Jafo

With 245/45 17 I've noticed that the tires stick to the road better. In particular, when the road gets uneven, the tires tend to pull the car in that direction. I was advised that changing the castor will get rid of this problem. Does anyone know what the castor must be adjusted to?

Newman

iTrader: (3)

the wider the tire the more it "obeys" the surface of the road. i dont think that is an alignment issue. its just your 245 tires following the irregularities of the road.

Norm Peterson

Increasing positive caster increases straight-line stability (and will also help front-end grip during hard cornering). Not a cure-all for the rut wander that wide tires are more apt to demonstrate, but it should help. BTW, some tires are worse than others in this respect.

Norm

BigDogJonx

iTrader: (7)

Newman, did you get your alignment done after the new wheels? I know I need to get it done since the tires on my last set of wheels were wearing incorrectly. Just wanted to know who was good at them here and at a resonable price.

Dixit

Newman

iTrader: (3)

no i havent done it yet. but i am down at school right now. i've only gone about 200 miles since i got them. i'm going to do it soon though.

mightima

It's really nice to learn new thing everyday. I'm having the same problem which I thought is alignment problem. My dealer fixed my alignment but after that my car seems to too sensitive and pull to either direction maybe depends on the uneven pavement...

What does a caster do? How can I adjust the caster? Can I just tell the dealer that I need to adjust it? Any side effect?

Thanks!!

Newman

iTrader: (3)

i am pretty sure when you get an alignment done they correct the caster. unless you purposely want the caster to be off a little bit to go with what Norm Peterson said about increasing straight line stability. but if you just want it to be "normal" then it already should be since you've had an alignment.

Jafo

Thanks Norm for confirming what I had thought. I just assumed that there are so many people running with tires that are wider than the OEM that someone would have already figured out the change in the Caster required to correct the problem.

Norm Peterson

If seems like it doesn't really want to go straight but suddenly "twitches" in either direction without particularly favoring either, toe is at least part of the problem. Toe out under running conditions doesn't favor straight-line directional stablity. Without considering the possibility of bent parts in the steering/suspension, a combination of caster at the minimum of its factory range and toe at the most toe-out end of its factory range could conceivably feel a little "nervous".

Maybe somebody will post the factory ranges and preferred settings.

To change caster you need to move the tops of the struts straight rearward (parallel to the longitudinal axis of the car). I haven't touched mine yet, so I can't provide any details regarding the means of adjustment. One side effect of caster settings that differ too far from the factory-preferred setting (either too much more or too much less) is that your bumpsteer curve will be affected.

Norm

SterlingMist00

How will the bumpsteer curve be affected?

mightima

Thanks! Newman.

Sorry about my ignorance. Could you guys explain "caster" and "toe" for me, pls? What should I tell my dealer that I want my car be serviced..?

Thanks!!

Norm Peterson

As you change the caster you also raise or lower the point where the outer tie rods attach to the steering arms, since those points are located several inches away from the ball joint in the car's longitudinal direction. This has the same effect as raising or lowering the rack or tuning the bumpsteer with a kit.

Think side view, and remember that the ball joint is the fixed point about which the caster angle is adjusted. Any point on the spindle/steering knuckle/strut that's not located in the transverse vertical plane that passes through the ball joint will have a vertical component of motion as the caster angle is varied. The further the point in question is from said T-V plane the greater the amount of this vertical motion.

Norm

Norm Peterson

Ideally they should be able to get it reasonably close from your description of the symptoms and their readings of where caster, camber, and toe are currently set.

Note that all three of these parameters are given normal ranges rather than strictly specified values. Within each range there's a factory preferred setting, usually at the midpoint of the range. The alignment tech should have the experience to understand when settings at other than the midpoints make sense. IOW, you can be slightly "off" with respect to the preferred setting but still within the allowed range. What you're unlikely to get is settings that are outside these ranges, unless you take it to an aftermarket shop that does "custom" alignments, as for race cars.

As for the definitions, toe describes the amount by which the two wheels on a given "axle" are not parallel as seen in plan view. Caster is the (usually) backward tilt of the steering axis as seen in side view. And camber is the amount by which a wheel is not perpendicular to a horizontal road surface as seen in front view. Most of the soft-cover books on suspension or handling provide similar definitions plus some sketches in case you're having trouble visualizing.

Norm

mightima

Thanks for the explanation, Norm!
You guys are awesome!

irvine78

iTrader: (2)

with 245s...you will go wherever the cracks on the pavement goes..

just a thing to deal with wide tires...you think 245s bad? try with 335 wide tires..now that's Bad~~

SterlingMist00

Thanks for the explanation. I also run 245s and experience the same problem as Jafo. I will take my car in and have them adjust the caster and see if it helps.

wdave

The Max has no provision for camber or caster adjustment. The most you can do with a stock car is move the strut tops to the rearward limit of their hole slop for a touch more caster. Otherwise you need camber/caster plates to change caster, or slot the holes in the strut tower. A little more toe - in, within stock specs, will help the wander a little.

SterlingMist00

Much appreciated wdave.