Caster angle question

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abqcruiser

abqcruiser

10 Year
Joined
Apr 1, 2013
Threads
18
Messages
887
Location
Albuquerque, NM
I've noticed after driving the pig over the weekend, especially at higher speeds, how sensitive the steering is. It dawned on me that when I had the alignment checked, they also checked the caster angle. I went back and looked at the print out: -1.6 degree on left front and -2 degree right front.

I have OME springs with no shims. 33" tires. Questions:

!. Do I buy 3 degree shims?
2. Should I buy two different degree shims to compensate for the different caster angle readings?
3. Should I buy 4 degree shims ( as suggested by Bryce at Cruiser Outfitters, due to the larger tire size
that I'm currently running with)?

Any help would be appreciated, thanks
 
Positive caster will definitely make for a more stable sense of steering!
The trick to using degree shims is that they will rotate your pinion flange away from the t-case flange. You do not want to severe of a mismatch between the two flanges. If you can, park the Pig, drop the front shaft, measure the angle on the 2 flanges. Chances are that the pinion flange is pointing slightly upward at the t-case now. If you know how much, you can approach the shims from an informed position instead of guessing.

Others might tell you to cut and turn. That is a lot of work for a SUA rig...
 
abqcruiser said:
Should I buy 4 degree shims ( as suggested by Bryce at Cruiser Outfitters, due to the larger tire size that I'm currently running with)?
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Just like Bryce at Cruiser Outfitters said you want 4° shims, that’s what I ran with my OME lift and 33” tires and they worked well..
 
J Mack said:
Just like Bryce at Cruiser Outfitters said you want 4° shims, that’s what I ran with my OME lift and 33” tires and they worked well..
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Thanks J Mack, Cruiser Outfitters didn't carry 4 degree shims. Did you buy yours some place else?
Also, should I worry about the different left and right readings?
 
abqcruiser said:
Thanks J Mack, Cruiser Outfitters didn't carry 4 degree shims. Did you buy yours some place else?
Also, should I worry about the different left and right readings?
Click to expand...


I only buy parts like this from @cruiseroutfit “Cruiser Outfitters” so I’m sure I bought them from them, give Kurt or Brice a call and let them find you a set.



In the old days they would have told you both sides are 2° out and you would have put 4° shims in and never looked back, now they use computerized alignment machines and breakdown into fractions of a degree, useful on a high speed highly adjustable vehicle with low profile tires but meaningless on a straight axle pig with 33”, if your balls are welded with a 0.4° difference the shims wont correct it anyway.
 
Lil'John said:
As others noted, get it back to stock(0 degrees??) My old FJ40 was sprung over with stock caster and didn't have any issues with "twitchy" steering at highway speeds(60mph)
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Stock is +1° to help with the arm strong steering box, once you add power steering +2°, +3° will greatly improve straight line stability.
 
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Lil'John said:
True... but as you adjust the caster beyond stock(+/-), you can impact the pinion angle and cause either vibration or binding :(
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Agree but for me when we’re talking about +/- 2° the 2° makes a bigger difference on the handling of the vehicle vs. the potential binding of the drive shaft. If I could only make one acceptable I would choose drivability (caster) every time. Like you said if you want everything perfect cut and turn is your only option..
 
abqcruiser said:
Pablo, wouldn't the computer read out from the alignment shop be fairly accurate?
Click to expand...

Lil'John said:
True... but as you adjust the caster beyond stock(+/-), you can impact the pinion angle and cause either vibration or binding :(

Once you commit to "cut and turn the knuckles", that opens up a LOT toward getting "perfect" caster.

The binding due to pushing the pinion downward would be my biggest concern with the FJ55 especially with the short stock front driveshaft :(
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J Mack said:
Agree but for me when we’re talking about +/- 2° the 2° makes a bigger difference on the handling of the vehicle vs. the potential binding of the drive shaft. If I could only make one acceptable I would choose drivability (caster) every time. Like you said if you want everything perfect cut and turn is your only option..
Click to expand...

