caster

[tony58]

I have been working on my 1977 fj40 with a caster issue It has a 2.5 spring lift, and a 5 inch [center to center bolt] shackle lift running bf Goodrich mud terrain km2 33/10.5xr15 tires The font end is tight center arm is good I have tried 2.5- and 4-degree shims I still can't get the steering wheel to center after a turn, any help would be appreciated, it is a handful to drive I just put in the 2.5 and the 4 degree shim together and it is about the same, what am I missing?​

 

[pjohnson]

Are your shims installed correctly?
Toe-in set correctly?

 

[tony58]

yes the shims have the fat part to the front do you think I should go more than7.5 degrees.thanks

 

[pb4ugo]

You need to measure what your caster is now. Do you have a cheap angle finder? With the 40 on level ground and tire pressures equal. Measure off of the bottom trunion bearing cap. Don't use the studs or nuts. You should be able to catch the edge of the cap/plate. In the pic below, pretend the level is an angle finder.

 

[tony58]

yes, I just did that it about 6 degrees.

 

[pb4ugo]

That means you need an 8 degree shim. I think you need shorter shackles if your caster is off that much. A 2.5* lift shouldnt need that much of a shim.

 

[77mustard40]

That's plenty of caster, I'm at about 3 degrees. So the issue is the wheel not wanting to self-center coming out of a turn? What steering setup do you have, i.e. stock manual box, mini-truck, saginaw or other? Issue may be in the steering box as opposed to being caster related

 

[tony58]

stock steering but i put in electric p/s front end is tight

 

[jim land]

Why using 5" shackles with 33" tire?
Stock one is 2 3/4"

 

[tony58]

yes the wheel does not want to center after a turn

 

[pb4ugo]

Is that 6 degrees negative or positive? with the shim or without? You need to be more clear of what's going on. Was the lift just added?

 

[tony58]

Why using 5" shackles with 33" tire?
Stock one is 2 3/4"

that is what came on the 40 do you think i should go down to a stock shackle

 

[tony58]

Is that 6 degrees negative or positive? with the shim or without? You need to be more clear of what's going on. Was the lift just added?

with angle finder on right wheel the needle points to 6 on the left of the finder as you look at it [if that makes sense] and yes shims are in place

 

[jim land]

that is what came on the 40 do you think i should go down to a stock shackle

Stock or a little longer (3.5 or 4 max) and probably 4° shim
You dont need 5" shackle

 

[60 40]

I know little about this but suspect that with the long shackles and placing the thick part of the shim towards the front you have rotated the axle down in the front much to much. This creates negative caster which will result in the issues you are describing (according to the interwebs).

Edit: actually the shim is rotating the axel up in front but the long shackles are negating their effect.

 

[pb4ugo]

I know little about this but suspect that with the long shackles and placing the thick part of the shim towards the front you have rotated the axle down in the front much to much. This crates negative caster which will result in the issues you are describing (according to the interwebs).

The thick part towards the frt rotates the top of the axle back which creates positive caster on a sprung under axle.

 

[pb4ugo]

with angle finder on right wheel the needle points to 6 on the left of the finder as you look at it [if that makes sense] and yes shims are in place

Your the one looking at the angle finder.

 

[tony58]

Your the one looking at the angle finder.

View attachment 3448063

looking at that i still have negative caster should i take all the shims out or get shorter shackles?thanks

 

[pb4ugo]

Idk, initially I would have put it together with maybe adding a 2* shim or not and then measure caster. The suspension needs to be loaded with the vehicles weight and level. .You say you have 6* shims installed and you're still at 6*-. If that's the case, somethings probably wrong. I run 4" skyjackers, I made shackles 2" over stk and installed 4* shims then took measurements. I was about 1*-. I made shackles 1" shorter which put my caster almost 1*+. I will likely install 6* shims in the future to put me at 3*+. Like I said b4, 2.5" lift with extended shackles shouldn't need 12* of shims. At some point you will have issues with the U joints and their yokes at full droop.

 

[77mustard40]

Let's see some pics please, shims installed, angle finder etc. so we can help with the caster issue.

Stiff steering sounds like something isn't right and its binding up. Is everything greased like the center arm? You should be able to turn lock to lock without effort with the front wheels off the ground.