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Proposed Solo Class STP(ony)

SteveW

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Just be careful about where you end up with gearing and 18" tires. At a safe 7200-7500 rpm on stock internals you'd need a really low ratio to get into the mid-60s in 2nd gear. Then when you DD the car with your 19" rains on you have to consider that scenario as well.
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DickR

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But isn't the tire wear better with the Rival? From what I hear the RE-71R wear rate is pretty high, making it a poor choice to waste them on normal street use.

There are multiple threads on 18s that will fit over PP brakes.
Mine have held up very well to thousands of miles of driving between Raleigh, NC and many out-of-state Pro Solos and major autocrosses in the Midwest. I don't know whether the Rivals do any better, especially since my understanding from very credible sources is that Rivals need significantly more tread depth to resist hydroplaning at highway speed.

However, if I did a lot of between event commute or other miles I would probably change to "normal" tires for that use.
 

boardkat

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Just be careful about where you end up with gearing and 18" tires. At a safe 7200-7500 rpm on stock internals you'd need a really low ratio to get into the mid-60s in 2nd gear. Then when you DD the car with your 19" rains on you have to consider that scenario as well.
bah, just blast it all the way to 8250. what could possibly go wrong??? :headbonk:

3.31 and 7500 rpm on a 315 rival-s gets you to a theoretical 71mph (call it 69high IRL). with the power you'll be making in STP trim (and absent E85/low end torque gains), it may feel "sluggish" relative to a 3.55 or (especially) 3.73 on that one or two slow digs you'll encounter at an event, but you will never have to worry about shifting on national courses (save for crows landing). 3.55 may be the ticket locally/regionally (65-66) - and having run 315s on them in what effectively amounted to STP trim early this season, i could still put the power down and got me all the mph i needed (but obviously ran a lot higher than 7500).
 

SteveW

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I wrote above that I would work on a budget to update my setup with the latest rules and kinda wished I didn't, haha. There should be a rule that autocrossers don't make budgets because the potential $$$ spent can look :crazy:

Phase 2 just refers to the fact I ran in the class last season and 2017 will have new allowances that drastically change setup needs compared to 2016.

Below is a screenshot of what I'm looking at. I can't do all this stuff in one season and if you're starting out from scratch you'd be looking at Part II plus a few extra thousand for weight reduction and other misc things. For a national level build anyway. That kind of stuff carries over for me.

Part I is where I'm going to have to work from. I obviously need to get a set of 11" wheels and since my 285s from last year have life left in them I'm leaning towards staying with 19" and running those on the wider wheels until tire silly season works itself out. I hear rumors about a couple new tires coming out that could be options plus, need to see what contingency programs become available before deciding on fresh rubber.

I also want more front spring and it looks like I can switch from OEM style springs to 2.25" race springs on my Roush V3 struts. I'll need new camber plates to go along with the springs.

To not get caught out by rain again I plan to get some brand of max performance tire in 255/40/19 to run on my 10" wheels. I can also use that set as the season's road rubber.

 

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jhols

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What size offset do you need on the 19x11s to clear everything up front? Also do you need a coilover to make the wide wheels work up front? Cause I would rather not get rid of Steeda adjustable shocks. My plan for springs is to run the gt350r springs up front (240 lb/in) and either the r springs in the rear or BMR SP085 (920 lb/in vs 980 lb/in)
 

Brent Dalton

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What size offset do you need on the 19x11s to clear everything up front? Also do you need a coilover to make the wide wheels work up front? Cause I would rather not get rid of Steeda adjustable shocks. My plan for springs is to run the gt350r springs up front (240 lb/in) and either the r springs in the rear or BMR SP085 (920 lb/in vs 980 lb/in)
That's the question none of the vendors are willing to tell anyone it seems. I've never encountered this problem with any other vehicle platform. I won't buy wheels without someone disclosing the offset before purchase. I was looking at 11 in squared before I picked up my apex wheels, but no one wanted to tell me the offset, so I bought from Apex instead. It's not like I can't measure myself once they arrive anyways. [MENTION=7150]boardkat[/MENTION] I believe knows the answer though and may be willing to share as he just picked up one of the wheel offset tools that lets you figure out what size offset you need plus this was what he ran for a while last year before moving to 18x12... and now 18x13(at least in the rear, not sure on the front). Let me know when you order your 19x11's. I may buy a set too and maybe we can save a little on shipping possibly. I know W. Agnor is looking to pick up a set as well. I forget what his SN is on here.
 

boardkat

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19x11/305 can be very straightforward or very difficult, depending on your shock/spring setup (offset struts help), and how much camber you're running (and how you're getting it - plates or bolts).

