How to Adjust Caster

[AVGeek99]

TL/DR... skip down to my questions on adjusting castor.

I've been getting a lot of shimmy in the steering wheel when hitting small to medium cracks or extended sections of unevenness in the road. In certain condtions it will go to full on death wobble and I have to slow considerably to get it to stop.

I had a MC 3.5" GC lift installed at 40k miles, currently at 43k. Prior to the lift the steering and suspension were as solid as the day I drove it off the lot. The shimmy started immediately after the lift so I believe it has to be related to suspension geometry. The Jeep does wander some and can get a little flighty or darty since the lift was installed, prior to that it tracked perfectly straight and would not wander.

A couple days ago I got an angle finder to check my caster. The axle appears to be leaning forward 2.5-3 degrees, which I believe puts the caster at 3-3.5. Is this correct? I would like to get the caster to 6 degrees as it should help with the wandering and also possibly the shimmy and death wobble.

I have questions on how to go about correcting the castor.

1. I know to correct my castor I can shorten the UCAs or lengthen the LCAs. Which is easier/better to do from my garage floor?
2. Is it best to do this with the Jeep on jack stands with the wheels off, or while on the ground? I was initially assuming on jack stands, but yesterday I saw a video of someone doing it all while the Jeep was on the ground.
3. After adjusting the length of the control arms I expect it will take some work to get the holes to line up. Is there a trick to make this easier, again, from my garage floor?
4. Any other tips/tricks?

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[Willys41]

Your shimmy is probably from a loos component in the steering and or your steering stabilizer
If you are running large tires a upgraded steering stabilizer is a must
Recheck to make sure every thing is tight. Mostly the track bar
Have someone turn the wheel back and forth and look for any loos component
Increasing you caster will help with the wondering put the biggest improvement you can do is add the updated Synergy Sector shaft brace with the though bolt on the bearing housing
There older Sector shaft brace along with steer smarts the two bolt version the bolts always came loos
This eliminates the steering box flexing on the frame and makes a huge difference
Here is a link explaining the flexing

 

[Jtphoto]

To be honest I prefer using MC geometry correction brackets to correct the suspension geometry and bring back the caster.

 

[AVGeek99]

Your shimmy is probably from a loos component in the steering and or your steering stabilizer
If you are running large tires a upgraded steering stabilizer is a must
Recheck to make sure every thing is tight. Mostly the track bar
Have someone turn the wheel back and forth and look for any loos component
Increasing you caster will help with the wondering put the biggest improvement you can do is add the updated Synergy Sector shaft brace with the though bolt on the bearing housing
There older Sector shaft brace along with steer smarts the two bolt version the bolts always came loos
This eliminates the steering box flexing on the frame and makes a huge difference
Here is a link explaining the flexing

My next upgrade (4-6 weeks) will be new steering components (tie rod, drag link, and steering stabilizer). I'll be moving to 37s a short time later.

I've been running 35s since day 1 and never had any shimmy or DW. Then I got the lift first week of November and immediately after getting it back there was a shimmy, and I had a couple episodes of full on DW about a week later. Then it seemed to get somewhat better, but not completely, still a small amount of shimmy, but no more DW.

This past weekend I retorqued everthing in the front end: UCAs, LCAs, track bar, tie rod and drag link. The only thing that was remotely loose were the LCAs at the axle, but they weren't too much out of spec. Now it's actually worse than before the weekend. Shimmy is very obvious with most bumps and yesterday I had another bad DW episode; had to slow to about 20mph to get it under control.

I believe the issue is somewhere within the lift. I've only put 1k miles on since the lift. Before the lift it was perfectly fine, after it's been bad. I want to try to get the issue resolved prior to the new steering components, and the only thing that is obviously out of whack is the caster.

The one thing I haven't tried, which I've seen recommended is loosening all suspension component bolts and then retorquing. I think I will do this next, or the same time I correct the caster.

Thank you for the recommendation on the Synergy brace. I watched the video and it seems like their primary issue wasn't so much shimmy and DW, it was more just wandering. Mine is definitely wandering like they described theirs in the video, but that is also a clear symptom of not enough castor, which I have confirmed on mine. Once I get caster corrected I may look into that Synergy brace, but I know caster is a problem so I want to resolve it first.

 

[AVGeek99]

To be honest I prefer using MC geometry correction brackets to correct the suspension geometry and bring back the caster.

