Castor Quesiton

tripped38

tripped38

Well-Known Member
Joined
Jul 9, 2008
Location
MI
Caster Question

Right now I am sitting at about 4 degrees castor. This is going to be run with hydro assist. IS this to little or do I need more? This Jeep will see the street, not a dd how ever.

The rig is an early 80's CJ 7 with a dodge dana 60 in the front.It is running leaf spring sliders up front instead of shakles. I could raise the jeep a couple of inches and be at 6-7 degrees. But right now the jeep is low. It has a flat drag link and I don't want to lift it any more then I have too.



Fixed because I shouldnt post when I am still asleep
 
Knuckles are leaned forward, so that would be positive?
 
yup...and you'll probably be ok with hydro assist. Without it the front end will want to wander with every bump you hit. I'd run it and see what happens.
 
thanks! From the reading I have been doing it sounds like I can get away with it, and if I am not happy I can change it...
 
You could add some angled shims to increase the caster.

shop%20shit%20085%20300x225.jpg


http://www.wfoconcepts.com/cr/Axle-Shims/3225
 
ok, i guess i don't understand, what is the benefit of such high positive castor? i thought with most solid axles, 1-2 deg positive is ideal? or is the high positive castor an advantage for front leaf setup?
 
as my understanding goes it has to do with when you make a turn and how the wheels come back to center.... I know there is a lot more to it then this, but that is as deep as I have really gotten....
 
Ok if the top of the knuckles are leaning forward (towards the front of the Jeep) then you have negative camber and I have never seen someone drive on the street with negative camber. Ideally you want positive caster but the exact amount is usually dependent on what your vehicle wants. I usually end up somewhere between 3-7 degrees positive on most of the Jeeps I have ever setup. With negative castor I think it is going to be a handful to drive on the street. The steering is going to be very lazy and it is probably going to wander a good bit.

Jeremey
 
Abadjeeper: I believe I was wrong when I said I had positive caster, as in fact it is negative caster. However I think that with the hyrdo assist and the minmal caster I have I am going to try it and see what happens. If it is horrible or unmanagable then I will either shim it or adjust it... and it is a long time before this will ever see the road.
 
tripped38 said:
Knuckles are leaned forward, so that would be positive?
Click to expand...


Soo.... is the upper ball joint forward of the lower or behind it?
You want the upper ball joint to be behind the lower which is positive caster. 4 deg. positive is not terrible but on something with a solid axle, big tires and negative offset wheels like most of us run I typically shoot for more like 5 to 7 deg.

How are you measuring your caster angle? What tool and where are you measuring it at. This can make a major difference in your actual measurements.
 
ABadJeeper said:
Ok if the top of the knuckles are leaning forward (towards the front of the Jeep) then you have negative camber and I have never seen someone drive on the street with negative camber. Ideally you want positive caster but the exact amount is usually dependent on what your vehicle wants. I usually end up somewhere between 3-7 degrees positive on most of the Jeeps I have ever setup. With negative castor I think it is going to be a handful to drive on the street. The steering is going to be very lazy and it is probably going to wander a good bit.
Jeremey
Click to expand...
True..but with hydro assit all that goes out the window because you have a cylinder holding constant pressure on the steering system, so it usually does'nt wander or set up death wobble. Again...run it and let us know.
 
I've been measureing from the top of the sping plate with the spring sitting on it. I probably should pull the top of the kingpin and measure from there. But yes the upper kingpin would be in ahead of the lower kingpin.

I have the ability to change this to make it correct. I just want it to work with out having to go back in and change it later.

Thanks for all the help and keep it coming.
 
The top of the spring plate will not give you an accurate measurement unless you know its angle in relation to the upper and lower bj. You are right that you should measure the top of the kingpin plate or high steer arm. This will also need to be done with the tires on or axle on jack stands and all the weight sitting at ride height.

If you truly do have -4 deg of caster then it will drive horribly with or with out hydro assist. Correct me if I'm wrong but hydro assist would be neutral when driving straight there would be no pressure directed in to the cylinder in either direction as long as the steering box isn't turning. It would be some what lockeddue to the equal pressure on either side but that alone wouldn't hold against road feedback. So my understanding is that it would act mearly as a steering stabilizer.
If you are using a kingpin dodge 60 with stock perches I can't figure out for the life of me how you'd have negative caster with any leaf setup, unless its like half moon springs or 14" long shackles. Do you have any pictures of the current setup.
 
Lets speak the same language.

ai85.photobucket.com_albums_k51_hadfield4wd_Other_20Jeeps_20type_20pics_caster1.jpg


Negative caster is a very bad idea. Positive caster gives you a return to center. Negative will give you a return to lock. Set up the caster right then mess with the hydro assist.
 
my set up is this...
I am using leaf spring sliders on the front. with waggy springs. I have not built the rear mounts for the springs yet. if I set the jeep up with a ride height were the frame is say 21 inches off the ground then I am coming up with the 3-4 degrees of negative caster. Meaning the knuckle is leaning forward. This is while it is sitting on tires that measure 35.5 inches.
IMG00015-20101102-2050.jpg
IMG00018-20101102-2252.jpg
That is best picture I have right now. If I lower the rear mount for the spring it will raise the jeep a few inches but perhaps give a better angle.
Tomorrow night I will pull the upper kingpin cover and get another measurement with the angle finder and see where it is at.
 
Yea now that I have see it I still see no way that you can have negative caster. Even with the rear of the spring sitting on the frame the front of the spring will still be higher than the rear because of the frame design. So If you were to measure caster on the u bolt plate like you said there is no way that its tilted forward.Now with that being said I think you're getting a little ahead of yourself. Once you get everything built including the rear hanger then I'd worry about caster. What you've got so far looks good so keep up the good work.
 
Thanks for all the input! I ended up with 3 degrees positive caster! Hopefully that will work!
 
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