DISCLAIMER: Another long winded post...
After tweaking my foam setup all last week, on a last minute decision to test the new car and myself, I took the new 05 racing with rubbers on a low grip bumpy asphalt track this weekend.
I was up all night Friday tuning & testing a setup in the street outside my house after rebuilding a motor.
So, due to time constraints and the setup theory I'm working on, I decided not to change the front bulkhead position and I actually kept the anti-dive with the front holders in the middle holes and the rear holders in the top holes. I was quite surprised that it actually ended up working very well on the low grip surface. However, I had to raise my rear ride height up .5mm higher than the front and use a Mazda 6 body for a lot of front down force to keep the steering very tight on and off power. We ran adjustable timing 19 turn motors and from what I could tell, I ended up having more front grip than all but the A main winner and was able to keep very tight lines even if late braking or getting on the power early.
Unfortunately I had a rash of broken bits during qualifying and had to run the B main with the 3 resulting DNF qualifiers. But the race director was kind and, after winning the B main by 3 laps, he bumped me up to last place for the A. Came through the pack and placed 3rd, but I would have held on to 2nd if I hadn't made 3 time consuming driving mistakes.
The rubbers came off in great condition after 4 runs and I could tell they were wearing evenly across by examining the "stretch" mark and wear line positions on the inside & outside edges of the tires. I didn't think to check their respective temps coming off each run though, but I've made a note to do so this weekend.
NOTE: In my opinion, anti-dive is the way to go in any condition with the new FK05 since it is so front heavy.
Even with a very bumpy track, my front end was glued over every single small and large bump and never skipped while on or off throttle. This included several times I went four wheelin over grass growing through the cracks between the curb concrete and asphalt on the back straight and a few trips crossing the accidentally folded over transponder pickup matt.
The spring/dampening combination I was running must have been perfect for the anti-dive setup.
Taking into account the weight bias toward the front, I eliminated the rear anti-squat and went for maximum roll by placing all the pin holders in the bottom mount holes. Rear was great and finally stopped stepping out mid-corner during throttle transition.
Thx Mario & Co for a great job on the new MultiDiff!
The locked one-way was excellent for my aggressive driving style in low grip conditions. Unfortunately, I had dialed in the rear AFTER making this change and I never had the chance to try the finished rear setup with a full one-way. This will definitely be on my list for this weeks testing.
Here is the complete list of changes I made from my foam setup:
- From Full One-way to Locked Solid One-way
- From 40lb to 22lb springs
- From 70wt w/1 hole open to 60wt w/3 holes open (Trinity)
- Added foam inserts inside shock bladders
- From upper shock mount #4 to #2
- Reduced outer camber link shims from 1.5mm to 0mm
- Reduced static camber from -1.75d to -1.0d
- Changed front outer steering link mount on blocks from #2 to #1 for more mid corner full lock steering on and off throttle
- From 40 shore foams to CS27's with hard inserts
- From anti-squat using pin holder holes #6 & #3 to lowest roll center using holes #1 & #2
- From 35lb to 17lb springs
- From 60wt w/2 holes open to 50wt w/4 holes open (Trinity)
- From upper shock mount #4 to #2
- From 4.5mm ride height to 6.0mm ride height
- From 30 shore foams to CS22's with medium inserts
* From Proline Nemesis (neutral) to Proline Mazda 6 (more front down force)
I kept the coned washers under the top deck screws on and the chassis was still stiff as a board as it was while running foams on carpet. Imagine that.
I also kept the following things the same:
* 6d aluminum caster blocks
* 1mm in-board front toe-out shims
* front toe at 0
* rear camber at -1.5d
* rear toe-in at -2.5d
* 2.5mm shims under rear outer camber link
* droop at 1.5mm front and 3.5mm rear
* camber link positions #2 in front and #1/#1 in rear
* foam inserts in rear shock bladders
* weight distribution
* minimum wheelbase of 257mm
* missing one top deck screw that is on the right side in between the motor mount and the rear most right screw. (Stripped & recessed screw in bulkhead
) The chassis was still rigid as ever though with the extra motor mount top screw in place.
Please take into account that some of the changes to the rear were made to dial in the new rear ends lower roll center position of the arms. I plan on testing this same configuration with foams on carpet this week, with the only changes being the harder springs, stiffer dampening, more upright shock positions, most likely a .5d increase in static camber, a harder rear tire and/or rear anti-roll bar. If my theory works, then all I'll have to do between the two extremes of surface condition is keep an extra set of shocks/springs already built, mount them up and make a few easy adjustments to camber and rear toe.
Even after more than a few hundred mentions, I have to take my hat off to Xray and say, "Congratulations on a job well done with such a great multi-purpose chassis design on the FK05!"
My new asphalt setup is here: