As I continue to prep my 2011 Ford Fiesta for track time, I have a couple of thoughts/questions.
I have installed the Bilstein B14 kit on the front and rear. Based on how things are measuring up right now, I think I can get to -2.5 deg camber up front without much work. I plan on using 200TW tires (Falken 615) and I am looking for thoughts on whether or not this tire would benefit from additional camber.
I can get adjustable camber plates that would hit -3 to -3.5 degrees of camber but that also requires new springs to allow adequate movement of the strut inward. The current springs are a progressive rate spring and I think (assume) it is important to keep in the same rate range to allow the non adjustable strut to properly dampen. One thought is that I can measure the current installed spring length as the car sits and then remove the spring and check load at that length as well as the next 2+” of travel. This seems like it would give me an idea of the spring rate the strut can handle and I could spec the new linear spring rate somewhere in this range. Does that logic work or is there a chance that the damping is variable depending on where it is in the strut stroke?
Other thoughts or things I am missing or should consider?
Tom1200
SuperDork
3/15/21 1:44 p.m.
It's going to totally depend on what the tire wants and your driving style. You won't really know to you get on track and are able to check the tire temps across the face of the tire.
It's a bit of a catch 22, if you only need say -2.2 degrees of camber than buying the camber plates is a waste of money but if you need 2.9 degrees of camber to maintain an even temp across the tire than the plates are worth the investment.
To further complicate things it's possible to have a situation whereby the tire temps are good but the car will be faster with a little more camber and so you may need the plates anyway.
So being notoriously thrifty I would confirm you can get -2.5 degrees and start with that and if it actually needs more camber install the camber plates.
Wait for Flatlander to comment, he knows a lot about setting up this chassis.
On a Miata the Falkens are pretty happy with 2.2 to 2.5 degrees camber but I have no idea what the Fiesta is going to want. I have limited McPherson strut and limited FWD experience and what experience I have tells me that they sometimes respond well to stuff that I wouldn't think about trying on a more performance oriented suspension design.
I recommend that you make sure the car is in good shape, pick a setup and document it and get out on the track and see if it and you are happy. I also don't know how much time I'd spend optimizing a car for the Falken 615. They're getting hard to find and the 660 is a much better tire.
A little extra caster will negate the need for extra camber.
preventing chassis roll is important on a strut car.
This worked great on my ZX2SR, 2.5 camber with Hoosier A7's
Thank you for the article links. I had read most of them when originally posted but forgotten about them already and apparently I must have also forgotten about the search function :)
The article with the Mini camber tuning was especially insightful and likely applicable.
dps214
HalfDork
3/16/21 7:43 a.m.
It's a not super light fwd strut car, it probably wants as much camber as it can get without having trouble putting power down. 2.5* sounds at least in the ballpark of enough though, of probably start there and see how it drives and how the tires wear.
If you go with camber plates, your spring rate measuring method is right. I'd want to measure across as much travel as you can though, to know how progressive it is and take that into account when deciding rate for the new springs.
In reply to dps214 :
Thanks for the feedback regarding spring rates. I agree that I would want to capture the complete load versus displacement curve in order to make sure I was looking at all of the information that I have available to me.
I think flatlander has a build thread on here for his 2, if I remember right he was running a lot of negative camber, at least -2.5 and 9” wheels on the front.
In reply to CyberEric :
Yes - when someone posted his name up above I searched and found the old thread. It was definitely helpful.
