Sears

Driveshaft = -6
Rear end T/A bracket = -3

According to BMR instructions you subtract the rear angle from the driveashaft angle.

(-6)-(-3)= -3

Is that accurate enough or is there a better way to set it. Visually the rear seems to be pointing up too much. Axle is under load.

Thanks,
Justin

Lar's SS

Oh boy, here we go. This is going to be a long thread. <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />
Do a search, you'll see.
<img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
It should be going slightly down or neg.

<small>[ February 27, 2003, 03:13 PM: Message edited by: Lar's SS ]</small>

Gustin

iTrader: (4)

For a street strip set up you only want about 4-5 of total pinion angle

So what you need to do is measure the angle of the drive shaft (which should be around 2 deg positive). So if the drive shaft measures 2 deg positive you want about 2 deg negative on the rearend pinion. Add -2 + 2 = 4 deg of total pinion angle.

Remember, if the pinion (front of the rearend) is pointing down toward the ground it is a negative angle (you will be able to tell by looking). So if the rearend is pointing down and your angle finder reads 3 it will be a -3 rearend pinion angle. Now if the driveshaft is pointing up toward the tranny it will be a positive angle. So if the angle finder reads 2 degrees it will be a +2 degrees. You never want positive rearend pinion angle you will spin your *** off! Some times you will have to lower or raise the tranny to get the right amount of driveshaft or total pinion angle.

Here is a good illustration:

http://www.2quicknovas.com/pinionangle.jpg

Good Luck,
Sean

Chad00ws6

Let me put this as simply as possible. Looking under the car from the drivers side do it like this.
1. See what the driveshaft reads. Mine is at 0 on the anglefinder. I just set it three days ago.

2. Now adjust the torque arm adjustment until the angle of the pinion is pointing down and the anglefinder is 2 degrees to the right of where ever it read on the driveshaft.

To hell with subtracting the numbers and such <img border="0" alt="[shoot]" title="" src="graemlins/gr_guns.gif" />
Just make it 2 degrees to the right of whatever the Driveshaft read if you are looking from the drivers side and two degrees to the left if you are looking from the passengers side. <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />

NUFF SAID

MacGyver

iTrader: (5)

Dont listen to anything anyone else in this thread said. If you dont take into account your transmission angle when you are setting your pinion angle you can easily have a very bad driveline vibration. The IDEAL way to set the pinion angle is to do this.

Place car on jackstands on the rear axle tubes as well as the front lower control arms so that the car is sitting like it would on the road with all the weight loading the suspension.

Remove the driveshaft. Place an angle finder on the flat part of the transmission seal on the transmission. Lets just say that it measures 89 degrees so to get the angle we subtract 90 from that figure and we come up with -1 degree. This is your transmission angle.

Now place the angle finder on the flat part of the pinion yoke on the rear end and measure that angle. lets say that that angle is 88 right now so we subtract 90 and come up with -2 degrees. So that means we have a -3 degree pinion angle.

Hope this helps

Will

<small>[ February 27, 2003, 05:16 PM: Message edited by: MacGyver ]</small>

DERTY

Justin,

Will has the right idea. I typically get the car on stands so that the center of the wheels are the same distance off the floor. I have a nice set of front ramps and some jackstands that when I do this the wheels are dead even with each other. Then you can measure off the transmission pan, the driveshaft and then the pinion. I usually spend about 15 to 30 minutes just going back and forth until I get all the measurements consistent.

I've had a helluva time looking at it visually. I once had it set at -14 degrees because it visually looked right and I got confused on if the arrow had to be on opposite sides of vertical. As soon as I backed up I knew something was wrong. The down angle on the pinion is ever so slight in contrast to the driveshaft. Take the measurements like Will mentioned and you should get a good number. Then double check that off the driveshaft. If you get any vibration after a quick drive, back off the angle a little (or a lot).

Gustin

iTrader: (4)

<small>[ February 28, 2003, 12:39 AM: Message edited by: Gustin ]</small>

Gustin

iTrader: (4)

Whatever technique you use I recommend that you use a drive on lift.

I wont hack at people that say "dont do it like that do it like this, period!" Its worthless.

I will say if you have a driveshaft (street strip car mind you) that reads "0" degrees, well this is just not practical on a street car. Alot more can be gained with a positive 2 or 3 degree reading on the drive shaft.

Call Denny aka "Quincy" at Denny's Driveshaft and he will definitely help you out on this issue. <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

Sean

Lar's SS

See I told ya!

Chad00ws6

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by MacGyver:

Dont listen to anything anyone else in this thread said. </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I disagree.... <img border="0" title="" alt="[Razz]" src="gr_images/icons/tongue.gif" />
I put mine on a rack that had the tires sitting on the rack so like it was on the ground. Like I said it's not important that my DS was at 0 or wherever it may have been. I put the pinion 2 degress down so you are saying that mine is wrong???? <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

MacGyver

iTrader: (5)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Chad00ws6:
<strong> </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by MacGyver:

Dont listen to anything anyone else in this thread said. </font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">I disagree.... <img border="0" title="" alt="[Razz]" src="gr_images/icons/tongue.gif" />
I put mine on a rack that had the tires sitting on the rack so like it was on the ground. Like I said it's not important that my DS was at 0 or wherever it may have been. I put the pinion 2 degress down so you are saying that mine is wrong???? <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Here is the problem with only taking into account the driveshaft angle and the pinion angle. If the angle between the driveshaft and the pinion is more than say 3-4 degrees different than the angle between the driveshaft and the transmission you will get a drivetrain vibration. If you look in a helms manual for our cars it goes over in detail about this. When a u-joint is turning it is constantly accelerating and decelerating. so since we have two u-joints operating in the driveline at one time they can effectively cancel eachother out if they are set at 90 degrees opposite of eachother. Here is an example.

