Pinion angle measurements... opinions?

[twistid]

Equipment is as follows: Eibach Sportline springs, Strange adjustable shocks and Whiteline LCA brackets. Stock UCA/DS. Steeda UCA in the mail.

First measurement taken from 2nd half of driveshaft near where it connects to pumpkin. It came in around -1 degree.

Second measurement was taken from pinion flange... It came in about +1.

Just for shits and grins I took a measurement from the bottom of the diff and it came in at -2.

My first question is why is the pinion flange angle so far off from the diff angle, shouldn't they be the same?

Second question, is it (DS angle) - (Pinion flange angle) OR (Pinion flange angle) - (DS angle)? Depending on which way I either have perfect -2 pinion angle or no bueno +2... In which case I have to set the pumpkin to +3 to achieve -2 pinion angle.

Also just to be clear, I do not have any driveline issues at all, no vibrations or noises. I drive pretty aggressively and want to continue autocrossing, so I'd rather perform some preventative maintenance and upgrades rather than wait until something breaks from driving like an asshole with a bad pinion angle :-D

 

[Mattio]

ive always just kept it somewhere between -3 and +3... never had a problem with that.

 

[blackbeast12]

Read this in its entirety:

cherod.com/mustang - LCAs

 

[twistid]

From that link...

You are interested in the difference between these two numbers. So, take the angle of the driveshaft and subtract the angle of the pinion from it.

The correct measurement will be about 3 to 1.5 degrees difference, with the pinion being closer to horizontal than the driveshaft is. In other words, 0 degrees would have the measurements the same: The driveshaft and the pinion would be perfectly in line. You want the pinion to be angled down lower by about 3 to 1.5 degrees. (Technically, this is called a negative angle, as in "-3 degree pinion angle", but wether or not the actual measurement is negative depends on how your angle gage is calibrated, so that is not always reliable)

So it is saying that only the difference between the two matters... the difference between my two measurements (-1) and (+1) comes out to 2 degrees... However it then states "You want the pinion to be angled down lower by about 3 to 1.5 degrees" So since my driveshaft measured -1 and pinion flange being +1 the difference is 2 degrees but the flange sits higher than the driveshaft, I need to drop the pinion flange down to -3. That way there is still a 2 degree difference but the pinion flange is now lower than the drive shaft.

 

[01bluesnake]

Yes, pinion angle is the difference between the two angles you measure. Also a -1 and a +1 is 0, not 2.

 

[twistid]

Yes, pinion angle is the difference between the two angles you measure. Also a -1 and a +1 is 0, not 2.

lol... yeah your right... I was thinking of an X-axis ...-2 , -1, 0, +1, +2 .... :banana:

 

[01bluesnake]

lol, ya. -2 is usually a good pinion angle to start but depending on what type of suspension is in back with bushing type, you may be able to go lower or may need higher. Pinion angle is more for proper axle rotation under acceleration which translates into traction although driveshaft vibration can come into play.

 

[ExTurbo]

Read this in its entirety:

cherod.com/mustang - LCAs

thanks for posting that, i had never seen it and it makes things a lot more clear to me and explains my traction issues, looks like i need some relocation brackets and an adjustable UCA. Everyones been saying that i should get them but now i understand why...great write up

 

[twistid]

Yeah, I've just read horror stories about people blowing pinion seal and destroying pumpkin internals from incorrect pinion angles... I do not want to be that guy!

Thanks for your help 01bluesnake, just to verify... current measurements are -1 driveshaft, +1 pinion flange... I now need to set pinion flange to -3 to achieve the correct 2* difference.

 

[01bluesnake]

Yeah, I've just read horror stories about people blowing pinion seal and destroying pumpkin internals from incorrect pinion angles... I do not want to be that guy!

Thanks for your help 01bluesnake, just to verify... current measurements are -1 driveshaft, +1 pinion flange... I now need to set pinion flange to -3 to achieve the correct 2* difference.

Your welcome. I think a lot of the problems come from pinion angles that are way off or driveline vibration finally killing the pinion bearing and/or seal. If your ds is at -1, you would be looking for a -2 at the pinion flange. The only thing to keep in mind though, as you move/rotate the axle to get the angle you want, the DS angle will also change. It may take a few time of measuring and adjusting to get it right. I actually have to do mine in a little bit as well lol. :beer:

 

[jymboslice]

Going to bump this.


Going to set my pinion angle in about a week. I have a DSS driveshaft, where would be a good place to take measurements from for the pinion angle?

and should I shoot for the -2 angle with the one piece driveshaft?