JBA UCAs, Clearance & Alignment

[lpittman]

Hey fellas.

Having some issues with clearance & alignment and hoping to both learn a few things and get some help figuring out what went wrong.

I have a '21 TRD Off-Road.

285/70/17 General Grabber ATX on the stock rims, with 1.25" spacers.

Installed a RevTech 3"/2.5" spacer level/lift kit.

Almost zero rub. Don't know the alignment specs at this point. Just a tiny bit under the right conditions.

Plan is to do the body mount chop, smash some seams and squeeze in 35s, but I knew I'd need UCAs. So... after all the research I purchased a set of the JBA high caster UCAs and installed them myself.

I don't think it's possible to install them wrong if you follow directions and aren't an idiot. However, I guess anything is possible.

After the install I got a lot more rub all at the rear of the wheels on the body mount area of the mudflaps. This was quite a surprise, but I figured it would clear up after an alignment.

However, I was wrong. The shop did the alignment and ended at the following:

Caster Left: 4.03*
Caster Right: 4.17*
Camber Left: -0.20*
Caster Right: -0.23*
Toe all in spec: 0.02, 0.04 for total 0.06.

The JBA instructions talk about making sure caster is at 4* so I assumed all was good... until I drove it home. Now it rubs so bad I feel like the mudflaps are gonna rip off.

I took it back today and they checked it again and told me I would need to reduce the caster to gain clearance by moving the rear LCA cams all the way inward, then adjusting the fronts to fine-tune. This is where it starts to get confusing for me.

When you look at the geometry, it only makes sense for the rear cams to be all the way OUT, to move the tire toward the front of the vehicle. You can then turn the front cams all the way in to move it forward even more, and then fine-tune the caster/camber using the front cams.

Is this not right? Am I missing something?

I drew cute little arrows on a LCA adjustment diagram to show what I am thinking.

Am I off? Am I an idiot? Or is it the shop that isn't getting it right?

 

[daytonaviolet]

JBA UCAs, Clearance & Alignment

I’m no alignment expert, but the geometry of the high caster jba suppose to give automaticity 3 degrees over oem UCA. If any anything you should have more clearance of body mount.

I’m running 285/70/17 and I rub mud flaps at full lock back out of my driveway only. I’m running trd pro wheels with 3”+ lift.

When do you rub ?

 

[lpittman]

I’m no alignment expert, but the geometry of the high caster jba suppose to give automaticity 3 degrees over oem UCA. If any anything you should have more clearance of body mount.

I’m running 285/70/17 and I rub mud flaps at full lock back out of my driveway only. I’m running trd pro wheels with 3”+ lift.

When do you rub ?

Yea - that's what I thought too.

Rub happens turning both directions, forward and reverse, at about 40* steering angle all the way to full lock.

Any chance you would have pictures of your LCA cams?

 

[comtn4x4]

Hey fellas.

Having some issues with clearance & alignment and hoping to both learn a few things and get some help figuring out what went wrong.

I have a '21 TRD Off-Road.

285/70/17 General Grabber ATX on the stock rims, with 1.25" spacers.

Installed a RevTech 3"/2.5" spacer level/lift kit.

Almost zero rub. Don't know the alignment specs at this point. Just a tiny bit under the right conditions.

Plan is to do the body mount chop, smash some seams and squeeze in 35s, but I knew I'd need UCAs. So... after all the research I purchased a set of the JBA high caster UCAs and installed them myself.

I don't think it's possible to install them wrong if you follow directions and aren't an idiot. However, I guess anything is possible.

After the install I got a lot more rub all at the rear of the wheels on the body mount area of the mudflaps. This was quite a surprise, but I figured it would clear up after an alignment.

However, I was wrong. The shop did the alignment and ended at the following:

Caster Left: 4.03*
Caster Right: 4.17*
Camber Left: -0.20*
Caster Right: -0.23*
Toe all in spec: 0.02, 0.04 for total 0.06.

The JBA instructions talk about making sure caster is at 4* so I assumed all was good... until I drove it home. Now it rubs so bad I feel like the mudflaps are gonna rip off.

I took it back today and they checked it again and told me I would need to reduce the caster to gain clearance by moving the rear LCA cams all the way inward, then adjusting the fronts to fine-tune. This is where it starts to get confusing for me.

When you look at the geometry, it only makes sense for the rear cams to be all the way OUT, to move the tire toward the front of the vehicle. You can then turn the front cams all the way in to move it forward even more, and then fine-tune the caster/camber using the front cams.

Is this not right? Am I missing something?

I drew cute little arrows on a LCA adjustment diagram to show what I am thinking.

Am I off? Am I an idiot? Or is it the shop that isn't getting it right?

You had the spacers and tires on before the UCA's were installed? If so, how was the rub before the UCA install?

Caster will need to be much higher to fit bigger/wider tires. I'd aim for 5 degrees +. Plan on a lot of cutting/hammering front and rear wheel well to fit a 35.

