Caster angle question for all you alignment experts

[FERAL 4R]

Jtraskell .. I can't say if your response is on the money or not. Stock 4Runners don't have any caster adjustment in the upper control arms; it's all in the lower control arms. Now that I have adjustable upper control arms things start to get confusing because now I have 2 places (each side) to adjust for more caster angle. In addition to having straight line tracking stability, what I'm really after is increasing my wheel base by about 1/4" to get the front tires a bit more forward in the wheel wells.

The fact that you are running 285's on a non-lifted 4Runner and have 4 degrees of positive caster on the passenger side with minimal rubbing gives me cause for hope. Thanks.

The answer is there... Up there, in my posts...

Since you have LR UCA's, set them to 0 (zero), go in for an alignment, take the instructions that came with your LR UCA's so the tech can set your camber to +4... What part is confusing you?

 

[pawzitiv]

The answer is there... Up there, in my posts...

Since you have LR UCA's, set them to 0 (zero), go in for an alignment, take the instructions that came with your LR UCA's so the tech can set your camber to +4... What part is confusing you?

Feral .. my confusion stems from my now having caster adjustment on BOTH the stock LCA and the LR UCA. The stock 4Runner only has caster adjustment on the LCAs AFAIK. What should the LCA caster adjustment be set at?

Maybe I'm a thick as two planks but if I understand your previous posts correctly, you're suggesting that I leave the LR UCA set a 0 and then have the alignment tech dial-in +4 degrees on the UCA. If the LCA caster adjust is left alone, I'm having trouble visualizing how a +4 setting on the UCAs will move the wheels further forward (if indeed the caster angle axis point is at the UCA ball joint).

You've had lots of hands-on experience with the alignment on your FJ so I'm sure what you're posting here is correct. Please just bear with me as I try to comprehend all this UCA/LCA caster angle hocus-pocus.

 

[FERAL 4R]

Think of the LR UCA as like having a 1" or 1.25" uniball...except yours don't "roll", they "slide"... they are "technically" not adjustable, but there's a lot more freedom of movement, way more than stock, and make it so you can achieve a better caster angle and still be able to get camber and toe in spec. The reason I say put it at 0, that's a good base to start from. Once the tech gets caster where you want it, camber and toe will be out of spec. Then he will have to loosen the top bolt on the LR UCA to fine tune caster and camber. Once you change one setting, they all change... That's where are good alignment tech comes in. Make sense?

 

[pawzitiv]

Think of the LR UCA as like having a 1" or 1.25" uniball...except yours don't "roll", they "slide"... they are "technically" not adjustable, but there's a lot more freedom of movement, way more than stock, and make it so you can achieve a better caster angle and still be able to get camber and toe in spec. The reason I say put it at 0, that's a good base to start from. Once the tech gets caster where you want it, camber and toe will be out of spec. Then he will have to loosen the top bolt on the LR UCA to fine tune caster and camber. Once you change one setting, they all change... That's where are good alignment tech comes in. Make sense?

I finally got it .. thanks!

I ran my question past Andries Engelbrecht at Overland Warehouse and his response also helped get this caster adjustment business clear in my mind's eye:

"In terms of alignment, the Lower CA are the only adjustment that can be made on the stock suspension. The tech should understand how to move the lower point forward with the cambolts on the frame and lower arms. Teh upper arms move the top part of the spindle to the back for more caster, so the bottom goes forward and the top backward for caster. I would recommend to have the LR arms in the 0 position as they provide some extra caster already in the position, and have the alignment tech do the rest on the lower arms (move the wheel forward)."

This echoes everything you posted, Feral. :thumb3:

 

[FERAL 4R]

I finally got it .. thanks!

I ran my question past Andries Engelbrecht at Overland Warehouse and his response also helped get this caster adjustment business clear in my mind's eye:

"In terms of alignment, the Lower CA are the only adjustment that can be made on the stock suspension. The tech should understand how to move the lower point forward with the cambolts on the frame and lower arms. Teh upper arms move the top part of the spindle to the back for more caster, so the bottom goes forward and the top backward for caster. I would recommend to have the LR arms in the 0 position as they provide some extra caster already in the position, and have the alignment tech do the rest on the lower arms (move the wheel forward)."

