Educate me on Castor (1 Viewer)

[Noahrob]

Help me understand castor and why I care. I put a slinky lift on my truck; 75mm and did the washer mod as per the instructions. My truck does not shake and seems to drive ok, but when I took it to the alignment shop, here are the results I saw.

I talked to Justin at Redline and he suggested a trunnin bearing kit to adjust the castor, but I’m wondering why adjust it if there is no vibration, just to extend the longevity of the Ujoint? If adjusting the castor is a must, then I’m thinking of just re-doing the washer mod as it is just heavy tacked on.


Opinions and thoughts?

<Flamesuit ON>

 

[Dork]

First lesson. Its caster, not castor.

 

[Fj81]

Have you driven it on the highway at speed yet? It will go all over the place and follow ruts much worse if the caster is not addressed. There was a thread not to long ago about caster adjustment.

 

[Noahrob]

Ha, spelling is clearly not my strong suit, Ha. The truck goes pretty good on the freeway, but seems less planted than I would like, maybe this is it...I think i'll lower the washer mod and see if it helps. I ?not, ill go the trunnion route...

 

[LINUS]

Caster is the angle the housing is relative to the ground.

Slight negative caster gives a small window of acceptable dullness to steering input - dead zero or positive degrees will make the steering input twitchy or over-animated (read sketchy & less predictable) where that negative helps mute any traits like that.

Is that what you were asking?

Seems you already know the rear radius arm pivot washer mod, and the eccentric trunion bearing correction method - so I swear I'm speaking under your knowledge base. IDK.

 

[Noahrob]

The way I understand it, the washer mod is for the front hole of the front radius arm and moves the mounting point down, creating positive caster.
I guess I just need to decide if I want to pull my washer mod apart or go the trunninon route. Washer mod is cheaper so I think I will go that route.

Happy Easter.

 

[Pin_Head]

Castor is an oil from the Castor bean that is used as a laxative.

 

[Rifleman]

Noahrob, Caster angle is how much of a tilt, fore, and aft, your front axles steering spindle is set at. Caster angle matters to you because it's what causes your front tires to return to steering straight ahead after completing a turn, and then stay steering straight ahead. If your caster angle is off, it can cause your truck to wonder around all over the road while trying to drive straight ahead. It can get really scary if the road your driving on has a uneven center crown, or ruts in it. Plus when you turn into a turn, if your caster angle is off, at first it may seem that your not turning the steering wheel enough, then without warning it will seem that you've turned the steering wheel to much. This can make your truck at the very least dangerous, and at the worst uncontrollable at highway speeds.

 

[LINUS]

The way I understand it, the washer mod is for the front hole of the front radius arm and moves the mounting point down, creating positive caster.
I guess I just need to decide if I want to pull my washer mod apart or go the trunninon route. Washer mod is cheaper so I think I will go that route.

Happy Easter.

Not if you're doing it the way 99% of the threads I've seen.
Not to say I know all about this, but you are trying to 'tilt' the entire axle clockwise if you are looking at the Landcruiser from the LH / USA driver side.

The way I know the 'washer mod' is the dropping of the rear of the radius arm as mounted to the frame. Seems ~3/4" or shy 20mm was the number, but worth a recheck.

Anyhow, caster correction is only going the right way if you either drop the rear radius arm mount, or the rear of the axle mount, or raising the front one.

I think your way is going the wrong direction if I read your post correctly.

You may want to just run the press-in bushings or buy caster plates - going the wrong way will really be maddening & if welded, you're stuck undoing & reworking.

 

[LandCruiserPhil]

Sadly the washer mod offers very little in the way of correction if you goal is excellent drivability.

The difference between 2 and 4 degrees is night and day.

What is your measurement from the wheel center to the underedge of your flare?

 

[aviador]

Hi guys.
In all of the threads regarding caster i always see that the options mentioned are either caster bushings or caster plates.
What is the consensus regarding castor bearings? I see that Slee offers them in 1 and 3 degree options and as far as i can tell they would be a good option as they are not increasing the driveshaft angle.
What am i missing?
Thanks

 

[Pin_Head]

Hi guys.
What am i missing?
Thanks

3 degrees is not enough for many lifts. It is good for 2 inches.

