Adjusting Pinion Angle

[EbyCreek]

Instructions for adding a FAD

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[Roky]

Instructions for adding a FAD

Thanks for chiming in, I was beginning to wonder if I actually read this or just something I thought I read..

 

[AVGeek99]

There was a couple guys on here that did it…. I think @EbyCreek was one of them, but not sure…… I’ve been on this board a long time, but I still suck at looking shit up, ….. I remember guys talking about using the Tazer to keep pcm happy…. Maybe make a thread, see if anyone chimes in….

LOL, I'm not very good at finding stuff either, that's why I asked . Sometimes it's easier to find stuff here by doing a Google search. If the search is Jeep related, 9 times out of 10, the first link or 2 or 5 are for JLWranglerforums.

Instructions for adding a FAD

Thank you for sending the info!

Right now I think I'm going to leave the FAD as my last resort. I like the idea and the benefits of a FAD; more flexibility with a higher lift, not the supposed fuel savings. And they've ended up being a lot more durable and reliable than a lot of people worried about when the JL first came out. But I want to try to avoid something electronic that the Jeep didn't already come with. I don't want to have to fight error codes.

Today I installed drop brackets and reduced caster to 2.5. It drives no different than it did previsously at 3.4; that is to say it drove and drives great! Very minimal wandering, no bump steer, dartiness, or any other ill side effects of a low caster setting. The Fox ATS is doing it's job.

This week I'm going take my front drivesfaft to a local driveline shop to have it balanced and inspected. I think long term (or maybe short, depending on what the driveline shop finds) I'll upgrade to Tom Woods 1350.

Next weekend I'll be installing 2.5" springs, which should drop it 1-1.25 inches. I will probably leave the caster at 2.5 just to keep the pinion pointed up as much as possible.

Thanks for all the help and guidance @Roky .

 

[Roky]

LOL, I'm not very good at finding stuff either, that's why I asked . Sometimes it's easier to find stuff here by doing a Google search. If the search is Jeep related, 9 times out of 10, the first link or 2 or 5 are for JLWranglerforums.



Thank you for sending the info!

Right now I think I'm going to leave the FAD as my last resort. I like the idea and the benefits of a FAD; more flexibility with a higher lift, not the supposed fuel savings. And they've ended up being a lot more durable and reliable than a lot of people worried about when the JL first came out. But I want to try to avoid something electronic that the Jeep didn't already come with. I don't want to have to fight error codes.

Today I installed drop brackets and reduced caster to 2.5. It drives no different than it did previsously at 3.4; that is to say it drove and drives great! Very minimal wandering, no bump steer, dartiness, or any other ill side effects of a low caster setting. The Fox ATS is doing it's job.

This week I'm going take my front drivesfaft to a local driveline shop to have it balanced and inspected. I think long term (or maybe short, depending on what the driveline shop finds) I'll upgrade to Tom Woods 1350.

Next weekend I'll be installing 2.5" springs, which should drop it 1-1.25 inches. I will probably leave the caster at 2.5 just to keep the pinion pointed up as much as possible.

Thanks for all the help and guidance @Roky .

Absolutely brother, no worries…. Sounds like a good plan, keep us in the loop on how you make out…..

 

[azjl#3]

I’m kinda glad A I is full of shit MOST TIMES, the day it gets everything perfect, that’s gonna render us old mechanics obsolete …...🫤

My AI fixed it for you

 

[AVGeek99]

The 2.5 springs arrived a few hours earlier than I expected. They arrived at about 2pm so I ended up getting them installed today.

The only things I have left to do are check the rear pinion and center the axles. I was expecting it to drop 1-1.25 inches, but it only dropped about .7 inches. Maybe because the 3.5" springs are 2.5 years old with about 43k miles on them, and the 2.5" springs are brand new?

