Secrets of the Mirage

Working on building up a car? Tell us about it here!

Moderators: Jamie, Native

Bill L-
Autocrosser
Drives: Golf Sportwagen
User avatar
Location:
Odessa
Joined: February 2017
Posts: 114
First Name: Bill
Last Name: L-
Autox Car: Golf Sportwagen
Location: Odessa

Secrets of the Mirage

Postby mymomswagon » Sun Dec 03, 2017 4:20 pm


Loren wrote:
3 degrees of camber gave the car a lot of front grip. Lowering the car by about 3" will get the suspension back into the range it was designed to work in. And maybe keep both of the front wheels on the ground.
saw this from around the trailer, clear air under 2 wheels.

Loren Williams
Forum Admin
Drives: The FASTiva
User avatar
Location:
Safety Harbor
Joined: December 2006
Posts: 12227
First Name: Loren
Last Name: Williams
Autox Car: The FASTiva
Location: Safety Harbor

Secrets of the Mirage

Postby Loren » Sun Dec 03, 2017 4:41 pm

Some quick math with measured corner weights and spring rates tells me that the front springs that come with the coilover kit (4kg/mm) are perfect for 2" of compression travel.

What this all boils down to is that my coilover kit seems to be pretty well thought-out. I can run as low as probably 2.5-3" of ground clearance if I wanted to and probably not scrape on "perfect world" flat surfaces.

My decision of how much to lower the car comes down to purely asthetics and "how much do I want to scrape speed bumps and the dip at the end of my driveway?"

I'll probably compromise with something like 2.5".
Loren Williams - Loren @ Invisiblesun.org
The "Push Harder, Suck Less" philosophy explained:
Push Harder - Drive as close to the limit of your tires as possible.
Suck Less - Drive something resembling a proper racing line.
Loren Williams
Forum Admin
Drives: The FASTiva
User avatar
Location:
Safety Harbor
Joined: December 2006
Posts: 12227
First Name: Loren
Last Name: Williams
Autox Car: The FASTiva
Location: Safety Harbor

Secrets of the Mirage

Postby Loren » Tue Dec 05, 2017 1:46 am

I planned to swap the rear springs today, ended up getting both front and rear done. I need to to some fine-tuning of the ride height and set the alignment yet.

Initial impressions: Steering feels sluggish... I'm betting that I added some more static camber and now have some toe-in. It felt a little bouncy at first. I added some shock stiffness, and that feels better. Otherwise... oh, y'all are gonna HATE it! It feels like it can do anything, and nothing feels dramatic. It's much more composed than it was.

I was careful to pay attention to droop travel when I set the shock length and perch heights. Ended up right in the middle of the shock travel. The rear has 5" of travel, and 2.5" of droop. The front has 4.5" of travel and right about 2" of droop.

I think I'm going to like it.
Loren Williams - Loren @ Invisiblesun.org
The "Push Harder, Suck Less" philosophy explained:
Push Harder - Drive as close to the limit of your tires as possible.
Suck Less - Drive something resembling a proper racing line.
Loren Williams
Forum Admin
Drives: The FASTiva
User avatar
Location:
Safety Harbor
Joined: December 2006
Posts: 12227
First Name: Loren
Last Name: Williams
Autox Car: The FASTiva
Location: Safety Harbor

Secrets of the Mirage

Postby Loren » Wed Dec 06, 2017 3:43 pm

Finished tweaking the suspension today. It's about 2" lower than stock. Still has 6" of ground clearance. Stock rake was about 3/4", now is about 1/2".

Ended up with the shock travel perfectly centered. 2.25" of compression and extension in the front. 2.5" in the rear.

Front camber is around 3-3.2 degrees. 1/8" total toe out. Rear suspension is not adjustable.

Car feels GREAT! Wheel hop problem is completely gone. Feels very composed and happy. Puts power down very acceptably even in 1st gear hairpins. (yeah, I know, it doesn't have any power to put down... but, it used to POGO in that situation!)

And it looks sort of like this:

Image
Loren Williams - Loren @ Invisiblesun.org
The "Push Harder, Suck Less" philosophy explained:
Push Harder - Drive as close to the limit of your tires as possible.
Suck Less - Drive something resembling a proper racing line.
Steve --
Forum Admin
Drives: whatever I can get my hands on
User avatar
Location:
St. Pete
Joined: November 2006
Posts: 6099
First Name: Steve
Last Name: --
Autox Car: whatever I can get my hands on
Location: St. Pete

Secrets of the Mirage

Postby Native » Wed Dec 06, 2017 10:05 pm

Needs a teal fender.
Steven Frank
Class M3 Miata
Proud disciple of the "Push Harder, Suck Less" School of Autocross
______________
I'll get to it. Eventually...
Loren Williams
Forum Admin
Drives: The FASTiva
User avatar
Location:
Safety Harbor
Joined: December 2006
Posts: 12227
First Name: Loren
Last Name: Williams
Autox Car: The FASTiva
Location: Safety Harbor

