SCCA F-Street Setup. What's Everyone Done so Far?

[Competition Orange]

You don't have to remove the strut from the car (leaving the 3 upper nuts on). However that can make it more difficult depending on your technique. I did the first set on the car, the second set off. To get to it you need to remove the brake caliper and rotor (simple), but the two bolts that hold the hub to the strut are in there like no other I've ever dealt with before and talking to others that have done this mod seem to agree so be prepared when trying to just hammer those bolts out doesnt work like you'd expect. An air hammer spits it out in 2 seconds.

Thanks for the information.

I have a compressor and an air hammer, so that'll be good. I'll plan on removing the strut to make things a bit less stressful and hopefully more accurate.

Looking forward to next year!

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[SteveW]

John, My car came with about 1/4 degree more negative camber on the left side front and rear and after the FS legal camber mod still has the same 1/4 more neg in the left front. This is without driver doing it at home with shims to level the garage floor. I haven't changed the rear from the delivered -1.7 LR and -1.5 RR. Rear toe is about 3/32 total. Due to measurement error (i.e. dumb me) Front toe out has been about 1/8 inch all season when I intended to have a little toe-in. (String alignment and brain fade). Got a set of toe plates last week and found my error and confirmed that the string problem was "me". I'll probably take the car to a local performance alignment shop this winter just to get some real measurements and see if they can find more legal front negative camber. My front camber is about -2.5 LF and -2.25 RF.

It would be wise to spot check the alignment maybe once a month during the season, I think. I just had my car on the alignment rack today and what I found was surprising.

When I got the car at the end of July I had the camber mod done and alignment set. -2.3 camber front, -.20 deg toe; -1.8ish rear camber, .40 deg toe.

Today, I still had the -2.3 camber but front toe had dropped a little (maybe within measurement noise from one day to another). I was more concerned with the rear alignment since I had noticed the rear tires had worn way more than the fronts.

I expected a little more wear on the rear tires but not all the way down to the wear bars in 4500 miles and less than 70 runs between my gf and I in 3 months. The rear alignment had changed dramatically: camber down to -1.3 deg and a whopping 1.07 deg of toe-in.

Something had to have slipped or settled or something. The techs had put witness marks on the bolts and cam adjusters the last time and those were still where they left them. Bolts weren't loose either and we couldn't slip anything with a prybar so, I guess various bushings and parts must have worn in or settled a bunch since the car was new.

I went to -2 deg camber and .34 deg toe in the rear. I'm also going to put some UHP all-seasons on to get me through the winter while I figure out either FS or STP for next season. It drives a little "free-er" down the road now too, :doh:

 

[dontlifttoshift]

Because silly season, does anyone have the math handy for top speed in second gear.

Where do we end up with a 285/35-20? Theoretical diameter of 27.85"

 

[ABQautoxer]

60.6mph given rev limiter behavior.

 

[boardkat]

eric yee did this on his '13 GT in 2014 with the rival - you might want to ping him on this experience.

 

[Norm Peterson]

60.6mph given rev limiter behavior.

Does this include tire tread compliance effects or is it based on the tire mfr's revs per mile data?

Tread compliance typically takes about 3% off from calculated speeds based on tire diameter. Autocross is one of the few places where small amounts like that actually matter.


Norm

 

[DickR]

Does this include tire tread compliance effects or is it based on the tire mfr's revs per mile data?

Tread compliance typically takes about 3% off from calculated speeds based on tire diameter. Autocross is one of the few places where small amounts like that actually matter.


Norm

Using Tire Rack specs for BFG Rival 285/35x20 revs per mile are 746. This calculates to 60.3 mph at 6800 rpm according to a spread sheet program I found somewhere. Pretty close to the 60.6 posted above.

 

[ABQautoxer]

Does this include tire tread compliance effects or is it based on the tire mfr's revs per mile data?

Tread compliance typically takes about 3% off from calculated speeds based on tire diameter. Autocross is one of the few places where small amounts like that actually matter.


Norm

Experience. Forum warriors like you make me not want to post anymore.

 

[OppositeLock]

Has anyone tried using the ford racing struts from the "track handling pack"? Im waiting on the koni's and want something better and FS legal.

 

[ABQautoxer]

I'm sure Norm can tell you all about how they would be if he had them and an S550.

