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

[Dana Pants]

Are there any other options for reasonably priced and reasonably not-heavy F Street legal wheels for PP car beside Forgestars and OZs (that are on Tirerack but do not take advantage of the offset allowance) ?

It looks like if the SCCA changed the street class offset rule from 7.0 mm to 7.5 mm we would have access to a lot of wheels that are ET45 for the rear. 18x9.5 Enkei PF01 for example. I actually just wrote the SEB requesting exactly that. I don't know how many other people have wrote the SEB about this in the past, but the more the merrier. My letter number is 25464. You might as well write in support https://www.crbscca.com/

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[Dana Pants]

More generally....

I recently acquired a 2018 GT PP1 without Magnaride and am seriously considering an FS build.

I have some questions:

Can someone post some pics and commentary about front-tire wear after camber slotting the front struts? I'm trying to gauge how quickly the outside fronts wear out. My current plan is 285 RE-71r square on FS legal wheels.

Koni Yellows are of course easy to acquire. Is there a go-to source for ultra premium mutli-adjustable FS legal shocks & struts? If so, where did you get them and how much did you pay?

Is the missing Magnaride regarded as an advantage or disadvantage at this point?

The front vs rear bar debate: was there ever a conclusion? A month ago I didn't know rear bars were a thing on RWD street class cars, but there is so much understeer stock that I can imagine where it's coming from.

Also, if you think a 7.5 mm wheel offset allowance would be helpful in street class, please write the SEB about it. I know I do. I already have someone willing to machine 0.5mm off a set of wheels if it comes down to it, but it seems so pointless.

 

[kz]

It looks like if the SCCA changed the street class offset rule from 7.0 mm to 7.5 mm we would have access to a lot of wheels that are ET45 for the rear. 18x9.5 Enkei PF01 for example. I actually just wrote the SEB requesting exactly that. I don't know how many other people have wrote the SEB about this in the past, but the more the merrier. My letter number is 25464. You might as well write in support https://www.crbscca.com/

Wouldn't the 18" wheel put you with an awful short tire though ? Looks 285/35 is the widest for 18", I know there are wider Rivals... Did you run the numbers to see what the max speed will be with the '18 gearing ?

I actually had a set of Axis Model 5 wheels (19"/9", ET45) for the old non-PP car. Found 9.5" version of them with 47.5mm offset at Tirerack closeout for really cheap, bought two and have FS legal set for PP car this way.

 

[kz]

Can someone post some pics and commentary about front-tire wear after camber slotting the front struts? I'm trying to gauge how quickly the outside fronts wear out. My current plan is 285 RE-71r square on FS legal wheels.

I have -2.0 degrees right now, probably over 100 runs on this set. Not horrible IMO, can send you pics if you're interested. Did 1mm as the manual allows, it doesn't really give that much.

Is the missing Magnaride regarded as an advantage or disadvantage at this point?

I would risk saying disadvantage. Compared to Konis, Magnaride is magical.

The front vs rear bar debate: was there ever a conclusion? A month ago I didn't know rear bars were a thing on RWD street class cars, but there is so much understeer stock that I can imagine where it's coming from.

You will have way more experienced people answer here (Dick, Chris J., Boardkat) but I ran car fully stock (short of wheels / tires) after getting it a month ago - it would not turn. Put the rear Strano bar on which I had from previous car and it drove IMO much better. I might experiment with putting front one, put for nearest future, staying with it. Note I ran it on the local event, with stupid tight turns. And it's not that foreign concept, talked to Danny Popp who aligned my car, he said if it pushes, put a rear bar on. I kinda trust him

 

[Dana Pants]

Wouldn't the 18" wheel put you with an awful short tire though ? Looks 285/35 is the widest for 18", I know there are wider Rivals... Did you run the numbers to see what the max speed will be with the '18 gearing ?

