what is usually the norm for running spacers between the steering block and upper a arm? I have been told by some to not run any but have seen some of the fast guys with gobs of spacers. How does the placement of the spacers affect the chassis entering/exiting the turns? My assumtion is that the more spacers you run on top of the steering block the less camber gain you will have, but you know what they say about assumtions. I have seen alot of setup tips on here but have not seen any guidance in this area. Any help/advice would be greatly appreciated.

i dont really know if there is a right or a wrong answer to your question i think a lot of it is just preference.. i know i personally dont ever run any spacers between any of the blocks i but i do have a few stacked on the top of the upper eyelet.... hope this helps

its all about camber gain and upper arm angle. the more shims you place ontop of the steering block the more you change the length of the upper arm and the amount of camber gain you get. The greater the angle the more gain the flatter the angle the less gain. Hope that helps

more camber gain should give you more steering as the suspension compresses, max at apex of turn.

is that on the left or right side?

right side.... another hint to, by coneing or rounding the top of your steering block or you can get a pair of these http://www.lefthander-rc.com/catalog/product_info.php?products_id=1326 , this will help the upper arm pivit easier without bidding, another words as you your suspention compresses and get more camber gain, a bidding between the upper eyelet and the top of the steering block may happen, because of the angle of the upper arm.

Thats for the right side. When you put them on the left side you actualy have camber loss during compression. You can start with more static camber this way if needed.

Thanks for the answers. I am currently using the KSG steering blocks. Like them alot.

As stated above it's the angle of the arm that dictates your camber gain. The holes on the caster blocks are camber gain 'rough' adjustments while placing shims between the steering knuckle and upper ball is a 'fine' adjustment.

Bob

Got it , Thanks

Robby heres a little more info on the subject, from Danny B's chassis book

Roll center and camber gain are two things that can be complicated, but they are a major part of oval racing. Camber gain is rather simple. When the spring is compressed the top of the tire leans in on the RF and the LF. On the RF this is ok a little camber gain makes it so you don’t have to run as much camber in the RF giving you more contact with the track on the straight-away which provides more stability. In the LF you don’t want to loose and camber in the corner. The more parallel the upper and lower a-arms the less camber gain you will have. You will see quite of few guys that will put an aftermarket castor block on the LF which allows you to have the LF a-arm perfectly flat, but they will leave a little angle on the RF to still have some camber gain there. I personally run the stock parts on flats tracks mainly because there isn’t a whole lot of spring travel on the LF on a flat track. On a banked track I take all the camber gain out of the LF.

The more parallel the upper and lower a-arms are the lower the roll center for your car will be. The roll center in its simplest form is how much the front end will roll in the corner. The lower the roll center the higher the center of gravity and vice versa. A good analogy is to think of a flagpole, if you were to grab a flagpole at the bottom (low roll center) the pole would sway back and forth easily. If you were to grab the pole in the center (high roll center) the pole would not sway as easily. The roll center is one of those things that is not a chassis adjustment but more of a building thing. You want the car with a low roll center; this will help the car turn in the corner. More roll equals more weight transfer therefore giving the car more steering. Once you get the car planted in the rear you will need this to make the car turn freely.

Thanks for the info Lee, starting to make heads from tails on this matter.

Robby heres a little more info on the subject, from Danny B's chassis book

The roll center in its simplest form is how much the front end will roll in the corner. The lower the roll center the higher the center of gravity and vice versa..

The roll center really doesn't have anything to do with the
center of gravity...

The roll center really doesn't have anything to do with the
center of gravity...

You'd have to call Danny Bartholomew out on that one, thats a direct qoute out of his chassis book, no way I,d say that much in one sitting, heres the link http://www.iroaronline.org/dannyb.html
However I agree with you must be something he overlooked?

Center of gravity (or center of mass) is exactly what it sounds like, the single point at which the entire mass of a body may be considered for analysis.

Roll center is the movement range that a suspension system limits a chassis to.

It's actually the interplay between center of mass and roll center that dictates how a chassis will handle.

Bob

It's actually the interplay between center of mass and roll center that dictates how a chassis will handle.
Bob

I'd say it's a "factor", in how a chassis will handle...
It doesn't dictate how it will handle..

I'd say it's a "factor", in how a chassis will handle...
It doesn't dictate how it will handle..

True, the last factor would be the suspension's resistance to movement. (But this is just the 50 thousand foot overview).

You'd have to call Danny Bartholomew out on that one, thats a direct quote out of his chassis book, no way I,d say that much in one sitting, heres the link http://www.iroaronline.org/dannyb.html
However I agree with you must be something he overlooked?

Danny's definition of roll center is oversimplified to the point of being inaccurate. Roll center is the movement range that a suspension system limits a chassis to. The front roll center is determined by figuring out the geometry (hint the Associated dynamic front end is an upside down McPherson strut design) while the rear is dictated by the T Plate pivot balls.

If you put a little thought into it you'll come to the conclusion that these two roll centers do not line up, and that the rear of the chassis has most of the mass and should therefore dominate. What this really means is that weight does not evenly transfer from left to right in a turn, and that through two decades of experimentation and backyard engineering we've have come up with design parameters that work well, and may actually be close to optimized for the task at hand.

The funny thing is that we've broken so many automotive engineering principles that if you gave one of our cars to GM or a big-time racing team and they would have to literally rewrite their analysis software to figure out what these 'little toys' are actually doing. And for all those guys who draw setup comparisons to NASCAR: Indy cars are probably the closest thing to what we do (front and rear roll center, rear weight bias, race in circles).

Bob