Simple, I like it.
Washer Caster Mod (1 Viewer)
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can someone help me with the geometry on this one? i’d really like to understand it.
at the axle there is a front bushing and a rear bushing.
the instructions say “moved the rear holes in the bracket 1/4” back and up 3/8 “”.
this is talking about the bushing just behind the axle (not the forward facing one)? which picture shows this? it looks to me like at least one photo shows 1/4” back and 3/8” DOWN. also can someone remind me which way i am rotating the axle to get the caster back to stock? i want to can’t it /forward/ more than it is after it was lifted? i can’t quite visualize this and would like to.
THANKS
at the axle there is a front bushing and a rear bushing.
the instructions say “moved the rear holes in the bracket 1/4” back and up 3/8 “”.
this is talking about the bushing just behind the axle (not the forward facing one)? which picture shows this? it looks to me like at least one photo shows 1/4” back and 3/8” DOWN. also can someone remind me which way i am rotating the axle to get the caster back to stock? i want to can’t it /forward/ more than it is after it was lifted? i can’t quite visualize this and would like to.
THANKS
If you are lifted 2" or more look elsewhere
shoot. i totally missed that phil. how much adjustment is here? it’s got a 2” lift phil? either way won’t the geometry be the same for all of them. i mean if you are just looking at the geometry it is 2 degree correction here for 2” lift. so if i wanted to sketch up the geometric relationship it would be like center if the rear bushing through a line at the driveline? and kevin’s “over and up” or “over and down” should let me sketch it up.
like 1/2” back snd 3/8 up or down should give you 2 degree adjustment or whatever adjustment this is.
I would suggest knowing what your caster reading is currently FIRST. The factory caster is 2°-4°. At 2° on a lifted 80 you are still chasing sheep when driving. At 4° your mom can drive your 80 at 80. YMMV
thanks. roger that.
i’m going to get measurements (3” lift) for caster.
i think part of what i was hoping to do was to figure out where the caster (and caster correction geometry) is coming from. meaning i wanted to draw up a diagram to see what the geometry was on the correction.
so like caster is the measurement between a perpendicular at the axle and the vertical at the axle (as best i can tell).
so the center of the three bushings are presumably in some relation to this. and the caster plates have some geometry in relation to correct it.
i /thought/ there was a thread somewhere showing this but i couldn’t find it.
do you know what i am saying? i want to draw the geometry so i can see how it is working geometrically.
seems like you could do this with the 1/2 and 3/8 if i could figure out how these holes are being adjusted.
Sure I do understand but you need to know your starting point. All 80s are slightly different from a starting point.
thanks. sorry. i am being super geeky about this so it is hard to explain.
i want to find or draw a diagram so i can see the angle correction in these plates.
they basically move the holes by some amount - 1/2” and 3/8” in some way in this example that i don’t totally understand.
i am saying i want to try to understand this example do i can draw it to see if i understand it.
as a theory exercise but not as it applies specifically to my rig.
for instance in kevin’s example what holes is he moving and by how much?
A. is the rear bushing staying where it is or is it moving? by how much?
B. same for the pair of bushings at the front. do one or both of those move in this example and if so by how much?
i want to draw the diagram is i can understand it.
like are all three of these images the front bushing at the front axle that is getting moved and is it being moved 3/8” /downward/ and 1/4” /backward/?
and if so is it for a total of 2 degree of caster adjustment?
and if so is it for a total of 2 degree of caster adjustment?
I don’t know exactly what you are trying to figure out. When you add longer coils to the front of an 80 series land cruiser the effect on the front suspension is the axle rotates. The bushings or plates offset this rotation to realign the axle geometry. The limitation on the realignment with bushings or the washer mod are about 1 degrees so a lift of more than 2 inches doesn’t typically get resolved with either method, but will improve things. Most OME lifts get you to about 3+ inches and would benefit more caster correction.
like here is the dobinson plate.
it’s trigonometry and i just wanted to draw it up to see if i can understand it.
seems like it is all right there i just haven’t seen a drawing of it.
yeah. i wanted to draw up the geometry so i understand it.
it’s trigonometry and i just wanted to draw it up to see if i can understand it.
seems like it is all right there i just haven’t seen a drawing of it.
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thank you medtro. i didn’t realize this was in a regional forum i must admit. still some of the best info out there on this topic.Suspension Geometry With Various Caster Correnction
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Honestly I don't understand your description. If you are looking for more than 2 degrees correction without buying caster plates, then may be this is what you need. Before you ask, no I don't have any geometry
. Last line says "Elongating by bolt diameter (14mm) moves caster two degrees. Four degrees change could be obtained by doing similar elongation to back mounting hole in opposite direction."
OK. i haven’t seen that link. who put that together? i did see a pdf elsewhere but it is the same as the info here.Honestly I don't understand your description. If you are looking for more than 2 degrees correction without buying caster plates, then may be this is what you need. Before you ask, no I don't have any geometry
also i did not know you could double your adjustment by also doing the rear one in the opposite direction. thanks.
but for this case he specifically says you should move the hole 1/4” BACK and UP 3/8”.
it looks like he meant 1/4” back and DOWN 3/8”.
your link says 0.55” down. kevin’s moves it relative to the front and back.
but i want to make sure i am not missing something on his method.
we are looking at the front most bushing in this photo? he says to move it back 1/4”. did he mean to then move it DOWN 3/8” i guess?
ToyotaDon
I am here
The front of the AXLE moves up, and the rear of the AXLE moves down to increase caster. The bolt (and radius arm) position in relationship to the axle would be the opposite, and seems to be moving in the pictures.
Another note is that Kevin recommended raising the rear of the axle slightly to provide clearance between the steering link and radius arms, something that at least one of the flavors of brackets is also designed to do.
Finding the degrees of rotation would require finding the actual center of rotation by comparing the geometry between the the trunion bearings and mounting points on the axle. Technically, you could get close by just comparing mounting points with level, then moving the desired number of degrees from that.
Another note is that Kevin recommended raising the rear of the axle slightly to provide clearance between the steering link and radius arms, something that at least one of the flavors of brackets is also designed to do.
Finding the degrees of rotation would require finding the actual center of rotation by comparing the geometry between the the trunion bearings and mounting points on the axle. Technically, you could get close by just comparing mounting points with level, then moving the desired number of degrees from that.
hi TD. thanks a lot.
appreciate the help on the idea of raising the rear axle. i do have to admit i have to get under the truck to look at this and figure it out so i understand what it means. i also need to spend some time figuring out what the trunion bearings are or where the mounting points are on the axle etcetera.
so apologies if this is thickheaded or just hard to communicate in a thread or i don't know what but the text states:
"Moved the rear holes in the bracket ~1/4" back and up ~3/8"".
so it seems to me it is specifically saying the hole has been MOVED 3/8" UP and 1/4" BACK.
but seems to me like it should read 3/8" down and not up. no?
or i am misunderstanding the geometry or what is being moved?!
ToyotaDon
I am here
That picture is the front hole, which gets moved down to raise the front of the axle (holes are in brackets welded to axle). The text is talking about the rear holes being moved up, bringing the rear of the axle down.
thanks. thats what i started thinking...
so if you are doing this modification so are going down 3/8" (9.5 mm) and back 1/4" (6.35mm) with the hole in the front of the bracket and up 3/8" (9.5mm) and back 1/4" (6.35mm) for the rear bracket?
and that nets 5 degrees of positive caster ("Rolled the axle ~5 degrees, has ~.5" of arm to tie rod clearance. Should work and flex better than correction bushings.").
is that about right?