Another weird thing. I'm annoyed by my garage floor as it's not completely flat. We moved to CO in Oct and I learned that the ground moves, expands and contracts a lot. To prevent cracking in garage floors, the floor is made of several ~10x8 slabs. If you dont' look too close it just looks like there are extra large expansion joints. But if you look closely they aren't connected, so they are free to move independently.

So my caster measurement varies depending on where my Jeep is parked in the garage. Of course it doesn't change when you move it, but depending on where you place the angle finder to zero it out it can be anywhere from 0 to 1 degree, maybe more.

When I was done yesterday, my caster, measureed on the flat part of the axle next to the diff, was 2.5 degrees. Before starting today I moved the Jeep to the middle of the garage. When I measured the caster there it came in a 4 degrees, WTF???

I didn't move it at all after starting work on it today. When I was done the caster measured 3 degrees. I didn't adjust the length of an CAs. I just left them as they were yesterday after installing the drop brackets. I was thinking I would have to shorten the LCAs, but the axle is positioned pretty well directly below the bump stop jounces. It looks like it is pushed forward just a little bit, but no more than an 1/8th inch.

I'll test drive it tomorrow and see what it's like.

 

[AVGeek99]

Everything drove good after test driving on Monday, but upon inspecting the front drive shaft I realized there weren't any balancing weights on the axel end of the DS. There was some scratch marks from where I hit it on a rock while in Moab (don't ask) a couple weeks ago, and near these marks it looked there was a spot that used to have some weights attached.

I brought the DS into Driveline Services of CO Springs. They inspected and balanced the DS and they said it was bent slightly so they straightened it.

Got it installed today and got a good test drive. At 75 it seems like there is very slight rumble, but barely noticeable and so faint it could just be road noise. I think I'm going to add a turn or two to lengthen the UCAs to point the pinion up just a bit more. Steering is still very tight and solid so I think I can get away with a little less caster. When I measured to day it was 3.4 degrees; stupid garage floor.

 

[AVGeek99]

Today I made my final adjustments and I think it's as good as I'm going to get it.

First, I figured out a good way to deal with my funky garage floor. I measured the slabs and they are 12'x10', with the long dimenstion running front to back, so I was able to park the jeep all on the same slab. I know it sounds dumb but when you when you're trying to get to a tollerance of a couple thenths of a degree, you need the entire vehicle on a flat plain.

Here's a prime example of how my garage floor is messing with my measurements. After yesterday I measured my caster and it was 3.4 degrees, unfortunately I didn't get a picture, but that measurement was taken from the middle of my garage. When I started today, I first checked my caster again, from the normal spot where I park; fricking 2.3 degrees!!!

This is when I measured the size of the slabs that make up my garage floor. Measured the caster from there. 3.7 degrees, and I was finally comfortable with that measurement becuase it was from all one slab. But of course, I forgot to get a picture. My goal was to get to 2.5-2.8 degrees caster to point the pinion up as much as possible. I ended up adding 3 full turns to both UCAs, which got me to 2.7degrees.

Then I took it out for a test drive hoping it wouldn't be too much different from yesterday. The steering was just a bit lighter, but it tracked straight without any eratic behavior when hitting bumps or uneven pavement; it was also pretty windy and it didn't have an impact even when coming from the side. So all in all I was happy with how it drove and decided to call it good.

Back at home, parked on the same slab again. I measured the pinion and the slope of the driveshaft. Pinion was 3.3 as expected. Driveshaft was 9.5 degrees. So with all the changes, drop brackets, 2.5" springs, caster adjustments, I got the pinion and DS to within 6.2 degrees of one another; I was trying to get as close to 6 degrees as possible. I know 6.2 degrees isn't great, but considering it was off by 8.9 degrees when I started I'd say it was worth it. At some point I'm guessing I'll need a new front driveshaft, time will tell. Or maybe when the time comes I'll get an ultimate 44 and put the 3.5 springs back on.

Front Pinion:

Front DS Slope:

 

[embedded rock]

Enjoyed reading this thread. Thanks for typing in all the details AND being clear about what was happening.

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