Rear end Pinion angle

[70_Fastback]

I'm doing my 4-link setup this weekend. What is a recommended rearend pinion angle - or does it just need to be set parallel to the transmission pinion angle?

 

[70_Fastback]

I should really Google things before just posting.

http://www.carcraft.com/howto/91758/index.html

Some types of rear suspensions offer more control than others and require different angles. According to Bickel, a ladder-bar suspension normally requires ½ degree of pinion angle, a four-link requires 1-2½ degrees, and a leaf-spring suspension requires up to 6 to 7 degrees. In all examples, we’re talking about negative pinion angle, i.e., the pinion is nose-down in relation to the driveshaft.

 

[Horseplay]

I was going to say no more than 2 degrees with a 4-link. You beat me to it.

 

[buening]

Leaf spring needs 6-7°???? Holy crap, mine from the factory isn't even close to that.

Jeremy keep in mind your transmission driveline angle as well. If you start changing the angle of the pinion you'll need to change your transmission angle as well so that they fall within 3° of each other.

 

[camachinist]

Can't speak for what's 'correct', but the pinion angle on the race car (4-link) is within 1/2 degree of parallel with the crankshaft centerline. It's set via adjustment of the upper control arm to 1/2 degree negative (below centerline in relation to the ground). The relationship to the driveshaft angle is IME irrelevant to parallelism of the start and end points.

YMMV, but that methodology has worked for as long as I've been (drag) racing.

 

[70_Fastback]

Thanks guys.

 

[daveSanborn]

Jeremy,

When you state:

I'm doing my 4-link setup this weekend


Do you mean you're welding all the brackets onto the frame/rearend? Welding the brackets should be a straightforward process and a LOT simpler if the arms of your 4link are adjustable. I'm unsure which arms you're using, but the arms I have use long shaft heim joints that screw into the arms. This allows the length of the arms to be adjustable to make infinite changes to the pinion angle. What type of arms are you using?

 

[70_Fastback]

Jeremy,

When you state:

I'm doing my 4-link setup this weekend


Do you mean you're welding all the brackets onto the frame/rearend? Welding the brackets should be a straightforward process and a LOT simpler if the arms of your 4link are adjustable. I'm unsure which arms you're using, but the arms I have use long shaft heim joints that screw into the arms. This allows the length of the arms to be adjustable to make infinite changes to the pinion angle. What type of arms are you using?

Same here Dave, DOM tubing w/ threaded weld in inserts with LH & RH Heims joints. I understand about the adjustability - but wanted to get it as close to correct from the baseline as possible.