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13's on EP rx7?

Old 11-19-04, 02:53 PM
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13's on EP rx7?

hey we're converting our ITA 7 car to EP this winter, what rims are most of the 1st gen guys running? we want to run 13's but are unsure if they'll fit with the SE brakes and calipers up front. We're getting the ISC racing body kit so the offset will be alot different from ITA, anyone have any help for us?

Thanks,
Ron
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Old 11-19-04, 11:29 PM
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PM RotaryAXer. He auto Xs with 13X10s around MI with his 85 or just wait and he will find this thread.
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Old 11-19-04, 11:35 PM
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I love proxy errors
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Old 11-20-04, 12:59 AM
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yea I talked to him just trying to get a feel for what the fast guys run.
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Old 11-20-04, 07:23 AM
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I'm running 15x7's. 90% of the ep cars run 15's. I still have the GSL brakes up front. Going with sevensonly kit this spring. I've got 3 very nice sets of wheels and want to retain the 4x110 bolt pattern. I've got the ISC body panels as well.

I'm sure you know this but 7" wide wheels is the max. allowed.
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Old 11-21-04, 12:39 AM
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Man, you guys are going to prod too? Heh. Looking at going the Weber route, or modified Nikki?
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Old 11-21-04, 01:17 AM
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its our little secret =) you tell me, i'll tell you. PM me
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Old 11-21-04, 01:39 AM
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eh screw it might as well make this the project page. yea we're **planning** on webbers for next year, assuming we can budget it. what body kit you guys going with? and nikki or webber?

This is pretty much the current state of the car, doors are off now though. We were bored and just figured we see how light it was. take a peek through the window. =)

Ron
Attached Thumbnails 13's on EP rx7?-ep1.jpg  
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Old 11-21-04, 12:14 PM
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Well, body kit we're not sure on... honestly just looking at an air dam, since AFAICT we already have as wide of wheels as are allowed and they fit just fine. If we get ambitious, there's the possibility of making 'glass body parts molded from the stock ones, but time'll tell.

I'm looking at Nikki, modified to the absolute bleeding limit of the rules (been spending a *lot* of time figuring out specifics) but I might not get all the R&D and machine work done in time unless I can talk someone into letting me use the CNC machine at school. We have a 48DCOE handy too... not as ideal as the IDA, but we have it.
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Old 11-22-04, 01:43 PM
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Kenku - have you tried the wheels with the cantilever sidewall slicks to see if they fit in your fenders?

The EP cantilever sidewall racing slick tires have a pretty wide section width, thus the need for bigger fenders.
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Old 11-22-04, 02:20 PM
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that and don't you remember those grand am or grand prix commercials...."wider is better"
be able to run different offset/backspacing that what ya do now. Kenku for EP you guys running with SCCA or MWC?
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Old 11-22-04, 03:44 PM
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speedturn: Hm, nope... we're moving up from IT, so haven't seriously seen what fits and what doesn't as far as tires go. Probably starting the season with leftover ITA tires... have to look up some info on the cantilever slicks for later.

BMS2004: Oh, MWC almost definitely, at least in the short term. Thus far, we can't really make more races per year than MWC has due to funding, reliability and doing other stuff, so not too much reason to go to SCCA as well of yet.
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Old 11-23-04, 09:09 PM
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1st gen EP

Hey guys -

I run a 1st gen EP car up here in the Northwest. Answers as far as I know:

- If you want to be competitive, you pretty much have to run a Weber IDA48. Lots of people say that they can get the same power out of a Nikki but no one has ever actually done it.

- there is a bit of a debate on 13 versus 15 inch wheels right now. It used to be a no-brainer. GSL-SE calipers so you don't have to change rotors every two weeks, which required at least 14" wheels for clearance. Nobody cares to make decent 14" slicks so everybody went 15x7 wheels. Now some guys are trying to get back to 13" because it means lighter, lower rotational inertia wheels and makes it easier to get the car as low as some would like to get. Somebody said that if the wheel was thin enough, SE calipers would just fit on certain 13" wheels. I don't know if it's true but this winter I will be trying one of the many 13" Diamond wheels I have lying around to see if it will work.

- Most Prod racers run either the Motorsports / ISC type bodywork or the Mariah Mode one stuff. Don't know if one has an advantage over the other, but both of the fast national guys around here run the Motorsports stuff.

Did I miss anything?
Boswoj

EDIT - Oh, forgot about tires. Since limitation is 7" width, both Goodyear and Hoosier make cantelevered slicks that get a lot more rubber on the road. That extra fender space is definitely needed to run the fast stuff. If your experience is all on DOT stuff, and have never experienced "turn-in" on slicks - get ready for some fun!

Last edited by Boswoj; 11-23-04 at 09:13 PM. Reason: added info about tires
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Old 11-24-04, 07:28 AM
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Originally Posted by finky
PM RotaryAXer. He auto Xs with 13X10s around MI with his 85 or just wait and he will find this thread.

Just to clarify a bit.

I have Diamond Racing Wheels 13x8 on an 84 GSL-SE with Ground Control coil overs adapters up front.

They fit great. This is on an Autocross CSP car so size and backspacing is unlimited in my case.

