Pinion Angle

Foose04 · 10-23-2011, 04:54 PM

Hey guys, was wondering about pinion angle and how it affects things. I was also wondering a good place to get this checked and adjusted.

Thanks -Rob

LXtasy · 10-23-2011, 05:35 PM

you can check it with an angle finder yourself. You can buy shims to put under your rearend, transmission etc to get the angle you want. What are you trying to shoot for?

gearmesh, inc. · 10-23-2011, 05:37 PM

When under power, you want the centerline of your pinion gear to be parallel with your output shaft of your transmission. That way, both front and rear u-joints swing in equal but opposite arcs, thereby cancelling out any vibrations. They don't have to be in line with each other, but just simply parallel. If you are making vibrations, that is energy that gets used up which doesn't get to the tires.

The variable is how much your particular suspension bushings or your leaf springs flex under power. The trick is to have an idea of how much pinion angle offset to dial in so that when your suspension flexes under power, your pinion angle is right on.

For the street/strip guys and gals, it would be recommended to have your pinion angle a little closer to ideal while cruising, and give up a little perfection while under power which would mean your pinion would be a little high while you are pouring the coals to it. Or, you could compromise and set your pinion to be a tad low while cruising, but under power it would be just a little high.

An easy way to get an angle measurement of your transmission output shaft is to put your angle finder on your valve cover. On most every engine, the top of the valve cover is parallel to the crankshaft, which is also parallel to your transmission rotating assembly centerline.

For you Fox body fans out there still using stock control arms and bushings out back, make sure you keep the pinion snubber bumper in place. You also need to keep that upper bracket part of that pinion damper weight in place. It's OK to ditch the weight, but you will need shorter fasteners to hold the upper bracket in place. The topside of this bracket is what bumps into the pinioin bumper when under power. It adds about 1/2 to 3/4 inch to the top of the rearend housing so that pinion angle doesn't rise up too much before making contact with the snubber. This will go a long way into getting your stock control arm bushings to last as long as they can. Once you go polyurethane or solid arms, you can then get rid of the pinion snubber.

For the leaf spring truck guys like Foose, those longer lowering shackles out back can be your friend. When you install these without changing your front spring eye location, your pinion angle will nose down just a little bit. That helps when you add power because you know your leafs will flex more than they did with stock power. Keep in mind, if you add caltracs, or traction bars, they will cut way down on spring windup, and you won't have to calculate for near as much pinion angle change when under power.

Chillerman · 10-24-2011, 08:25 PM

Do what Gerald says. If you want to see what proper pinion angle does at the track, then look at the video of my car in the race against Bad Bob when I almost went to the rear bumper. Diablo took the video so it will be up when he's able to post them. This race was Sunday night 10/23 @ Dorchester.

399stroker · 10-25-2011, 08:04 AM

Is there a ballpark upper control arm length that gets you close or does the length not necessarily matter as you just adjust it till the pinion angle is correct.

What about spherical bushings for the uppers? With the uppers being able to pivot around on the ball, does that have any effect on pinion angle while under load?

WTFWSAT · 10-25-2011, 09:04 AM

It depends on your ride height so theres not really a certain length. Just try to adjust them evenly. Ill have a set up adjustable uppers and spherical bushings for sale with in the next month if you need them.

k5hart · 10-25-2011, 09:55 AM

Is there anyone local that sells angle shims for a leaf spring set up?

BigdaddyDupree · 10-25-2011, 10:02 AM

Parks. We gots it

gearmesh, inc. · 10-25-2011, 10:09 AM

Quote:

Originally Posted by 399stroker

Is there a ballpark upper control arm length that gets you close or does the length not necessarily matter as you just adjust it till the pinion angle is correct.

What about spherical bushings for the uppers? With the uppers being able to pivot around on the ball, does that have any effect on pinion angle while under load?

When you go solid bushings, you have pretty much eliminated flex. You will have just a little body flex, depending on your power level. Like WTFWSAT said, changing your ride height can change your angle, too, since upper arms are shorter than lower arms.

While adjusting your upper arms, keep in mind that the upper arm lengths dictate the left to right positioning of your rearend housing, so take measurements from your tires to your wheel well lips to make sure you are centered.

399stroker · 10-25-2011, 10:09 AM

Quote:

Originally Posted by WTFWSAT

It depends on your ride height so theres not really a certain length. Just try to adjust them evenly. Ill have a set up adjustable uppers and spherical bushings for sale with in the next month if you need them.

