rear end. Like this:



Another picture showing what 0* of pinion angle looks like. Note: Center line of transmission parallel to the center line of the pinion.



Or am I completely wrong here?

CW00BlackTA

iTrader: (31)

That's exactly the idea. Once they are parallel, you set your angle to compensate for how you are using the car so that they remain parallel when loaded. Less angle for street driving (low load), more angle for 1/4 mile racing (high load).

98catfish

iTrader: (13)

Ok if your right then a 4wd w/ a suspension lift, the d/shaft would be at a 60dg angle. If you've ever seen a 4wd w/ a lift the pinion is pointing up to match the d/shaft.

The correct way is to w/poly bushings get rear pinion pointing down 1dg more than d/shaft angle, w/ stock 2-3 dg angle down more than d/shaft angle. This is to create a 0dg driveline angle under accleration.

The pinion angle has NOTHING do do w/ tranny angle.
Do you guys actually think the guys at BMR dont know how to properly set a pinion angle.


Doug

Jimmard

iTrader: (12)

I'm pretty sure they know what they're doing..... It's just different than the way I was taught to do it so I thought I would ask so that they could clear things up for me.

leadfoot4

iTrader: (1)

"Jimmard", somewhere along the road, I saw the illustration that you posted, and set my pinion angle the way it's posted there. It seems to me, that's it's also the method that "CWOOBlack TA" is describing.

I set my pinion angle that way, and it just didn't work out, although in theory, I was positive it would. I watched the BMR video a couple of times, went out to the garage and reset the angle the way they describe, and the car has been vibration free ever since.

I guess that's why they call things "trial and error".........

BMR Tech

iTrader: (9)

Yes all of the adjustable arms come with angle finder
The pinion angle thing has been debated 1000 times. The method we show in the video is the method we are sure will yield the results we are looking for. Not say it's the only right way to do it just the way we recommend setting it using our products.