Secrets of the Mirage

Postby Loren » Wed Dec 06, 2017 10:25 pm

I actually bought some red vinyl to wrap a mirror in memory of the Fastiva. Wrapping a mirror is a daunting idea, though.
Loren Williams - Loren @ Invisiblesun.org
The "Push Harder, Suck Less" philosophy explained:
Push Harder - Drive as close to the limit of your tires as possible.
Suck Less - Drive something resembling a proper racing line.
Steve --
Forum Admin
Drives: whatever I can get my hands on
User avatar
Location:
St. Pete
Joined: November 2006
Posts: 6099
First Name: Steve
Last Name: --
Autox Car: whatever I can get my hands on
Location: St. Pete

Secrets of the Mirage

Postby Native » Wed Dec 06, 2017 10:29 pm

Loren wrote:Wrapping a mirror is a daunting idea
Truth.
Steven Frank
Class M3 Miata
Proud disciple of the "Push Harder, Suck Less" School of Autocross
______________
I'll get to it. Eventually...
Benji Wheaton
Moderator
Drives: The FASTiva
User avatar
Joined: July 2013
Posts: 190
First Name: Benji
Last Name: Wheaton
Autox Car: The FASTiva

Secrets of the Mirage

Postby BrilloHeadBen » Thu Dec 07, 2017 10:52 am

Do you have any left over spray paint?
Ben W.
The FASTiva
The dirty 10AE 3908/7500
Loren Williams
Forum Admin
Drives: The FASTiva
User avatar
Location:
Safety Harbor
Joined: December 2006
Posts: 12227
First Name: Loren
Last Name: Williams
Autox Car: The FASTiva
Location: Safety Harbor

Secrets of the Mirage

Postby Loren » Thu Dec 07, 2017 11:44 am

Probably have some paint. Not gonna use it.
Loren Williams - Loren @ Invisiblesun.org
The "Push Harder, Suck Less" philosophy explained:
Push Harder - Drive as close to the limit of your tires as possible.
Suck Less - Drive something resembling a proper racing line.
Joe Brannon
Experienced Autocrosser
Drives: M Roadster
User avatar
Joined: August 2012
Posts: 384
First Name: Joe
Last Name: Brannon
Autox Car: M Roadster

Secrets of the Mirage

Postby jbrannon7 » Thu Dec 07, 2017 1:13 pm

Loren wrote:Probably have some paint. Not gonna use it.
Yep, wouldn't be prudent.
Steve --
Forum Admin
Drives: whatever I can get my hands on
User avatar
Location:
St. Pete
Joined: November 2006
Posts: 6099
First Name: Steve
Last Name: --
Autox Car: whatever I can get my hands on
Location: St. Pete

Secrets of the Mirage

Postby Native » Thu Dec 07, 2017 3:29 pm

Not at this juncture...
Steven Frank
Class M3 Miata
Proud disciple of the "Push Harder, Suck Less" School of Autocross
______________
I'll get to it. Eventually...
Loren Williams
Forum Admin
Drives: The FASTiva
User avatar
Location:
Safety Harbor
Joined: December 2006
Posts: 12227
First Name: Loren
Last Name: Williams
Autox Car: The FASTiva
Location: Safety Harbor

Secrets of the Mirage

Postby Loren » Thu Dec 07, 2017 4:20 pm

:pointlaugh:
Loren Williams - Loren @ Invisiblesun.org
The "Push Harder, Suck Less" philosophy explained:
Push Harder - Drive as close to the limit of your tires as possible.
Suck Less - Drive something resembling a proper racing line.
Doug Adams
FAST Elite
Drives: Rotary or Vette
User avatar
Location:
Spring Hill
Joined: April 2011
Posts: 3191
First Name: Doug
Last Name: Adams
Autox Car: Rotary or Vette
Location: Spring Hill

Secrets of the Mirage

Postby twistedwankel » Sun Dec 10, 2017 9:44 pm

So long as you beat Mike in his hyper miler powered by WI cheese and lithium with dryer duct battery I vote an unequivocal :thumbwink:
Loren Williams
Forum Admin
Drives: The FASTiva
User avatar
Location:
Safety Harbor
Joined: December 2006
Posts: 12227
First Name: Loren
Last Name: Williams
Autox Car: The FASTiva
Location: Safety Harbor

Secrets of the Mirage

Postby Loren » Sun Dec 10, 2017 10:58 pm

Gave the new suspension a shakedown today with Philip. 10 runs, no issues. Philip thinks the car needs to "rotate" more. I think neither of us were actually pushing the car to the limit consistently enough to say for sure what it might need. But, it gets around a course quite nicely.

