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Author Topic:   caster & caster gain?
Braided Dirt
Dirt Newbie

Total posts: 4
posted September 21, 2001 11:07 PM
Recently I have heard a lot about setting caster at extremly high degrees such as 10-13. I've also had it explained to me that caster gain will effect the loading of the left rear tire off when countersteering. Is this better applicatably to high banked, semi-banked, etc, or does it matter? What is the best way to trace the effects of caster gain? How much would it acually gain and is there any accurate way of telling? Can anybody tell me the ways of detecting visually, if a car has higher caster? Would increased caster have any effects on the straightways? I'm interested to hear about anything you could tell me on this.

jammin
Dirt Administrator

Total posts: 3375
posted September 21, 2001 11:51 PM UIN: 16262997
This is what turnplates are made for. Checking at specific degree readings will tell you exactly where your at as far as static weight at this point. With caster settings, you can place weight on the car wherever you want it during the turning point of the car. This is all in preference. The higher the caster split, the more weight transfer the car has when the wheels are turned.

jammin

Braided Dirt
Dirt Newbie

Total posts: 4
posted September 22, 2001 09:52 AM
Where will the weight transfer? the LR? how do I tell how much weight is transfered? I've heard of a few things to do to check this but what is used more often?

CHAMP00
Dirt Roller

Total posts: 5
posted September 22, 2001 10:38 AM
A GOOD chassis should not have any caster gain or as litte as poss. take you spring and shock out check caster then go up 1 inch check agian do it for 4 to 5 inch of movement and see how much it gains. CHAMP

CUSTOMPERFORMANCE
Dirt Freak

Total posts: 229
posted September 22, 2001 11:28 AM
champ is correct. what you guys mean is setting the right front with considerable more caster than lf, like 8+ rf and 3lf+
the more the rf has than left, hence split can have an effect on the car by loading the lr when counter steering to the right coming off the corner. like champ said you dont want any gain thru travel because it would make for a erratic car because the caster could change different settings based on how much the suspension travels.

CUSTOMPERFORMANCE
Dirt Freak

Total posts: 229
posted September 22, 2001 11:31 AM
when you have a high caster split do this:
turn your wheels left and right. when the rf has more caster than lf, it will raise higher turning to the right, than the left wheel turning to the left.

Braided Dirt
Dirt Newbie

Total posts: 4
posted September 22, 2001 02:26 PM
So if you've had a problem with it not tranfering weight onto the right front, a higher caster split is not the way to go, or is this wrong?
Will turning the steering wheel right then weighing the car give me an accurate picture of the amount of LR I'm going to be gaining?
Is this becoming more of a common practice? or is the normal caster settings still the way to go. I'm looking at changing it, but I want to know everything I can before I make the change.

On another subject... how often should we be checking the front roll center? we haven't checked it since....well.. I dont' know when I think we might have checked it at the begining of the year, but we've bent the frame since then.

CUSTOMPERFORMANCE
Dirt Freak

Total posts: 229
posted September 22, 2001 02:36 PM
more caster split also helps the car turn left. yes i would scale the car normally with the wheels straight and then turn them to the right to see how much lr you gain. yes this is also something more people in my area are expermenting with. too much split can make it difficult to get the wheels turned back coming off. its just something you may want to try and go up gradually.

racerraw
Dirt Roller

Total posts: 8
posted September 23, 2001 09:40 PM
OK guys, Ive been doing all forms of racing and here is my take on caster.
1) Caster on the left or right does the same thing to your cross weight.
2) Caster effects your contact patch when the wheel is turned.
3) Caster split is used on asphalt.

The biggest benifit of caster is it will save you from spinning if you get to carried away!

c21
Dirt Roller

Total posts: 24
posted September 24, 2001 01:27 PM
Wow, my head is spinning, we are covering so much ground here.

"Caster gain", Braided Dirt, in case you are still interested is caused by upper and lower contol arm axi (axis's?) non-parrellelism (which is mostly designed out of IMCA cars by re-laying out the upper "A" mounting locations).

"Caster split", helps to turn (pulls) the car left.

AND... the affect that caster has on loading and unloading of rear tires is compounded by Kingpin inclination, the greater the number, the greater the effect (this is a fixed number, usually 7 - 10 degrees depending on which spindle you are using).

Of couse you can quantify the effect castor has on rear loading (the greater TOTAL positive for both left AND right the GREATER the effect) but the bottom line is the more total (positive) castor you have the more the chassis will loosen when you turn left and tighten when you turn right.

On the question of checking your roll center hight. A colision hard enough to change your roll center would probably have you re'clipping your car .... which is always a good time to recheck everything!

My advice, as always .... small changes.

Braided Dirt
Dirt Newbie

Total posts: 4
posted September 26, 2001 04:53 PM
Thank you all for the information. It was needed and is going to be put to use. If anyone has anything else that might be helpful on this subject please pass it along, I don't mind hearing more.

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