Caster and Pinion

[catbones2010]

Let's talk caster and pinion. I get that there isn't a magic number for caster or driveshaft angle. I'm just trying to understand where about i should start at.

Jerry would say go as high in caster until you get vibrations and back off.

Looking at the service manual, it's 7 caster with .65 difference allowance between passenger and driver.

So with a 2 inch lift and 33 inch tires I'm looking for 5 caster driver side and 5.65 passenger? Correct me if I'm wrong.

Is there a degree of the front DS and pinion i should be looking at or just work with caster until vibes are gone?

 

[catbones2010]

Here's my current reading at ride hight with tires off. Driver and passenger.

Guessing I should be near 5 not 7...8.

 

[JMT]

Let's talk caster and pinion. I get that there isn't a magic number for caster or driveshaft angle. I'm just trying to understand where about i should start at.

Jerry would say go as high in caster until you get vibrations and back off.

Looking at the service manual, it's 7 caster with .65 difference allowance between passenger and driver.

So with a 2 inch lift and 33 inch tires I'm looking for 5 caster driver side and 5.65 passenger? Correct me if I'm wrong.

Is there a degree of the front DS and pinion i should be looking at or just work with caster until vibes are gone?

You get as much caster as you can without any binding at full droop.

The difference in driver and passenger side caster is what it is when the arms aren’t fighting one another.

 

[jjvw]

Let's talk caster and pinion. I get that there isn't a magic number for caster or driveshaft angle. I'm just trying to understand where about i should start at.

Jerry would say go as high in caster until you get vibrations and back off.

Looking at the service manual, it's 7 caster with .65 difference allowance between passenger and driver.

So with a 2 inch lift and 33 inch tires I'm looking for 5 caster driver side and 5.65 passenger? Correct me if I'm wrong.

Is there a degree of the front DS and pinion i should be looking at or just work with caster until vibes are gone?

You start with something and if doesn't work, you change it.

 

[catbones2010]

You get as much caster as you can without any binding at full droop.

The difference in driver and passenger side caster is what it is when the arms aren’t fighting one another.

I see. Not bidding what so ever at full droop and I ended up at 5.9 driver and 6.3 passenger.

However, I'm thinking i might redo that with removing both lowers and then just lifting the Pinion up until I get what I get your saying? So lift the pinion to about 6 at the ball joint then adjust the lower control arms to it. Mine top ones are adjustable to but are set same length as they are. My ony issue seems if I do it this way seems my driver will have more caster then passenger. From my understanding passenger should have more then driver. Correct?

 

[jjvw]

I see. Not bidding what so ever at full droop and I ended up at 5.9 driver and 6.3 passenger.

However, I'm thinking i might redo that with removing both lowers and then just lifting the Pinion up until I get what I get your saying? So lift the pinion to about 6 at the ball joint then adjust the lower control arms to it. Mine top ones are adjustable to but are set same length as they are. My ony issue seems if I do it this way seems my driver will have more caster then passenger. From my understanding passenger should have more then driver. Correct?

You are getting hung up on numbers when all you care about is what works. Also, the left and right sides will always be different caster numbers due to the factory compensation for the road crown.

 

[catbones2010]

You are getting hung up on numbers when all you care about is what works. Also, the left and right sides will always be different numbers due to the factory compensation for the road crown.

Right. But if I take both lower control arms out and I use a jack under the pinion to lift it up, passenger will have like 5.5 and driver will have 6.0. If there is compensation for the crown the passenger should be higher on passenger not lower then driver. With that, I've jacked up the driver until I got 5.5 and put in the bolt going easily in at that for the LCA and went to the passenger and jacked the front of the axle since it was at that time with 5.5 on driver at like 4.8 and jacked it up to 6. Which then brought the driver side equal to 5.9 / 6.

 

[jjvw]

Right. But if I take both lower control arms out and I use a jack under the pinion to lift it up, passenger will have like 5.5 and driver will have 6.0. If there is compensation for the crown the passenger should be higher on passenger not lower then driver. With that, I've jacked up the driver until I got 5.5 and put in the bolt going easily in at that for the LCA and went to the passenger and jacked the front of the axle since it was at that time with 5.5 on driver at like 4.8 and jacked it up to 6. Which then brought the driver side equal to 5.9 / 6.

If the vibes have been adjusted out and the control arm bolts can slide in easily, then you are done. Notice that I made no mention of caster numbers.

 

[mrblaine]

I see. Not bidding what so ever at full droop and I ended up at 5.9 driver and 6.3 passenger.

However, I'm thinking i might redo that with removing both lowers and then just lifting the Pinion up until I get what I get your saying? So lift the pinion to about 6 at the ball joint then adjust the lower control arms to it. Mine top ones are adjustable to but are set same length as they are. My ony issue seems if I do it this way seems my driver will have more caster then passenger. From my understanding passenger should have more then driver. Correct?

