should I change my pinion angle?
11-04-2011, 03:54 PM
#21
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So let me make sure I'm getting this right:
You're basing your driveline misalignment angle off of the angular difference between the centerline of your pinion, and the surface your tires are sitting on? Have you checked to see if your crank centerline angle is indeed parrallel to the the ground the car sits on?
Using your method, On a 101" wheelbase car, changing from a 26" rear tire To a 28" rear tire will "show" .5* difference in driveline angle. In reality, only the relationship between your pinion centerline and the ground has changed. The driveline hasfollowed suit, and thus, adjusting pinion angle to compensate actually does nothing but complicate Driveline misalignment angles.
I fully understand that pinion able adjustments are meant for driveline misalignment angle only, not for trying to make the car hook harder.
If you're seeing no difference in adjustment from the ground reference compared to the driveline refference, then you're either dealing with a car that has a driveline that's perfecty parallel to the ground, or a suspension that's still deflecting somewhat.
You're basing your driveline misalignment angle off of the angular difference between the centerline of your pinion, and the surface your tires are sitting on? Have you checked to see if your crank centerline angle is indeed parrallel to the the ground the car sits on?
Using your method, On a 101" wheelbase car, changing from a 26" rear tire To a 28" rear tire will "show" .5* difference in driveline angle. In reality, only the relationship between your pinion centerline and the ground has changed. The driveline hasfollowed suit, and thus, adjusting pinion angle to compensate actually does nothing but complicate Driveline misalignment angles.
I fully understand that pinion able adjustments are meant for driveline misalignment angle only, not for trying to make the car hook harder.
If you're seeing no difference in adjustment from the ground reference compared to the driveline refference, then you're either dealing with a car that has a driveline that's perfecty parallel to the ground, or a suspension that's still deflecting somewhat.
11-04-2011, 05:23 PM
#22
Rod ended suspension parts, and a solid front tq arm mount don't deflect any more then the tq arm's flex will allow them to, I can't imagine the tq arm is flexing a whole lot.
I have checked to see if the crank is level with the ground when I had my junk together and it was just about level, I went to the point of putting the rear springs on a big table top belt sander to "surface" them where they sat on the rear to get it level once I had the car close, fwiw. With the car fully loaded, driver in, full nitrous bottle, 1/4 tank of fuel as I usually ran it the pinion angle was checked in relativity to level ground. I would put the angle finder on the ground, under the rear, zero it out, and then flip it over and stick it on the tq arm bracket. That was the only way it was ever checked, I tried changing it everywhere from 0, to -3, and never saw any improvement over running it at about -3/4 to -1 degree.
It worked for me.
Again, if your engine is way off from level with the car loaded and on the ground I would seriously look at fixing the ride height of the car, or fixing your driveline. The engine shouldn't be leaning backwards or forwards a ton. 99% of the time when I see something that's way off from level it's due to a set of motor mounts that are shot, a tranny mount that's shot, or someone put a spacer, or forgot to put the spacer on the trans mount, and it's kicking the trans and engine up or down.
Also, fwiw, I have set a few other cars the same way and they've all worked out pretty well too... this is not a single isolated case. I have found that cars without solid mounted control arms and tq arms seem to need a little more angle to be in the happy spot, around -2 depending on how new the bushings are, what they're made of, etc.
The one that I hate the most that I have found to mess with all of this is the crappy poly bushing that is in the front of most of the aftermarket tq arms. The things seem to give up pretty quickly, and then if someone uses grease to get the tq arm into the bushing during install it softens up the bushing something terrible and then it's total junk, cars with those junk bushings in them probably need -3 or -4 degrees since the rear's wrapping up on them alot.
The madman type of mount, that's solid with a sliding rod is really the only way to properly mount the front of the tq arm so that there's absolutely no deflection at all. 2nd best way would be the smaller metal plates, coming off the mount to a heim joint, this way there's no sliding rod in the tq arm, and I don't think it's quite as nice, but it will work and not have a ton of deflection. 3rd would be the spohn type that has the HARD plastic bushings in it, they're not poly, or if they are they're rock hard and don't move much if at all. After that, it's all down hill, and will need more pinion angle to prevent the axle from wrapping as the bushings deflect/give.
I have checked to see if the crank is level with the ground when I had my junk together and it was just about level, I went to the point of putting the rear springs on a big table top belt sander to "surface" them where they sat on the rear to get it level once I had the car close, fwiw. With the car fully loaded, driver in, full nitrous bottle, 1/4 tank of fuel as I usually ran it the pinion angle was checked in relativity to level ground. I would put the angle finder on the ground, under the rear, zero it out, and then flip it over and stick it on the tq arm bracket. That was the only way it was ever checked, I tried changing it everywhere from 0, to -3, and never saw any improvement over running it at about -3/4 to -1 degree.
It worked for me.
Again, if your engine is way off from level with the car loaded and on the ground I would seriously look at fixing the ride height of the car, or fixing your driveline. The engine shouldn't be leaning backwards or forwards a ton. 99% of the time when I see something that's way off from level it's due to a set of motor mounts that are shot, a tranny mount that's shot, or someone put a spacer, or forgot to put the spacer on the trans mount, and it's kicking the trans and engine up or down.
Also, fwiw, I have set a few other cars the same way and they've all worked out pretty well too... this is not a single isolated case. I have found that cars without solid mounted control arms and tq arms seem to need a little more angle to be in the happy spot, around -2 depending on how new the bushings are, what they're made of, etc.
The one that I hate the most that I have found to mess with all of this is the crappy poly bushing that is in the front of most of the aftermarket tq arms. The things seem to give up pretty quickly, and then if someone uses grease to get the tq arm into the bushing during install it softens up the bushing something terrible and then it's total junk, cars with those junk bushings in them probably need -3 or -4 degrees since the rear's wrapping up on them alot.
The madman type of mount, that's solid with a sliding rod is really the only way to properly mount the front of the tq arm so that there's absolutely no deflection at all. 2nd best way would be the smaller metal plates, coming off the mount to a heim joint, this way there's no sliding rod in the tq arm, and I don't think it's quite as nice, but it will work and not have a ton of deflection. 3rd would be the spohn type that has the HARD plastic bushings in it, they're not poly, or if they are they're rock hard and don't move much if at all. After that, it's all down hill, and will need more pinion angle to prevent the axle from wrapping as the bushings deflect/give.
