Castor Correction - how much?

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May 7, 2006
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Since I installed 35" tires my truck wanders badly on the highway, especially on rutted pavement ( my axle is moved forward 30 mm with OME suspension). Prior to the 35's going on the castor was 0 degrees

The available castor shims seem to be 2.5 degrees and 4 degrees. What angles are people running with 35's ?
 
. Most people with a 2.5" to 4" lift and 33" to 35" tires will go 4 degree shims.
 
I'd have an alignment shop check the uncorrected castor and go from there. Specs call for 0-1 degree +, as I recall, for the 70 series.
 
castor isn't all that critical, as long as you have enough of it.

go with the bigger shims. worst case scenario, you have a degree or two too much, and this causes your truck to drive beautifully on the highway, and track straight. Not really any negatives.

Most cut and turned SOA'd cruisers like to end up with 5 deg positive.

always amazed toyota gives this clunky old buckets only 1 degree of castor...
 
castor isn't all that critical, as long as you have enough of it.

go with the bigger shims. worst case scenario, you have a degree or two too much, and this causes your truck to drive beautifully on the highway, and track straight. Not really any negatives.

Most cut and turned SOA'd cruisers like to end up with 5 deg positive.

always amazed toyota gives this clunky old buckets only 1 degree of castor...

We had a jeep at NWF and they had negative 7 or 8, this truck was scarey at 80 plus K a hour, hit a bump and it would start swapping really bad...:beer:

Rob
 
Models from Jan.1990 to Aug.1999

LEAF SPRING

Caster - Short, Middle, Semi-long: 1°15' ±1° (1.25° ±1°)
Left-right error: 30' (0.5°) or less

Caster - Long (Van): 0°50' ±1° (0.83° ±1°)
Left-right error: 30' (0.5°) or less

Caster - Long (Pickup): 0°30' ±1° (0.5° ±1°)
Left-right error: 30' (0.5°) or less


COIL SPRING

Caster: 4°05' ±1° (4.08° ±1°)
Left-right error: 30' (0.5°) or less


Models from Aug.1999-

Caster - 79 series: 3°35' ±60' (3.58° ±1.0°)
Right-left error: 45' (0.75°) or less

Caster - Others: 4°20' ±60' (4.33° ±1.0°)
Right-left error: 45' (0.75°) or less
 
Caster - Long (Van): 0°50' ±1° (0.83° ±1°)
Left-right error: 30' (0.5°) or less

Caster - Long (Pickup): 0°30' ±1° (0.5° ±1°)
Left-right error: 30' (0.5°) or less

impressed with those ones ..
 

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