[blueracecar]

i have an 89 gt drag car(no street) with a 302 in it a c-4 and 4500 stall.i just got done putting new upper and lower control arms and 4.30s (it had 4.10s). all the bushings are solid now and i welded up the torque boxes while i was under there.i also put new brakes all around.i never had a problem before but with the brakes like they were i could only get about 2000 rpm comfortably in the staging lights.now i can get about 3500 and hold it all day. heres my question,the front end isnt coming up anymore.when it comes out of the hole, it comes out flat.i am pretty sure from the people i have talked to i need to change my pinion angle.i dont know where its at right now but where is a good starting point.

[RLG34750]

I would set pinion angle 1 degrees to 1½ degrees downward.

and for those who do not know how to measure pinion angle....



Measuring Pinion Angle

Pinion angle is the difference between the centerline of the driveshaft and the centerline of the pinion shaft of the differential. To measure it you must be able to work under the car with the suspension fully loaded and the car level. A drive-on lift works best for this. Method "A" - (recommended)

Method A (recommended) Use an angle measuring gauge (adjustable protractor) to measure the difference between the pinion flange and the drive shaft directly. These gauges are available for under $10 from a hardware store. Place the edge of the gauge vertically against the front of the pinion flange, beside the driveshaft. Extend the measuring arm forward parallel to the bottom of the driveshaft. Extend a straight edge under the driveshaft to the measuring arm of the angle gauge. Hold the straight edge flat against the bottom of the driveshaft and adjust the measuring arm to read the angle. Depending on the gauge you use, you may have to subtract 90° from your reading to get the correct number. Your final measurement should be between 0 and 5. Examine the diagram at the bottom to determine if the pinion angle is nose up or nose down.

Method "B"
Use a gravity angle gauge (Available at hardware stores) to measure the angle between the driveshaft and the ground. Hold the gauge on the bottom of the driveshaft. Align the gauge front-to-back under the car in line with the driveshaft and read the number from the gauge. Write down this number.
2) Next, hold the side of the gauge against the front of the pinion flange (beside the driveshaft). Measure the angle between the pinion shaft and the ground. Write down this number.
3) Subtract the first number from the second number. This is your pinion angle. Examine the diagram at the bottom to determine if the pinion angle is nose up or nose down.

[blueracecar]

thanks for the info Reggie.i put 1.5 degrees negative (downward) in the pinionand went to the test and tune today.its pulling the front wheels about 4" and 60' times only varied from 1.56-1.57.i even placed in the money in the jackpot race.

[RLG34750]

Originally Posted by blueracecar

thanks for the info Reggie.i put 1.5 degrees negative (downward) in the pinionand went to the test and tune today.its pulling the front wheels about 4" and 60' times only varied from 1.56-1.57.i even placed in the money in the jackpot race.

sound like you had a good day.......

glad the info helped you.....