Join Date: Sep 1999
Location: Palmyra, WI
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Re: Do front lift springs cause castor change???
You don't really want pinion angle to change. The u-joint yokes should be parallel (unless running a CV shaft), No matter what the angle of the driveshaft. If you only change pinion angle (on the diff) the angle at the t-case is still the same causing bad vibes. Yes, if the u-joint angle is too steep you will get vibes as well. This is what we live with in our SWB Jeeps. The correct way to get rid of driveline vibes in a lifted Jeep is to point the pinions at the t-case and have CV shafts made.
To answer your question, NO, new springs 'shouldn't' change pinion or caster angle, but everything is manufactured within a set of tolerances, so they might. Have it checked on a 4 wheel alighment rack after it's all together and ask them for a copy of the caster/camber/toe numbers. I've had a couple alignment shops tell me "It's all good" only to have a front tire junk in 3000 miles.