This echoes everything you posted, Feral. :thumb3:

Sweet.

 

[harper7]

I just had an alignment done today and I went max caster that we could get with the aftermarket LR UCA's set at zero. You need aftermarket UCA's to get this much caster though.

Now I have more then 1/2 inch clearance between the 32.8 inch tires and the rear of the front wheel wells at full wheel lock. Still plenty of room up front too, at least with the TE fender liners I have.

It drives and feels more stable then ever too. I can take my hands off the wheel and it just stays straight as an arrow. He adjusted the camber more pos on the drivers side to accomodate the angle of the roads for water drainage.

If anybody around DFW needs an alignment,this shop has a tech that has specialized in alignments for 15 years. He's very good and you can stand right there with him and learn something too.Jeff's the manager and Greg does the alignments and it's only $49.99. Highly recommended!

My new specs.
5.7/5.6 caster
.4/-.1 camber
.05/.05 toe

Drivers side rear clearance

The name of the shop.

 

[FERAL 4R]

Harper, those numbers look perfect...But...

With that much Caster dialed in, are you feeling any bumpsteer? And, he couldn't get Camber to 0?

What machine did he use?

 

[harper7]

Harper, those numbers look perfect...But...

With that much Caster dialed in, are you feeling any bumpsteer? And, he couldn't get Camber to 0?

What machine did he use?

No bump steer. He said I might if I was loaded real,real heavy in the back or towing with a heavy tongue weight as that increases the caster even more. Said he's done some custom Chevy 4x4's up to 7 degree on the caster.I'll be the guinea pig and report back after some miles next month. Driving about 3000 miles in the next 2 weeks as I head west for Ca. next Monday . Up the coast,then circle back down to Colorado for the FJ summit.

He could have brought the camber to zero but it's to compensate for the crown(lower on the right) in the major highways for water drainage. I said make everything equal and he explained to me it's not a myth about road crown even though we can't see it so I went with his suggestion on that. He would have set them anywhere I wanted as I was standing right there with him. The rear eccentric on the LCA is caster adjustment and the front is the camber.

Could be BS but not the first time I've heard it about road crowns and hard to argue with a guy that's been doing it daily for 15 years. He's aligned big rigs ,buses,4x4's and about everything and really colorful knowledgeable old guy that knows his shat. That's all he does.Believe me I had a big grin feeling the results the whole way home.

 

[cv470]

Caster

Just had my alignment done this weekend becuase of the wandering issue my caster was set to 3.3 and 3.5 after the alignment it's now 4.11 4.12 positive and the guy also told me they had to adjust the toe in mind you guys I know nothing about caster toe in or alignment I just went by what some of the guys here on the forum recommended and I will just say this it's only been three days and you could feel the difference I have not felt the wandering at all but i guess I should wait a week or two and the steering feels much tighter too!!! so my question guys is when ever I get another alignment do I need to have the caster adjusted or this like a one time thing?

 

[Narkhelek]

Just had my alignment done as well. For some reason the dealership was only able to set the caster to +2.0 and still keep the camber within 'spec' at +.1. I was kind of surprised I could only get that much caster as I have Camburg uniball UCAs installed. I figured the aftermarket UCAs would have been able to get more caster than they did.

Would having my front coil-overs adjusted to level out my truck reduce the amount of caster I'd be able to get?

 

[FERAL 4R]

Just had my alignment done as well. For some reason the dealership was only able to set the caster to +2.0 and still keep the camber within 'spec' at +.1. I was kind of surprised I could only get that much caster as I have Camburg uniball UCAs installed. I figured the aftermarket UCAs would have been able to get more caster than they did.

Would having my front coil-overs adjusted to level out my truck reduce the amount of caster I'd be able to get?

Go somewhere else. Most dealerships try to keep it "within spec"...

With aftermarket UCA's, you can get up to +4 or more.

