Scca STX autocross build

[M-Sport fan]

^^^THANK YOU for those pics/text!!

 

[Cligedy]

The Rivals are mounted and ready to go. This is a good way to start the season. I had definitely gotten my money's worth out of the Dunlops, but I'm glad to have something new.

Speaking of something new, this showed up yesterday.

M-Factory had this on my doorstep just a few days after I placed my order. I think this is the most important part of an STX build, and I'm ready to find out how this matches my expectations. The fact that I won't have it on before the season opener means I'll have a benchmark in place for event #2 with it.

 

[Cligedy]

Ok, at the last minute I decided to go to a test & tune in the next region over, so I had to get some stuff done quick.

No pictures, but I added a CPE rmm. I don't have the complaints about how the car shift and bangs that other people reference, but a stiffer drive train mount should help to improve responsiveness which is always nice for autocross.

I also did a minor weight reduction and swapped out the battery for a Odyssey PC680. This is an AGM battery that weighs about half of the stock lead acid battery. Part of this was spurred by my oem battery being on its last legs after only 3 years,which makes me suspicious that the FiST may be hard on batteries. This makes me feel OK about not buying a 3lb ultralight lithium battery, since the PC680 has a good reputation.

The battery is small enough that I fabricated a small aluminum bracket to keep it from tipping over in the housing. This didn't feel like it would keep the battery from sliding around though, so I cut out a section of closed cell foam, about 1.5" thick to surround the base of the battery.

This should be a 15lb reduction, right over the front wheels, so money well spent.

 

[Plainrt]

Nice job on battery

 

[M-Sport fan]

Will that battery setup (with the foam securing it in place) pass the tech inspectors' scrutiny at your local autocrosses, or do they not even bother with stuff like that?

Was the lithium battery setup you were looking at a FULL stock power/ratings replacement (even though it would be like 1/3rd the weight, or less, of the stocker), or was it severely reduced power, like the PC680 you got?

 

[Cligedy]

Will that battery setup (with the foam securing it in place) pass the tech inspectors' scrutiny at your local autocrosses, or do they not even bother with stuff like that?

Was the lithium battery setup you were looking at a FULL stock power/ratings replacement (even though it would be like 1/3rd the weight, or less, of the stocker), or was it severely reduced power, like the PC680 you got?

Tech inspectors can and should check the battery. This setup will absolutely pass, it is quite secure.

The Odyssey battery is about 80% as powerful as stock. The 3lb batteries would have about 40-50% of the stock capacity.

 

[Cligedy]

Nice job on battery

Thanks!

 

[Kazz]

I went through 3 Odyssey PC680s on my Evo before switching over to Braille. You might try them if that Odyssey fails you in the future.

 

[Cligedy]

If I can get at least 2 years out of it, I'll be happy. I've heard anecdotal shitty things about Braille too. For the near future, small batteries will continue to be a compromise. Lithiums are getting better every day though.

 

[M-Sport fan]

^^^Yes, I may try and hold out for an affordable, featherweight, but FULL factory power, lithium setup in the future.

I hope it does not take to long to happen.

 

[awwwww_shift]

^^^Yes, I may try and hold out for an affordable, featherweight, but FULL factory power, lithium setup in the future.

I hope it does not take to long to happen.

https://www.pegasusautoracing.com/productdetails.asp?RecID=12589

This is the CLOSEST thing you're going to see for a while. Planning on picking one of these up for my Shelby project....

 

[M-Sport fan]

https://www.pegasusautoracing.com/productdetails.asp?RecID=12589

This is the CLOSEST thing you're going to see for a while. Planning on picking one of these up for my Shelby project....

Yeah, THANKS for reminding me of that one, as I also noticed that as a new item in their printed catalog which I have received every year for the last 15+years.

I may just have to spring for that as it's not ridiculously more coin than the Odysseys/Brailles, and the future lithiums may not be any less $$$$ than those.

(I would even consider stepping up to their 24 cell, 720 CA version, which only weighs a little more {.60 lb.} than that one.)

 

[Cligedy]

So in addition to the battery and rmm, I was able to make a bigger change.

I actually bought a set of the Swift lowering springs on a black Friday sale and got a pretty good deal. I had lent the Koni struts I'd built to a local driver who went to the 2016 Nationals. He only just pulled those off getting ready for the new season, and I decided kinda last minute that I would go to the test and tune. This didn't give me much time to get everything ready.

I had faith that the Swift springs would be the best lowering spring option for autocross. I was worried that lowering springs in general would not be a good idea. Too low springs on a MacPherson strut car can cost camber in corners, not to mention that the FiST already has a problem with big tires rubbing.

When I had the car lifted, I took measurements and it looks like at stock height, the car has about 40mm of compression before it starts losing camber. The Swift set is designed to drop the car by about 26mm, so not perfect, but it put my mind at ease.

I got the springs mounted and installed without any trouble. One thing I tried differently is the upper strut bushing. This part is apparently made from recycled soup cans and paper mache. Any time you pull the front struts apart, plan on replacing these. I took one that had gone south on me, pulling apart, cleaned and repacked the bearing with fresh grease. That is apparently not good enough (sad trombone sound), and I can tell that I will need to replace it with a fresh one soon.

The last thing I did before finishing is to add camber bolts to the struts. I used the SPC bolts that advertise they can add ~1.5? of camber. I don't have a camber gauge that I trust, so I I'll take their word for now. I've never used camber bolts like this before, but these don't seem like a good long term solution. We'll see I guess.

