How much Kingpin Inclination?

[swong46]

Hi, this is our first year in FSAE and I am doing some research for suspension.

I am reading about SAI and KPI and I know its for self centering but how much is too little? How much is too much? Is there a ball park to be in?

Thanks in advance

[swong46]

Hi, this is our first year in FSAE and I am doing some research for suspension.

I am reading about SAI and KPI and I know its for self centering but how much is too little? How much is too much? Is there a ball park to be in?

Thanks in advance

[ed_pratt]

Welcome to the forums,

First up, before this post becomes yet another flaming, let me say please please please use the forums as they were intended.

There are several posts "stickied" to the top of the open FSAE discussion page. Read them.

Secondly, use the search function. A lot.
there are plenty of posts already asking and answering similar things to you.

Thirdly, this advice was given to me by Pat Clarke and I'm more than happy to pass it on;

If you are reading about KPI, why did you stop? why not go further and read some more?!

Think about what KPI dictates, where does the inclination axis meet the ground? where do you want it to meet the ground?

People here will generally answer your questions if they are well thought out and researched i.e. do a little thinking and you'll et some answers

best of luck

Ed

[Nick Renold]

To add on to what Ed said,

If you ask for a specific suspension parameter value, you are unlikely to get an answer. Aside from the fact that the suspension setup of another team probably won't work on your car very well, most teams simply do not want to share their suspension parameters because they can have a large influence on performance and take a lot of designing to get right.

With that said, I have heard some teams run KPI = to static camber (easy manufacturing of uprights), and some other texts I have read (Think Fast maybe?) suggest using as little KPI as possible. You should figure out for yourself why this would be a good goal.

The key with suspension design is to think not about the parameter in isolation, but about what happens in interaction. KPI comes into play with cornering forces, steering inputs, caster, camber, and other parameters during a steady state turn. These parameters all interact and you should think about what will give you a good compromise between turning and braking performance.

[Peter7307]

As Ed and Nick have already suggested the actual number of degrees comes as much from the WHY as it does from the WHAT.

Just getting a number is virtually meaningless unless you know the reasoning behind the selection of the end result.

Have a thorough read of one of the many discussions on this topic via the search facility.

Peter.