off season pondering pinion angle

[Don Fardie]

Hi Larry,
I ended using a Go-Pro camera to record what was happening and found I had too much Pinion Angle. As you can see in the video going down the track I was running a negative angle, so I removed 2 deg. Also at launch it was really never going past 0 or postive degrees.
When using the Go-Pro editing software you can slow it way down and zero in on any area of concern within the lens area.

[ame]http://www.youtube.com/watch?v=3SVoqUKEJNg&safe=active[/ame]

[Tom Goldman]

Hey Don ,nice video.
exactly what I was describing.

[tj310]

Great video thanks for posting. I believe the misconceptions on the importance of pinion angle go back to when Mopar racers ran pinion snubbers instead of traction bars. ---Trevor

[Run to Rund]

My understanding is that you don't want the diff to rotate enough to make the angle opposite, meaning pointing up enough to give a reverse angle at that u joint compared to the direction of the angle at the front u joint. Ideally the angle would be the same front and rear, but suspensions allow the angle to change so you compensate by pinting the nose of the diff down a degree or two.

[Chris Hill]

Originally Posted by Don Fardie

Hi Larry,
I ended using a Go-Pro camera to record what was happening and found I had too much Pinion Angle. As you can see in the video going down the track I was running a negative angle, so I removed 2 deg. Also at launch it was really never going past 0 or postive degrees.
When using the Go-Pro editing software you can slow it way down and zero in on any area of concern within the lens area.

Awsome video! Now put a strobe light on it and see what happens.

[treessavoy]

Mother Mopar was the first to really science out the leaf spring suspension and they published their findings in their Chassis book.

Standard Leaf Springs 5 to 10 degrees nose down, 5-7 best

Leaf Link 3 to 5 degrees down

4 Link (double pivot) 2 degrees down

Ladder Bar (single pivot) 1 degree down

Note:Front Universal Joint Angle ( all suspensions ) 2.5 degrees or less

I run 6 degrees down on the Max Wedge with the real SS Springs. I'm going to switch to Cal traks this year and I figure it might be prudent to ask them about the angle used with the new springs and traction bars.

JimR

[Don Fardie]

Originally Posted by Chris Hill

Awsome video! Now put a strobe light on it and see what happens.

Not sure I could do that without triggering some Flashbacks!!!!!

[gmonde]

Originally Posted by Don Fardie

Hi Larry,
I ended using a Go-Pro camera to record what was happening and found I had too much Pinion Angle. As you can see in the video going down the track I was running a negative angle, so I removed 2 deg. Also at launch it was really never going past 0 or postive degrees.
When using the Go-Pro editing software you can slow it way down and zero in on any area of concern within the lens area.

don :great footage !! are the springs caltracs also ??? is this before removing 2 degrees
gmonde

[Dave Gantz]

Don, you have the right idea, imo. I've always heard all of the different angles for different suspensions. I've always wondered how anyone really knew what it looked like under there to recommend a given angle. I wouldn't know how to put whatever camera under a car to see it working (not to mention I'm hardly ever at a track anymore), but it would be interesting to test a large sample of cars and see if these recommended angles are working.

[Jeff Lee]

What is it that measures shock travel and records it on the data logger? Whatever that thingamajig is called, you need to fabricate one for the nose of the differential and actually measure the movement from the base angle. You could build a mechanical apparatus not using a data logger.
I know a guy that was video'ing the movement with a strobe light on his BBC SS car back in the '80's. I don't remember if it was a 4-link or ladder bar car. But as I recall, it was difficult or impossible to keep the pinion angle below zero with shocks and chassis tuning that would enable the car to launch correctly. This was a National record holding car.