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Scca STX autocross build
- Thread starter Cligedy
- Start date
Proper shims would be complex to build and would include keeping the ABS sensors in alignment. shims on both sides of the axle flanges to fix the camber and toe and relieve any stress on the bolts. Likely the mount for the ABS sensor would need at least drilled out and new mounts on the shims, etc.....
I cut my flanges loose all around but the upper right corner barely left in place then using a digital camber gauge, string alignment to the chassis, etc...I moved the flanges where I wanted them and applied heavy tack welds, put it back together and drove up and down the road over bumps to settle everything and it came out wrong, 8 hours of setup and fab work and it did not come out right.
I thought I made an error or did not load the axle properly so I did it over again but added all the weight onto the axle flanges I using a beam across them, barely keeping the rear of the car in contact with the lift. Another 8 hours of setup and fab work and it still came out wrong.
I determined I simply could not load the axle properly that way and each side was a bit different so I measured on the ground after properly settling the suspension, noted the difference of what they measured at and what I wanted, -2.0 degrees and zero toe. Then back up on the lift, pull off everything, cut the tack welds, add in the correction figures, tack welded again, put it together, drive up and down the street.....this time it took around 4 hours....
Results were -1.9 degrees on each side and zero toe so I drove the car carefully a couple of times, a few miles each to ensure fully settled, same numbers resulted, back on the lift, all apart again, fully welded it up then back together and drove over all the harshest bumps I could find over a couple of days time, different temps, etc....
Back on the lift, apart again very very carefully inspected for cracks, etc...no worries and a month or so later when more miles on the car as did the mod with just 293 miles on it, two track days and pounded over the curbs and no issues at all, 2.5 years later, 13.5k miles on the car, over the Sierras on really bad roads, still working fine.
Now if I had my shop setup I could do the mod in 3-4 hours instead of the 30-40 invested or just buy the none ST rear axle with -1.5 camber but that axle is softer and still it would be hard to fit 15x9 wheels with +35 offset and any 225 tire as my tires barely clear with -1.9 offset and my way of doing this adds more clearance than shims can add. With the none ST axle I might of had to run a rear sway bar as well and I have a 5-way race spec bar I modded from a BMW project I could test but so far found no reason to use it on the modded ST axle as my spring rates are controlling body roll quite well.
Even with rolling and pulling the fenders as much as I could the 225 Hoosiers which are more like a 240 wide tire simply would not fit but RA1 and Rival S fit, barely.
I could fit 15x10 6ul wheels with 245 Rival S, RS4, 225 Hoosiers or possible wider ones up front with max fender rolling and pulling but the rear would require flares, cutting the metal out of the way and welding in fillers, etc...and nobody yet offers real flares I know of. Bunny rocket flares are a styling fad, not applicable as a real mod due to horrid aero design.
I cut my flanges loose all around but the upper right corner barely left in place then using a digital camber gauge, string alignment to the chassis, etc...I moved the flanges where I wanted them and applied heavy tack welds, put it back together and drove up and down the road over bumps to settle everything and it came out wrong, 8 hours of setup and fab work and it did not come out right.
I thought I made an error or did not load the axle properly so I did it over again but added all the weight onto the axle flanges I using a beam across them, barely keeping the rear of the car in contact with the lift. Another 8 hours of setup and fab work and it still came out wrong.
I determined I simply could not load the axle properly that way and each side was a bit different so I measured on the ground after properly settling the suspension, noted the difference of what they measured at and what I wanted, -2.0 degrees and zero toe. Then back up on the lift, pull off everything, cut the tack welds, add in the correction figures, tack welded again, put it together, drive up and down the street.....this time it took around 4 hours....
Results were -1.9 degrees on each side and zero toe so I drove the car carefully a couple of times, a few miles each to ensure fully settled, same numbers resulted, back on the lift, all apart again, fully welded it up then back together and drove over all the harshest bumps I could find over a couple of days time, different temps, etc....
Back on the lift, apart again very very carefully inspected for cracks, etc...no worries and a month or so later when more miles on the car as did the mod with just 293 miles on it, two track days and pounded over the curbs and no issues at all, 2.5 years later, 13.5k miles on the car, over the Sierras on really bad roads, still working fine.
Now if I had my shop setup I could do the mod in 3-4 hours instead of the 30-40 invested or just buy the none ST rear axle with -1.5 camber but that axle is softer and still it would be hard to fit 15x9 wheels with +35 offset and any 225 tire as my tires barely clear with -1.9 offset and my way of doing this adds more clearance than shims can add. With the none ST axle I might of had to run a rear sway bar as well and I have a 5-way race spec bar I modded from a BMW project I could test but so far found no reason to use it on the modded ST axle as my spring rates are controlling body roll quite well.
Even with rolling and pulling the fenders as much as I could the 225 Hoosiers which are more like a 240 wide tire simply would not fit but RA1 and Rival S fit, barely.