The inners of offset bearings are smaller than the originals and may not handle the load as well.

 

[Noahrob]

Thanks guys, right now the measurement from the middle of the hub to the bottom of the fender flare is 24". I have the OME caster (not castor correction bushings as well as the offset rear radius arm bushings. In looking at the Slee caster correction plates, it appears it does the same thing that I am attempting to do with the washer mod, namely it moves the front radius arm mounting bolt down about 1/2".

 

[Lankan]

Hey guys,

Wanted some advice on my set-up, as even with SLEE caster plates (designed for up to a 4” lift) I am at +2.6° of caster, and the vehicle still feels a little like it’s “on it’s toes”, and not as steady/planted on the highway as I would like it to be. Here’s what I have installed, and how it sits:

1. Slinky/Icon intermediate 3.5- 4” lift (center of axle to bottom of fender is 23.75”; I do not have fender flares).
2. SLEE castor plates that are advertised as suitable for up to a 4” lift.
3. As you can see from the pictures during full articulation, my drag link is hitting the radius arm, and the drive shaft is quite close to the sway bar.
   1. Due to these two factors, caster correction with trunnion bearings or adding radius arm caster correction bushings (in addition to keeping the current caster plates) would not be an option, correct?
4. I do not have any driveline vibrations, and still on the stock drive shafts.

The only options (I think) I have for correcting the castor are:

1. Drop brackets from Extreme Landcruiser (@ $299 + shipping). Minimum they have is a 4” lift drop bracket. If I add this and keep the castor plates that are currently welded on, would I have too much +caster?
2. Extreme Landcruiser radius arms (@ $1499 + shipping)
3. Slee radius arms (@ $1145 + shipping)
4. Delta radius arms (@ $990 + shipping)

If I get new radius arms, do I HAVE to remove my castor plates (that are welded-in), or I can use a lower lift radius arm (ex: 2”) and keep the castor plates? I am going to stay with this lift and not go any higher, along with 35’s, as I DD my 80. Figured I would ask on this post/forum so I can fix it on my first try! Thanks in advance for any/all advice!!

 

[landtank]

you could swap in my caster plates and eliminate the tie rod contact with the radius arms and add a little more caster as well.

As for the drive shaft contacting the swaybar, do you have drop blocks in place?

edit: that tierod clamp should be rotated into the proper position so it doesn't contact the radius are when you turn.

 

[Lankan]

you could swap in my caster plates and eliminate the tie rod contact with the radius arms and add a little more caster as well.

As for the drive shaft contacting the swaybar, do you have drop blocks in place?

edit: that tierod clamp should be rotated into the proper position so it doesn't contact the radius are when you turn.

Roughly how much caster would yours add... the SLEE for example is yielding +2.6*? I do have drop brackets for the sway bar, and yeah, I will check for interference and rotate the tie rod clamp, thanks!

 

[landtank]

another 2*, but would likely measure less because of a slight bump in height from better aligned spring perches.

 

[toyota guy]

What all of the caster plates and bushings don’t take into account is the driveshaft angle which is pretty important on a full time 4x4. I recommend getting your driveshaft angle correct by whatever caster plates are necessary to do that (or make your own for free like many people do) and then search for instructions on a “cut and turn” for your knuckle balls. It’s very easy, I did mine from start to finish in about 3hrs. Then you can make the driveshaft angle correct and the caster correct. You do need access to a welder though.

 

[pnwcruiser]

https://m.tirerack.com/tires/tiretech/techpage.jsp?techid=4

 

[landtank]

What all of the caster plates and bushings don’t take into account is the driveshaft angle which is pretty important on a full time 4x4. I recommend getting your driveshaft angle correct by whatever caster plates are necessary to do that (or make your own for free like many people do) and then search for instructions on a “cut and turn” for your knuckle balls. It’s very easy, I did mine from start to finish in about 3hrs. Then you can make the driveshaft angle correct and the caster correct. You do need access to a welder though.

my caster plates align the pinion for use with a DC shaft that runs clean and induces caster correction equal to a cut and turn. No need to go through all that.