Alignment specs for 5" long arm kit?

DaBank

DaBank

Member
I have a 2017 JKU Rubicon Recon with a Fabtech 5" Long Arm Crawler kit with aftermarket drive shafts, adjustable trackbar, raised track bar mount, Copper SST Pros 37x12.5x17, Fuel 17x9 4.5 wheel's, winch, front and rear bumpers.

I just had a Dostech Aluminum Tie Rod/ Drag link flip installed and now going to have it aligned this week .
Was told by Fabtech that the kit uses stock Jeep alignment specs. They said that .5 more caster on the passenger side is ok to help with the crown on the road.

I always thought caster on a lifted Jeep required more caster than stock?
What is the best toe in 1/16 or 1/8?

I want all the arms adjusted to make sure everything is squared up.
What numbers should I be looking at on the alignment print out?
 
wayoflife

wayoflife

Administrator
Staff member
Think about it for a second... how do you add more caster to just one side on a SOLID axle?

1/16" is what you want for toe. As your Jeep moves forward, your tires will pull outward and be parallel when driving. Too much toe and you will have poor tire wear.

More caster is always nice to have as it will help your Jeep to track straight. However, too much caster on a Jeep that's been re-geared to a higher ratio and running a u-joint style drive shaft WILL most likely have driveline vibes.
 
DaBank

DaBank

Member
I appreciate your response.

I would imagine adjusting the control arms different lengths?

Let me know if I am correct.......
1. Front upper CA set caster?
2. Front lower CA move axle?
3. Rear upper Ca move axle?
4. Rear lower set pinion?

So I been told 1/16 to 1/8 toe. You say 1/16 so that is what I will tell them I want.

I do have 488 gears and U Joint style Fabtech drive shafts.

What would be a good front caster number on my set up? How about a good rear pinion angle?

Is there any other adjustments I should be aware of?

Thanks again!!
 
wayoflife

wayoflife

Administrator
Staff member
DaBank said:
I appreciate your response.

I would imagine adjusting the control arms different lengths?

Let me know if I am correct.......
1. Front upper CA set caster?
2. Front lower CA move axle?
3. Rear upper Ca move axle?
4. Rear lower set pinion?

So I been told 1/16 to 1/8 toe. You say 1/16 so that is what I will tell them I want.

I do have 488 gears and U Joint style Fabtech drive shafts.

What would be a good front caster number on my set up? How about a good rear pinion angle?

Is there any other adjustments I should be aware of?

Thanks again!!
Click to expand...
Lower arms set axle position.
Upper front set caster.
Upper rears set pinion.

+4.2° is what comes factory and it'll be what'll help keep vibrations at bay. You can try more and if your shaft is really well balanced, you may not have vibes.

Pinion angle should be set in line with the drive shaft.
 
DaBank

DaBank

Member
wayoflife said:
Lower arms set axle position.
Upper front set caster.
Upper rears set pinion.

+4.2° is what comes factory and it'll be what'll help keep vibrations at bay. You can try more and if your shaft is really well balanced, you may not have vibes.

Pinion angle should be set in line with the drive shaft.
Click to expand...
I just checked and my rear upper CA are not adjustable. All the other CA are ajustable with 5 Ton joint's.
So this long arm kit does not let you adjust the rear pinion angle.
I also notice that the rear coils have a bow in them so that would explain why since the axle cant be adjusted?

I emailed them yesterday to ask about what their base line CA lengths out of the box are and what they suggest on alignment.

This is what I received.

Hi Frank,



Our kits are designed to be run with factory alignment specs, but it is always good to add more positive caster in the front whenever possible. Usually we set ours to 5 degrees positive, with just a little more (maybe .5 degree) on the passenger side to compensate for the crown in the road.
 
CalSgt

CalSgt

Hooked
Fabtech make’s suspension kits for many vehicles that DO have the ability for different caster on each side… Some customer service rep sent you a copy/paste response that gets sent out repeatedly regardless of the vehicle make.
 
CalSgt

CalSgt

Hooked
Also, and just an FYI… depending on where you are taking it for an alignment they might not even be willing to mess with your adjustable arms, pinion angle, Etc. None of that is part of an alignment for a factory vehicle. If they are, you may get charged hourly shop rate for that type of work.

If that is what you’re getting, you may just let them do their job as opposed to mandating every detail to them. If they set it up and it drives like shit then it’s their fault. If you tell them how to do their job and it drives like shit it’s your fault.
 
wayoflife

wayoflife

Administrator
Staff member
DaBank

DaBank

Member
My question is for how my Jeep is set up would be better for them to set it at the factory 4.2 caster or at 5.0 like Fabtech suggested?

Would having a little more caster on the passenger side be beneficial?

