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My 20B FC Redline Time Attack experience

Old 04-01-08, 12:43 PM
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My 20B FC Redline Time Attack experience

Sorry in advance if this is too long and blog like...

Thursday - I head down to Lucky 7 to pick up my car and get ready for action.

Earlier in the week I had replaced the rear trailing arms with OEM instead of the modified ones that were already on the car. EProdRX7 on this forum (who I bought the car from) has created a very effective modification of the stock trailing arms that reduces camber gain when lowering the car, ideal for use with bias-ply slicks that require very little camber. Now that I am running radials I needed lots more camber and had to swap the stock arms back in. It was kind of a pain in the ***, and of course in the process I realized I was missing a set of bushings. Pretty much standard but got resolved the next day.

I also had to replace the fiberglass front bumper that I destroyed when unloading the car at Willow Springs a couple of weeks before, and the splitter that goes along with it.

Loading up and the drive are both fairly uneventful and I get to the luxurious Motel 6 in Buttonwillow, CA around 10pm, park, and sleep. My buddy Danny who drives in a Modified class Evo was supposed to get there around 10pm, but gets there at 6am instead as he underestimates how long it will take to align his car.

Friday - We have a garage rented at the track from today through Sunday. It's relatively inexpensive and has become a 'must-do' for us whenever we go to the track. Our plan is to spend some time setting up whatever is left on the cars and try and get some practice in as Fridays are open-test days at Buttonwillow. This is the first time really for either of us as we've replaced the majority of the setup on both our cars.

As usual though, we spend way too long taking care of the remaining items and it's 9pm by the time we're finished so testing is cancelled. And I still didn't get time to corner balance. Tom from 7's Only sells me on a new fire extinguisher (he's good) so I now have a fire system, a small fire extinguisher, and a big fire extinguisher mounted in the car. I also make a last-minute decision to use Redline 50wt race oil instead of the VR1 20w50 I was planning on using. We had to grind out a section of the camber plate on the passenger side in order to get an equal amount of camber to the drivers side (still only 3.5*), other than that fairly uneventful again. So far so good. I do get to weigh the car and it's only 2440lbs with 11 gallons of gas and an almost perfect 50/50 front/rear split. Impressive!

Saturday/Sunday - I'm always nervous at these types of events as there are alot of powerful cars and some maybe questionable drivers behind the wheels of them. First practice session goes 'ok', I am having serious problems shifting into second gear and the brakes don't seem to be working properly and require a superhuman pedal effort. By working properly I mean that I can't get the front brakes to lock up at all, but the rears are going nuts. I'm using the Tilton pedal assembly that uses 3 master cylinders (1 for clutch, 1 for front and 1 for rear) and a balance bar with adjuster - after adjusting the balance bar full front it's better, but still something is off and the brakes are completely non-linear feeling. After the event I discover that I have the master cylinders the wrong way around for the front and rear - the front is supposed to be 5/8" bore and the rear 7/10" but they are backwards. I also discover that I was sent the wrong ratio pedals - I have the 5.5:1 pedals instead of the 6.2:1 pedals. The best analogy (and the way it was described to me) is imagine holding a wrench 5.5" away from the end versus 6.2" away - this explains the superhuman pedal effort to some extent.

The shifting issue; the Mazdatrix short shifter is just way too notchy for my preference. The effort trying to shift while trying to steer with no power steering and brake using superhuman pedal effort is killing me after a couple of sessions. I have a spare transmission with me which luckily has the stock shifter installed and I swap it out - Tom and the 7's Only guys are kind enough to also give me a different shift **** as the shift **** I had on my Mazdatrix shifter is for an S5 and the stock shifter I just installed is an S4 (doh). Next session out the shifting is much better, but still very difficult. After some investigation the engagement point on the clutch pedal is really really far down the stroke - the only way to bring it any closer to me would be to actually move the whole pedal towards me more, and it's already sitting about an inch closer than the brake pedal already. After the event on Monday and talking with a Tilton tech guy he recommends changing out the 5/8" master cylinder to 3/4" or larger - this will increase the pedal effort but should bring the engagement point much further up the pedal travel. Will have to experiment with it and see how it goes next time out.

The rest of the practice sessions are uneventful, I am having some oil temperature issues after 3-4 hard laps - I currently have the oil cooler mounted behind the intercooler and it's obviously not working out too well. I am seeing oil temps as high as 240* and have to go into cool-down mode for a lap, which brings them down to 200-210 and I can get another lap in before having to cool down again. I figure if I move the oil cooler in front of the intercooler it should work pretty well so will try that next time. Water temps were fine though and stayed below 210 the entire time.

I've also decided that I just have to run power steering. I don't know if it's the added weight of the 20B or if I've just always hated no-ps and just realized it, but the car is a real pain in the *** to drive. Now that I think about it, the last 3 cars I've raced have not had ps and I've always hated something about them - I think this was it. Counter-steering I find to be impossible to do quickly and I have to really hang onto it in some of the faster corners. I'm told by Lucky 7 that the right course of action is to install an S5 single-line ps rack and pump, which I will be doing. The rack currently in there is a plugged S4 ps rack which needs a computer to control.