I didn't take any time to really align the camera, so I got crappy video. The front one shows fender clearance, and the fact that it's got LOTS of droop travel that it didn't used to have. The rear one doesn't show much at all... except for that cone I hit.

phpBB [media]


phpBB [media]
Loren Williams - Loren @ Invisiblesun.org
The "Push Harder, Suck Less" philosophy explained:
Push Harder - Drive as close to the limit of your tires as possible.
Suck Less - Drive something resembling a proper racing line.
Loren Williams
Forum Admin
Drives: The FASTiva
User avatar
Location:
Safety Harbor
Joined: December 2006
Posts: 12227
First Name: Loren
Last Name: Williams
Autox Car: The FASTiva
Location: Safety Harbor

Secrets of the Mirage

Postby Loren » Mon Dec 11, 2017 11:38 pm

Damned event photographers.

Looks like our work is not done yet, kids.

Mirage-On-2.jpg
Loren Williams - Loren @ Invisiblesun.org
The "Push Harder, Suck Less" philosophy explained:
Push Harder - Drive as close to the limit of your tires as possible.
Suck Less - Drive something resembling a proper racing line.
Philip / Travis Petrie
FAST Elite
Drives: 1996 Mazda Miata
User avatar
Joined: August 2014
Posts: 736
First Name: Philip / Travis
Last Name: Petrie
Autox Car: 1996 Mazda Miata

Secrets of the Mirage

Postby Carracer » Tue Dec 12, 2017 9:25 am

Need more low.
Joe Brannon
Experienced Autocrosser
Drives: M Roadster
User avatar
Joined: August 2012
Posts: 384
First Name: Joe
Last Name: Brannon
Autox Car: M Roadster

Secrets of the Mirage

Postby jbrannon7 » Tue Dec 12, 2017 10:39 am

Appears the car is just too top heavy.
Loren Williams
Forum Admin
Drives: The FASTiva
User avatar
Location:
Safety Harbor
Joined: December 2006
Posts: 12227
First Name: Loren
Last Name: Williams
Autox Car: The FASTiva
Location: Safety Harbor

Secrets of the Mirage

Postby Loren » Tue Dec 12, 2017 11:16 am

jbrannon7 wrote:Appears the car is just too top heavy.
Probably.

But, I don't think it's so top-heavy that it can't be fixed.

Going lower is certainly an option. Even in this photo, you can see that the fully loaded side still has PLENTY of ground clearance. And the suspension also has plenty of adjustment left. If I wanted to scrape every speed bump, I could lower the car another 2.5-3". Give up another inch of compression travel. And probably go a long way towards solving the problem. But, I don't want to be that low. I could probbably go another inch lower, though. I wouldn't like the wheel tuck that comes with it. But, I don't think it would be too bad, otherwise. As it is, it doesn't scrape anything with 5" of ground clearance. I could live with 4".

Even keeping the ride height the same and shifting the shock travel 1" so that it can extend another inch would probably help. Remember, I've only got 2" of extension travel in the front right now. That's what's pulling that inside front wheel up. If it had more travel, it would still be in the ground. (it wouldn't have significant weight on it, but it wouldn't be in the air)

I keep reading about roll centers vs CG height. I'm going to take some measurements and try to find my roll center. I don't know where my front CG is, but I can assume that it's somewhere between 1/3 of the total body height and half the hood height, and I'm betting I can't get the roll center anywhere near that. But, getting closer to it is supposed to help reduce body roll. Can't find any kind of quantification for that... how much will it reduce body roll? How much will it help? Don't know. But, it's worth experimenting with.

Gotta take some measurements and draw some pictures. Got nothing else on my agenda for today.
Loren Williams - Loren @ Invisiblesun.org
The "Push Harder, Suck Less" philosophy explained:
Push Harder - Drive as close to the limit of your tires as possible.
Suck Less - Drive something resembling a proper racing line.
Steve --
Forum Admin
Drives: whatever I can get my hands on
User avatar
Location:
St. Pete
Joined: November 2006
Posts: 6099
First Name: Steve
Last Name: --
Autox Car: whatever I can get my hands on
Location: St. Pete

Secrets of the Mirage

Postby Native » Tue Dec 12, 2017 12:07 pm

Spacers for wider front track?
Steven Frank
Class M3 Miata
Proud disciple of the "Push Harder, Suck Less" School of Autocross
______________
I'll get to it. Eventually...
Loren Williams
Forum Admin
Drives: The FASTiva
User avatar
Location:
Safety Harbor
Joined: December 2006
Posts: 12227
First Name: Loren
Last Name: Williams
Autox Car: The FASTiva
Location: Safety Harbor

Secrets of the Mirage

Postby Loren » Tue Dec 12, 2017 12:10 pm

Native wrote:Spacers for wider front track?
Thats on the list, but I can only go maybe 1/4" before I hit fenders. Not ready for fender flares yet! They will clearly become a necessity to run wider tires and "really" develop this car, though. Tough commitment to make. I guess the front fenders are bolt-on, though.
Loren Williams - Loren @ Invisiblesun.org
The "Push Harder, Suck Less" philosophy explained:
Push Harder - Drive as close to the limit of your tires as possible.
Suck Less - Drive something resembling a proper racing line.

Return to “Projects”

Who is online

Users browsing this forum: No registered users and 2 guests