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First AX for my 2018 Fiesta ST

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Phoenix, AZ, USA
#1
Just checking in... not the most experienced autocrosser or race driver, and not trying to do well at Nationals or anything advanced like that, but just getting back into it after some absence.

Haven't done too much testing prior (except tire sizes, shock settings, rear sway bar). I do like testing and analyzing, dialing things in. So another thought perhaps for people looking to get into it more than tips for the guys at the sharp end for sure.

Class restrictions -- SCCA H-Street (Stock) -- This is the most handicapped class
Wheels --
Min offset allowed 41.5mm (using 42mm and also tried wheels and combinations with 45)... the 40 and 38 and such are not allowed.
Wheels -- Max 18" min 16" allowed, must be 7" wide, went with 16" front and rear but have seen a larger diameter rear combined with the smaller diameter front to get the best rotation behavior with Bridgestone tires but some top guys.
Tires -- 200 max treadwear (stock tires are 140 BTW so they not only have less grip than some of the competition level rubber but per rules allowances not allowed for H-Street). Tried BFG Rival Hankook RS4 and Dunlop DZIII. Tried various sizes, worn but sticky 215/45R16 for the Rivals, 205/50R16 for the DZIII and 205/45R16 for the Kooks. Just a little bit of testing and prefer the behavior and overall the DZIII although I think the Bridgestones and BFG's are quicker in terms of outright grip when in the propoer temp range. Ended up with 46PSI warm front 36PSI rear warm, 100 degree day with good grippy surface.
Shocks -- stock rear shocks and Koni yellow which are adjustable for rebound setting only -- the Koni is more plush than stock at all but the stiffest setting as I think that the shock is for all Fiesta not necessarily just the ST... and they are a PITA to adjust. I ended up with a rebound setting 1 full turn out from fill stiff, but I'm also running a rear swaybar now so otherwise all the way in may work... sort of... back to the theory of every suspension works if you don't let it. Haha... anyway, most people recommend full in, so perhaps a half turn out might have been the sweet spot. Rebound is designed to properly match and control the spring, but AX is about getting through a course faster, so it can help the car rotate as it pack's down and the valving may influence compression damping somewhat.
Sway Bar -- allowed to modify one end or the other to tune the balance of the car, some people change the front, I've added a 22mm bar to the rear, and this was the last step in my testing before going out on course on Sunday.
Alignment -- there was way too much toe in from the factory on my car, even had tire wear dust on the side skirts from the increased wear. Minimized toe, and it was so much sweeter on the highway also. Didn't mess with trying to squeeze outa bit of camber, maybe next time... and slight toe out will probably improve the AX performance/response.

Changed the Air Filter (green), Oil (Penn Ultimate 5W20), and added a different shift knob. Other than struts and different tires/wheels than I chose, that's pretty much the most that can be done.

Result -- Happy with much of the high speed behavior of the car, especially on the many difficult decreasing radius stuff, it as great braking and turning from top of second gear and made made look good in this difficult area, although it was on the edge and could get to be a handful if you over drive it. For the slaloms it was lazyer than I would prefer, I expected the car to be absolutely awesome here and so maybe that's why I'm more critical, and perhaps trying to get more camber and toe out might help. Seems as fast as any H-Street car on this day, first time out for the car and my first time in over a decade, although the driver needs infinately more work than the car.
 


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Location
Portland, OR, USA
#2
Sorry to bump an old thread.

You tried 3x tires, but not the RE-71? Your front pressures sound high, was that to calm the tail, or just to prevent rolling edge over? Maybe the people I have heard running 38ish were running the RE-71 with a stiffer side wall compared to the DZIII.

Shocks, am I reading that right that you have stock rears, but Koni Yellow in the front? Talking with the guy that won nationals, he ran the Yellows, rear 1/2 click from full stiff, then front 1/3-1/2 on the soft end. This was to help the car rotate. He also ran stock sways on a 15 car (17 or 18 and newer cars have softer springs according to him).
 


kivnul

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#3
Everyone is different but for me to minimize tire rollover & maximize grip I run 42 psi front & 38 psi rear with 215/45r17 RE71R's (both hot and cold, I bleed / air up the tires as the day progresses)
 


OP
A
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Thread Starter #4
Another reference: Higher grip surface 44/35 hot lower grip surface 41/32 hot... RE71 205/50/16... any higher than that and I slide around too much, so that's on the back side of the performance friction-load chart... but I'm not the AX SuperStar some of you all are

Only 7 events on the Fiesta so far and all within the last three months, and I'm a little rusty, but trying all sorts of tires, pressures swaybars, dampners, and even full vs empty tank, etc.
 


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Location
Portland, OR, USA
#5
Another reference: Higher grip surface 44/35 hot lower grip surface 41/32 hot... RE71 205/50/16... any higher than that and I slide around too much, so that's on the back side of the performance friction-load chart... but I'm not the AX SuperStar some of you all are

Only 7 events on the Fiesta so far and all within the last three months, and I'm a little rusty, but trying all sorts of tires, pressures swaybars, dampners, and even full vs empty tank, etc.
Yeah those pressures sound more in line with what others, including Kivnul have stated.