18x11 +55 w/ forgestar CF5 is what i ran on 315 a7/rival-s w/ MCS coilovers (30mm front spacer) on vorshlag camber plates with about -3.5f/-2.4r camber - goal was to minimize inboard clearance (to minimize track), so there's lots of fender clearance. fwiw, on my new offset JRZ struts, i'm able to run 15mm less spacer.

also had to run a 6" spring up front to keep the perch above the wheel/tire. with an additional 1/2" radius due to wheel, there's no way you'll be able to clear 6" springs/perches (and especially not OEM-style springs) with a similar setup - and 5" springs won't give you enough travel without coil bind (unless you're running VERY stiff - think 900lbs+). unfortunately, you're going to need to be a trailblazer on a 19x11 (and i assume 305 RE-71R tire) setup, especially with OEM-size springs and struts, since nobody is running that up front (yet) that i'm aware of - although chris cox may be heading that route in STP next season (albeit on coilovers and, i think, offset struts) if you're up for the challenge, i highly recommend you get in touch with him, or pick up something like this to help you on the journey:

https://www.summitracing.com/parts/wwk-10072450/overview/
 
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SteveW

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Thanks for the info, boardkat! Question though...with the 305/30/19s being almost a half inch shorter radius than the OEM sized 255/40/19 why would it have problems fitting under a factory strut perch?
 

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boardkat

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Thanks for the info, boardkat! Question though...with the 305/30/19s being almost a half inch shorter radius than the OEM sized 255/40/19 why would it have problems fitting under a factory strut perch?
i was using the 18x11/315 setup as a baseline (and it was CLOSE to the underside of the perches on my non-offset MCS struts with 6" springs with the ride height i was running). haven't even really thought on how to make a 19x11/305 fit under OEM struts/springs because if you're making the effort to go that wide, then you may as well run the appropriate setup - i.e., 2.25/60mm/2.5ID springs are a heckuva lot cheaper (and more available in the "right" rates) than OEM-sized springs. like i said, if others want to trailblaze a path fitting OEM-sized springs on a wide wheel/tire up front, all the power to them, but it definitely doesn't qualify as the straightforward way i was describing in my initial reply :)
 

SteveW

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i was using the 18x11/315 setup as a baseline (and it was CLOSE to the underside of the perches on my non-offset MCS struts with 6" springs with the ride height i was running). haven't even really thought on how to make a 19x11/305 fit under OEM struts/springs because if you're making the effort to go that wide, then you may as well run the appropriate setup - i.e., 2.25/60mm/2.5ID springs are a heckuva lot cheaper (and more available in the "right" rates) than OEM-sized springs. like i said, if others want to trailblaze a path fitting OEM-sized springs on a wide wheel/tire up front, all the power to them, but it definitely doesn't qualify as the straightforward way i was describing in my initial reply :)
Ahh, the question came up about OEM perches with the 11" wheels so what the heck, it is curious if that kind of setup would fit or not. I penciled out some figures this evening while I was killing time:

Current wheels: MRR M350 19x10 with 285/35/19 RE71Rs bolted up to Roush (KW) V3 non-offset struts, but slotted. With non-knurled strut bolts and knuckle pushed all the way in for max camber at the strut bracket I had less than the width of a piece of cardboard gap between the strut body and the tire. So I ran them with a 1/4" spacer.

M350 19x10" wheel - 40mm offset, 180mm backspacing = barely fits (with max camber adjusted at knuckle). So this is the control measurement.

M350 19x11" wheel - 55mm offset, 208mm backspacing = not gonna fit without a spacer. It's going to be a whole lot closer to the strut than the 10" wheel. Like, hitting it.

208mm - 180mm = 28mm spacer required to make the M350 11" fit the same towards the strut as the 10" wheel.

Not sure at this point what an extra inch of wheel and tire at the fender is going to look like.

I need to replace the current front springs and camber plates for something more appropriate so, thanks also for the comments about running 6" springs. I need to figure out what size springs to slip in there somehow. I believe 2.25" is the ID but free length (sounds like 6") and rate are the next questions.
 

boardkat

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I need to figure out what size springs to slip in there somehow. I believe 2.25" is the ID but free length (sounds like 6") and rate are the next questions.
join us late spring @ dallesport - a small group of us are renting the airport for a day and running until we've logged enough data on the skidpad/slalom/offset courses and/or our tires are corded :)
to prep, i suggest all rates in 50lbs increments from 550-800 for the front and 200lbs increments from 1200-2000 in the rear (non-coilover, obviously) - and the 'vert/PP/stano/eibach-bmr front and rear bars. add 150 in the front and 250 in the rear as your starting points if you're joining me on 335 A7s in ESP ;)
 

SteveW

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join us late spring @ dallesport - a small group of us are renting the airport for a day and running until we've logged enough data on the skidpad/slalom/offset courses and/or our tires are corded :)
to prep, i suggest all rates in 50lbs increments from 550-800 for the front and 200lbs increments from 1200-2000 in the rear (non-coilover, obviously) - and the 'vert/PP/stano/eibach-bmr front and rear bars. add 150 in the front and 250 in the rear as your starting points if you're joining me on 335 A7s in ESP ;)
I would love to be there. PM me with the details, please.

Where have you been getting your rear springs at?
 

jhols

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What about running 18x11 vs the 19x10.5/11? Is it worth having the rival s tire in a 315 vs the re71r in a 305? Or would the tire compound and size a moot point?
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