Adjusting front pinion angle

Mazepam

Mazepam

TJ Enthusiast
Joined
Aug 31, 2020
Messages
189
Location
New Jersey
Hi all just wanted to run this by the board to see if this is a good idea.
what I was thinking of doing was putting a jack under the pinion then removing both lowers or uppers, and then lowering or raising the pinion output. Would this rotate the axle sufficiently?

Other option is to just slowly inch the 4 of them forward one at a time with a racket strap.
 
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I know i went on a tangent my question is, is the method I said in the post a good way to adjust it at home? By removing both uppers or lowers and using a jack to raise and lower the output?

I just edited my post cause a lot of it was just Rambling
 
No do not remove both uppers or lowers. Raising your pinion to match the driveline angle will reduce your caster. Ideally you want to run as much caster as the pinion will allow. So if you have no vibes I wouldn’t mess with it. Reducing caster will not help any wandering you may experience.
what control arms do you have?
Tire size? Tire pressure? Is your steering feel tight or loose with excessive play?
 
Tire size is 33 inches and they have less than 500 miles on them
. Psi is 26 in each. I have the rough country adjustable lower and upper front control arms and the bushings in the uppers on the axel are new.

Steering is perfect except when I'm going straight on the highway above maybe 60 mph. Then it seems like it wanders in almost a dead zone. And when I try to correct it, it's really sensitive I have to be super easy on the wheel to stay straight. Also my tires really give the camber of the road.

When I'm stopped though if I turn the wheel even a little bit the tires will move so I know there's not really a dead zone in the system just feels like it on the highway.
 
Ok will do tomorrow morning. Everything Is brand new. I had death wobble after my 2.5 inch lift so everything is replaced. It drives great besides the sketchyness over 60 mph.

Just put a zj linkage up front last weekend. All 4 ball joints are new, track bar is new and adjusted, all bushings are new on the control arms. The track bar that came with the kit has a drop bracket but it's really not a drop bracket it's a about 1/4 of an inch lower so the angle of it in relation to the pitman arm is the same I do not have any bump steer whatsoever. I'll send a pick though.

I have a feeling it's the control arms I'm thinking this weekend of just putting the stock ones back on and see how it feels I only put on the new adjustable ones because I thought my caster could contribute to my death wobble it was at 5.5 degrees at that point from a shops machine measurement. I'm not sure rhat was the case I think it was the track bar honestly.
 
Here are some pics I snapped d quickly this morning not sure if they are good enough for this. Rainy day in NJ..

Yeah its just like driving a boat on the highway, till move left and right ONLY when I'm going straight and then when i try to correct its very sensitive with the wheel. I think this just started after i put the new control arms on, im not really sure though as ive done a lot of work on the front end to fix the death wobble.

I'm going to do an experiment this weekend and put all the stock control arms back on and see how that feels. I know i only have a 2.5 inch lift i don't really need adjustables.

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taking mine to a shop to figure all this out. I tried messing with it after my new lift but will just let someone else do it.

currie lays out specific numbers that i am not able to hit.
 
Yeah i was thinking of just having a shop check all the angles and makes sure there in line. I still might do that i stopped by a place and they told me to come back on Saturday or Sunday when there best guys are there.
 
sierradmax said:
Caster is more important that pinion angle on a front axle.
Click to expand...
That’s not accurate. You want as much caster as you can get away with before the pinion and driveshaft angles lead to vibrations.

2 helpful threads about adjustable control arms and front pinion angle:

https://wranglertjforum.com/threads/adjustable-control-arm-lengths-for-a-2-5-ome-lift.9705/
https://wranglertjforum.com/threads/adjusting-front-axle-pinion-angle.3718/
Up front, the pinion angle should be the same or slightly greater than the angle of the driveshaft.
 
yeah so mine is lower that's why I'm going to reduce my caster, my pinion measured at the front of the diff is 8 and the driveshaft is 10 or so.

Its going to be a job though getting these back to stock length haha, i guess i cant just remove both uppers or lowers at once and then rotate the axel with a jack, so i guess ill just use a racket strap or a come along then and go little by little on each until I'm set.

On the rear I'm fine because its the opposite.

So I'm just going to put the stock lengths back and see what happens. I only changed the lenghts because i feared it was causing my DW which im 99% sure it wasn't.
 