You'll obviously be looking at different wheels to fit 35's?

 

[lpittman]

Thanks for the reply.

You had the spacers and tires on before the UCA's were installed? If so, how was the rub before the UCA install?

Correct. There was next to no rub. Tiny bit, turning right, full lock. Had a few days of fairly intense wheeling as well and never had -any- rub during that.

Caster will need to be much higher to fit bigger/wider tires. I'd aim for 5 degrees +. Plan on a lot of cutting/hammering front and rear wheel well to fit a 35.

You'll obviously be looking at different wheels to fit 35's?

Yep, aware of the work required to get to 35s and am okay with it. Have just been taking it one step at a time. And yes I will be looking at wheels at that point as well.

 

[comtn4x4]

Ok so if the wheels, spacers and lift were installed prior to the UCA's and you didn't have any rubbing... You did have it aligned after the UCA install right?

Thanks for the reply.

orrect. There was next to no rub. Tiny bit, turning right, full lock. Had a few days of fairly intense wheeling as well and never had -any- rub during that.

Yep, aware of the work required to get to 35s and am okay with it. Have just been taking it one step at a time. And yes I will be looking at wheels at that point as well.

 

[daytonaviolet]

JBA UCAs, Clearance & Alignment

Yea - that's what I thought too.

Rub happens turning both directions, forward and reverse, at about 40* steering angle all the way to full lock.

Any chance you would have pictures of your LCA cams?

I looked at my caster specs after alignment and I’m 5.07 left and 5.67 right and I also have std high caster jba.

Here are my cam settings

 

[lpittman]

Ok so if the wheels, spacers and lift were installed prior to the UCA's and you didn't have any rubbing... You did have it aligned after the UCA install right?

Yep. Order was:

1. Lift 3"/2.5", 1.25" wheel spacers & 275/70/17 wheels + alignment. No rub.

2. Bump up tires from 275/70/17 to 285/70/17. No alignment. TINY bit of rub, nothing I would worry about.

3. Installed JBA UCAs. Bad rub. Turning both directions, forward + backward, etc. Figured the issue was I needed the alignment.

4. Got alignment (giving them the 4* caster spec provided by JBA). Rub is worse. Almost undrivable at times.

5. Brought back for second alignment. Shop said they had to REDUCE caster to create more clearance. I disagreed (see original post) but they kept insisting. They made the changes and it rubs as bad or slightly worse.

6. Cry.

lol

 

[lpittman]

I will be going to a different shop on Thursday to get another opinion and look at the alignment... but I wanted to learn more about it on my own before showing up.

 

[comtn4x4]

I'd pull the spacers off and see what happens. Generally they make rubbing worse.

Do you have the alignment sheet with the before and after specs?

Yep. Order was:

1. Lift 3"/2.5", 1.25" wheel spacers & 275/70/17 wheels + alignment. No rub.

2. Bump up tires from 275/70/17 to 285/70/17. No alignment. TINY bit of rub, nothing I would worry about.

3. Installed JBA UCAs. Bad rub. Turning both directions, forward + backward, etc. Figured the issue was I needed the alignment.

4. Got alignment (giving them the 4* caster spec provided by JBA). Rub is worse. Almost undrivable at times.

5. Brought back for second alignment. Shop said they had to REDUCE caster to create more clearance. I disagreed (see original post) but they kept insisting. They made the changes and it rubs as bad or slightly worse.

6. Cry.

lol

 

[jamoc]

I had a ton of rub at not even full lock after installing my JBA UCA, 285/70/17, and Eibach lift.

Might sound weird, but without the aftermarket UCA's you might have been in that non rub 'sweet spot' of caster. Adding the UCA might have put you smack dab on the body frame mount.

I had a professional shop do body entire mount relocation, and hammer pinch weld area. Zero rub since, full lock reverse on a steep incline.

Easiest solution without swapping parts is a BMC or entire BM Relocation. Those alignment specs basically perfect.

 

[jamoc]

Also,

Have someone drive the truck while you visibly inspect where it's rubbing. That will confirm the rub location.

If you like the look of the spacers, I'd keep them. If you're ok with letting them go, def. remove them and do a rub test as well.

A BMC will run around a $100 more than the cost of those spacers.

 

[lpittman]

I'd pull the spacers off and see what happens. Generally they make rubbing worse.

Do you have the alignment sheet with the before and after specs?

Afraid I don't have the means to remove the spacers currently. Either way that's the look/stance I want in the end, so I'll keep working around it.

After the UCA install, before the alignment.

Caster: 5.07 | 4.81
Camber: -0.46 | -0.78
Toe: -0.61 | -0.61

After alignment (when rubbing got worse):

Caster: 4.03 | 4.17
Camber: -0.20 | -0.23
Toe: 0.02 | 0.04

After second alignment attempt:

Caster: 2.74 | 2.96
Camber: -0.49 | -0.65
Toe: 0.04 | 0.04

Worst part is the alignment shop was telling me I needed to keep reducing caster to get clearance... but I don't agree.