I currently have some, got both the spherical bushings and double adjustable uppers, just seems weird to me that the uppers can move around all over the place as both ends are pivoting on the spherical balls.

Been thinking about getting rid of my current upper setup and going with this.

http://www.baselinesuspensions.com/kits/prolaunch1.htm

399stroker · 10-25-2011, 10:18 AM

Quote:

Originally Posted by gearmesh, inc.

When you go solid bushings, you have pretty much eliminated flex. You will have just a little body flex, depending on your power level. Like WTFWSAT said, changing your ride height can change your angle, too, since upper arms are shorter than lower arms.

While adjusting your upper arms, keep in mind that the upper arm lengths dictate the left to right positioning of your rearend housing, so take measurements from your tires to your wheel well lips to make sure you are centered.

Maybe I am just looking at this all wrong... I dunno, but it seems like with the spherical upper bushings that the angle of the pinion changes as it rotates around. I know for sure that the length is not changing as the jam nuts on the uca's are locked down but I can twist both of my uppers all around laterally as they just move on the spherical balls on both ends.

I just changed over from weight jackers to team z for the lowers, and it had a drastic effect on my pinion angle. I havnt screwed around with it yet though to try and get it back. I never realized it but my weight jackers were adjusted to just over 18 inches. I installed the team z's at 17.5, which from what I understand is where they should be to start, and then adjust it from there as you stated with wheel well measurements etc to make sure it is centered on the chassis correct? Then adjust the uppers to correct the pinion angle correct? Or do I have that backwards?

gearmesh, inc. · 10-25-2011, 11:53 AM

Quote:

Originally Posted by 399stroker

Maybe I am just looking at this all wrong... I dunno, but it seems like with the spherical upper bushings that the angle of the pinion changes as it rotates around. I know for sure that the length is not changing as the jam nuts on the uca's are locked down but I can twist both of my uppers all around laterally as they just move on the spherical balls on both ends.

I just changed over from weight jackers to team z for the lowers, and it had a drastic effect on my pinion angle. I havnt screwed around with it yet though to try and get it back. I never realized it but my weight jackers were adjusted to just over 18 inches. I installed the team z's at 17.5, which from what I understand is where they should be to start, and then adjust it from there as you stated with wheel well measurements etc to make sure it is centered on the chassis correct? Then adjust the uppers to correct the pinion angle correct? Or do I have that backwards?

If both your uppers and lowers are adjustable, you can even manage to move your whole rearend forwards and backwards in your wheel wells if needed. Just be careful that you don't move your rearend back too far or you will not have many threads left for reliable engagement in your uppers.

As far as adjusting your uppers to obtain a centered rearend, if your body is straight, your upper adjustments should be no more than one turn different from each other. You can adjust either your uppers or your lowers to obtain the pinion angle you want. Keep in mind that if your lowers are adjusted to different lengths from each other, your rear will move a little from side to side, too, but not as dramatically as the same amount of turns on your uppers.

For your lowers, I would strive to keep them the same length/number of turns out from full closed. That way, as long as you keep the turns equal from one side to the other, you know they will be the same length. Then just use your uppers to center the rearend to start with. Once the rear is centered, then any further pinion angle adjustments will be an equal amount of turns from side to side for the upper pair and the lower pair.

399stroker · 10-25-2011, 12:42 PM

Good to go, Im gonna mess around with it today when I get off work.

10-23-2011, 04:54 PM	#1
Foose04 Senior Member Join Date: Feb 2010 Posts: 965	Pinion Angle Hey guys, was wondering about pinion angle and how it affects things. I was also wondering a good place to get this checked and adjusted. Thanks -Rob __________________ 12 GMC Denali HD: 4x4, 12" Bullet Proof, 24x12 American Forces, 40x15.50 Toyo M/T's, h&s mini max, deleted, 5" axle dump, S&B intake,tractions bars, air bags. 04 GMC 1500RST: TMS Iron 347/S480/4l80E - 9.63@143.22 05 GMC 2500HD: LLY@372HP/669TQ, 4x4, 8" FabTech, 4.56 gears & 37" Toyo M/T's Last edited by Foose04; 10-23-2011 at 05:13 PM.

