Daily Driver, Go Where I Want To Build

[jjvw]

All of that is to say that I cycled the axle!

Somehow through skill or luck, everything cleared despite guessing while I raised the pinion to zero. Trust me that there is about 1/32" between the tie rod and track bar!

The next step is to add caster and see what happens above 75mph. At this point, I know I can shorten the upper arm to do this.

 

[jjvw]

After rolling the axle, the front bump stops are now a bit short. To get as close as I did, I removed the bottom half of the upper shock bushing. Everything shown here is the fully compressed shock without that bushing.

Driver's at bump. Both sides.

Passenger's at bump. Both sides.

Savvy truss near the oil pan. Barring the body, I could actually go up another 1/4". This is good to know.

Hard to get a shot, but the frame side track bar easily clears the diff and truss.

The tires clear and spin lock to lock in the position. That is the factory jounce bumper stuck under the flare.

 

[tworley]

Front drive shaft update!

After reading a bunch, I have decided to start from scratch and forget what I think I know.

The front pinion was low. I'm embarrassed to say how much. I brought it up the 0°, straight in line with the pinion. Toe in is right about 1/8". 77mph seems about as smooth as no front drive shaft. Steering feels a bit floaty, but this may be muscle memory. More time is needed.
View attachment 95551

Next I want to pull the springs, move the axle around to double check the steering and track bar and fine tune.

Those who know better, is there caster left to add without trouble? Or is this as good as it gets?

Maybe it's early (still sipping coffee) but isn't the low pinion giving you the most caster?

 

[jjvw]

Full flex is a different story as shown earlier.

Bump stops do not touch.

The tires are hitting the body.

Again, this is setup to mimic 6" up, 6" down. As it sits, mine has about 6" up, 4.5" of down, so things aren't really mashing together as hard as these pics appear.

The rubbing in this position is all at slow speed, so I am not concerned about it.

 

[jjvw]

Maybe it's early (still sipping coffee) but isn't the low pinion giving you the most caster?

It would. I brought it to zero knowing that should be the happiest the driveshaft could ever be. Now I can add caster until it isn't happy. It might only be a degree or two. I do know that 3° gets buzzy in the rear view on the highway. Right now at 0°, it doesn't. Or at least, the lightly fuzzy image seems to follow the road noise more than anything.

I am going to head up to Fort Collins today, so I'll have some highway time to study and maybe make an adjustment. Adding caster will also help the bump stops get closer again.

 

[tworley]

It would. I brought it to zero knowing that should be the happiest the driveshaft could ever be. Now I can add caster until it isn't happy. It might only be a degree or two. I do know that 3° gets buzzy in the rear view on the highway. Right now at 0°, it doesn't. Or at least, the lightly fuzzy image seems to follow the road noise more than anything.

I am going to head up to Fort Collins today, so I'll have some highway time to study and maybe make an adjustment.

I gotcha. You gave it the most amount of caster possible but at the same time your ujoints aren't exactly in best possible position now. Fine tuning indeed

 

[jjvw]

I gotcha. You gave it the most amount of caster possible but at the same time your ujoints aren't exactly in best possible position now. Fine tuning indeed

That's what I did several years ago. Bad idea. I also wonder if I bent the centering pin at some point along the way. All of it adds up to this new driveshaft that I want to keep for a long time.

 

[mrblaine]

Full flex is a different story as shown earlier.
View attachment 95607

Bump stops do not touch.
View attachment 95608

The tires are hitting the body.
View attachment 95613

View attachment 95611

View attachment 95612

Again, this is setup to mimic 6", 6" down. As it sits, mine has about 6" up, 4.5" of down, so things aren't really mashing together as hard as these pics appear.

View attachment 95609

View attachment 95610

View attachment 95606

The rubbing in this position is all at slow speed, so I am not concerned about it.

The proximity of the truss to the oil pan is the same we ran into putting the coil overs on the last one with the stock Dana 44's. 1/4" away was our hard bump and also why we had to install the high lines. Also set up with 6/6 on 35's. The amount of cycling to make sure all that works is ridiculous.

 

[tworley]

That's what I did several years ago. Bad idea. I also wonder if I bent the centering pin at some point along the way. All of it adds up to this new driveshaft that I want to keep for a long time.

I'm going to stop telling people to set their pinion based on droop then.