Would love feedback on full/vs empty fuel tank. I just got my car last week, and no events till March, so its all bench racing for me to have a baseline for starting my testing from.
 


Messages
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Location
Portland, OR, USA
#6
Everyone is different but for me to minimize tire rollover & maximize grip I run 42 psi front & 38 psi rear with 215/45r17 RE71R's (both hot and cold, I bleed / air up the tires as the day progresses)
It just dawned on me, your running a larger then stock tire size! Does that improve top end 2nd gear speeds? Motor is so torque that going up a size cant hurt and could help. Wondering your experience.
 


kivnul

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#7
It just dawned on me, your running a larger then stock tire size! Does that improve top end 2nd gear speeds? Motor is so torque that going up a size cant hurt and could help. Wondering your experience.
I run SMF class so things may not be directly comparable. The increase in top speed in 2nd gear is very welcome and I do not notice a difference in acceleration / deceleration due to the extra rotational weight and gearing. The taller tire with stock suspension does rub both front and back liners. It is the primary reason I got coilovers. Stiffer springs @ stock height eliminated rubbing. Lowering the car would have its own benefits.

Dunno which would be better overall: Taller tire (with increased speed per gear) VS lower center of gravity (with a faster slalom rate). I really wanted to run 215 RE71's so this is the route I took. I would probably run the new Yokohama Advan A052's which would let me squat down some but the jury is out as to their wear rates (sound like I might only get 2 weekends out of them which is an instant deal killer)
 


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Location
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#8
I run SMF class so things may not be directly comparable. The increase in top speed in 2nd gear is very welcome and I do not notice a difference in acceleration / deceleration due to the extra rotational weight and gearing. The taller tire with stock suspension does rub both front and back liners. It is the primary reason I got coilovers. Stiffer springs @ stock height eliminated rubbing. Lowering the car would have its own benefits.

Dunno which would be better overall: Taller tire (with increased speed per gear) VS lower center of gravity (with a faster slalom rate). I really wanted to run 215 RE71's so this is the route I took. I would probably run the new Yokohama Advan A052's which would let me squat down some but the jury is out as to their wear rates (sound like I might only get 2 weekends out of them which is an instant deal killer)
Oh that makes sense. Its a bit shocking to me that with an extra 7mm (if you can fully exploit this) of offset going up only 10mm in width causes rubbing. Maybe its the extra height along with the width.

I am watching the A052s also. Just price (204 vs 135) keeps me from running them, then if they dont last as nearly as long, that to is a deal killer. I will watch, and if I go to nationals, would do a set. They have a 225/45R16 that could be awesome, slightly taller then stock, but can they be fitted with stock suspension. Though.... the rules say the spring perch shape/location needs to be kept stock, but doesnt say you couldnt cut part out and re-inforce for tire clearance... I did this on the ZX2 Chumpcar to run 245s on it.
 


OP
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Location
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Thread Starter #9
Yeah those pressures sound more in line with what others, including Kivnul have stated.

Would love feedback on full/vs empty fuel tank. I just got my car last week, and no events till March, so its all bench racing for me to have a baseline for starting my testing from.
The full tank, at very least, didn't hurt it seems, but the Jury is still out. I will try it a few more times to get a feel for what it does, and how I'm doing on raw times. Perhaps gas up between the first run group and time only group, I don't know. Sneak in the spare tire also.

I will ramble on about it for a few:

First of all, I often think of how very smart car manufacturers add a lot of heavy parts to the rear of the car without any regard for sprung weight savings, and then everything up front is exotic lightweight materials... sure it's nice to focus on weight loss at the front, but to they have to make the trunk lid so insanely heavy, and the extra wiring for all of the modules in the back, and then the rear portion of the exhaust seems to be 100lbs. On race bikes, everything is light weight, but adding weight in the right place can be very beneficial, and at times it over comes the overall weight penalty.

Second, I installed a VERY light weight exhaust on the Fiesta ST and it perhaps helped zero, even suspect it hurt a little bit... most of the weight was the VERY heavy rear silencer, which has a poor PMI but very low and far back to help with balance. The front silencer was light weight and low CG also.

