When you build a high horsepower hot rod you want to get that power to
the ground. Let's talk pinion angle and how we're going to get that power down.
Hi I'm Damien Brase with QA1. Today we're going to talk about pinion angle adjustment
or more appropriately driveline adjustment. So when we're looking at pinion angle adjustment
we actually need to look at the entire driveline and the angles associated with the driveline and
the driveshaft in order to get everything set appropriately. When we're talking pinion angle
adjustment we really need to look at the entire driveline as a system and that's why we want
to start with the engine. We want to figure out what angle or engine and transmission are at so
we can make sure that our pinion runs at an angle parallel or close to the engine and transmission
angle to get everything set appropriately. So we want to have them run approximately parallel to
each other and we'll adjust the pinion up or down a little bit depending on the application and the
vehicle how everything's actually set in relation to each other. But there's a couple tools that
you're going to need to do this. First off we're going to start with an angle finder. Now you get
the inexpensive dial type like this from the local hardware store. A digital angle finder works much
better or you can also get a phone app that would allow you to do that as well. We're going to use
the digital angle finder today. So first thing we want to do is find a surface on the engine
transmission or slip yoke where we can get a measurement from. This car has exhaust running
underneath the drive shaft so it is difficult to get to the slip yoke but we can actually go
off the front of the balancer this car has an LS and a nice flat surface on the front of the
balancer. So we're going to put our angle finder up here zero it out on the front of the balancer
and we're going to use that for the rest of our measurements. With the manual transmission
in this car it does have a nice flat surface on the bell housing here. So we'll double check it
and make sure that it's still zeroed out. And that looks good.
Now if you've got a machine slip yoke you can use that as well this car we just don't have access
to it with the exhaust running underneath and it's pretty tight up against the floor pan up
here. So we've got our angle we'll go to the rear end. Now on the rear end we've got an 8.8 in this
car so we've got the nice flat flange on the front of the diff that we can measure off of we
can also measure off the u-joints on the housing. This car we've actually got about a half a degree
or so of pinion up. Now this car has the factory upper trailing arms in it they're non-adjustable.
Putting an adjustable trailing arm in like the QA1 trailing arms would allow us to bring that pinion
angle down a little bit and reason we want to do that is under load that pinion is going to wrap up
the rear diff is going to wrap up and it's going to straighten out that angle. So having the pinion
pointed down a degree or two is really going to help everything operate more efficiently as the
car is under load and going on the track. Now that I've covered what we're measuring now we need to
look at the how. If you've got adjustable trailing arms like these that we've got right and left hand
threads so loosen up the jam nuts you can actually adjust this on the car. With this car in order
to rotate the pinion down a little bit we would actually lengthen the upper trailing arm if you've
got a car where you need to rotate the pinion up you would want to shorten the trailing arm up.
So if you've got a leaf spring system you would use shims differing types of suspension have
differing methods. But in general we're looking at the same type of thing and making similar
adjustments to it. When measuring driveline angles and making adjustments to the pinion angle the
suspension does need to be loaded and the car sitting at ride height. If you don't you're
going to get wrong angles because you do have some dynamic changes in the rear suspension that will
change those angles. Proper drive train angles are going to help apply the power to the ground and
extend the life of your drivetrain components. For more information visit QA1.net and go drive it.