Spindle Orientation

[Cranky]

When looking at the left front spindle on my car, I noticed it is leaning forward and not straight up and down. Should the spindle be oriented more center and straight up as opposed to leaning towards the front of the car? I realize this is a caster issue. I made an upper control arm change and hadn't noticed this before.

[Kromulous]

Depends on what your after i guess, what kind of Chassis is it?

A lot of Castor split in the front, +4 on the RF, and 0 or positive will make the car pull hard left, you will have to hold it straight but when you want to turn left it will really pull you down in the corner.. I hear some Longhorn guys dont like it.

Anyway, if its positive it will de-wedge the car when you turn left as well. Desirable? not but on counter steer it will add wedge, or weight on the RR corner.

[Cranky]

So Krom, I'm still learning this stuff. Is positive on RF the upper balljoint leading or aft of the lower balljoint by 4 degrees? Same on Left front, forward or after? Thanks.

[TheJet-09]

Positive caster is the upper ball joint behind (towards the rear of the car) compared to the lower. Visualizing it is one thing, but you really need to check it with a gauge, both sides.

[Kromulous]

Yes Measure it, but Yes the top ball of the Ball joint will be in front of the lower ball, towards the front of the car will indicate positive castor.

Some people like a lot of Castor on the RF, the spindle leaning (the top) backwards, to the rear of the car. Some don't, the tricky part is measuring it at attitude because sometimes not enough and you end up sweeping in negative Castor on full counter steer, or you may want that, who knows.

I will say, I liked a lot of castor, and castor split, puts a lot of feel and response in the front end to me. Plus the fastest steering I could get, I ran 2x steering quickners in one car.

[MasterSbilt_Racer]

Positive caster is the upper ball joint behind (towards the rear of the car) compared to the lower. Visualizing it is one thing, but you really need to check it with a gauge, both sides.

This is correct. Top BJ behind bottom for pos caster.

[Cranky]

So, on the right front, top balljoint towards front of car is positive or towards back of car? and left side, top balljoint towards front is positive or negative? Sorry guys. I appreciate your input. I do plan to use a gauge but trying to get my mind around how everything works especially now knowing that caster can dewedege or put wedge in the car while racing. I know what I see other cars doing at a higher level and I'm now understanding the why's and how's. I'm adapting my personal car to fit me and my driving style. I realize that chassis manufacturers give you a "starting" point and those change from week to week. Just trying to learn as much from you guys that have the experience.

[TheJet-09]

Caster is measured the same regardless of what side (meaning positive is top BJ back/rearward of the lower BJ).

It would take me two pages to describe what I could show you in a couple minutes, so I won't try because it will probably be very confusing. But my simple description regarding caster is this: Imagine the front wheels of a shopping cart (ironically called "caster" wheels). They are mounted with a great deal of negative caster, which is why they tend to wobble back and forth, and subsequently make the cart easy to steer (this is what I would call a lack of directional stability). Now imagine the front wheel/tire on a bicycle or motorcycle. It has a great deal of positive caster built in through the forks, giving it directional stability (which is why we are able to take our hands off the handle bars and the bike/cycle still goes relatively straight).

So without getting too far ahead of myself, just know that caster is only one aspect of our front suspension. There is also camber, spindle inclination, weight jacking, etc.

In the words of the late, great Bloomer, "There's more speed in the front end of a racecar than there is in the back."

[KTMLew]

Positive caster=closer to driver
Negative=closer to radiator.

That help?

[MasterSbilt_Racer]

Caster is measured the same regardless of what side (meaning positive is top BJ back/rearward of the lower BJ).

It would take me two pages to describe what I could show you in a couple minutes, so I won't try because it will probably be very confusing. But my simple description regarding caster is this: Imagine the front wheels of a shopping cart (ironically called "caster" wheels). They are mounted with a great deal of negative caster, which is why they tend to wobble back and forth, and subsequently make the cart easy to steer (this is what I would call a lack of directional stability). Now imagine the front wheel/tire on a bicycle or motorcycle. It has a great deal of positive caster built in through the forks, giving it directional stability (which is why we are able to take our hands off the handle bars and the bike/cycle still goes relatively straight).

So without getting too far ahead of myself, just know that caster is only one aspect of our front suspension. There is also camber, spindle inclination, weight jacking, etc.

In the words of the late, great Bloomer, "There's more speed in the front end of a racecar than there is in the back."

You can make the front faster, and not actually know it if you don't give the rear more grip to take advantage of it.