pinion angle?

badnotch wrote:i run - 3.5 and my car loves it

you sure Gerry ???

100 % went from 1.65 sixty with a -1.5 to a -3.5 to a 1.28 didnt wheel stand for the hell of it

I would have to extend my lowers even more to even get 3.5 degrees. I already have them extended almost an inch. Wheelbase is right at 102" now. Consistently sixty foot 1.21.

Neither here nor there, I don't use it for tuning aid anyways. I may be a little stupid but I haven't figured out how it effects how a car hooks anyways if everything else measures out right. I thought it was just used to keep your u-joints together.

i was told the 4 bar setup like a mustang was kinda like a short 4 link and the pinion was how you put bite in the car and took bite out correct me if im wrong but i hope that isnt stupid for me to say but thats what ihave always been told

whatbumper wrote:I haven't figured out how it effects how a car hooks anyways if everything else measures out right. I thought it was just used to keep your u-joints together.

What is happening is he is putting the U-joint(s) in a greater bind increasing the frictional drag & taking away some of the engine power from reaching the rear tires thus allowing them a better chance too hook. It's nothing new, some of the old Pro Stock guys tried this way, way back in ancient times to kill some launch power. This was back before there was the advent of the good, highly adjustable suspension components like we have today. But a safer way to kill some of the engine power reaching the tires during the launch is to leave the pinion angle at -1 to -1.5* and "steal away" some of the launch power another way (like with engine timing using a Digital 7). At least with the 7 box you can ramp the timing back to where it needs to be after the initial launch, and your not increasing the friction/binding of a loaded drive line component. He could have also achieved a (somewhat) similar effect during the launch by going with a two speed trans vs a three speed.

Of course if someone decided they didn't want to use the band-aid trick of binding up the U-joints trying to get a car to hook there is always the "old fashioned" way of getting a car to hook........by adjusting the actual chassis/suspension (aka shocks, struts, I/C placement, air pressure, moving weight around, etc, etc) since that's what it's there for.

all junk wrote:i was told the 4 bar setup like a mustang was kinda like a short 4 link and the pinion was how you put bite in the car and took bite out correct me if im wrong but i hope that isnt stupid for me to say but thats what ihave always been told

Don't worry, it's not a stupid question.

It can be hard to weed out the misinformation that has been around forever. This myth that somehow the pinion magically causes the "bite" (vs engine torque & the suspension doing it) even though the pinion isn't physically/mechanically interacting with a moving or fixed suspension/chassis component never seems to go away. The only exception to this is of course a "pinion snubber" traction device because with this setup the pinion's physical actions during the launch (upward rotation) are transferred to a chassis mounted bracket holding a rubber snubber. Part of the myth stems from ancient times back when stuff like ladder bars (and such) were much less adjustable. Back then sometimes when someone lowered/raised the bars to other front holes, they couldn't correct the pinion angle back to where it needed to be afterwards (or were too lazy to try). It lead to the confusion as to what really caused the suspension to have more/less leverage, the different bar hole & a different I/C....or the pinion angle.


As mentioned the combined pinion & driveshaft U-joint operating angle (aka "pinion angle") can't "hit" a tire, engine torque & the rear suspension leverage does that. The only "side effect" adjusting pinion angle can have is when adjusted to the point that it causes the U-joint to operate in an increasing bind. This increased bind causes more friction which in effect uses up some of the engine power from reaching the rear tires. So in effect your not "smacking" the tire with pinion angle, your actually removing some of the engine's usable torque/power from the initial launch giving an over powered tire more of a fighting chance. But as I have said before some people do have success using a bunch of pinion angle & U-joint binding to get a car too hook vs adjusting the suspension instead. But a possible U-joint failure from increased binding is not something I would want to mess with.

It's a small part of the even bigger misconception that "hitting" a tire harder means it will always "hook" harder. It incorrectly assume that because a given action caused "more" traction, it must therefore have been a more energetic or more violent action. Nothing could be further from the truth since a tire needs the "correct" amount of applied energy to hook as effeciently as possible. Correct means the right amount, not too much, and not too little.

Since it hasn't been brought up yet I thought I would add that a number of driveline sites say that there is a direct correlation between max accepted safe U-joint operating angle vs a given driveshaft RPM/speed. As max driveshaft RPM/speed increases, max safe operating angle decreases.

The RPM vs angle chart you see on a number of sites has these numbers........

SHAFT RPM vs MAXIMUM OPERATING ANGLE
5000..... 3.25°
4500..... 3.67°
4000..... 4.25°
3500..... 5.00°
3000..... 5.83°
2500..... 7.00°
2000..... 8.67°
1500..... 11.5°

Even though the charts usually top out at 5000 RPM, from these numbers you can figure a close rough estimate for higher driveshaft RPM's too.


And Spicer's site says 3* or less for best life.