best way to check and set caster

I have to replace the spring perches on my D30 axle riding on my YJ springs. The perches are not wide enough for the springs. I figure that i can set my caster to 7* with these new perches. What is the best way to find and set this angle?

Thank you,
Chris

 

Thank you Patrick.
Can I go off the bottom ball joint or this boss to the left of the ball joint on the knuckle?

I would rather not take off the spindle and everything to get a degree reading.

 

The flat portion of the bottom ball joint works well. I wouldn't trust that flat casting next to the upper ball joint. No way of knowing for sure if it is square to the steering axis and could give false readings.

 

Thanks a lot. I will take my brand new angle finder and stick it on the bottom ball joint to see where I get the right angle after I cut off these old spring perches. I appreciate the info.

 

This is the angle finder on the bottom ball joint. This is where I start. I had 5* shims under there so my caster was about 6 or so. I will cut off these spring perches and set it to 7* I will want to put some weight on the rear and the front to simulate actual ride weight.

 

YJ springs are 2.5 inches wide. The old spring perches on this drum 1974 D30 were 1.75 wide and only at the ends. In order for the new perches to fit, I had to first grind off the old ones. On the drivers side, its a direct fit. The passenger side is more involved. The new perch will ride ON the differential carrier, or housing. Yes, the housing is called the "carrier". ( What you're going to say is the "carrier" is what the ring gear rides on, no, that is the "case". A man who teaches this at a school has stated this is the correct nomenclature. Take your argument to him.)


back side


I didn't measure the radius, I just set the part on the axle tube and traced the housing. I was going to grind the radius with a 4.5 grinder, but why do that when I have a rotary table I have never used?


So thats how i made that part fit right.
I have this mocked up at 9* or so. The magnetic protractor is stuck to the bottom ball joint. I will be using slightly longer shackles so I will probably leave it at or around 8*, tack the spring perches and see what the number is when I put on the new shackles.


The protractor was under 10 bucks at the orange box store. No excuse to not have one when doing this.

 

I set the caster to 8*. I will be buying or making longer shackles that will cut the angle down to 6 or 7.

 

Looks great. That's how I do mine as well. 7 is a good number for a jeep.

 

Good work here, Chris. You do pretty well for claiming only novice status. Your work is helping many expand knowledge bases and abilities if not actually inspiring folks to try to do things that they once they were not capable of doing. Thank you.

You are quite correct sir. And I have probably disappointed the teacher with a recent post of mine, which I have just corrected. My apology, teach.

 

Dave,
You're much too kind.

The great thing about this site is that if you cannot find an answer to your issue doing a search, someone will correct you if you're wrong, but not in a derogatory or demeaning way. That polite constructive criticism, that this site expects, helps us all grow, learn and do better work. Without this framework the conveyance of high quality information would be diminished.

Thank you all for allowing this forum to be such a positive place.

 

I've got to pitch in a comment here...
I don't post much, but I do read a bunch. I want to join in and thank the members for keeping this sight a positive one. I look forward to visiting here. I also want to thank the OP for this inquiry. I've been wanting to replace the springs on my cj5 (79) with YJ...hoping for a better ride. I have been leery of this as I wasn't sure what to base the degrees off of. I am still curious though about the welding. Isnt the " carrier"
cast iron? How would that be approached, if it is? Thanks



QUOTE=47v6;1230539]Dave,
You're much too kind.

The great thing about this site is that if you cannot find an answer to your issue doing a search, someone will correct you if you're wrong, but not in a derogatory or demeaning way. That polite constructive criticism, that this site expects, helps us all grow, learn and do better work. Without this framework the conveyance of high quality information would be diminished.

Thank you all for allowing this forum to be such a positive place.[/QUOTE]

 

Did you also check the Pinion angle? Sometimes the need arises that in order to adjust the caster angle the large C's have to be cut off and moved to preserve the pinion angle set by the spring hangers.

 

I think its cast steel. I don't really think it is a strong weld. It will hold though. The weld on the tube is strong for sure and the combination of U bolts, center bolt in the spring and the spring perch should be plenty.

I didn't check the pinion angle. If I was running this thing in 4x4 all the time I would be concerned or if it was the rear differential it would matter a lot. Since I put in in 4wd seldomly, I am not all that concerned. I had really contemplated cutting the welds on the C's and doing that. Posimoto did. For him being a mostly off road trail rig, that was important. Maybe someday it will be to me as well and then, I have another project waiting.

 

That's so true... propbably the only forum were people stay polite!
It seems that the fact to be 'distant' with a forum name give to people the possibility to 'talk' badly.
It is like if they were invisible, like in the Greek history, ring of Gyges by Plato.

 

Why do you think the spring perches are not wide enough? I have YJ springs with a D30 axle. I didn't change perches.

 

I could have left the old ones on, but I needed to change the caster anyway and this was the easiest way to do it and put on the correct width perches matched to the springs. I am sure I would never had an issue and I am sure you won't either. Its just what i did.