Mazepam said:
yeah so mine is lower that's why I'm going to reduce my caster, my pinion measured at the front of the diff is 8 and the driveshaft is 10 or so.

Its going to be a job though getting these back to stock length haha, i guess i cant just remove both uppers or lowers at once and then rotate the axel with a jack, so i guess ill just use a racket strap or a come along then and go little by little on each until I'm set.
Click to expand...
If you remove front control arms, the pinion will rotate up. You can control this by placing a jack under the driver side spring perch.

Read the thread about adjustable control arms a few times. You want to make your adjustments with the passenger side upper removed. When everything is set, only then would you install that control arm.
 
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I know this doesn't help you at this point, but the front axle is where double adjustable upper control arms 100% pay for themselves.

If you're measuring 10° pinion angle then you have about 2° of caster which I'm going to break from the pack and say definitely could be contributing to a lack of return-to-center perceived at the steering wheel. You should be able to get 3 ish more degrees of caster without inducing driveline vibrations.
 
freedom_in_4low said:
I know this doesn't help you at this point, but the front axle is where double adjustable upper control arms 100% pay for themselves.

If you're measuring 10° pinion angle then you have about 2° of caster which I'm going to break from the pack and say definitely could be contributing to a lack of return-to-center perceived at the steering wheel. You should be able to get 3 ish more degrees of caster without inducing driveline vibrations.
Click to expand...

so i know I have AT LEAST 8 degrees of caster i know this because i had 9.2 degrees measured by a shop and i put on the uppers about 1/8th of an inch longer so it still super high.

I know about the double adjustable ones i should have just saved up and go them in the first place, just double adjustable uppers haha
 
AjRagno said:
If you remove front control arms, the pinion will rotate up. You can control this by placing a jack under the driver side spring perch.

Read the thread about adjustable control arms a few times. You want to make your adjustments with the passenger side upper removed. When everything is set, only then would you install that control arm.
Click to expand...

Ok so your saying i do this by removing just 1 at a time, or can i remove more than 1 at a time and do this? Sorry this is what i was trying to get at with this post in the first place how to do this adjustment without struggling too much.

When i first adjusted them i had to get a come along and use my dads truck to basically move the hole axel forward 1 and a time. I guess if all else fails i can just do the same.
 
Mazepam said:
so i know I have AT LEAST 8 degrees of caster i know this because i had 9.2 degrees measured by a shop and i put on the uppers about 1/8th of an inch longer so it still super high.
Click to expand...

Mazepam said:
yeah so mine is lower that's why I'm going to reduce my caster, my pinion measured at the front of the diff is 8 and the driveshaft is 10 or so.
Click to expand...

you can't have 8 degrees of caster and 8 degrees of pinion unless you have an axle swap or somebody cut your inner c's off, rotated them on the tube, and welded them back on. They're 12 degrees apart, so if you have 8 of pinion, you have 4 of caster, and if you have 4 degree pinion, you have 8 caster.
 
freedom_in_4low said:
you can't have 8 degrees of caster and 8 degrees of pinion unless you have an axle swap or somebody cut your inner c's off, rotated them on the tube, and welded them back on. They're 12 degrees apart, so if you have 8 of pinion, you have 4 of caster, and if you have 4 degree pinion, you have 8 caster.
Click to expand...

ok then im measuring it wrong i know for sure i have a lot of caster i had over 9 degrees before i adjusted the uppers, and they only moved a tiny amount.

If i know one thing i know i have a ton of caster my return to center is great, to the point where i feel like i have oversteer on the highway which is causing my floating issues, its very very sensitive when i try to correct the wandering.

WE will see what happens when i put everything back to stock length that will give me around 5.5-6 degrees which is what it was before i added the arms.

That such be sufficient with 33's.


Here is my printout, since then the only thing i did was add adjustable upper arms and they are longer by maybe 1/8th of an inch only a few turns of the arms.

Alignemnt Specs.jpg
 
Ged a block of wood to put on your floor jack and support the front of the driver side spring perch here,
100_0872.JPG

Remove the driver side upper arm at the axle, then jack the floor jack enough to relieve the preload from the passenger upper until you can unbolt it from the axle side by hand. Once both uppers are removed you can use the floor jack to set your pinion angle. Once you have it where you want it, adjust the length on you arms so they bolt in easily.

You need an angle finder so you can dial this all in.
 
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