Say you put your angle finder on your transmission and it reads 1 degree up. In order to keep the u-joints perfectly in sync when they are turning would be to set your pinion angle to 1 degree down. effectively cancelling out the two angles acting as though there were 0 degrees of difference between them. For racing we want the driveline to be at 0 degrees under full aceleration so what we do is set the pinion angle down another 2-3 degres from where we found was a 0 degree difference. So if we still have a +1 degree transmission angle we would need to set the pinion angle to -3 to -4 degrees in order to achieve a -2 to -3 degree negative pinion angle.


Will

Pro Stock John

iTrader: (34)

If it visually points up it will rotate up a bit more when you are at the track.

I believe my buddy measures it at the torque arm and we have mine at -2.5 pinion angle. I'll call him now to confirm.

I have gone 1.49 off the footbrake.

Tim98TA

iTrader: (7)

Justin, I talked to a guy that builds chassis and he told me to do it this way.
Place the angle finder on the flat part of the pinion yoke. Adjust to -2 degrees. Done deal. YES you need to have it on a drive on lift for the best results. Screw all that tranny measurements subtracted by the driveshaft measurements, added to the alignment of Venus to the moon crap.

Tim

MacGyver

iTrader: (5)

Well fact of the matter is the way I posted is the correct way to do it. I did it like you do before I learned how to do it right and had a bad driveline vibration. I then did some research and did it the way I posted and it cleared the vibration up completely. But to each his own.


Will

Sears

I just spent a couple of hours messing with this. Had some interesting results.

Supported the rear end with jack stands and the front control arms to load the car on all 4 corners, car was level. Removed the driveshaft. The angle on the rear of the tranny was 88* (-2) , got the angle on the rear yoke to 88* by adjustng the T/A, so that leaves me with a -4* total pinion angle. Alright, so I put the driveshaft back in and measure the driveshaft angle and T/A bracket angle to see how the numbers would compare. I had +1 on the driveshaft ( was pointing up towards the tranny ), and -2 on the T/A bracket. So that gives me a -3 pinion angle. Only a slight difference but I thought it was interesting to see. I don't have any driveline vibration although I never did, maybe it's b/c I have a CF driveshaft? I appreciate all the help and I know have a good understanding of how it works.

I took a few pictures while I was at it..
http://bellsouthpwp.net/j/s/jsears8/pinion/

Thanks again, I feel much better now knowing what my pinion angle really is.

Justin

MacGyver

iTrader: (5)

Glad to hear you got everything under control and worked out. I was going crazy for awhile trying to figure the correct way to set the angles up and the vibration I had was killing me.


Will

gillbot

iTrader: (27)

I cheat, I use my companies Laser Alignment system to check mine. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

Tim98TA

iTrader: (7)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by MacGyver:
<strong> Well fact of the matter is the way I posted is the correct way to do it.
Will </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">WELL STOP THE PRESSES!!!!!!!!
Will, what makes you think that your way IS the right way and EVERYBODY elses, including chassis builders, is dead wrong?

Think about this for a minute as far as adjusting the tranny angle. If you adjust the tranny angle downward to equal the pinion angle, what happens to the tranny angle when you launch? Pinion angle goes towards a positive # and tranny stays the same. Then all your hard work becomes null and void. You want to set the pinion angle, NOT the tranny. It is a fixed #, the pinion angles varies, but only for a brief moment when you launch. It then settles back to your settings.

Tim

MacGyver

iTrader: (5)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Tim98TA:
<strong> </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by MacGyver:
<strong> Well fact of the matter is the way I posted is the correct way to do it.
Will </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">WELL STOP THE PRESSES!!!!!!!!
Will, what makes you think that your way IS the right way and EVERYBODY elses, including chassis builders, is dead wrong?

Think about this for a minute as far as adjusting the tranny angle. If you adjust the tranny angle downward to equal the pinion angle, what happens to the tranny angle when you launch? Pinion angle goes towards a positive # and tranny stays the same. Then all your hard work becomes null and void. You want to set the pinion angle, NOT the tranny. It is a fixed #, the pinion angles varies, but only for a brief moment when you launch. It then settles back to your settings.

Tim </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Never ONCE did I say anything about adjusting the tranny angle. The tranny angle is used as a reference to allow you to get the pinion angle to an angle that effectively cancels out the angle the transmission is at. Once you have to pinion angle set to the angle that cancels out the transmission angle then you go from there with setting a -2 to -3 degree angle. I'll try to explain this once more for you.

Say the tranny angle is +1 to effectively cancel this angle out you need to set the pinion angle to -1 so then we effectively have 0 degree driveline angle (they cancel eachother out and this is the point you should have no driveline vibration at all and no premature u-joint wear) So after we get the angle to cancel out then we go from there setting the pinion angle down another -2 to -3 degrees so in our case from above that would mean setting the pinion to -3 to -4 degrees down. Hopefully you can understand this and next time fully read my post before posting something like you did. AGAIN NEVER ONCE DID I SAY ANYWHERE THAT YOU NEED TO ADJUST THE TRANNY ANGLE It is merely used as a reference point.


Will

10.5 Dave

iTrader: (5)

My very simple way to set pinion angle(spohn t/a).Park car on flat surface,put angle finder on bottom of t-a where it mounts to pumpkin.Adjust top nut to negative 3 degrees for drag racing,front of diff will move toward ground when turning.Wouldnt recommend setting this for driver vibrates above 100mph (1.47 60 FT).