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Caster shims

PostPosted: Wed Oct 09, 2019 6:12 pm
by Binder Mike
I'm trying to get all my ducks in a row for my new front leaf springs on my S120 4x4. I'm ordering up new U bolts, bushings etc when it occurred to me that maybe this truck had caster shims from the factory. Besides being flat as a pancake the springs that are in there now are a mish mash of wrong leaves and knackered parts so I can't go by what I have which is no shims. A look at the manual does not show shims.

Somewhere in the murky past (35 years ago) I converted an old ford bronco to a leaf spring front end. I seem to remember measuring caster in degrees with a magnetic degree finder stuck to the back of the pinion yoke for the U joint before I welded on the new spring perches. Can I use the same method to find my caster angle on my Binder and also what is the correct degree setting for my axle. While I am getting the new springs in I feel the truck would handle its best if I get this dialed in at the same time.

Re: Caster shims

PostPosted: Wed Oct 09, 2019 8:34 pm
by PaulH
I think whether you'll need shims depends on what you get without them. But for the FA15, code 02015 front axle on the S120 4X4:

Camber at rim (degrees) 1-1/2
Knuckle pin inclination (degrees) 7-1/2
Caster (degrees) 2-1/2 to 3-1/4
Toe-in (measured from tire tread centers with caster and camber according to specifications) (inch) 1/8 to 3/16

Re: Caster shims

PostPosted: Thu Oct 10, 2019 7:11 am
by Binder Mike
Thanks for those numbers and being the voice of reason. Last night after I read your post I spent quite awhile online reading about caster angle, things that effect it , where to measure and how to correct if it's off. One interesting thing I found was that just the fact that my front springs have sagged lowering the front of the truck in relation to the rear has changed the caster angle so as you correctly pointed out I need to get my new springs installed, park the truck on a level surface and take my reading and see if it even needs shims.

Re: Caster shims

PostPosted: Tue Oct 22, 2019 5:59 pm
by Binder Mike
Update: The new springs are now in and the old ones are in the scrap pile where they belong. They were mismatched piles of leaves someone threw together to try and correct sag in both. One side had eleven leaves and the other had nine. The correct number should be eight plus neither spring pack indexed itself correctly in the spring perches , the whole thing was a mess. So now with a good set that locks into the perches plus regaining the original ride height the truck drives and tracks way better than it did before. While I haven't taken any readings my seat of the pants road test tells me to leave well enough alone. No shims needed!