98_red_z28

I am fixing to install a UMI tunnel mount adjustable torque arm and founders on-car adjustable lower control arms and I've looked through all the threads and couldnt really find any answers to my questions. What does my pinion angle need be, roughly, to hook good on the street on 315/35 R18 drag radials in a 6 speed car?? I am really trying to hook on these tires so i dont have to buy a drag pack... Thanks in advance guys!!

1 FMF

iTrader: (1)

i don't know who started it, but the setting of "pinion angle" has no affect on how the tires hook.... unless the u-joint angle of operation is so large that you break the u-joint then don't go anywhere.

forget the term "pinion angle".

there is only "u-joint operating angle" and "u-joint phasing".

i would hope the purpose of an aftermarket torque arm is so that it prevents the ujoint operating angle at the pinion yoke from changing at all under any load,
therefore you set the ujoint operating angle at the rear pinion yoke to match the operating angle on the ujoint on the front of the drive shaft. this gives a 0° difference in angles between the two ujoints, which means they operate in phase and cancel each other out as they spin and there is no vibration. at most you set the rear pinion yoke to point downward 0.5° to 1° to account for the tendency of it to spin upward under load resulting from weak parts, or from possible body flex since you have the tq arm mounted to the body instead of the transmission.

regarding your goal of launching and hooking tires, i honestly don't know much about that except the drive shaft and ujoint angles play no part in it. you simply want minimum ujoint operating angles not less than 1/2 degree and not much more than 3°. a ujoint is supposed to have some angle to operate properly so you don't want 0.000° such that the drive shaft is exactly in line with something.

BMR Tech2

iTrader: (5)

^ Good explanation. I can't tell you how many calls I get about this. Here is a video we made of setting and adjusting your pinion angle. I personally don't like to measure it this way, but it will get you close

98_red_z28

Thanks guys, I don't really know much about setting up the suspension so this answered most of my questions!!

98_red_z28

One more question, what degree am I looking for with a 6 speed car? It said 2-3 with an auto, or is it even different for a 6 speed?

BMR Sales2

iTrader: (40)

-2 to -3 degrees of pinion angle will be a good baseline for you. I would set it within that range initially and as long as you don't have any vibrations you will be good to go.

98_red_z28

Okay, thanks again!