I could fit 15x10 6ul wheels with 245 Rival S, RS4, 225 Hoosiers or possible wider ones up front with max fender rolling and pulling but the rear would require flares, cutting the metal out of the way and welding in fillers, etc...and nobody yet offers real flares I know of. Bunny rocket flares are a styling fad, not applicable as a real mod due to horrid aero design.
OK, rather long winded, I am retired and have the time though about to embark on changing to a different RV and many mods on it, still tweaking the ST as my cars are never done, always something to try out, fine tune, etc....
-----------
I found the Rival S to be far quieter and induce less chassis vibration, ride hugely better in 225/45/15 than the 205/45/17 Mich PS-3 A/S tires I ended up giving to my daughter.
The are a bit harder and noisier than the 205/50/15 on 8" wide wheels but not by much and both are quite acceptable wife my lady who nearly hated the Michelins they were so bad.
The stiffer sidewall of the 1.5 must be adding more to the noise and harshness of the tire compared to the prior version which makes sense.
-----------
I found the Rival S to be far quieter and induce less chassis vibration, ride hugely better in 225/45/15 than the 205/45/17 Mich PS-3 A/S tires I ended up giving to my daughter.
The are a bit harder and noisier than the 205/50/15 on 8" wide wheels but not by much and both are quite acceptable wife my lady who nearly hated the Michelins they were so bad.
The stiffer sidewall of the 1.5 must be adding more to the noise and harshness of the tire compared to the prior version which makes sense.
Thread Starter
#124
Finally had a chance to upload my fastest run from the last event. This is an ugly run; I was overdriving the car for most of the run, but I was really trying to test the diff.
As you will hear, the Rival 1.5 makes noise at the limit (or past) but doesn't shriek in agony. Good tire.
https://youtu.be/YtfhyvK6cQE
As you will hear, the Rival 1.5 makes noise at the limit (or past) but doesn't shriek in agony. Good tire.
https://youtu.be/YtfhyvK6cQE
?
Thread Starter
#126
Sorry for the lack of updates. I'll be making new additions soon, but I missed the last local event to go to a family wedding. I'm not that upset I missed it. We got flood levels of rain that day.
Next step is upgraded bushings, probably in a couple of weeks. I have the parts, now I need time.
Next step is upgraded bushings, probably in a couple of weeks. I have the parts, now I need time.
Thread Starter
#131
Okay, time for an update. No new parts since last time, but after the last event I was unhappy with how the car is rotating. I pulled the rear shocks so that I could increase the rebound. The shocks had been set at 50% stiff, one turn of two. I wanted to move to 1.5 turns. I had forgotten how much of a chore it is to set the Koni Yellows. The shocks have to be removed from the car (easy) then remove the top mount (easy) then fully compressed and turned(pain in the ass). The shocks take a good bit of effort to compress and it's hard to tell if you have them pushed into the detents that actually change the shock setting. Get ready for some uncertainty and sore palms before you get this job done.
Our next autocross took place at the Michelin Proving Grounds, nicknamed the Black Lake because it is a huge completely piece of asphalt used by Michelin for wet tire testing. This site is actually smaller and less grippy than our main site, but gives us a look at different types of courses than we usually run.
With the shocks being the only change made before the event, setup on site was minimal. I used 33psi for the Rivals up front and 42psi in the rear. No complaints about how the tires drove, but looking at shoulder wear, I think I'll be moving up a few psi in front to cut down on rollover.
The shock adjustment did exactly what I was hoping for and some of the rotation is back. It still isn't as loose as stock but the improvement is evident. I would like a bit more rotation still, but I'll wait until another event at our normal site to make a final judgment as to how much further to go.
Finally, the results from this event were my best so far this season. My first two runs had me in the mix but in 3rd place with most times close together. I decided to be more conservative at a couple places on course hoping to carry a bit of extra speed and it paid off better than expected. It feels really good to knock off 1.5 seconds from a previous run, but that also shows how poorly I attacked the course before. I wound up taking first by about 0.6 seconds which is my healthiest margin this season. I paxed 31st of 119, which I think is better %-wise than my other events this season.
https://youtu.be/rB8MVeN2ChM
This is my 3rd and fastest run. I was the last STX driver and knew I'd won the class before my last run so I was able to take it easy for my 4th. I didn't like the sweeper at the far end of the course. According to Solostorm, I was driving at +1g for 7 seconds. That made me worry about oil starvation, but I didn't have any problems and we had 120 drivers with no mechanical failures so I was apparently worried about nothing. Otherwise it was a great course and a lot of fun. That's why we do this right?
Our next autocross took place at the Michelin Proving Grounds, nicknamed the Black Lake because it is a huge completely piece of asphalt used by Michelin for wet tire testing. This site is actually smaller and less grippy than our main site, but gives us a look at different types of courses than we usually run.
With the shocks being the only change made before the event, setup on site was minimal. I used 33psi for the Rivals up front and 42psi in the rear. No complaints about how the tires drove, but looking at shoulder wear, I think I'll be moving up a few psi in front to cut down on rollover.
