Spank

iTrader: (1)

Racers I need your help. I may be going from SM2 into AP or BP and will be running slicks. Does anyone on this list have first hand experience with the difference between say the Hoosier A3so3 to their full race slick? Or any other racers going from a race DOT tire to a full race slick?

I am considering running 16x10 in front and 16x12 in the rear. Currently I am running 275's in front and 335's in the rear. I am hoping with the slicks I will get much better traction.

Thanks for your help.

Allan

Carl Byck

What car, and what mods to the body?. Definitely stay in SM2 if you can. Check the PAX factors, and do the math, are you going to be that much faster on slicks? I have what should prove to be an EARLY hook-up on the new Kumho V710, It might as well be a slick, it's supposed to be substantially faster than the A3S03. As far as size you could get those in 17s, but not 16s. What tires are you running that give you those sizes in a 16? Or are you running 17s, if so, what tire? There are not many choices. I am almost certainly going to run 18x10.5(25x10x18), and 18x12(25.5x12x18) with Grand Am take-offs(slicks). this will be primarily for road racing, and some local autocross. Later, Carl
BTW for reference, the 25.5x12x18 is a 345-28-18

redrotorR1

Strongly suggest you stay in SM2 with DOT's. AP Vettes are running around 2300 lbs and making 500+RWHP .... more importantly, 450ish RWTQ. And it looks like the SCCA is penalizing BP RX-7's again with yet another weight addition. Erik & Beth have their SM2 beast up to full spec now ... it's STOOOOPID fast! You'll have good company in SM2 at National events.

Carl, the Kumho 710 is only slightly faster than the Hoosier A3SO3 under auto-x conditions. And Hoosier has repeatedly stated that the A3SO4 will be significantly faster than the A3SO3 ... so it looks like Kumho will get leapfrogged again! But, put your order in now ... the waiting list is getting LONG.

DamonB

I would definately stay in SM2. Prepared isn't about tires, it's about P-R-E-P-A-R-E-D. The fast cars in prepared are highly developed. If you're not willing to go that far with the car no sense in going there for the sake of running slicks.

in2twins

Red, agreed,but I can actually afford the 710s
Damon-agreed.
Try VCMC forum for a REAL hookup on V710s, they have the attention of, and the support of Kumho directly. They are taking size, and quantity requests, but not actual orders. Carl

DamonB

Who is VCMC????

redrotorR1

Vancouver Chinese Motorsports Club. I'll withold any comments about their events on this forum .... see corner-carvers.com for any relevant details.

Spank

iTrader: (1)

Hi Carl, Pax is not what I am interested in. I want to win the Nationals. Last year I was 3rd at the Pro Solo Nationals and want 1st.

I have seen the new Kumoh's and Hoosiers. Currently I run A3SO3's both front and rear. I have tried the Victor Racers, Ectsa and Hoosier and can tell you first hand how they compare. Yes the new Kumoh's are said to be faster than the A3S03 (as said by Kumoh). However Hoosier is also coming out with a A4S04 that will be faster yet. I would love to run the wheels I have on the car now but the rules state that they be 16x10 or 16x12, so as you can see I have no choice.

Spank

iTrader: (1)

Thanks for all the info guys. I did not realize that the AP corvettes were at 2300 lbs. I was looking at the times at the events and that was it.

Steve will not be running in BP next year but AM. Rules for RX7 just stated that he must be 2250. They penalized him some in weight.

However with everything that has been said SM2 is looking better.

Thanks

Allan

in2twins

Spank, I only meant to use the PAX for comparison, ie will you be that percentage faster merely by switching to slicks? Cograts on the great job at Nats.
As far as the Kumhos go, They may not be the fastest, but for me, the speed/dollar is unbeatable. The comments about them being faster than the current hoosiers came from the IT forum. Later, Carl

in2twins

Would these(corner carvers) details effect my using them to get tires? I'll not be driving to Vancouver anytime soon

redrotorR1

Probably not. I just don't endorse or patronize organizations that hold un-safe events. But otherwise, I wouldn't hold them as the only place to get the 710's. There's gotta be someone relatively local that can get you a set.

Spank, where in Prepared rules does it say that wheel sizes are restricted? I don't have a rulebook handy, but that seems illogical .... unrestricted wheels in SP but restricted in Prepared? That can't be right.

in2twins

They are restricted in SP to the sizes he listed, I know, becuase I could not run my 17X12s, 16" was max. I suspect the rule is archaic in that nobody was running 17s, and 18s when that was written(its been there for a long as I've been Autocrossing (~10yrs). Might not be hard to get it changed to allow up to 18s since they weigh more, and may not be considered an advantage. Also there are many more tires available for 17x10-12, and 18x10-12, than 16s, in which the only available DOT tire is Hoosier. Time to write a letter

DamonB

I ain't a Prepared guy so that is not my expertise but I think there are weight/wheel width rules?

