leveling_only_crowdOPOn 35sAmarillo, TX28 posts · joined Nov 20252018 Silverado 1500 LT 5.3 · 4 in lift · 35x12.50R18
#1
i am the leveling kit guy who finally broke his own rule and went to a 4 inch lift on my 2018 Silverado 1500 with 35s. two questions, one about the law and one about the way it drives, because i am now the guy i used to argue with.
first the law. i keep reading that there is a legal limit on how high you can lift and a separate one on bumper height, and that it is different in every state. i am in Texas but i run up into New Mexico and Oklahoma for work. how do people actually find the real rule for their state instead of the stuff somebody posts on a forum from 2009. i do not want a ticket and i really do not want to fail an inspection over frame or bumper height i could have checked first.
second, the drive. since the lift the truck darts when only one front wheel hits a bump or a rut, like the bump steers the truck for me. straight smooth road it is fine. is that bump steer from the lift geometry, or do i have a worn drag link, and how do i tell the difference before i start buying parts. the shop that did the lift says it is normal and i do not believe them.
mod_dale_rModeratorBillings, MT71 posts · joined Nov 20252015 Ram 2500 6.7 · 4.5 in Carli · 37x12.50R17, 4.10s
#2
taking the drive question because that is my old job. bump steer is the steering changing by itself as the suspension moves up and down, and on a lifted independent front truck like your Silverado it comes from the tie rods and the steering linkage ending up at a different angle than the control arms after the lift. a kit that includes a steering correction, a knuckle or a relocated tie rod, keeps the angles matched. a cheap kit that just spaced everything leaves the steering on a different arc than the suspension, and the truck darts over one wheel bumps exactly like you describe.
how to tell it from a worn part. jack the front, grab the tires at 9 and 3, and feel for play in the inner and outer tie rods and the idler and pitman side. no play but it still darts is geometry, which means the kit needed a correction piece it did not come with, or the alignment, especially toe and caster, is off. play in a linkage part is a worn part, replace it and realign. do the free hands on check before you believe either me or the shop.
your truck is IFS so you will not get a dropped pitman arm or a drag link flip, those are solid axle fixes. on yours the answer is usually the right tie rod and steering geometry for the lift plus a proper alignment. if the shop set it up without correcting the steering angle, that is on them, not on you.
speedo_recal_helpLeveledYakima, WA19 posts · joined Nov 20252015 F-150 XLT 2.7 · 2.5 in level · 33s
#3
on the legal side, the trap is that there are two separate rules and people mix them up. some states regulate frame or body height, some regulate bumper height, some regulate headlight height, and a few do not have a hard lift limit at all but will still fail you if the headlights or the bumpers are out of range. so "is a 4 inch legal" has no national answer.
the only way i trust is to read my own state's actual vehicle code or DMV page, not a forum. do not take my word or anybody's here for your state either, laws change.
bds_or_rough_countryOn 35sKnoxville, TN47 posts · joined Nov 20252016 Silverado 1500 5.3 · 6 in lift · 35x12.50R20
#4
same truck as you one generation apart and i will confirm dale cold. my 6 inch kit darted exactly like yours until i figured out the alignment shop set the toe but never touched caster, and a lifted IFS truck with low caster wanders and darts and does not want to come back to center. they reset caster to the high side of spec and it calmed down most of the way, then the right tie rod turned out to have a little play and that was the last of it.
for Texas specifically, the state publishes the rules, go to the state's own motor vehicle site and read it rather than trusting a sticker on a shop wall. the official Texas page is txdmv.gov and for New Mexico and Oklahoma you want each of those states' own DMV pages since you cross lines for work. check all three since a legal truck at home can be over the limit one state over.
leveling_only_crowdOPOn 35sAmarillo, TX28 posts · joined Nov 20252018 Silverado 1500 LT 5.3 · 4 in lift · 35x12.50R18
#5
update and you all nailed it again. jacked it up, inner tie rods were fine, but the right outer had a little play, enough to feel with the tire at 3 o'clock. so it was both things dale split out: a worn part and a geometry problem riding together.
took it to a different alignment shop, not the one that did the lift. new outer tie rod, 70 dollars, and they reset caster to the high side and corrected the toe. the dart over one wheel bumps is basically gone, it tracks straight and comes back to center now. the first shop telling me it was normal was them covering a lazy alignment.
and i read the actual Texas page off that link instead of trusting the forum lore. my 4 inch on 35s is inside the rules here, and i checked bumper height too, which is the one most people forget. thanks, this is the second time this board saved me from throwing parts at a truck.
mod_dale_rModeratorBillings, MT71 posts · joined Nov 20252015 Ram 2500 6.7 · 4.5 in Carli · 37x12.50R17, 4.10s
#6
that is the whole lesson in one thread. darting after a lift is almost always a worn linkage part, a lazy alignment, or geometry the kit did not correct, and usually some mix of them. check for play by hand, fix the worn part, then get caster set to the high side by a shop that is not the one defending its own install.
and on legal height, read your own state's code and every state you drive for work, because none of us can answer it for you and the rule is not the same across a state line. good fix for seventy bucks and an honest alignment.
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