Caster camber.

[robo]

Cant get my addled brain round this ongoing caster thing. Surely the only way to increase caster is to move the top pivot point back. Nothing that is done between top and bottom pivot will change caster. These mushroom offset gadgets at best could only be used as a camber adjuster which surely can be done off the top balljoint. Would it not be best to have adjustment on all three corners of the top wishbone ie rose joints on the chassis end of the wishbone and retain the ball joint on the other end. That would give all that was needed for tipping back the kingpin axis and altering camber/ caster. Or have i got this very wrong?
bob

http://www.ozebiz.com.au/racetech/theory/align.html

http://www.locostusa.com/forums/view...t=3517&start=0

[trick-kit]

You are correct, the only way to change castor angle is to move the ball joint position. The only change you can effect with the mushrooms is to mount them in the wrong postion where thay can change the camber.

What the mushroom inserts are designed to do is to correct a design fault when using the Sierra upright. Basically when you draw a line through the top and bottom ball joints it is ideal to have the spindle axis on this line. The Sierra upright's isn't, hence the offset mushrooms, which rotates the hub to align the ball joints with the axle centre line better and increase the trail, which is what helps with self centring.

Hopefully that all makes sense

TK

[Talonmotorsport]

You also have to consider that the bottom ball joint sits flat on the wishbone plate which gives it limited movement. If you plan on running more caster the plate will need to be angled or twisted to accomadate this otherwise the bottom joint could come to it's limit and snap.

[snapper]

If there is usable play in the wishbone to chassis mounts you can pack the top wishbone back and pack the bottom forward.
3 to 6 degs is the accepted range

[robo]

Extra confused.

If the chassis is built to book specs from what i have gathered there is not enough caster dialled into front suspension, Causing lack of self centering and iva problems plus a tippy toe feel to the steering. Is there an ideal amount of caster that suits the car? If the magic number of 5 dgrees is attainable from book specs its obviously not enough and a tad bit more is needed. If this is the case why cant the this just be adjusted on the brackets as you suggest during build and a log made of the mod so future builders can be in the picture from the off?

Bob

[trick-kit]

Originally Posted by robo

Extra confused.

If the chassis is built to book specs from what i have gathered there is not enough caster dialled into front suspension, Causing lack of self centering and iva problems plus a tippy toe feel to the steering. Is there an ideal amount of caster that suits the car? If the magic number of 5 dgrees is attainable from book specs its obviously not enough and a tad bit more is needed. If this is the case why cant the this just be adjusted on the brackets as you suggest during build and a log made of the mod so future builders can be in the picture from the off?

Bob

Hi Bob,

Do you have a picture of your set up so forum members can see if you have everything assembled correctly, as plenty of cars have been built to book spec so far, Ash's for example, that don't exhibit the things you are.

If everything is correct then you can start looking for other probable causes.

TK

[robo]

No car yet, I am going to get talon to build the chassis. I have built several kit cars and after the builds have had to sort major suspension problems. The car i am finishing at the moment is a gtd 40 which is the second one of a pair we built. To cut a long story very short on these cars the caster which is adjustable has to be pushed back as far as you can get it to obtain anything like enough to bring it to spec. Obviously not enough adjustment was built in to start with. Then there is the steering rack which has to be raised 3/8" to reduce bump steer, something else that should have been sorted at the jigging stage. Then I had to send the thing off to have the whole rear of the car cut off to fit an aftermarket engine cradle fitted to lower the engine and fit an adjustable suspension system to dial out lift off oversteer that was present in the first car. None of this is cheap and in most cases avoidable if the homework is done,any alterations can be done at chassis building stage hence all the questions. This forum is proving valuable as its giving me a direction on the build. If it needs extra caster or cortina type front hubs and different type top wishbones that is the sort of thing i would like to know about as i am at the shopping stage.
bob

[MarkB]

You will like the new upright and wishbone set up we have designed then..dials out all the issues on the front end of the haynes roadster...

[robo]

Is this a stand alone system and does the chassis builder need to mod something?Also While on the subject are there any issues on the rear that need addressing? Was looking at the amount of squat on this car, is this just a tad soft or could it be in need of some anti squat?

http://1.bp.blogspot.com/-8Say7fFlpZ...%2Bday%2B4.jpg