There appears to be a few assumptions based on the comments that the side to side caster angles may vary. They do not unless something is terribly broken. To change them from side to side without adjustable ball joints, you would have to twist the tubes in the center diff or twist the C on the tubes. Just work off of the driver's side and stop using to top of the upper ball joint. If you care to see and understand why, set your angle finder on there, get the angle and then ever so slightly rotate the angle finder. The angle will change and the only time it is accurate is when it is aligned with a perfect front to back line that is parallel to the centerline of the vehicle. You can't eyeball that very well so quit doing it. There is a machined flat spot just inboard of the lower ball joint on the bottom of the inner C. Use that.

 

[catbones2010]

There appears to be a few assumptions based on the comments that the side to side caster angles may vary. They do not unless something is terribly broken. To change them from side to side without adjustable ball joints, you would have to twist the tubes in the center diff or twist the C on the tubes. Just work off of the driver's side and stop using to top of the upper ball joint. If you care to see and understand why, set your angle finder on there, get the angle and then ever so slightly rotate the angle finder. The angle will change and the only time it is accurate is when it is aligned with a perfect front to back line that is parallel to the centerline of the vehicle. You can't eyeball that very well so quit doing it. There is a machined flat spot just inboard of the lower ball joint on the bottom of the inner C. Use that.

So putting a straight edge on that lower flat spot next to the lower ball joint and measuring from there would be the best place??

I'll check it there. And you agree that I should do driver side for 6 caster and lock that in with a control arm then go to passenger side and adjust that to 6 caster and lock it with control arm? Or should I take both lowers out and use a jack under the pinion / driveshaft to raise it until I hit 6 no matter on what side?

 

[mrblaine]

So putting a straight edge on that lower flat spot next to the lower ball joint and measuring from there would be the best place??

I'll check it there. And you agree that I should do driver side for 6 caster and lock that in with a control arm then go to passenger side and adjust that to 6 caster and lock it with control arm? Or should I take both lowers out and use a jack under the pinion / driveshaft to raise it until I hit 6 no matter on what side?

They are not separately adjustable.

 

[catbones2010]

They are not separately adjustable.

Ok... sorry if I sound bumb in this.

So my caster on driver and passenger should be equal. If it's 6 on driver, I should have 6 on passenger? With passenger possibly having slightly higher because of the factory crown set with the C? Correct?

 

[mrblaine]

Ok... sorry if I sound bumb in this.

So my caster on driver and passenger should be equal. If it's 6 on driver, I should have 6 on passenger? With passenger possibly having slightly higher because of the factory crown set with the C? Correct?

I've never seen them to be equal. There is a small amount of cross caster to compensate for road crown. Just work off of one side and quit futzin with it.

 

[jjvw]

Ok... sorry if I sound bumb in this.

So my caster on driver and passenger should be equal. If it's 6 on driver, I should have 6 on passenger? With passenger possibly having slightly higher because of the factory crown set with the C? Correct?

They cannot both be equal when they are different from the factory.

 

[catbones2010]

I've never seen them to be equal. There is a small amount of cross caster to compensate for road crown. Just work off of one side and quit futzin with it.

Got it.

How does pinion angle work up front? Should the angle measured on driveshaft tube be equal to the machined donuts by the pumpkin or should the donut angle be 1 degree lower then whatever the driveshaft angle is?

 

[mrblaine]

Got it.

How does pinion angle work up front? Should the angle measured on driveshaft tube be equal to the machined donuts by the pumpkin or should the donut angle be 1 degree lower then whatever the driveshaft angle is?

No idea, I've never measured the front pinion angle. If you get your caster set and you have pinion vibes then you are going to dial out caster until the vibes go away. If that becomes excessive to the point you lose good steering and return to center, then you have some decisions to make but none of them involve knowing the actual pinion angle in degrees.

 

[catbones2010]

No idea, I've never measured the front pinion angle. If you get your caster set and you have pinion vibes then you are going to dial out caster until the vibes go away. If that becomes excessive to the point you lose good steering and return to center, then you have some decisions to make but none of them involve knowing the actual pinion angle in degrees.

Got it. Will shoot for 6 with raising just the pinion driveshaft and letting caster be whatever for driver, will work with one side (passenger to get 6 of caster there before checking driver).

Any other way to measure the axle centering then taking out my springs and using bump stops?

 

[mrblaine]

Got it. Will shoot for 6 with raising just the pinion driveshaft and letting caster be whatever for driver, will work with one side (passenger to get 6 of caster there before checking driver).

Any other way to measure the axle centering then taking out my springs and using bump stops?

If you don't stop with checking the other side bullshit, I'll quit responding. The two sides have a small amount of crosscaster. The two sides are not independently adjustable from each other. Pick a side, work it, and forget the other side exists.

I don't remove anything to center the axle.

 

[catbones2010]

If you don't stop with checking the other side bullshit, I'll quit responding. The two sides have a small amount of crosscaster. The two sides are not independently adjustable from each other. Pick a side, work it, and forget the other side exists.

I don't remove anything to center the axle.

Ok

 

[catbones2010]

so what do you use to make sure your axle is centered in the wheel well? Hole on the frame vs something on axle? Just want to make sure that it's centered.

I guess I could measure 96.6 from rear axle center to front. Just thought I'd ask and see how you guys doing vs what I'm going to conclude to use.