GPS top speed completely stock is 76 mph in 2nd gear. Running the diameter numbers gives me 67.8 mph with short 285 30 R18 inch tires. Also lowers the car 1.5 inches.

 

[kz]

GPS top speed completely stock is 76 mph in 2nd gear. Running the diameter numbers gives me 67.8 mph with short 285 30 R18 inch tires. Also lowers the car 1.5 inches.

Hmm, thanks for doing the work, I was too lazy. Very interesting Very. Any other decent 18" FS legal wheels on the market fitting over the brakes ?

 

[DickR]

More generally....

I recently acquired a 2018 GT PP1 without Magnaride and am seriously considering an FS build.

I have some questions:

Can someone post some pics and commentary about front-tire wear after camber slotting the front struts? I'm trying to gauge how quickly the outside fronts wear out. My current plan is 285 RE-71r square on FS legal wheels.

Koni Yellows are of course easy to acquire. Is there a go-to source for ultra premium mutli-adjustable FS legal shocks & struts? If so, where did you get them and how much did you pay?

Is the missing Magnaride regarded as an advantage or disadvantage at this point?

The front vs rear bar debate: was there ever a conclusion? A month ago I didn't know rear bars were a thing on RWD street class cars, but there is so much understeer stock that I can imagine where it's coming from.

Also, if you think a 7.5 mm wheel offset allowance would be helpful in street class, please write the SEB about it. I know I do. I already have someone willing to machine 0.5mm off a set of wheels if it comes down to it, but it seems so pointless.

Some comments regarding your questions. Keep in mind that my "fast and winning" days/decades are a long time ago.

MagneRide vs single adjustable Konis or even much fancier struts/shocks: MagneRide is great if you will be satisfied with the various damping and other dynamic characteristics the Ford engineers selected for the various drive modes. You will not be able to tune front/rear balance etc like you could with even single adjustable dampers. On the other hand you won't have to worry about getting everything all screwed up. Compared to the SA Konis I had on my 15 GTPP I really like the normal mode ride characteristics of MagneRide on the street even with RE-71R's and as expected the ride with the oem PS4S's is even better. I only use track mode for autocross simply for the increased transient damping. Obviously if you are an expert with shock tuning and don't care about street ride characteristics that much (SA Konis are not "bad" by any means on the street but normal mode magneride is better) then shocks you can tune can be a major advantage.

Source for ultra premium shocks: Sam Strano is obviously a very good choice. Jeff Wong at Pro Parts USA is another good source.

Outside front wear: Too many variables including driving style (how much steering angle you use when the car is understeering already), tire pressure, flipping, front/rear rotation, course surfaces, ratio of highway miles to autocross runs, how bald you let the center grooves get, and so on. That said, I have worn out many sets of RE-71R's without flipping or rotating and never corded the outside edges. However I drive thousands of highway miles to/from distant autocrosses and trash the tires with at least 2 or 3/32 tread depth in the inner "center groove" of the front tires because I'm "deathly afraid" of hydroplaning at highway speed. :-) Plus by then the rears have less tread depth anyway. My 15 had around -2 deg neg front camber and the 18 has -2.2.

Front vs rear bar: The first thing to keep in mind is that the front bar's bushings are bonded to the bar and the bushings are clamped firmly by the mounts. As a result the bushings have to twist as the bar attempts to twist/rotate. How much this adds to the effective bar rate at the wheels only the Ford suspension engineers know. As noted in a previous post I ran various versions/settings of stiffer rear bar on my 15 and found that no matter how stiff I made the rear bar it didn't "solve" the slow corner understeer problem for me and made the car had to control in slaloms/offsets, etc. Therefore I initially left the bars stock on the 18 until Mark Daddio drove it at the NJ Pro Solo. Even Mark who likes a loose car said that the car would be better with a bigger front bar with conventional (bushings that allow the bar to rotate) bar so I changed the front bar. More importantly none of the many FS Mustang drivers who beat me in the 15 and 18 ran bigger rear bars. Most ran bigger front bars or drilled the stock bar to make it stiffer.

