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I wanted to share some much improved auto-x results and the changes that got me there with everyone. In the past I struggled to feel competitive and had a slew of challenges that got me feeling pretty down about the car and my driving.
I suffered the following:
- under-steer and plowing in corners at reasonable entry speeds
- couldn't trust the car accelerating thru slaloms
- no power coming out of turns in second gear (so, basically all the time)
- inconsistent turbo behavior
What I changed throughout this summer:
- Ohlins DFV (7 clicks out in front and 9 clicks out in back)
- Speed of light's wonderful, simple turbo solenoid fix https://www.rx7club.com/3rd-generati...ctive-1120259/
- FC Edit Settings 1: I raised the turbo low transition point to 3800 rpm across the TPS range. This made the car very responsive coming out of low speed turns.
The results were first place in ASP. Overall 17th out of a 66 car field on a very tight course with the top third being competitive drivers and cars. I beat several cars and drivers that I wouldn't have had a chance at before.
The Ohlins were nothing short of amazing compared to my touring shocks with eibach springs. No tire change, no camber change. The car felt miles more capable and I built a lot more trust in it than I had before.
The combination of the solenoid fix and turbo transition meant I had power on tap anywhere in the course.
Nothing like beating up on modern cars like C7 vettes and Focus ST's with a little antique Mazda!
Great result, congratulations! Thank you for sharing your story and feedback.
Thanks! It's taken a while to get here for many reasons.
Thinking about dialing in max camber over the winter and see where that gets me. Hopefully that will let me run 285's in front but I'm afraid to go through that again cuz I just got these 255's to clear!
I might just stick with a staggered setup and focus on getting better rubber when the NS-2R's wear out.
Staggered setup won't help you with understeer. How old are your tires? Maybe new/better rubber and a little softer on the front shocks
Sorry if I wasn't clear - I meant before this event I was having those symptoms/challenges. I haven't seen understeer since installing the Ohlins. The car felt pretty neutral with slight bias towards over-steer.
Best guess is the higher rear spring rate is helping the car rotate and the tired stock touring struts were just DONE.
I'm thinking I will get the shop to max out camber and see how much more clearance that gives me for a square 285 setup. I am around -1.5 degrees all around right now.
Sorry if I wasn't clear - I meant before this event I was having those symptoms/challenges. I haven't seen understeer since installing the Ohlins. The car felt pretty neutral with slight bias towards over-steer.
Best guess is the higher rear spring rate is helping the car rotate and the tired stock touring struts were just DONE.
I'm thinking I will get the shop to max out camber and see how much more clearance that gives me for a square 285 setup. I am around -1.5 degrees all around right now.
What tire sizes, spring rates and sway bar are you running?
I run 265 square with stock bars and 11k springs that comes with Ohlins. That car is way too tail happy on turn in and on power. Going to see if the removing the rear bar is going to help!
Tires are Nankang NS-2R semi slicks 120 treadwear version.
Front 255 35 18
Rear 265 35 18.
Their 265 is more like a 275 in tread width.
Pressure is around 26 psi. These tires are stiff.
Springs are Ohlins 11kg all around. The only thing different than the recommended setup from Ohlins is rear at 9 clicks out.
Camber -1.5 all around for now.
Sway bars are both stock 1993.
I will say that before I made the turbos more responsive I had traction problems. Seems counter-intuitive, but the boost always came on too late so I was always on the throttle too early trying to counteract the "turbo lag". Now I can stay off the throttle and get the front to bite and turn. Then get right back on it with minimal delay.
Tires are Nankang NS-2R semi slicks 120 treadwear version.
Front 255 35 18
Rear 265 35 18.
Their 265 is more like a 275 in tread width.
Pressure is around 26 psi. These tires are stiff.
Springs are Ohlins 11kg all around. The only thing different than the recommended setup from Ohlins is rear at 9 clicks out.
Camber -1.5 all around for now.
Sway bars are both stock 1993.
I will say that before I made the turbos more responsive I had traction problems. Seems counter-intuitive, but the boost always came on too late so I was always on the throttle too early trying to counteract the "turbo lag". Now I can stay off the throttle and get the front to bite and turn. Then get right back on it with minimal delay.
What tires do you have and how do you run them?
Thanks for the info! Seems very similar to my setup besides less camber on the fronts, and also less tire.
I run Federals 595 RS-R 265/35/18 with the alignment:
So far I've tried to run them 30 ish cold and around 35-36 hot pressure. But, reading more, it sounds like I need to go 2-3 PSI on the rear! I will try that first and then process to disconnect the rear bar.
Also, I run the dampers at 7 clicks from full hard front and 13 clicks in the rear Rear.
I don't personally know those tires, but for street tires 36 psi sounds REALLY high for a light car on 265's. I talked to an E36 M3 driver on RS-R's at one event and they had aired their tires way down to get grip.
When I looked up what the vette guys are running for autocross they are high 28-32 psi with street tires. I take a C5 vette as a similar, if slightly heavier example.
Can I ask if all those changes happened at the same time or maybe you were first able to drive the car with the suspension or solenoid fix only?
Having a non responsive car that will not push the car down/forward or make it rotate can indeed induce understeer. At least until the turbo comes alive when two things can happen. A) Fall into more understeer or B) Sudden power oversteer.
