Altering pinion angle.....Q

After lowering a car.....So...Duh-pinion angle changes. I know that. I know what to shoot for. Problems are as follows.....Car is slammed,or well,lowered. 4'' block,and added an 1/4 for fun since i'm there. Relocating perches-which side to side is done with offset pinion in a 9'' rear. Just asking about what degree to compensate for a 4 1/4 difference.? . I have a measurement with the 4'' block,and have added another 1/4 inch. I'm talking degrees here guys.... I understand how the pinion rotates,how things move when the rear is "moved up" in a car,and how things change. I've never driven the car at speed,or farther than around the block a couple of times. Race cars with 4 links and ladder bars are a different animal(from what I know), but principal is the same. In my head,i'm thinking 2 degrees to compensate. Sound close? Front yoke is burried into the X frame,and cannot take a reading even with a small angle finder. I have to go off my initial measurements with the stock rear sitting "static". The frame is sitting on stands,"as" it would sitting on the ground.Before I strike an arc,I just want to make sure i'm relativelly close..Repete- I can only go off my measurements taken from the rear(stock) that was in the car. Things are lined up,and have the same numbers. But- since it's lowered,I woul like to correct,or get closer to "plane".Insight please....

 

I've only done this a half dozen times so I'm by no means an expert. I'm sure others will add their 2 cents worth as well...

Instead of guesstimating I would measure off the crank pulley or harmonic balancer. Set your pinion at the same angle then rotate the pinion another 2-3 degrees nose down.

 

Agreed ching $0.02

 

I would be looking for some drop springs, 4" blocks add a lot of leverage to the spring and may very well give you some scrubline issues.

as for the pinion angle yeah what them other Dudes said.

 

I hear you guys- and very true to get the "exact" line. Springs are new(stock).By no means trying to skimp out on this at all.....= half ***ed. Just figured if compensating raising the rear,and changing the angle with the blocks,AND my measurements,I could compensate by dropping the pinion somewhat. So- say If I "raised" the rear,and changed the angle,say 2 degrees for numbers sake,and before I weld the perches,and dropped the angle 2 degrees from my initial measurements, I should be closer than I was actually before the blocks? I can take other measurements as well. The new driveshaft will be installed shortly,and that will help things. I am just trying to get a "if you move it this much,you should be in the ball park with this much" kinda thing.Kinda like a 4'' block requires X amount of degrees sort of thing.........So many people run blocks and just "go". I would like to "straighten things" out. Just me. I will keep measuring-1000 times=weld once. Just the block/moving the pinion up thing factor.... No scrub line/ interference/rubbing issues at all. Thanks.

 

can also get a angle measurement off the starter-since you are running the extra 1/4''
spacer replace it with a angle wedge and get the correct angle and keep the 1/4"-search summitracing.com., etc. to source them

 

1/4" change in pitch/angle at 1 foot is very close to 1 degree of angle change.
It works.

 

Or you could just jack it up and put jackstands under the axle and control arms so the suspension is compressed and sitting just like it does on the ground. Then you can put an angle finder on the driveline to take a measurement, then move it to the bottom of the pinion and see what angle is there. Just calculate the difference to get your perfect pinion angle.