steering allignment

[Finnsllc]

Afternoon, im doing a bit of fine tuning on a couple of the cars. Was wondering how precise everybody goes with off road steering allignment. Camber and toe in as well as arm adjustment then servo arm adjustment. Not racing but nce in awhile on the street thats where i see that fine tuning needs to be done. On dirt is close, close enough?thx

[Mad Ax]

For me, a lot depends on the quality of the car.  Some kits have so much slop that they'll vary widely from toe in to toe out depending on an unpredictable number of outcomes.  But generally under acceleration a driven axle will pull towards toe-in and under braking it will go towards toe-out.  (IIRC, the Mk1 and Mk2 MX5s had soft rubber bushes on the front mount of the rear lower wishbones, so that under hard acceleration the rear axle would go toe-in to add stability but would return to neutral under cruise and braking for better tyre wear and faster steering.  Lots of people didn't know this so they fitted "uprated" poly bushes thinking they were getting a handling improvement).  An undriven front axle will generally slop towards toe-out except under some cornering conditions.  Again, slop in the camber will cause negative camber at rest but will go positive on the outside wheel when cornering.  With that in mind, make setup adjustments based on the loads that corner is likely to experience under the conditions you want to control rather than the conditions at rest.

In fairness most basic chassis don't have that much adjustability anyway, as you get more adjustability you also get more quality, and therefore less slop.

As for what difference it makes - YMMV.  I find toe angle makes the biggest difference on fast tracks with long straights.  If your bashing area has some long straights, especially narrow straights, adding some toe-in will make the car more stable.  If you find the car wants to veer of left and right on flat-ish ground then a bit of toe-in might make it more controllable.  It might slow down your steering response a little but if you're only bashing, you might not notice.  For bashing, I would choose a fairly neutral, stable, slow-responding setup, especially as my current bash-zone is restricted to my little garden and has some fairly solid wheel-level obstacles.  If your bashing area is bumpy enough that the wheels are mostly off the ground, geometry changes aren't going to be that noticeable (or if they are, you'll only notice then when the wheels hit the dirt).  You need to control the bumping before you can control the direction, which you'll do with shock and spring adjustments, if you can - if your bumps are bigger than your car's suspension travel then you're beyond the scope of tuning.

Setup changes do make a difference, or racers wouldn't spend ages getting them right, but it's all down to track surface, conditions, tyre choice and driver preference.  I'm not a good enough racer to know what's what, I stick with close to book settings for most cars.  90% of setup is tyres and Tamiya off-road tyres are too generic to be competitive.  Unless you've got a stack of tyres to choose from, you could be chasing setups every time the weather changes or you go to a new place to bash.

IMO the best thing is to get a consistent setup when you build the car.  When I'm building or reconfiguring a car, first thing I do is centre the servo, with the servo removed from the car.  Often with the servo centred, the horn / servo saver will be off at an angle when installed.  I use the subtrim option on my Tx to get it properly centred.  That means the horn will always be in the right position with the trims centred, unless the horn/servo saver shifts on the spines or the servo itself is junk.  IMO, trim should only be used to make adjustments from stock under running conditions - e.g. if I hit a barrier on track and my steering goes out of trim.  With some cars and handsets this just isn't an option.

Then I install in the car and build as per the book.  I don't usually bother doing any setup until the entire car is assembled and loaded with electrics, as sag will affect geometry.  (If I'm setting up a drift car, it's necessary to have the shell installed when making measurements, as the suspension is sensitive even to shell weight).  I start with book settings but, assuming the car has an adjustable link between servo and steering assembly, I'll adjust that first for centre neutral steering.  I have the radio powered in case the servo is moved during adjustment.  For cars that have no adjustability, there's nothing more I can do at this point.

Once a neutral straight position is achieved, I'll set the front toe angle.  Generally I'll go neutral under braking/drag (put the car on a flat surface / setup deck and push backwards lightly on the front wheels to take up any slop).  If it's a 4wd buggy, the wheels will pull to toe-in under acceleration but be neutral when braking and cornering.  My reactions aren't that good so I don't like a toe-out setup.

Does it really make that much difference?  Hard to say, since there's so much at work, but since I've been paying attention to stuff like this (only the last year or two) I have noticed all of my cars have become easier to drive.

I hope that helps, as I said YMMV, have a play and see how you get on.  Only change one thing at a time.  Try changing from one extreme to the other, then swing back and forth until you get a setup you like.