 

[M-Sport fan]

^^^I REALLY want to hear your opinion/review of THIS setup, as it is one of the possibilities I am considering, as well as a GC coil over conversion kit using Swift coil over springs on Koni Yellow sport dampers (OR even the race DA Konis which you used with the GC coil over conversion sleeves over them).

PLEASE keep us informed!

 

[Cligedy]

Coming soon...

 

[awwwww_shift]

Yeah, THANKS for reminding me of that one, as I also noticed that as a new item in their printed catalog which I have received every year for the last 15+years.

I may just have to spring for that as it's not ridiculously more coin than the Odysseys/Brailles, and the future lithiums may not be any less $$$$ than those.

(I would even consider stepping up to their 24 cell, 720 CA version, which only weighs a little more {.60 lb.} than that one.)

helps living within a 30 minute drive of the showroom. lots of last minute shopping before track weekends there. Also have a few friends who work there.

Back on topic. A cheaper option would be your standard lawn tractor lead acid cell. Not as much weight savings, but a cheaper alternative.

 

[awwwww_shift]

So in addition to the battery and rmm, I was able to make a bigger change.

I actually bought a set of the Swift lowering springs on a black Friday sale and got a pretty good deal. I had lent the Koni struts I'd built to a local driver who went to the 2016 Nationals. He only just pulled those off getting ready for the new season, and I decided kinda last minute that I would go to the test and tune. This didn't give me much time to get everything ready.

I had faith that the Swift springs would be the best lowering spring option for autocross. I was worried that lowering springs in general would not be a good idea. Too low springs on a MacPherson strut car can cost camber in corners, not to mention that the FiST already has a problem with big tires rubbing.

When I had the car lifted, I took measurements and it looks like at stock height, the car has about 40mm of compression before it starts losing camber. The Swift set is designed to drop the car by about 26mm, so not perfect, but it put my mind at ease.

I got the springs mounted and installed without any trouble. One thing I tried differently is the upper strut bushing. This part is apparently made from recycled soup cans and paper mache. Any time you pull the front struts apart, plan on replacing these. I took one that had gone south on me, pulling apart, cleaned and repacked the bearing with fresh grease. That is apparently not good enough, and I can tell that I will need to replace it with a fresh one soon.

The last thing I did before finishing is to add camber bolts to the struts. I used the SPC bolts that advertise they can add ~1.5? of camber. I don't have a camber gauge that I trust, so I I'll take their word for now. I've never used camber bolts like this before, but these don't seem like a good long term solution. We'll see I guess.

Just wondering what sparked the idea for standard lowering springs vs a full coilover setup? streetability?

 

[Cligedy]

Just wondering what sparked the idea for standard lowering springs vs a full coilover setup? streetability?

A couple of reasons. A) This lets me keep the high quality Koni double adjustable struts I fabricated for the front. II: I was able to get a pretty good deal with a black Friday sale, and I have a somewhat limited budget for the build this season. 3 - I like that this is a linear rate spring, not progressive like most lowering springs. 2^2 - This spring is not tremendously stiffer than oem, which is nice since I am continuing to DD the FiST.

 

[Cligedy]

Ok, so I was able to get enough runs in at the test and tune to draw a few conclusions. To begin with, I am rusty. I only drove 2-3 events last year and I was leaving time across the whole course. On the 45 second course I think that the car had at least another half second compared to my best times. I would have needed 3 seconds to top pax.

First, I tried to find tire pressures for the new Rival. I've read that these like crazy low pressures, ~28psi. I kept lowering the tires but I was starting to get rollover. It wasn't bad, but it was eating the shoulders. This didn't cost me any time though. I'll be sticking with 32psi this season. I'll probably play with the rear pressures more later if I need different balance.

The combination of lowering springs and the camber bolts did give me a bit more static camber and it actually makes a difference. The car still rides on the outside edge when cornering. Throughout the event, the tire temperatures were nowhere near as uneven as before. There was only ~10? difference between the inside and outside. The weather was mild so the temps never got above 120?. I wasn't expecting much of the camber bolts, but the did their job and I am impressed.

The springs were the biggest change next to the tires. I had concerns, but also felt confident that of the lowering springs offered for the FiST, the Swifts were the best choice. After driving the car on course, I have no regrets. The springs are said to be 10% stiffer and that matches how they feel. The steering response is noticeably improved, and the car transition is lovely. The overall balance is close to stock, but the rear end is a bit more planted. Lifting off the throttle mid-corner doesn't turn in as much as stock. I'll probably use rear tire pressures to loosen it back up depending on course layout.

On the streets, it's obvious to me that the springs are stiffer. It's also not a drastic difference. If you think that the FiST is already too stiff, these aren't the springs for you. If you can tolerate a minor increase then these should be at the top of your list.

This event was also a reminder that the car isn't perfect and that a LSD is a critical part of my build. I was fighting wheelspin on corner exit throughout the course. Even without the diff, wider tires would have helped make up some of that time. I'm giving up a meaningful amount of tire width with these Rivals. 15" wheels are still a priority, but without decent options, I will just wait and see for the rest of this season.

This is my best raw time, with a cone in the last slalom. Feel free to tell me how I should have done everything differently.

https://youtu.be/o43LCmRm25k

 

[M-Sport fan]

^^^THANKS for that review, as the Swift Spec-Rs are what I will use for a factory mount type spring, and the 2.5" ID Swift springs are what I would use for a coil over/coil over conversion type spring.

Absolutely agreed on the diff being a requirement for these cars, and if it weren't 3 times the labor cost of one for me to get it into this car, I would already be 'rocking' one.

What do you want to do as far as greater wheel/tire width goes, a 15x8/8.5 with 225/45-15 Rivals on them??