I ordered a few things from MC last night and was looking at the geometry correction brackets. I actually have the DB3 brackets, which do the same thing in the rear. I wasn't aware MC had such brackets for the front until I saw someone else mention them.

The geometry correction brackets hang 2.5 inches below the bottom of the frame, so technically they reduce ground clearance. But does this cause any real world clearance issues when off road, or are they close enough to the wheels that they really don't take many hits?

I may add these in the near future to improve ride, if they don't cause too many problems off road.

 

[Jtphoto]

I ordered a few things from MC last night and was looking at the geometry correction brackets. I actually have the DB3 brackets, which do the same thing in the rear. I wasn't aware MC had such brackets for the front until I saw someone else mention them.

The geometry correction brackets hang 2.5 inches below the bottom of the frame, so technically they reduce ground clearance. But does this cause any real world clearance issues when off road, or are they close enough to the wheels that they really don't take many hits?

I may add these in the near future to improve ride, if they don't cause too many problems off road.

I’ve never had any ground clearance issues with the brackets. I ran them on all my JKs as well as the JLs.

 

[AVGeek99]

I’ve never had any ground clearance issues with the brackets. I ran them on all my JKs as well as the JLs.

Since my caster is off, axle leaning forward, is it difficult to get the holes to align correctly when installing the control arms in the bracket? Any tricks to make this simpler?

Is it easier to install the brackets with the Jeep on the ground or on jack stands?

 

[Jtphoto]

Since my caster is off, axle leaning forward, is it difficult to get the holes to align correctly when installing the control arms in the bracket? Any tricks to make this simpler?

Is it easier to install the brackets with the Jeep on the ground or on jack stands?

I’ve installed brackets in a coffee shop parking lot. No stands, no jacks.
- Do one side at a time.
- Loosen all 8 control arm bolts but don’t remove
- Start at the driver side and remove the upper control arm as per the instructions they give you.
- Remove the frame side lower control arm bolt and let the end of the CA drop.
- Instal the bracket
- Instal upper control arm and use the top adjustment hole in the bracket to start.
- Instal lower control arm in bracket. The only trick is you may need a ratchet strap to turn the diff a bit to get the bolt in.
- Leave the bolts loose at this point and do the passenger side.
- Once the passenger side is done, which is now easy because driver side has been done, you can determine which adjustment hole in the brackets you should use (as per the guide in your instructions).
- Then just torque everything up and you are good to go.

 

[AVGeek99]

I’ve installed brackets in a coffee shop parking lot. No stands, no jacks.
- Do one side at a time.
- Loosen all 8 control arm bolts but don’t remove
- Start at the driver side and remove the upper control arm as per the instructions they give you.
- Remove the frame side lower control arm bolt and let the end of the CA drop.
- Instal the bracket
- Instal upper control arm and use the top adjustment hole in the bracket to start.
- Instal lower control arm in bracket. The only trick is you may need a ratchet strap to turn the diff a bit to get the bolt in.
- Leave the bolts loose at this point and do the passenger side.
- Once the passenger side is done, which is now easy because driver side has been done, you can determine which adjustment hole in the brackets you should use (as per the guide in your instructions).
- Then just torque everything up and you are good to go.

LOL about the coffee shop!! But thank you for the detailed response and info.

I will hopefully be getting my Jeep back tomorrow. Warranty repair for an oil leak 36hrs after getting it back from warranty repair for lifters, cam, and rocker arms.

A couple nights ago I ordered the jam nut wrenches from MC, but wont get them until next week. So probably not doing any caster adjustments until next weekend.

This weekend I may loosen everything, jump up and down on both front and rear bumpers, and then retorque everything to see if that has any sort of impact.

 

[Terpsmandan]

Since my caster is off, axle leaning forward, is it difficult to get the holes to align correctly when installing the control arms in the bracket? Any tricks to make this simpler?

Is it easier to install the brackets with the Jeep on the ground or on jack stands?

I installed a set of those in my driveway. Make sure you get a set of these

https://www.harborfreight.com/hand-tools/hammers-pry-bars/pry-bars/pry-bar-set-3-piece-68339.html

I needed them to get the bolts in the back that go into the frame to line up. Also a ratchet strap is necessary. I had to move the lower half of the axle back to get the LCA’s to line up with the brackets. I am on 37’s and the lower of the three bolt hole options to mount the uppers will get you 9.6-9.7 degrees of positive caster. That will lower your pinion angle too much and make it vibrate in 4hi at 60 mph. According to MC, each hole up reduces the caster by about 1 degree. I moved the uppers to the highest and still no DW and 4HI works now.