I am pretty sure I have 4.5" backspacing and I run 225/45/13 Hoosier DOT radials front and 225/50/13 rear.
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Old 11-24-04, 07:42 AM
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Originally Posted by Boswoj
- there is a bit of a debate on 13 versus 15 inch wheels right now. It used to be a no-brainer. GSL-SE calipers so you don't have to change rotors every two weeks, which required at least 14" wheels for clearance. Nobody cares to make decent 14" slicks so everybody went 15x7 wheels. Now some guys are trying to get back to 13" because it means lighter, lower rotational inertia wheels and makes it easier to get the car as low as some would like to get. Somebody said that if the wheel was thin enough, SE calipers would just fit on certain 13" wheels. I don't know if it's true but this winter I will be trying one of the many 13" Diamond wheels I have lying around to see if it will work.

Oh, forgot about tires. Since limitation is 7" width, both Goodyear and Hoosier make cantelevered slicks that get a lot more rubber on the road. That extra fender space is definitely needed to run the fast stuff. If your experience is all on DOT stuff, and have never experienced "turn-in" on slicks - get ready for some fun!
Welcome to the forum! I'm just curious, what is the weight difference between the 13" and 15" wheels/tires? I would think going to the sevensonly or kc raceweare front rotors would give you a larger weight loss than the wheels. I'll have to call a panasport dealer later.

Great point about "turn-in", if you run dot tires you will never be competitive in ep.

The Diamond wheels are steel and very heavy, or do they make alloy wheels as well? My rains are Diamond steel's.

Last edited by cpa7man; 11-24-04 at 07:45 AM.
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Old 11-24-04, 08:25 AM
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"if you run dot tires you will never be competitive in ep" - Amen
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Old 11-24-04, 04:23 PM
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Heads up on SevensOnly and KC brake set-ups

The January Fasttrack is out (the official rules journal of the SCCA) and I noticed that they have amended the clarification pertaining to the two piece brake set-ups you mentioned. There has been a lively debate over the last year concerning these brake substitutions on Rx-7's. Since the original for both the standard and SE setups is a one piece hub and rotor, some of the other competitors feel that the lightweight aluminum hub and ferrous rotor combination is illrgal. After the runoffs, the Comp Board affirmed that they were indeed legal, provided they matched the originals in all dimensions. Someone argued that "weight" could be considered a dimension, and further requested that the board rule on that issue. In the just posted Fastrack, I see that they posted a minimum weight for the assembly, and I am guessing that it is heavier than the currently available assemblies. I don't have it in front of me, but I think that weight was 11 pounds for hub and rotor (correct me if I am wrong). Does anyone know what Sevens Only or KC say their two piece rotors weigh?

As for the wheel thing, Diamonds are still not THAT heavy. I'd love to have a full set of Panasports, but they are a bit to rich for my development budget right now. I will finish the major development issues this winter and have the thing close by race season. If I am close enough for wheels to make a difference, then maybe I will pony up!

Thanks for the welcome - nice to be chatting with other Mazda racers. You never know when we might get to meet on a windy bit o' track some time. I'm running in the 25 hour, anyone else be there?

Boswoj
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Old 11-24-04, 06:48 PM
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Originally Posted by Boswoj
The January Fasttrack is out (the official rules journal of the SCCA) and I noticed that they have amended the clarification pertaining to the two piece brake set-ups you mentioned. I don't have it in front of me, but I think that weight was 11 pounds for hub and rotor (correct me if I am wrong). Does anyone know what Sevens Only or KC say their two piece rotors weigh?

As for the wheel thing, Diamonds are still not THAT heavy. Boswoj
Yes, I just looked it up 10.2 pounds. The two were talking about must work since they are the only game in town (I'll double check before I order). I'm going sevensonly as I can retain my 2 sets of light wheels. The kc racewear kit only works with the gsl-se wheel size. Should work great for you.
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Old 11-25-04, 01:11 PM
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That ruling was just made!

I was also going to source some from Seven's only as I got seriously taken by one of the people involved with KC for a lot of money. I trusted a racer to not take advantage of another racer, and lost a lot of my ability to believe in the innate goodness of people in our sport over it. It's a shame that a mans word or a handshake can no longer be trusted, but thats how it is these days. I'll get off the subject with no more than the statement that I would get out of racing before I would ever patronize them to the tune of another dime....'nuff said.

From what I hae heard about Seven's Only, I'm sure that they would never intentionally sell an illeagal part, so I am assuming that if they need to "fatten up" their assembly to make it legal again they will do it before selling another part. I wonder if that causes a problem with people that already have them being underweight?

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Old 11-25-04, 01:16 PM
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Boswoj, I've been a customer and friend of Sevens Only since 1998 and they do everything by the book and do real nice work. I don't know about the weight of their hub/rotor assembly but if you call them, Bette will probablly answer the phone and can get you that answer. If Fasttrack says there is a minimum weight, rest assured that Sevens Only will fix it.
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Old 11-25-04, 01:49 PM
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Boswoj, Sorry you had a problem. I have purchased a bunch of stuff off the production forum lately and have had no problems with fellow racers. This forum on the other hand can bite you, but overall the RX-7 group is great.

I enjoyed your post on the IT forum. Right now I have two 19 year olds in the garage.
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Old 11-25-04, 08:14 PM
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Guys, I am also moving up to EP. Bought Jesse Prather's tub, will be moving some of my ITA stuff over for first year running regionals and getting kinks worked out, then move up to nationals. Stay in touch.

Rich
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Old 11-25-04, 10:57 PM
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talk about a thread hi-jack.... =) actually this is good, now I won't have to start a post about the brakes. anyone think of anything else we should/cover talk about while we're here? 31rx7 what division you run with? we'll be running cendiv anyone else?
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