Unexpected Pinion Angle setting benefit.

[Trainman]

I was doing research on Pinion Angle to improve my 60' time. I made a phone call to FastJack and got some insight. Also talking with some other racers at the track and someone suggested that a -2 degree pinion angle was ideal. Did some online research (FastJacks idea) and discovered that the ideal angle varies with type of suspension (4 Link..Vs ..Leaf spring..etc.). I have a 2004 RC that is stock suspension, except for CalTracs. My pinion angle was +2.5 degrees. My suspension shop suggested a 4 degree wedge placed under the leaf spring pad would be a place to start. This took all of 5 minutes. By placing the thicker part of the wedge to the rear of the vehicle the pinion angle was changed to exactly 0 degrees. I took the truck out for a road test as the suspension guy says sometimes you can create a vibration if the angle changes too much. Wow....lo and behold the truck is WAY smoother, and the XMetal shifter is a lot quieter. I stomped the throttle in 1st gear ( from a roll on street tires) and left two even black marks and not the usual fishtail effect. It appears the power application is more even. Friday May 9th is the next Test and Tune evening at Famoso Raceway and I will report the result on any improvement on the 60' time.

 

[Marc T]

Very interesting !!:rock: Keep us updated on this!!

 

[Kevan]

Pics?

 

[sleeper]

I don't understand. Shouldn't a 4 degree wedge change it to -1.5?

 

[Trainman]

Yes, I thought it would change to -1.5 degrees but apparently the geometry of the wedge at the axle and the nose of the pinion are different, in as much as it isn't a 1 to 1 ratio. Maybe someone else can expain it better. I just know what was measured.

 

[04rcmoneypit]

I always thought a certain degree of angle was needed to keep the needle bearings turning in the u-joint?

 

[Trainman]

You are correct 04rcmoneypit, but the 0 degree pinion angle is just the angle of the face of the differential to the ground and not in relation to the driveshaft, which still has an upward angle in relation to the differential.

 

[moparracing]

You are correct 04rcmoneypit, but the 0 degree pinion angle is just the angle of the face of the differential to the ground and not in relation to the driveshaft, which still has an upward angle in relation to the differential.

not sure i understand what you mean ?
if the point of connection where the driveline u-joint connects to the rear end (the pinion shaft, i think) is perpendicular to the ground, is that what you mean ?:dontknow:

 

[Trainman]

Yes, that's what I mean. 0 degrees means the differential is essentialy level with the ground, in other words not pointing upward or downward.

 

[Kevan]

Wouldn't it also improve short distance times if the pinion angle was offset slightly (L-R)?
If you removed some of the lash, the power would transfer quicker....in theory.
It would also increase wear on said gears and bearings.

Example:
5.5 deg. on Pass. Side
4.0 deg. on Drivers Side

Just a thought.

 

[Trainman]

I have no idea on that, Kevan. I'm trying to keep this simple as I am just a driver!

 

[Kevan]

Just thinking aloud.

(Hopefully that doesn't get me into trouble....my suggestion didn't come from any manual but instead from actual life experience in working with gears that cost more than your average house riding on bearings with $30,000 races....)

 

[FATJACK]

I think my pinion angle must be off with my new rearend. Can't get the wheelhop out of it, even with the Cal-Tracs.

 

[SANTEEN]

I think my pinion angle must be off with my new rearend. Can't get the wheelhop out of it, even with the Cal-Tracs.

That's cuz ur ass got fatter and it's keeping the rear end down a bit more.

 

[Troy's QC SRT]

lol your an ass Steve....but funny! time to hit the treadmill old man!

 

[fastestbrickonearth]

Any different results trainman?