Spank

iTrader: (1)

Red Rotor you are exactly right in stating that in SP you can run any size wheel you want. However P is determined by weight and original size. You would think going to P instead of SP the rules would be more flexible. Unfortunately they are not.
What a mess!

redrotorR1

I suspect you meant Prepared. Street Prepared (SP) is unrestricted in wheel sizes. No worries.

in2twins

Yes, I did, sorry for that. Frustrating, since I cannot run in SP, and I cannot run Prepared due to wheel size, I guess I'll run in Fast, BUT not fast Enough . My car is for road race primarily, so no big, but I think my rationale(above) for allowing 17s, and 18s still applies, what do you guys think?

25BP

I assume by the tire sizes you stated you are running a FD. BP is not the place for you unless they change the rules as they do not allow 93+ vehicles.

AP you may be able to run, and cetainly SM2. Slicks are a totaly different beast then DOT tires. The DOT hoosiers are nothing to sluff at, they are fairly close to a true slick. They do not take as much to come to temp, and for autox that is farily important as you may only get 3 runs. It may not be that big of a difference to totally set up your car differently and go Prepared for simply wanting to run slicks. If you want to go fully prepared then I would say to strive to build a car to run slicks.

Not sure what it takes to make a FD carry 10"s & 12"s but I can tell you first hand that making them fit on a FC is not as easy as you might think. But certainly do able, just takes money, time and patience.

It has been proven that the FC can contend in BP, and even with the extra 100lbs it will still be a strong contender. There are inly a few FC's that run in BP so competition may be harder to come by, the class is certainly stuggling to exist.
SM2 is a pretty compeditive class and the FD can hang, it is a fairly new class, and others will be joining the band wagon to make it exciting.

in2twins

25BP, are you running 10s, and 12s? i am about to order mine, but in 18s. I came up with offsets in the -10mm range, I think it was -7mm on a 10.5 in front, and -13mm on a 12 in back. It looks like as long as I stay with a tire less than 26" it should fit. Carl

25BP

I am running 16x12 front and back. Currently I am running 25x12x16's Hoosiers all the way around, but may switch to 23's up front to gain more clearance and lower the car more.

in2twins

I assume you have to buy those slicks new? I am looking at the 18s due to the good availability of scrubs from Grand Am. What do those run? Also can you share your backspacing on the rims, and also any special mods you had to do to get those wheels to fit? I would love to be able to run 12s up front. If you want, PM me your phone number, and I can call you at your convenience. Thanks, Carl

25BP

Usually that size slick is new only as not too many GT1 cars are using that size any more. You might check with the guy who sells them in the back of Sportscar.

I am still working out the issues to make it fit. At first I just used spacers, about 3/4"ers and 3" wheels studs. Not the best, but it worked for starters.

To make it work, you need to have a strut purch either made or weld on tabs to ba able to push the top of the tube out, closer to the tub. I had a custom unit made up with a threaded section and new extended tabs. We are finding that the set up we thought would be best, which is keeping the top + bottom holes spaced out at the same distance may actually not be the best. I may have to drill a new hole on the bottom only to push the bottom of the shock in toward the wheel. The bottom of the strut and the ball joint are not aligned correctly and that will create issues.

Also the swaybar endlink mounting bracket is comming in contact with the bottom of the strut. The entire strut was dropped about 1" for better travel. This is not a big issue, it may just require some fabbing.

The wheels I am using are Real Racing wheel. They have a "0" offset. The way the wheel is made it slightly will rub on the calipar so I have to either grind down the calipar (the little nip next to the Mazda Logo) or just use a 1/8 spacer. At this time I have a small spacer and have no issues.

I am still working with my friend at Bilstien, we are working together to make this happen.

Let me know if you have any more ??

in2twins

pics? So, there is 7.25" of room from the hub to the inside of the Tripoint fender? or are your wheels sticking outside of the body work? I guess pictures would be the ultimate. I am probably going to use GC/Advanced Design dampers, they are already shortened, so this may help me with the ride height issues. In talking to Mark at Tripoint, he said that initially their car was too low, ie the roll center was actually below the pavement. I am not sure what the negative effect of that is, but they later raised the car, and got better results. I guess I will spend the winter reading about suspension set-up. You can email any images to cbyck@ybhc.com(weekdays), or c.byck@comcast.net weekends. Did you get your rear flares done? What material did you use for fender liners(if any)? I was thinking of using a rubbermaid industrial trash can sectioned for my liners. Thanks for your input, Carl

25BP

Yes there is a issue with having the car too low. The A arms start to point up toward the hub. This is not ideal.
The "0" offset will mean that there is roughly 6" on each side of the wheel center, then average the width of the wheel center (maybe 1/2"ish). So you should have an extra 1.25" to the fender. Tire buldge and spacers will deminish that as well. I am stuck right now as I have to buy longer springs to make the ride height issues go away. I have the threaded collar jam nut all the way up and the tub wants to still sit on the tire. Time for 10" springs.

I haven't done anything on the rear flares. I have to have the inner/outer skins welded and need to get it on the trailer to go to the shop. Can't do that till I have taller springs.

Also I have been taking a class that has been consuming all my free time. It is finished this weekend so I can zip some update photos.

I am not using any inner fender liners.

in2twins

So are you using a shortened strut? With ordinary Konis, I have to run a 5" spring in the front. Funny how are set-ups can be so completely different , huh. Later, Carl