The shock adjustment did exactly what I was hoping for and some of the rotation is back. It still isn't as loose as stock but the improvement is evident. I would like a bit more rotation still, but I'll wait until another event at our normal site to make a final judgment as to how much further to go.
Finally, the results from this event were my best so far this season. My first two runs had me in the mix but in 3rd place with most times close together. I decided to be more conservative at a couple places on course hoping to carry a bit of extra speed and it paid off better than expected. It feels really good to knock off 1.5 seconds from a previous run, but that also shows how poorly I attacked the course before. I wound up taking first by about 0.6 seconds which is my healthiest margin this season. I paxed 31st of 119, which I think is better %-wise than my other events this season.
https://youtu.be/rB8MVeN2ChM
This is my 3rd and fastest run. I was the last STX driver and knew I'd won the class before my last run so I was able to take it easy for my 4th. I didn't like the sweeper at the far end of the course. According to Solostorm, I was driving at +1g for 7 seconds. That made me worry about oil starvation, but I didn't have any problems and we had 120 drivers with no mechanical failures so I was apparently worried about nothing. Otherwise it was a great course and a lot of fun. That's why we do this right?
Maybe your Koni yellows are different from what I had, but this was pretty easy: Clamp the shock upper mount in a vice upside down. Now grab the body with both hands and use your weight to compress the shock and keep weight on it while rotating to catch the cogs. Worked easy for me, but maybe the shocks aren't the same.
The purpose of more rebound in enhancing rotation is to transfer more weight from the inside to outside rear tire. This to reduce total grip. Since most of our cars are willing to lift an inside tire, weight transfer can only take you so far. Maybe you should play with different rear tires chosen to offer less grip to start with? I was able to get more rotation than I knew what to do with on a WRX this way. Never did get fast in that car though. But it wasn't for lack of rotation.
The purpose of more rebound in enhancing rotation is to transfer more weight from the inside to outside rear tire. This to reduce total grip. Since most of our cars are willing to lift an inside tire, weight transfer can only take you so far. Maybe you should play with different rear tires chosen to offer less grip to start with? I was able to get more rotation than I knew what to do with on a WRX this way. Never did get fast in that car though. But it wasn't for lack of rotation.
I talked to Mike King at Dixie Tour, and he said he just disconnects the bottom of the rear damper and pushes the body up towards the top mount, using the top mount as a vice. Then, he twists the damper to get the adjustment, let it go, and rebolt. May be worth a shot.
When I degassed my Mazda3 Koni Yellows, they were MUCH easier to adjust without the pressurized gas...
When I degassed my Mazda3 Koni Yellows, they were MUCH easier to adjust without the pressurized gas...
IF you are really worried about the above scenario;
http://www.mountuneusa.com/1-6L-EcoBoost-Oil-Control-System-Fiesta-ST-p/2364-oc-aa.htm
...and if that does not put your mind at ease;
http://www.accusump.com/
Given that I don't know the draconian SCCA's STX rules legality concerning both of the above.![[wink]](/images/smilies/wink.gif "Wink [wink]")
http://www.mountuneusa.com/1-6L-EcoBoost-Oil-Control-System-Fiesta-ST-p/2364-oc-aa.htm
...and if that does not put your mind at ease;
http://www.accusump.com/
Given that I don't know the draconian SCCA's STX rules legality concerning both of the above.
Thread Starter
#136
I almost tried doing it upside down, but Koni specifically advises keeping the shocks upright. I can't say whether or not that makes a difference, but I have to imagine there's some circumstance where it matters. I don't see how the on the car method could work unless you remove the bumpstops.
You are right about the rear pressures, but I probably won't play with that until I've decided to leave the shock settings alone. That way I can use the pressures for fine tuning.
You are right about the rear pressures, but I probably won't play with that until I've decided to leave the shock settings alone. That way I can use the pressures for fine tuning.
Cycling it inverted can get air into the works. So cycle it upright before reinstalling. I put a socket extension thru the upper hole so I could use weight to compress the shock a couple times. I agree with you on the bumpstops -- not seeing how that would work.
Can one of the Koni master stations convert these to an easier single-adjustable? It might be worth it so that you can play with settings on site. I have a request in to get Bilstein B6 rears converted to adjustable, but they don't know yet. Fingers crossed.
Can one of the Koni master stations convert these to an easier single-adjustable? It might be worth it so that you can play with settings on site. I have a request in to get Bilstein B6 rears converted to adjustable, but they don't know yet. Fingers crossed.
![[thumb]](/images/smilies/icon_smile_thumb.gif "Thumbs Up [thumb]"){kind=icon}
![[:)]](/images/smilies/smile.png "Smile [:)]")
At event yesterday I was also running 33 in fronts and started to notice the rollover also and went up to 35. Felt better but I'm not really impressed yet with the 1.5. Rear end seems very unpredictable compared to past years.Maybe I haven't been on right surfaces yet but when I look back to vids of re71r's on same track it makes me sad.
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