7.5 deg or 12.5 deg yokes

[Rob_B]

As it says really. What are the differences between the two? And what do people tend to run. Cheers

[ian h]

Generally more caster will give more entry and less exit steering. On the sx3 I find the 7.5 give me a good feel to the steering however on the sx/sx2 I found that the 12.5's better in more situations. Must be something to do with the better balance of the sx3 generating more natural steering than the sx2. That's my experience anyway. Maybe others will see it differently.

[mark christopher]

thats odd, hudy maunal and xxx guide all say that more caster gives les turn in and more on exit, and less caster gives more initial turn in and less on exit

EFFECTS OF CASTER ADJUSTMENT
Less caster angle
(more vertical)
• Decreases straight-line stability
• Increases off-power steering at corner entry
• Increases suspension effi ciency
More caster angle
(more inclined)
• Increases straight-line stability
• Decreases off-power steering at corner entry
• Makes the car more stable through bumpy track conditions
MEASURING FRONT CASTER

http://www.google.co.uk/url?sa=t&rct=j&q=hudy%20set%20up%20manual&source=web&cd=2&ved=0CD8QFjAB&url=http%3A%2F%2Fcsor.co.uk%2Fwpress%2F%3Fdl_id%3D 4&ei=9_xiT7aPOYi08QPnqNWRCA&usg=AFQjCNHaBOuoV0TY_kchCvMaXgX64droMA

[Cardnim]

thats odd, hudy maunal and xxx guide all say that more caster gives les turn in and more on exit, and less caster gives more initial turn in and less on exit

EFFECTS OF CASTER ADJUSTMENT
Less caster angle
(more vertical)
•
Decreases straight-line stability

•
Increases off-power steering at corner entry

•
Increases suspension effi ciency

More caster angle
(more inclined)
•
Increases straight-line stability

•
Decreases off-power steering at corner entry

•
Makes the car more stable through bumpy track conditions

MEASURING FRONT CASTER

http://www.google.co.uk/url?sa=t&rct=j&q=hudy%20set%20up%20manual&source=web&cd=2&ved=0CD8QFjAB&url=http%3A%2F%2Fcsor.co.uk%2Fwpress%2F%3Fdl_id%3D 4&ei=9_xiT7aPOYi08QPnqNWRCA&usg=AFQjCNHaBOuoV0TY_kchCvMaXgX64droMA



Isnt there a difference though between the caster of the front section and the kick up (caster) on the yokes (ie. at the wheel)

On the SX3, for example, its very different running 7.5 degree blocks on the wishbones, as opposed to running the 7.5 degree yokes.

Is that where the difference lies? :confused:

[mark christopher]

no you add caster to kick up, so 10 kick up and 7.5 caster block is 17.5 caster
read section 1.6 on the link i posted

TOTAL CASTER ANGLE
Total caster angle also depends on the front kick-up angle.
To determine the total caster angle, combine the kick-up angle + C-hub caster angle.
Example: 10° front kick-up + 10° caster in C-hub = 20° total caster

[Cardnim]

no you add caster to kick up, so 10 kick up and 7.5 caster block is 17.5 caster
read section 1.6 on the link i posted

TOTAL CASTER ANGLE
Total caster angle also depends on the front kick-up angle.
To determine the total caster angle, combine the kick-up angle + C-hub caster angle.
Example: 10° front kick-up + 10° caster in C-hub = 20° total caster


No I understand that one Mark, however, I see something different.

On my SX3, if I run only 7.5 yokes then I get one affect
but if I run only 7.5 caster blocks then its a different affect.

Going by your maths, the affect should be identifcal, as its simply a total of 7.5 caster.

Isnt that correct? or am I missing something (as usual! :blush: )
:)

[mark christopher]

kick up alters other things too

1.10 KICK-UP (FRONT)
Front kick-up is the angle of the front lower
suspension arm when viewed from the
side of the car. With kick-up the front of
the arm is higher than the rear of the arm.
Kick-up may be built into the design of the
chassis plate (bend upwards at the front)
or it may be accomplished by altering the
angle of the front lower inner pivot pins.
Front kick-up is used to adjust the amount
of weight transfer to the front when the car
is off-throttle or under braking.
EFFECTS OF FRONT KICK-UP ADJUSTMENT
FRONT KICK-UP
ANGLE CHARACTERISTICS
More kick-up
• More weight transfer to the front of the chassis off-throttle or
under braking
• Chassis compresses or drops more off-throttle or under
braking
• Handling is improved on bumpy tracks
• Decreased steering response
Less kick-up
• Less weight transfer to the front of the chassis off-throttle or
under braking
• Chassis compresses or drops less off-throttle or under
braking
• Handling is improved on smooth tracks
• Increased steering response
ADJUSTING FRONT KICK-UP
Some vehicles (like the XB808) have fi xed
front kick-up, though optional parts may
be available to allow adjustment. When
front kick-up is adjustable, it is typically
adjusted via adjustable holders for the front
lower inner pivot pin.

[Cardnim]

Ok, cheers mate.

Do you have a link to this thread somewhere?
Thanks! :thumbsup:

[mark christopher]

yup bottom of my 1st post

[ian h]

Caster in a nutshell. (Elvo's guide)

3.2 Caster

http://users.telenet.be/elvo/4/caster.gif
Caster describes the angle c between the kingpin and the vertical plane. In case of a double wishbone-type of suspension, the axis through the centers of the ball links serves as a 'virtual hinge pin'. If the kingpin is leaning back, as in the pic, the caster angle is said to be positive. Negative caster (kingpin leaning towards the front) is never used. Note that the contact patch between the tire and the ground is behind the intersection point of the extension of the kingpin and the earth. (Dimension d) This will cause the wheels to 'trail'.
The caster angle will cause excessive camber in the front wheels as they are steered, lifting the front of the car up. This lifting effect is what causes the front wheels to have a tendency to straighten out when there's no steering force applied: when the wheels are pointed straight ahead, the chassis sits at its lowest position, steering the wheels requires some force, to lift the car up. When the force is removed, gravity will return the wheels to their original position. The bigger the caster angle, and the heavier the car, the stronger this effect is. Also, the bigger he caster angle, the bigger the camber difference induced when the wheels are steered. This camber difference is to compensate for the chassis roll and tire squirm when the car is cornering. Hence, a lot of caster will provide more steering in high-speed corners, where chassis roll is more pronounced, and whilst turning in. It will also make the car more stable in rough conditions, and the car's straight-line stabili ty will also be improved. A small caster angle will provide more steering in low-speed corners, and less turn-in.


Note that the caster angle isn't always constant. Cars with double wishbone suspension, where both wishbones aren't parallel, will experience a change in caster angle as the suspension is compressed or extended. If the lower wishbone has less kickup than the upper wishbone, the caster angle will decrease as the suspension compresses, like when the car is turning or braking. This is called 'reactive caster'.