 

[jjvw]

The proximity of the truss to the oil pan is the same we ran into putting the coil overs on the last one with the stock Dana 44's. 1/4" away was our hard bump and also why we had to install the high lines. Also set up with 6/6 on 35's. The amount of cycling to make sure all that works is ridiculous.

I need to come to terms with my tire, travel and fenders.

I think I also want to switch to Currie bumps. I think the domed shape might be useful when I go to set this all up again.

Here is where a 19.6" compressed 12" Fox can live if I go that long.

 

[mrblaine]

I'm going to stop telling people to set their pinion based on droop then.

I've never heard of that. How does that work? We set at ride height for best caster and vibe angle. Check at droop for collapsing too far and go from there. How does droop affect pinion angle and why would you alter the angle due to any droop?

 

[jjvw]

I've never heard of that. How does that work? We set at ride height for best caster and vibe angle. Check at droop for collapsing too far and go from there. How does droop affect pinion angle and why would you alter the angle due to any droop?

It doesn't work very well. It's something that came up on Jeep Forum a long while back. The result is a low pinion.

 

[mrblaine]

I need to come to terms with my tire, travel and fenders.

I think I also want to switch to Currie bumps. I think the domed shape might be useful when I go to set this all up again.

Here is where a 19.6" compressed 12" Fox can live if I go that long.
View attachment 95616

I think you may be overlooking a couple of things. When we do a Fox up front, we lower the axle mount so the top has room to get in there easier. I don't use 12's because I don't chase travel. I make sure that stuff doesn't tear up other stuff and then quit worrying about it. The problems chasing travel don't pencil out with all the complications that are created.

 

[jjvw]

I think you may be overlooking a couple of things. When we do a Fox up front, we lower the axle mount so the top has room to get in there easier. I don't use 12's because I don't chase travel. I make sure that stuff doesn't tear up other stuff and then quit worrying about it. The problems chasing travel don't pencil out with all the complications that are created.

I can see why 11s make more sense in this case.

 

[mrblaine]

It doesn't work very well. It's something that came up on Jeep Forum a long while back. The result is a low pinion.

I'm still confused. What methodology would one use to define pinion angle at full droop and why? I'm trying to get my head around any pertinent detail that one would use to define it and I'm just lost. The only thing you want to know is if the driveshaft has enough slip spline to allow the axle to droop all the way without bottoming out. Maybe you want to know if the shaft hits a skid if you have one, but that's it. How is this even a thing and who do I throw rocks at to get them to stop repeating it?

 

[jjvw]

Hang the axle from the shocks. Add a bunch of caster. Make sure the shaft clears and spins freely. That would be the extreme end of it.

The concept is to maximize caster at the possible expense of rebuilding the drive shaft more frequently. I don't recall where it came from. It's backwards thinking and ignores a lot like the ideal operating angles.

You'll find me suggesting it some time ago, so I'll take a few of those rocks.

 

[mrblaine]

Hang the axle from the shocks. Add a bunch of caster. Make sure the shaft clears and spins freely. That would be the extreme end of it.

The concept is to maximize caster at the possible expense of rebuilding the drive shaft more frequently. I don't recall where it came from. It's backwards thinking and ignores a lot like the ideal operating angles.

You'll find me suggesting it some time ago, so I'll take a few of those rocks.

Where is the relevance to how the vehicle operates 99.9% of the time which is a very narrow zone right around ride height?

Operating angle has about zero to do with it since the caster angle will prevent too much lowered pinion angle so the angle at ride height will never be bad enough to damage anything. The only time the axle sees full droop is if it gets jumped, big whoops, or you hang the belly skid when you fall off the line. The only concern in all of those is that the driveshaft can collapse fully without causing a problem. Caster is set at ride height, no other height matters.

Put another way, you can't dial in enough caster to cause excessive wear at the DC joint and still drive it. Even if you tried to get 10-15 degrees of positive caster, the length of the shaft away from the t-case means that extra bit of operating angle is minimal and certainly much less exaggerated than the rear sees.

 

[jjvw]

Just to be clear to all following along, the front pinion right now is at 0° at ride height.

 

[bobthetj03]

Just to be clear to all following along, the front pinion right now is at 0° at ride height.

When you say 0*, is that in relation to the DS angle, meaning the ds and pinion are parallel?

 

[jjvw]

When you say 0*, is that in relation to the DS angle, meaning the ds and pinion are parallel?

Correct. In my pic earlier, the angle finder was first zeroed out on the front of the diff.