 

[Snooperstyle]

Got another alignment, and it was after hitting a huge pothole which knocked off my camber because it somehow loosened the UCA bolt. Anyways, I fixed the UCA myself with a torque wrench and then took it to a different alignment shop than who I used before. The readings came out like this:

BEFORE:
0.1 / 0.1 Camber
3.0 / 3.5 Caster
-0.31 / -0.29 Toe
-0.60 Total Toe
-0.01 Steer Ahead

AFTER:
0.1 / 0.1 Camber
3.0 / 3.5 Caster
0.04 / 0.03 Toe
0.07 Total Toe
0.00 Steer Ahead

Now before I get flamed, I know you all are going to tell me that my caster is not high enough (actually he never adjusted it for this alignment), but on my first alignment (with a different person who failed to provide me with a report), I actually had to take it back and make him reduce the castor on the front left to keep the tire from rubbing. So, is is possible that these numbers from this particular shop are not factoring in the built-in 2degrees of caster that the LRUCA's provide? The truck rides better now and my tires are now quieter. They seem equally spaced between my fender wells. So, should I revisit this or leave it for a while?

Another thing to note, cranking down the bolt on the Light Racing UCAs to 150lb ft of torque may not be enough. The thing came loose after hitting a nasty pothole. I was very surprised it came loose at that amount of pressure. Prior to the alignment the other day, I cranked it back down (and as it turns out I somehow ended up getting it to be back in the exact same spot), but I asked him to crank it a tiny bit more for good measure. Anybody else have the LRUCA bolt come loose?

Thanks and sorry for the long post...

 

[mrvandelay]

My driver's side wheel sits further back in the wheel well than the passenger side even with identical caster settings (4).

Any issue with increasing caster to 5 on the drivers and leaving the passenger at 4?

 

[Ducmonsta]

My driver's side wheel sits further back in the wheel well than the passenger side even with identical caster settings (4).

Any issue with increasing caster to 5 on the drivers and leaving the passenger at 4?

If you have adj UCAs, you can even out the wheelbase and still have even caster. If caster is not even on both sides, this will cause a pull.

 

[Qjake]

You're saying UCA bolt, by this i'm assuming the long bolt but have the feeling you're talking about the upper ball joint nut.

I've taken a few hard hits from potholes and not had an issue with the ball joint torqued to spec. I have had the nut come loose on both long bolts with them torqued to spec but didn't affect my alignment.

 

[Snooperstyle]

^^ Yup. Its the big one on the top that takes 1.25" socket. My bad.

 

[Bradley]

Can only get 1.7º Caster on 2012 Runner

Thanks everyone for your responses.

I do have Light Racing UCA's so I am able to dial-in 4 degrees of positive caster. I do understand the physics of caster angle and its' effect on straight line steering stability (ie more positive caster gives more stability but requires more effort to turn the wheels).

My question relates more to where the caster pivot axis is on the 4Runner. If a line is drawn between the UCA and LCA and the LCA ball joint can't be moved far enough forward, the UCA ball joint will need to move rearwards to get more positive caster angle.

I think I'll first fully flex out my new suspension and then drive my 4Runner fully loaded for a few weeks to get the ride height to settle. Then I'll go back for another alignment and get the alignment tech to dial-in 4 degrees of positive caster. If 4 degrees doesn't help my rubbing issue, I can always go back to less positive caster .. it's just the cost of another alignment.

Interesting note I have to add here, or rather it's a question to all based on this thread. I just put OME on my 2012 4Runner SR5, stock control arms. I've had it to 2 alignment shops and the best they can do is get 1.7º positive Caster on each side. I do think it tends to wander just a touch more now. I'm just wondering how you guys with stock arms are able to get the 2.5-4.0º?

 

[Jeremy556]

Interesting note I have to add here, or rather it's a question to all based on this thread. I just put OME on my 2012 4Runner SR5, stock control arms. I've had it to 2 alignment shops and the best they can do is get 1.7º positive Caster on each side. I do think it tends to wander just a touch more now. I'm just wondering how you guys with stock arms are able to get the 2.5-4.0º?

They are getting it with stock UCAs and no lift.