Measuring Pinion Angle

[TheJet-09]

In now thinking I've been doing it wrong this entire time, I'm curious how others measure pinion angle?

Are you measuring the angle of the output shaft on the trans and adding that to what you get off the back of the rearend cover? Or are you taking the angle of the driveshaft into consideration? Or are you just putting an angle finder on the back of the rearend and calling it good?

As always, thanks in advance!

[petesbuyin]

I measure it on the j-bar mount or the rear cover surface. Driveshaft or trans is not used in finding the pinion angle.

[MasterSbilt_Racer]

You measure both for total pinon angle. Follow your chassis builder instructions and you should be fine. Not sure any of them want you to measure that way.

[Basecircle]

I’m actually surprised this isn’t being measured dynamically like everything else. Full hike with a specific load on the 5th coil and measure u-joint working angles. Maybe some are doing it? Maybe if you set static to your chassis manufacturer’s specs it’s close enough and doesn’t make much difference? I’ve always just set it to specs and checked for driveshaft length issues or clearance and called it good.

[AmickRacing]

I'd say if you let the LR droop, push the RR up a few inches, and compress the 5th coil 2.5ish inches, make sure the u-joints aren't straight, if you wanted to be really in depth.

I have always had an issue with setting the pinion angle at 5-7 (average numbers from what I've heard anyway), but the motor is mounted 2" up from the lowest holes... so many adjustments affect something else in these cars.

[TheJet-09]

I agree. I was thinking of doing what you first described, because with the 5-7 statically, plus the trans/engine angle, I'm probably more like 10* true pinion angle.

When soft on the 6th coil, I've actually picked up a decel vibration that I attributed to pinion angle.

[Len72P]

Do a google search on Spicer Driveline Operating Angle Calculator. Interesting.

[Kromulous]

Are you manipulating pinion angle for set up reasons or to see if there is a potential bind?

I am starting to believe that springs in the 5th and 6th coils is not the best way, to much rebound force. A combination of spring and rubbers of some sort is the best i think. There is a new item out there called a lift stick, and i think it solves a lot of issues, but have not ran it yet.

As for pinion angle, some argue that it can have impact on your set up, i know on leaf cars it was real, not sure now. I have been running 3 static up to 5 and not really noticed a lot of difference.

[Matt49]

Are you manipulating pinion angle for set up reasons or to see if there is a potential bind?

I am starting to believe that springs in the 5th and 6th coils is not the best way, to much rebound force. A combination of spring and rubbers of some sort is the best i think. There is a new item out there called a lift stick, and i think it solves a lot of issues, but have not ran it yet.

As for pinion angle, some argue that it can have impact on your set up, i know on leaf cars it was real, not sure now. I have been running 3 static up to 5 and not really noticed a lot of difference.

Pinion angle affecting "drive" is a thought process that carried over from antiquated drag racing stuff. Yes, on a leaf spring car it changes things with wrap up. On a 4-bar car, unless you believe that having an inefficient drive train is a good form of traction control, there is nothing to be discussed on the matter in terms of setup.

[FlatTire]

The technically correct way to measure pinion angle is the procedure shown on Spicer's website. I have a feeling most racers and chassis builders just stick their angle finder on the pinion plate and take a reading. This is not how its done in the world of engineering and there is good reason. The height of the transmission has everything to do with it. Call your chassis builder to be sure.

[Kromulous]

Matt49, cant use quotes browser wont work, i agree, but i know folks that will argue all day long about it. I think what some people see when it affects set up is the u joints phasing in and out, and you can feel it in the seat. That's my guess thou.

[Matt49]

Old, low quality video but still interesting:
https://www.youtube.com/watch?v=Idk3BVDVHq4

[Kromulous]

Cool video !

[let-r-eat]

Pinion angle matters! You have a (not a nice word)(not a nice word)(not a nice word)(not a nice word) lift arm on the car!