 

[OppositeLock]

Lol

 

[Norm Peterson]

Experience. Forum warriors like you make me not want to post anymore.

It was a seriously intended question . . . . and listing speed to the nearest 0.1 mph should beg exactly such a question even if you aren't/weren't an engineer. My SOTP isn't nearly that sensitive, nor my car's speedometer that accurate.

The concept is something I remember out of 800 pages or so of not exactly light reading ↓↓↓ . Some guy named Pacejka also contributed to this book.

FWIW, I might be a little more than a "forum warrior", as you put it. Turns out I'm generally running in the same second around NJMP/Thunderbolt as a couple of guest drivers for Automobile mag did in a GT Mustang and an SS Camaro a few years back.


Norm

 

[ABQautoxer]

Because none of us use the speedometer. It's inaccurate especially when we are changing tire sizes away from OE sizes. Then factor in the rev limiter's behavior, something we've been dealing with every event.

No one cares if you are fast or not in a forum for the most part. What is valuable is what you have tried, not tried, what has worked and not worked to help increase the collective experience to save other time and headaches and generate new ideas/methods. It's great to ask questions and have discussions regardless of experience levels here because we all can use help. However those that don't know you have no idea what it takes to do well at SCCA autox at a National Level wouldn't know that because of the demeanor you attempt to dispense information in something you have very little or even perhaps no experience doing. I can't find you in any results I looked at in the last several years in any class. I normally ignore guys like you (yes there is someone like you on every forum, it might actually be you) but I fear someone reading this thread 6 months down the road will be mislead by you. It's even more strange you insist on doing so in a car forum of a car you don't own or autocross/develop to share with the rest of us that do or might soon. Don't worry, you can keep going, I'll put you on ignore from this point forward.

 

[Norm Peterson]

I have autocrossed at various times since the 1970's, but have been out of it for several years now due to personal difficulties involving heat stress (and one emergency room visit because of this). The only 'new' thing to me here is the rev limiter behavior.

You apparently thought I was just another keyboard jockey, so I gave you evidence otherwise. I'm making no claims as a driver, but at least I'm not making any big setup errors, which comes back to understanding what's going on.

Understanding concepts can be just as useful as direct experience, just in a different way. At the very least it gives a better sense of direction to what car behavior(s) your experience is telling you needs tweaking.

As far as my participation here goes, it seems kind of short-sighted to ignore what I might be getting into a little ways down the road - my 2008 probably isn't going to last forever and stick axle cars are now all relegated to history. So I might as well start the learning curve ahead of time and in return share what I do know that might help.


Norm

 

[DickR]

It would be wise to spot check the alignment maybe once a month during the season, I think. I just had my car on the alignment rack today and what I found was surprising.

When I got the car at the end of July I had the camber mod done and alignment set. -2.3 camber front, -.20 deg toe; -1.8ish rear camber, .40 deg toe.

Today, I still had the -2.3 camber but front toe had dropped a little (maybe within measurement noise from one day to another). I was more concerned with the rear alignment since I had noticed the rear tires had worn way more than the fronts.

I expected a little more wear on the rear tires but not all the way down to the wear bars in 4500 miles and less than 70 runs between my gf and I in 3 months. The rear alignment had changed dramatically: camber down to -1.3 deg and a whopping 1.07 deg of toe-in.

Something had to have slipped or settled or something. The techs had put witness marks on the bolts and cam adjusters the last time and those were still where they left them. Bolts weren't loose either and we couldn't slip anything with a prybar so, I guess various bushings and parts must have worn in or settled a bunch since the car was new.

I went to -2 deg camber and .34 deg toe in the rear. I'm also going to put some UHP all-seasons on to get me through the winter while I figure out either FS or STP for next season. It drives a little "free-er" down the road now too, :doh:

Steve - As an FYI my rear settings are the same at about 12K miles as they were at around 2K. However the are still at the original factory setting with no attempt at adjustment. Rear tire wear on both 5K plus sets of RE-71Rs is no more than the front wear except slightly more mid tread wear in the rear. Camber is about -1.7 LR and -1.5 RR with very little toe in. Lots of tire spinning Pro Solo practice and competition "drag race" starts but mostly interstate and highway driving other than autocross.

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