All this said if your goal is to win at the National level (or at least beat the other Mustangs) you will need to test and tune and plan on spending lots of money on tires. For anyone who lives near Raleigh I might be willing to sell the Strano and Eibach rear bars I used on my 15 since I seriously doubt that I will try them on the 18 in FS and I'm absolutely not going to STP or CAM.

One last comment on MagneRide: The Solo Events Board is seriously examining allowing aftermarket controllers for electronically controlled (including MagneRide) dampers in one or more street or street touring classes. We may hear soon.

Offset: Good luck with getting another 0.5mm. The 7.0 mm change was after decades at 1/4 inch (6.35 mm) and was chosen because it helped a lot of cars and was consistent with the industry practice of using metric for offset specs without going much past the previous limit. I think other proposals to increase past 7 mm have been rejected so you would need a compelling argument other than it works for "you". :-)

 

[Coyote Red]

Any news on Bilstein rear shocks going to market?

 

[Dana Pants]

An incredibly well written and generous download of the inner workings of FS.

Hi Dick,

Thanks so much for the info. I have no idea how long to took to write that post, but seriously thanks.

I'm quite comfortable tuning bars, tire pressures, alignments, and single adjustable shocks. I've been autocrossing since 2012 but my previous car (2012 V6 Mustang) was SCCA classing incompatible, so I chose to run only in local clubs with lots of runs and few rules. Here's an example of my driving and the car:

The car was tragically totaled, and I don't think I have the time and emotional energy to do another deep build (insert FS classing here).

My competition goals 2019 aren't so grand: actually compete in local SCCA events for an entire season and do a tour or two. Nationals 2019 are a reach goal right now, my 2nd child is due any day and my wife would prefer cars did not exist.

 

[DickR]

Dana - You are welcome. Was the video at the Ft Devens airfield? I ran my first autocross at a community college (or similar) not too far from there in my brand new 69 Mustang GT 351 Windsor when I was stationed at Devens.

FYI the post just covers basic stuff. The top contenders will experiment with front and rear toe both in and out and with rear camber. They will also remove exhaust system weight and find the lightest wheels. The fastest FS Mustangs at Nationals this year were on SA Konis. Ditto in previous years. I think (but am not sure) that Jeff Wong's Camaro was on a custom shock setup that he "built" at Pro Parts but I don't know what brand(s). I do know that he did a lot of adjustment changes between runs and heats at the several Pro Solo's and Tours that we both attended.

That said my understanding is that the stock 18 PP shocks and struts aren't "bad". Keep in mind that the M3 and the Camaro's are the faster cars in FS :-(

 

[Dana Pants]

Dana - You are welcome. Was the video at the Ft Devens airfield?

Yep. Ft. Devens.

 

[Whiskey11]

Can someone post some pics and commentary about front-tire wear after camber slotting the front struts? I'm trying to gauge how quickly the outside fronts wear out. My current plan is 285 RE-71r square on FS legal wheels.

On my car, the 285's are lasting about 80 runs or so between myself and co-driver, both trophy capable drivers. Caveat is that I run pretty much ONLY on the Lincoln Airport's concrete which is particularly hard on tires when run consistently. Generally flip after the 4th or 5th event depending on runs per event. We buy two sets of tires a season, usually a new set before spring nationals and one before nationals.

Koni Yellows are of course easy to acquire. Is there a go-to source for ultra premium mutli-adjustable FS legal shocks & struts? If so, where did you get them and how much did you pay?

I'm sure any of the premium damper manufacturers out there will have options available if your wallets are deep enough... I believe Eric Simmons had a set of JRZ's on his car with stock perches before deciding to do what he does and get rid of the car.

Is the missing Magnaride regarded as an advantage or disadvantage at this point?