10-23-2011, 05:35 PM	#2
LXtasy Senior Member Join Date: Dec 2006 Location: Summerville, SC Posts: 9,564	you can check it with an angle finder yourself. You can buy shims to put under your rearend, transmission etc to get the angle you want. What are you trying to shoot for? __________________

10-23-2011, 05:37 PM	#3
gearmesh, inc. creepy azz cracka Join Date: Nov 2008 Location: Summerville Posts: 1,587	When under power, you want the centerline of your pinion gear to be parallel with your output shaft of your transmission. That way, both front and rear u-joints swing in equal but opposite arcs, thereby cancelling out any vibrations. They don't have to be in line with each other, but just simply parallel. If you are making vibrations, that is energy that gets used up which doesn't get to the tires. The variable is how much your particular suspension bushings or your leaf springs flex under power. The trick is to have an idea of how much pinion angle offset to dial in so that when your suspension flexes under power, your pinion angle is right on. For the street/strip guys and gals, it would be recommended to have your pinion angle a little closer to ideal while cruising, and give up a little perfection while under power which would mean your pinion would be a little high while you are pouring the coals to it. Or, you could compromise and set your pinion to be a tad low while cruising, but under power it would be just a little high. An easy way to get an angle measurement of your transmission output shaft is to put your angle finder on your valve cover. On most every engine, the top of the valve cover is parallel to the crankshaft, which is also parallel to your transmission rotating assembly centerline. For you Fox body fans out there still using stock control arms and bushings out back, make sure you keep the pinion snubber bumper in place. You also need to keep that upper bracket part of that pinion damper weight in place. It's OK to ditch the weight, but you will need shorter fasteners to hold the upper bracket in place. The topside of this bracket is what bumps into the pinioin bumper when under power. It adds about 1/2 to 3/4 inch to the top of the rearend housing so that pinion angle doesn't rise up too much before making contact with the snubber. This will go a long way into getting your stock control arm bushings to last as long as they can. Once you go polyurethane or solid arms, you can then get rid of the pinion snubber. For the leaf spring truck guys like Foose, those longer lowering shackles out back can be your friend. When you install these without changing your front spring eye location, your pinion angle will nose down just a little bit. That helps when you add power because you know your leafs will flex more than they did with stock power. Keep in mind, if you add caltracs, or traction bars, they will cut way down on spring windup, and you won't have to calculate for near as much pinion angle change when under power. __________________ "I came into this world kicking, screaming,and covered in someone else's blood, I have no problem leaving the same way!" ÔÇ£If you carry a gun, people will call you paranoid. ThatÔÇÖs ridiculous. If I have a gun, what in the hell do I have to be paranoid about?ÔÇØ -Clint Smith, Thunder Ranch.

10-24-2011, 08:25 PM	#4
Chillerman Senior Member Join Date: Nov 2007 Location: Goose Creek Posts: 1,232	Do what Gerald says. If you want to see what proper pinion angle does at the track, then look at the video of my car in the race against Bad Bob when I almost went to the rear bumper. Diablo took the video so it will be up when he's able to post them. This race was Sunday night 10/23 @ Dorchester. __________________ 88 Mustang LX mild 302, no laughing gas, and the rest is secret. Best 1/8th 7.843 @ 87.98, best 1/4 12.427 @ 111.20, best 60 1.601 89 Mustang LX wheels up @ Pinks All Out

10-25-2011, 08:04 AM	#5
399stroker Member Join Date: Oct 2011 Location: Knightsville Posts: 43	Is there a ballpark upper control arm length that gets you close or does the length not necessarily matter as you just adjust it till the pinion angle is correct. What about spherical bushings for the uppers? With the uppers being able to pivot around on the ball, does that have any effect on pinion angle while under load? __________________ "Happiness is being stroked and blown at the same time"

10-25-2011, 09:04 AM	#6
WTFWSAT Senior Member Join Date: Nov 2007 Location: Summerville Posts: 861	It depends on your ride height so theres not really a certain length. Just try to adjust them evenly. Ill have a set up adjustable uppers and spherical bushings for sale with in the next month if you need them. __________________ Fastest stock computer 5.0 on the planet! Looking for cheeep msd 6al! PM me! 88 Coupe (turtle) 03 Cobra (tortoise)

10-25-2011, 09:55 AM	#7
k5hart Senior Member Join Date: Mar 2011 Location: James Island Posts: 277	Is there anyone local that sells angle shims for a leaf spring set up?

10-25-2011, 10:02 AM	#8
BigdaddyDupree Senior Member Join Date: Jul 2008 Location: MACEDONIA Posts: 4,967	Parks. We gots it __________________ . What you wanna do?

10-25-2011, 12:42 PM	#13
399stroker Member Join Date: Oct 2011 Location: Knightsville Posts: 43	Good to go, Im gonna mess around with it today when I get off work. __________________ "Happiness is being stroked and blown at the same time"