Third, let's look at the results. Ran full tank last Sunday, but let's rewind to the weekend before, under 1/4 tank, it was a fast course with many decreasing radius turns, and I thought PERFECT, with this car that is my specialty... the S2000's tremble and I'm confident (I'm sure they still beat me). I can dive-bomb the apex with agression, and the car rotates great with gentle brake application, and then on the gas as soon as I can ease off the steering pressure on exit... it couldn't be better. That's the one thing this car would do exceptionally. The course a few weeks ago, also had lower traction as the skid pad was somewhat polished and seasoned chip seal asphalt. Now this last Sunday, there were a lot of constant radius sweepers, and the benefit with the full fuel seemed to be there, the car rotated very nicely with neutral throttle, but it had a lot more rear grip, and couldn't rotate the last 180 before the finish to get on the gas early as it did the weekend before. I figured a full tank would be like a pendulum swinging out the rear, and it was the opposite, more grip in the rear... an extra 8 gallons is like a 50 lb barbell weight strapped under the rear seat area, that's a big deal on a 2700lb car. More grip is usually better, and it was a super star on the slalom, just didn't have the same divebomb trick in the toolbox. Just some thoughts, please don't read too much into it, it was a different course, different grip, and I had a few other slight tweaks.

Biggest issue with weight for me by far, is the DAMN power sunroof, and I would do a lot to make that disappear, tried very hard to find a decent car without it, and I ended up with one. I have the heavy 50lb each Recaro seats also, love the fit, but it hurts more than helps with AX times I'm sure. But then I have to remind myself that I'm doing this for fun, and I'm keeping it in H Street so I don't go overboard with another project (added to the supercharged M5, four Ducatis, and three "other" bikes). No more rambling, back to work.
 


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Location
Portland, OR, USA
#10
Thanks for the info to fuel the bench racing discussions.

The fuel tank being in front of the rear axle, and so low... yeah it could help being more full vs very empty.

What light weight exhaust are you running? I was going to build one out of aluminum piping and an aluminum muffler.

But your right, this goes to all the weight coming off the back of the car, which just will exacerbate the tail happy nature that we are striving for with the stiff koni's.

When picking out my car, my only hard requirement was sunroof, and hearing your statement combined with another forum members, that was a good choice. I did get the Recaros, figuring the advantage of being securely in the seat was worth the extra few lbs.

Did you say what wheels your using? I got the Enkie RPF1s from OAKOS, as they are the only ones with them in the 108 bolt pattern. That was my big spend, but figured 13.7lbs of sprung weight was a significant differentiator vs the next lightest wheel I could find at 17lbs. Or maybe I just liked the bronze color?
 


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Thread Starter #11
Ok... I’m against the sunroof BTW... not sure what you meant.

Nice wheels, that’s what I was looking for at first and TD’s were second choice but everything seemed expensive and tough to jump on used... or wrong backspacing (40mm being popular but out of spec)

Wheels are Rota Grid 16x7 ET42 with 64mm hub centers machined, 14.4lbs and under $600 shipped (5 something can’t remember). Ended up being much more expensive because... Also had a similar set of the Sparco Assetto Gara but they were 16.6 lbs and needed a cheap plastic canter spacer, and they were not as easy to keep clean... probably looked better but I sold them with some good tires and bolted on the Rota with 50 series RE71 and that’s the current formula. (Not getting the right stuff the first time is expensive) Those Bridgestone tires BTw seem to me, to have a narrow range of temps and pressures it seems and it’s easy to get them out of whack and they lose grip.

Tuned Plus exhaust https://adamtuned.myshopify.com/collections/2014-2015-2016-2017-2018-2019-ford-fiesta-st-catbacks (22lb Stainless system, not the Titanium)
 


Last edited:
Messages
314
Likes
267
Location
Portland, OR, USA
#12
Ok... I’m against the sunroof BTW... not sure what you meant.

Nice wheels, that’s what I was looking for at first and TD’s were second choice but everything seemed expensive and tough to jump on used... or wrong backspacing (40mm being popular but out of spec)

Wheels are Rota Grid 16x7 ET42 with 64mm hub centers machined, 14.4lbs and under $600 shipped (5 something can’t remember). Ended up being much more expensive because... Also had a similar set of the Sparco Assetto Gara but they were 16.6 lbs and needed a cheap plastic canter spacer, and they were not as easy to keep clean... probably looked better but I sold them with some good tires and bolted on the Rota with 50 series RE71 and that’s the current formula. (Not getting the right stuff the first time is expensive) Those Bridgestone tires BTw seem to me, to have a narrow range of temps and pressures it seems and it’s easy to get them out of whack and they lose grip.

Tuned Plus exhaust https://adamtuned.myshopify.com/collections/2014-2015-2016-2017-2018-2019-ford-fiesta-st-catbacks (22lb Stainless system, not the Titanium)
Ha yes, I meant to say NO sunroof, but without the no, it doesn't make sense.

I cant find the article, but yes the RE-71 has a narrow temp range, but the Rival 1.5 is happy up to 200deg. Talking to people, they general consensus is that RE-71 is great from the first run, but doesn't get significantly better with heat. But the Rival, while terrible the first run, good the 2nd run, and fantastic the 3rd run.

I hadn't seen that exhaust, 22lbs is lighter for sure. I am going to try peicing together a track only system using aluminum tubing and a 2.5lbs muffler. My goal being 10-12lbs total. And will put the muffler up where the resonator is to keep the weight forward and lower CG.
 




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