 

[LazyJL]

For installing control arms and track bars, a come-along is the ticket for single-handed work.
I have used one for more than two decades setting up my Jeep’s suspensions.
https://www.harborfreight.com/autom...pullers/4000-lb-cable-winch-puller-69855.html

 

[dayusmc]

On my last JT it drove fine, no wandering, no DW. I installed a level kit (1.5" Teraflex Spacers), it started to wander and got DW. I assume it was something I did wrong. I went round and round with it for teo weeks. Finally I decided I did everything correctly so I read hundreds of DW threads. I checked all the normal stuff, all was good. Then after reading about the plastic in the ball joints I decided to replace them -Yep, it was the ball joints.... Before I replaced them I checked them the normal ways and they seemed good, but they weren't...
Just food for thought.

 

[AVGeek99]

On my last JT it drove fine, no wandering, no DW. I installed a level kit (1.5" Teraflex Spacers), it started to wander and got DW. I assume it was something I did wrong. I went round and round with it for teo weeks. Finally I decided I did everything correctly so I read hundreds of DW threads. I checked all the normal stuff, all was good. Then after reading about the plastic in the ball joints I decided to replace them -Yep, it was the ball joints.... Before I replaced them I checked them the normal ways and they seemed good, but they weren't...
Just food for thought.

Yes, I have also checked my ball joints and they seem fine.

Got my Jeep back earlier this week and my Jam Nut wrenches from MC arrived as well. I also got MCs toe alignment bracket set.

Coffee is ready and I'm headed to the garage to get working. Hopefully all goes well.

 

[dayusmc]

Keep us posted on your progress....

 

[AVGeek99]

I corrected my castor yesteday. I got a digital angle finder to get a more accurate caster measurement. With the analog angle finder, the measurement wasn't consistent, it was somewhere between 3 and 3.5 degrees. I like that the digital angle finder lets you zero it out to account for any slant in the surface your're on.

Here's a before picture, a reading of 85.8 equates to a caster angle of 1.8 degrees, which is a decent amount worse than I originally thought. But it explains the dartiness and wandering.

Here's an after picture. This is right after I go the length of both LCAs adjusted. After I loosened all nuts on suspension parts and retorqued everything it settled in at 89.8, which would be a caster of 5.8, much closer to the stock 6 degree angle. To get the caster corrected I had to lengthen both LCAs by about 3/4 to 7/8 of an inch.

I also checked my toe allignment. Looking at each side from straight on, it looks like it is obviously toed out. But when I measured it with the MC allignment brackets it was actually toed in about 1/16 of an inch so I left that as is.

My Jeep now drives much better. Correcting the caster didn't do much for the shimmy or DW, but it completely got rid of the dartiness and wandering. It now tracks straight, which I'm very glad for. The shimmy and DW seemed worse yesterday than today. I put about 60 miles on it today and it does still shimmy some occasionally, but it almost seems like it has settled in, it's better than yesterday.

After watching some videos and those answering my questions about how to go about correcting the caster, here is what I did. All work was done from the floor of my garage with the wheels firmly on the ground. I started on the driver side.

1. I started by breaking the jam nuts loose. The crow's foot wrenches from MC came in handy, but I had to make a run to the store to get a 30" breaker bar. The 18" one I had just wouldn't make it budge
2. I disconnected the LCA at the axle. While it was disconnected I torqued MC lower shock bracket mount.
3. I lengthened and reconnected the LCA multiple times and rechecked the axle angle. I lengthened the LCA until the axle angle read about 89.5 degrees. I figured it would increase once I lenthened the passenger side.
4. Reconnecting the LCA after lengthening it turned out to be easier than I thought. All I did was put my floor jack on the frame rail. I did have to make a block with 2 pieces of 2x6 in order to get it high enough. But once I got it high enough the hole lined up perfectly.
5. Repeated above steps on the passenger side.
6. Once the passenger side was done I checked the axle angle and discovered I had gone too far, so I shortened LCAs by two full turns.
7. Once I had the caster corrected I loosened all the bolts on all four front CAs and the track bar. I then jumped up and down on the front bumper a bit and then torqued everything to spec.

Next up I'm going to look into larger bolts for the front track bar. In another thread I read the MC track bar holes are a bit larger than stock so with the stock bolts there is some play even when torqued to spec, which can cause DW. Whether that fixes the shimmy and DW or not, Steer Smarts Yeti drag link and tie rod will be coming in a few weeks.

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