Maybe? Maybe not... it really depends on how much you trust Ford's damping curves and whether or not they allow changes to those curves with aftermarket modules. Do I think it's an advantage? Yes, do I think it's enough of an advantage to get rid of my car for a new one? No.

The front vs rear bar debate: was there ever a conclusion? A month ago I didn't know rear bars were a thing on RWD street class cars, but there is so much understeer stock that I can imagine where it's coming from.

I think there was... as far as Performance Package cars goes, your top PP cars both the last two years are running front bars, either an aftermarket one (mine) or a drilled factory one (Paulson). Burdette is running a rear bar on a base GT. The differences to me were tangible... you don't need much front bar, but enough to settle the back end of the car down. The rear bar allows the car to turn more at corner entry while giving it up at the exit. Not my idea of a fast way to drive a RWD car. I'd rather slow down a little more and come out significantly harder than come in hot and not be able to translate that into exit speed and use the power of the coyote to move the car on course for the trade off in a more stable car in transitions.

That's just me... if you think the car is loose now, I can tell you that adding a rear bar will make it unbearable. I bought both bars (BMR in my case) just in case, but after driving a rear bar setup, I'd never run it. My Co-Driver and I are EXTREMELY happy with the car!

Also, if you think a 7.5 mm wheel offset allowance would be helpful in street class, please write the SEB about it. I know I do. I already have someone willing to machine 0.5mm off a set of wheels if it comes down to it, but it seems so pointless.

I'm not sure it'd make much of a difference on these cars to be honest... I'm not sure 7mm makes that much of a difference either...

 

[Dana Pants]

More good info.

Thanks for the download.

So I attempted to get my rear suspension alignment in order over the last few days which was almost enough to make me burn the building down. I cannot believe the interaction between toe and camber on these cars. It seems that extraordinary amounts of math are required to get this done in a few shots.

To hopefully save someone else's time:
-A 1 degree change in rear camber will result in roughly a 0.75 degree (5/16 inch) change in rear total toe.
-Adding camber causes toe-in, removing camber causes toe-out.

Said the other way:
-Adding toe-in reduces camber, adding toe-out increases camber...a lot.

Also it seems that max negative camber is about -2.5 degrees after you get the toe zeroed... probably a bit too much. I'm currently sitting about about -1.3 deg rear camber and 1/32 in rear total toe-in (0.08 degrees). I guess I'll have to wait till I have FS parts on my car to fine-tune. I intended -1.8 deg camber, but the toe interaction outsmarted me.

 

[Whiskey11]

Also it seems that max negative camber is about -2.5 degrees after you get the toe zeroed... probably a bit too much. I'm currently sitting about about -1.3 deg rear camber and 1/32 in rear total toe-in (0.08 degrees). I guess I'll have to wait till I have FS parts on my car to fine-tune. I intended -1.8 deg camber, but the toe interaction outsmarted me.

You'd be surprised... I run -2.2 out back on my car and I think that makes me unique among the Mustang drivers. Rear toe set to zero. Alignment guy said he could get me up to -3.5 degrees out back pretty easily... don't need that much but nice to know the option exists I guess lol! Front camber is about -2.0 with again, zero toe.

Why more camber out back than factory? Because I want the rear tires to be happy before I start balancing out the car in some way. Our rear tires are almost to a 2:1 ratio of life compared to the fronts. Surface temp readings indicate pretty even across the tire after a run on the Test and Tune course although the pictures show it could use a little more to keep the tire flat when powering out of a corner (max compression of the rear suspension basically). No adverse wear on the street thankfully! Not that these tires last long enough for me to notice! LOL

 

[Dana Pants]

You'd be surprised... I run -2.2 out back ...

I took a quick zip around the block with the -2.5 rear camber and got a lot of surprising inside tire fire. Granted this is on the 4S tires, but it seemed like something unfair to put my snow tires through. I would have left it if the car was behaving well. At least now that I have good alignment notes, fine tuning should be a relatively painless process next summer.

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