I am having it aligned tomorrow and they are adjusting everything.
 
wayoflife

wayoflife

Administrator
Staff member
DaBank said:
My question is for how my Jeep is set up would be better for them to set it at the factory 4.2 caster or at 5.0 like Fabtech suggested?
Click to expand...
Hell, add in 6 or 7 if you want and if you don't get driveline vibes, all the better. The 4.2 is mainly to mitigate vibes and to be honest, if your drive shaft isn't balanced super well, you'll still get them even with that.
DaBank said:
Would having a little more caster on the passenger side be beneficial?
Click to expand...
As I mentioned, you CANNOT add more caster to just one side of a solid axle. You can shorten or lengthen your upper control arm all you want but all it will do is make your bushings crush, be in a state of bind and can even lead to the tearing off of an upper control arm mount or worse, breaking the axle tube. BOTH are things that I have personally seen happen. The advice you got is terrible.
 
DaBank

DaBank

Member
wayoflife said:
Hell, add in 6 or 7 if you want and if you don't get driveline vibes, all the better. The 4.2 is mainly to mitigate vibes and to be honest, if your drive shaft isn't balanced super well, you'll still get them even with that.

As I mentioned, you CANNOT add more caster to just one side of a solid axle. You can shorten or lengthen your upper control arm all you want but all it will do is make your bushings crush, be in a state of bind and can even lead to the tearing off of an upper control arm mount or worse, breaking the axle tube. BOTH are things that I have personally seen happen. The advice you got is terrible.
Click to expand...
 
DaBank

DaBank

Member
I appreciate your advice!!
Can't believe Fabtech would suggest doing it.
The Jeep has always drove great but I just had front axle seals,ball joints,pitman arm, flipped drag link and aluminum 1 ton steering done and the Jeep has 52k miles now so just want to make sure everything is correct. I never had any driveline vibrations before so hopefully that does not happen after the alignment.
Thanks again,
Frank
 
wayoflife

wayoflife

Administrator
Staff member
DaBank said:
I appreciate your advice!!
Can't believe Fabtech would suggest doing it.
The Jeep has always drove great but I just had front axle seals,ball joints,pitman arm, flipped drag link and aluminum 1 ton steering done and the Jeep has 52k miles now so just want to make sure everything is correct. I never had any driveline vibrations before so hopefully that does not happen after the alignment.
Thanks again,
Frank
Click to expand...
As CalSgt said, they probably were referring to a kit that would allow for caster to be set separately such as, on a vehicle with IFS.

If you haven't had vibes before, you'll probably be fine with 5-6 degs. Just know that IF you get vibes, the fix would be to lower that back down to about 4.
 
Bierpower

Bierpower

Hooked
DaBank said:
I appreciate your response.

I would imagine adjusting the control arms different lengths?

Let me know if I am correct.......
1. Front upper CA set caster?
2. Front lower CA move axle?
3. Rear upper Ca move axle?
4. Rear lower set pinion?

So I been told 1/16 to 1/8 toe. You say 1/16 so that is what I will tell them I want.

I do have 488 gears and U Joint style Fabtech drive shafts.

What would be a good front caster number on my set up? How about a good rear pinion angle?

Is there any other adjustments I should be aware of?

Thanks again!!
Click to expand...
Just a side note but alignment racks don't give anything in inches so if you tell them to set the toe at 1/16 they may give you a funny look.

Usually all of the factory specs for the vehicle are stored in the system and that's what they use to set the alignment. If Fabtech says to use factory settings you should be good but as stated above you may ask about the adjustable control arms before hand. Some places will only do a toe adjustment on straight axles which is pretty much a waste of money.
 
DaBank

DaBank

Member
The dealer said my front axle housing is bent and they are going to warrenty it.
They are going to adjust the control arms when they install the new housing.
Here is the print out of the alignment measurements. Disregard the before toe settings being so off since they just installed the new track bar, tie rod and drag link.
How do the after measurements look beside the caster being low?
 

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WJCO

WJCO

Meme King
DaBank said:
The dealer said my front axle housing is bent and they are going to warrenty it.
They are going to adjust the control arms when they install the new housing.
Here is the print out of the alignment measurements. Disregard the before toe settings being so off since they just installed the new track bar, tie rod and drag link.
How do the after measurements look beside the caster being low?
Click to expand...
The only thing really adjustable is the toe angle and it looks like they did just that.
 
WJCO

WJCO

Meme King
DaBank said:
What should the thrust angle be?
Click to expand...
That's how the rear axle center is compared to your front axle center. But on a Jeep it's tricky because of the way the track bar causes the thrust angle to change over every single bump as the axle moves. If each axle is centered perfectly, they still move as soon as you start driving so it's pretty useless to measure it on a Jeep.
 
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