 

[lpittman]

I had a ton of rub at not even full lock after installing my JBA UCA, 285/70/17, and Eibach lift.

Might sound weird, but without the aftermarket UCA's you might have been in that non rub 'sweet spot' of caster. Adding the UCA might have put you smack dab on the body frame mount.

I had a professional shop do body entire mount relocation, and hammer pinch weld area. Zero rub since, full lock reverse on a steep incline.

Easiest solution without swapping parts is a BMC or entire BM Relocation. Those alignment specs basically perfect.

Gotcha. Weird. So if I had that sweet spot, do I put the stock ones back on? (don't really want to!). Or can a good alignment tech get me back in that sweet spot?

I am getting the BMW done next weekend - but was hoping that would get me into 35s. At this point it'll just make the current tires clear I think.

 

[jamoc]

Gotcha. Weird. So if I had that sweet spot, do I put the stock ones back on? (don't really want to!). Or can a good alignment tech get me back in that sweet spot?


I am getting the BMW done next weekend - but was hoping that would get me into 35s. At this point it'll just make the current tires clear I think.

The last thing I would do is swap the JBA UCA's. I'd swap the spacer lift to a proper lift, before the UCA's.

I would def. get the BMW work done regardless. I think the body mount work will solve your problem

Also, for drivability, MPG, etc. I was recommended by multiple people who have installed and drove 35's on our trucks, to not pass a true 34 inch tire (285/75/17). Now, that doesn't mean you can't, or shouldn't put 35's - that's what was simply recommended to me by those with real world experience.

 

[lpittman]

The last thing I would do is swap the JBA UCA's. I'd swap the spacer lift to a proper lift, before the UCA's.

I would def. get the BMW work done regardless. I think the body mount work will solve your problem

Also, for drivability, MPG, etc. I was recommended by multiple people who have installed and drove 35's on our trucks, to not pass a true 34 inch tire (285/75/17). Now, that doesn't mean you can't, or shouldn't put 35's - that's what was simply recommended to me by those with real world experience.

Appreciate that. I was considering stopping at the 285/75/17 too. But was gonna see if I could find a set of mounted 35s to try out after I do all the work.

 

[comtn4x4]

Afraid I don't have the means to remove the spacers currently. Either way that's the look/stance I want in the end, so I'll keep working around it.

After the UCA install, before the alignment.

Caster: 5.07 | 4.81
Camber: -0.46 | -0.78
Toe: -0.61 | -0.61

After alignment (when rubbing got worse):

Caster: 4.03 | 4.17
Camber: -0.20 | -0.23
Toe: 0.02 | 0.04

After second alignment attempt:

Caster: 2.74 | 2.96
Camber: -0.49 | -0.65
Toe: 0.04 | 0.04

Worst part is the alignment shop was telling me I needed to keep reducing caster to get clearance... but I don't agree.

Yes you're right, the alignment shop is wrong. The Caster needs to be increased, probably back to what it was in the beginning, around 5*.
I understand the spacers provide the look you want, however, it will become more and more challenging to get bigger tires to fit without rubbing using them. Maybe consider a smaller spacer, or a different wheel

 

[Happysmiley]

X 2 , increase caster , push the lower forward for clearance.

Aftermarket upper arms move the upper arm ball joint pivot back to increase caster when the suspension is pushed down for lift.

The anti-dive angle of the upper arm is why caster changes so much.

When the upper arm ball joint pivot is moved back it rocks the whole spindle back which moves the hub centerline back slightly putting the wheel closer to the rear of the wheel well.

 

[Gclark949]

X 2 , increase caster , push the lower forward for clearance.

Aftermarket upper arms move the upper arm ball joint pivot back to increase caster when the suspension is pushed down for lift.

The anti-dive angle of the upper arm is why caster changes so much.

When the upper arm ball joint pivot is moved back it rocks the whole spindle back which moves the hub centerline back slightly putting the wheel closer to the rear of the wheel well.

x2. This is exactly correct. The high caster UCA achieves this by moving the upper pivot location rearward. The alignment shop can only now adjust the lower control arm forward as much as possible which will further increase caster and of course gain clearance from the body mount. But, as they make this adjustment it also affects camber.

I went from Camburg UCA to JBA HD High Caster and immediately had mud flap rubbing because the JBA has more built in positive caster.

 

[delloro]

Also, for drivability, MPG, etc. I was recommended by multiple people who have installed and drove 35's on our trucks, to not pass a true 34 inch tire (285/75/17). Now, that doesn't mean you can't, or shouldn't put 35's - that's what was simply recommended to me by those with real world experience.

Why, what is different about driving on 35's, vs. 34's? Besides women throwing themselves at the driver on 35's? :wink2: