string alignment vs. hunter machine alignment

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i had been thinking of getting an alignment machine if i could find one cheap enough. one came up on craigslist at the salvage yard for $500 large so i thought i would check it out. it had been sitting for a few years and was pretty dirty and the guy wouldn't guarantee it, so i had to decide if i was going to gamble the 500 and maybe have to invest more or get a really sweet deal. i gambled.

it is a hunter d111 with the laser heads. had to have the service rep come out and play with it but finally got it working without having to replace anything, just labor, and the guy likes to race

the machine is real sensitive. we could bump one post and effect the head on the diagonal wheel, anything running on the same breaker would effect the readings.

anyway, for the alignment, i had done an alignment with a smart gauge and string for the toe. for the toe i had ran a string down the middle of the chassis using a plumb bob and tried to center everything toe wise then did the final fine tuning measuring outside wheel to outside wheel with a straightedge across the tires held on with bungee cords and a plumb bob off these to a tape stretched across the lift.

the camber using the smart gauge was the same as the hunter, i didn't check the caster. the toe on the rear was the same, i'm not sure the difference on the front. the thrust line was offset as i knew using the string but i couldn't do anything about that, with the hunter i changed that and got the wheels closer or pretty exact on the thrust line front and rear.

with the string alignment the car drove fine, with the hunter alignment it is dead in the water smooth. i set the front toe to 0, and the rear was close to 0 except the half turn of the heim caused the rear to toe out .010, it was either that or toe in .090, another 1/2 turn would be .190 toe in, so i think it was pretty consistent.

pretty cool machine anyway. i think for camber and caster the smart gauge works fine, but getting the toe set which is critical for a suspension with heim joints is pretty hard to do with the string. just a quarter turn on the front ball joints was worth .010", and tightening the lock nuts would move the toe .010".