I very much doubt the alignment shop looked at how your flanges in the front drivetrain are angled. You need to look at the angles of the pinion flange in your front diff vs. the flange coming out of the front of your t-case.

As John points out, the front shafts on these Piggies is pretty short.

And here comes the cut-n-turn comments! :-)
 
PabloCruise said:
I very much doubt the alignment shop looked at how your flanges in the front drivetrain are angled. You need to look at the angles of the pinion flange in your front diff vs. the flange coming out of the front of your t-case.
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If you don’t cut/turn your front axle the drive flange vs. caster angle is fixed as in set at the factory. Assuming your factory caster angle was + 0.5°/1° and the drive flange was at an acceptable angle then if you restore your caster angle back to +1°/2° with caster shims after you lift with shackles and or springs then your drive flange will be within 1° of its factory setting, not enough by its self to cause issues.

If your drive shaft looks like the top picture changing it to the bottom picture wont make it better.

ujoint_driveshaft_angle_alignment.webp
 
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use steel shims...
 
Lots of information here, thank you.

I'm making an assumption that I have Old Man Emu springs. I'm not sure on how much lift I have. Here are some pics.

IMG_0535.webp

IMG_0536.webp

I'm also assuming, if they are OME's, that I shouldn't have to do any cut and turn, just shims, right?

Also, I'm still using the stock steering box, but I put in an electrical assisted steering system. That last part I was saving for another thread, but it seemed appropriate to make you all aware of my set up .
 
abqcruiser said:
I'm also assuming, if they are OME's, that I shouldn't have to do any cut and turn, just shims, right?
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I probably know the least about Toyota and all the aftermarket parts for them of everyone helping in this thread so take this with a grain of salt.

Those front shackles look very long for front shackles so I would assume most if not all your lift is coming from them and not the springs. At one point I did the math for front shackle length vs. caster in degrees but that info is escaping me at the moment but it’s something like every .5” equals one degree or something like that, at any rate that is what’s causing your lack of caster. Your two options are if you keep that setup is add shims or cut and turn to get your positive caster, my preference with power steering is +2° to +3° but depending on the power of your electric assist +1° to +2° might be better.



Good luck!!!
 
From center to center of the spring bolt to hanger bolt, the shackle measures approximately 5 1/2". I don't know how that translates to the amount of lift I have. I'm not opposed to dropping down to a smaller shackle height if that will help to get to a better sweet spot.
 
I had bought the complete kit from Cruiser Outfitters and I believe that my front shackles were 110 mm or 4.33” and the rest of the lift was in the spring itself. This is the kit: Cruiser Outfitters



I would call Kurt and ask him what the best long term solution is.
 
PabloCruise said:
That shackle angle looks a little ugly - straight up and down. Not sure if you will get more angle with shorter shackles?
My understanding is that correct angle gives nicer ride...
Click to expand...

I've noticed that as well, based on comparisons with other's posts. I'll give Kurt a call and see if he can shed some light on this.
 
Lil'John,

I ordered a 4 degree shim to put me at 2 degree caster. I might go less, 3 degree. The only reason I think it is an OME set up is because the shocks are OME as well, and from what I've seen the spring kits come with shocks as a package deal. There are 7 leafs on those springs, that's consistent with the heavy duty springs that OME offers. I'm not familiar with how many leafs are on the stock springs.
 
Lil'John said:
In looking at those pictures, those really look like stock springs at first glance. It has spring clamps. But at the same time, it doesn't have the military wrap at front. It also looks very flat to me. Anyone more knowledgeable?

Lil'John, you are correct, or at least Kurt at Cruiser Outfitters agrees with you. He says they are definitely not OME's. So the PO just stuck on some longer shackles, OME shocks, and called it a day. Crap!

So now I need to decide what to do next.

J Mack, what size OME lift did you go with and what version, the light or heavy duty?
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