So, that fix alone - regardless of the suspension upgrade which of course helps - might be the solution to your problems already!
Anyway, glad to hear that you are now enjoying your car and events!
I drove on the street between upgrades, but didn't race.
I can confidently say that each change played a huge part in changing the car for the better. I had identified problem areas and took these specific steps to remedy them once I figured it out.
There were sections of the course where I would have been under full boost with or without the solenoid fix and higher primary turbo transition and the car just nailed it like I had never experienced on the stock shocks and Eibachs.
I was able to run again this past Sunday. It was cloudy and windy with high in the mid 40's. Cold track surface. No changes to the car except lower boost 10/12 PSI. Injectors are hitting 95% in these temps. Different venue with rough/uneven asphalt.
My only addition this time was a set of $40 RV tire blankets like this:
They are vinyl and fuzzy backed. PITA to get on the front wheels, but I believe they kept some heat in the tires.
Engine ran beautifully and the suspension felt great.
Grip was tough. The car felt more prone to over-steer from throttle input.
The slalom also had me puzzled. I felt like I could go faster in it, but at higher speeds it started to feel like I was driving on a washboard/vibrating and losing rear grip. Maybe should have turned up the dampers to keep the suspension from oscillating.
I had a rare opportunity to do 3 re-runs back to back thanks to sketchy course workers. The last run the tires finally came in a little and I was able to nail it. Dropped almost 2 seconds.
My gap from 1st was about the same as the warmer/shorter event. As a ratio of gap to course time I did better than the previous event, so at least I'm going in the right direction.
I do enjoy these tires and they are a blast to drive at/over the limit... but they just aren't competitive when it comes to grip.
I am considering the following:
255/35/18 A7's (Hoosier makes this size almost as wide as a 285/30/18) on a spare set of mustang wheels
265/35/18 Federal FZ-201 40 TW Soft version on a spare set of stang wheels (not sure if this is comparable to A7s, but intend to ask a distributor) might rub too, but they say it's 25.2" OD
AD08 R / RE71R for no tire change (replace the Nankangs, which sucks because they are actually wearing incredibly well)
Ran another autocross event on Hoosier A7's. I have run exactly 2 events and 1 practice on the tires, so still getting used to them.
Got into the top 10 raw times (9th out of 75 cars). Put a few 100th's between me and a good driver in a Model 3 P dual motor that I've been targeting for a while. I'm super stoked about that!
I drove to the event on the A7's with A/C and then matched or beat a number of trailered race cars in raw times, so I'm feeling pretty good about the car as my goal for it is dual purpose street/auto-x.
I got my best improvements from keeping the hammer down more and blending my braking deeper into corners.
I spun on my last run coming out of a corner (the corner the white Porsche is about to hit in the photo below). This happened last event too. Pretty sure I got on throttle too soon after I tried to plant the front more to get it to rotate better (it did!).
Changes made:
18x10's with Hoosier A7's
-2.5 camber all around reduced boost from 1.0 to .85
intercooler fan
tire sprayer (also used on intercooler)
Looking to run again on Dec 6th. Hopefully I'll have my passenger bucket seat in by then and remove a few more pounds.
Not sure what else is next for the car.
-thinking about an ASP legal spoiler, but I really don't know if that's going to be worth hacking up the rear of the car. Maybe something that replaces the center tail light section.
-more camber up front, but I need to take a close look at the tire temps and see if I really need it
-try disconnected rear sway bar
-diff?
With even springs front and rear I would recommend a big front sway bar, especially when looking at the roll in one of the pics. I run a stock rear bar , medium Speedway engineering front bar with adjustable end links. With square tires ( 345 width A7 ) I had to reduce rear spring from 1300 fr and rr, and now run 1300 front , 1150 rear to get a neutral car .
With even springs front and rear I would recommend a big front sway bar, especially when looking at the roll in one of the pics. I run a stock rear bar , medium Speedway engineering front bar with adjustable end links. With square tires ( 345 width A7 ) I had to reduce rear spring from 1300 fr and rr, and now run 1300 front , 1150 rear to get a neutral car .
I really appreciate the advice on setup! Those photos are on the Nankangs with -1.5 camber so I would guess the roll is even worse with -2.5 and Hoosiers. What kind of mounts are you using? Did you have to reinforce the sheet metal at mounting points?
I do feel like my main hurdle right now is preventing oversteer in or exiting low speed turns. The last two times I have found the limit it was there.
I would really like to get some more seat time before deciding on my next change in setup. At this point I am still learning the tires, but I will keep what you said about F/R stiffness in mind as I push the limit.
Sadly the rest of the season was just cancelled due to covid concerns so it will probably be next year before any race related updates. When they're available I will post up a few photos of my car running the course from the last event.
For Reference
Suspension & alignment specs for our dedicated SSM autoX '93 FD
Koni 28 dampers
Stock suspension arm bushings & ball joints replaced with Spherical bearings
Tripoint front sway bar
Stock rear sway bar
CCW front 18x11 with 315/30 A7
CCW rear 18x12 with 335/30 A7
Alignment
Front cam/cas/toe.....-3.5 / 5.6 / zero
Rear cam/toe.............-2.2 / -0.25 total
10-07-19, 09:35 AM