I'm currently using 16x10 wheels all around with Kumho V710's 265/45/16. This is clearly not even close to enough tire in the rear as any kind of corner-exit acceleration quickly turns into something out of Formula D. I'm not sure if a 12" wide wheel will fit under the AWR rear fenders, it looks like it might be close, but that would allow me to run a 335 wide DOT tire or a 290/645 17" radial slick in the back. Generally getting used to the amount of torque was harder than I thought and I ended up figuring out that I could use 3rd gear in alot of spots that I was used to having to shift into 2nd (all cars that I've driven on track have been 'small' engined in the past).

My Sunday practice/time-attack was cut short when the turbo gasket I was using literally snapped in half during one of the sessions. I was using a slightly thicker gasket made by Cometic instead of the thin metal one, but I guess it sucks. Back to the metal one for next time.

Overall fairly pleased with how it went as I learned alot regarding the brake setup and the engine ran like a champ all weekend. Next event targeted is the NASA event on April 26-27th and should have all of the above resolved by then!

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Old 04-01-08, 12:53 PM
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Sweet. I just got back from doing DE at a NASA event over here on the East Coast myself. Got any more pics of that machine? I have a feeling that mine might be needing a similar wing to yours sooner or later depending on the results of my "spins under the brakes in a straight line" issue. Where did you get it and those brackets?
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Old 04-01-08, 12:56 PM
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There are more pics here: https://www.rx7club.com/20b-forum-95/my-20b-fc-roadrace-car-underway-663170/

The wing is from RE-Amemiya in Japan and comes with the brackets. I got it via Corksport and it's about $1100 and takes a few weeks to come in.
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Old 04-01-08, 07:25 PM
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I forgot to mention, I have the manual rack in mine, not a de-powered power rack, and I really like it. Since it's designed for manual use it's a little lower ratio, so it requires more turns lock to lock, but it's not really an issue on the track, and I like the feedback it gives, you can really feel what the front tires are doing. It also saves some weight and clears up clutter under the hood, and it's one less thing to break.
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Old 04-01-08, 07:55 PM
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thetech: what alignment are you running? Castor has a big impact on steering weight with manual steering. Depending on what you've got you could lower it a bit which should reduce the steering effort. I'd also wonder about the conversion, if it's just a stock power steering rack that's capped, then the piston is compressing the air and any fluid left in there every time you steer, making it harder. If you take it apart and cut out the piston that'll reduce friction and get rid of the air spring internal to the rack. It'll also give you the opportunity to weld up the pinion shaft, which is a source of slop on a manual converted power rack.

http://forum.teamfc3s.org/showthread.php?t=54847

I'd say that the S4 power rack is the one to have since it has a superior speed sensing controller, not the inferior rpm sensing one in the S5 NA's, and the S5 NA rack is a slower one, at 17.4:1, rather than 15.2:1 that you've currently got. Sure it'd be more effort to do, but it'll be better in the end IMHO. Back when I still had PS I could outrun it at the autocross at low speeds and with fast steering and the assist would suddenly disappear, probably not an issue for you, but still...
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Old 04-01-08, 10:09 PM
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Originally Posted by Black91n/a View Post
thetech: what alignment are you running? Castor has a big impact on steering weight with manual steering. Depending on what you've got you could lower it a bit which should reduce the steering effort. I'd also wonder about the conversion, if it's just a stock power steering rack that's capped, then the piston is compressing the air and any fluid left in there every time you steer, making it harder. If you take it apart and cut out the piston that'll reduce friction and get rid of the air spring internal to the rack. It'll also give you the opportunity to weld up the pinion shaft, which is a source of slop on a manual converted power rack.

http://forum.teamfc3s.org/showthread.php?t=54847

I'd say that the S4 power rack is the one to have since it has a superior speed sensing controller, not the inferior rpm sensing one in the S5 NA's, and the S5 NA rack is a slower one, at 17.4:1, rather than 15.2:1 that you've currently got. Sure it'd be more effort to do, but it'll be better in the end IMHO. Back when I still had PS I could outrun it at the autocross at low speeds and with fast steering and the assist would suddenly disappear, probably not an issue for you, but still...
That's interesting to note - unfortunately my car is completely gutted and has none of the stock wiring/ecu components left inside it. I like the idea of the simplicity of the single line system - wasnt there an S5 single line that was 15.2?

Caster is non-adjustable on my JIC's and I haven't actually checked it. Appreciate the suggestion but I'd rather just stick with the PS
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Old 04-01-08, 10:57 PM
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Look into putting a stand alone electric PS pump, a bunch of cars have them now so you can find them cheap. I'm probably going to end up with one on my car after some testing. I thought it would be cool to have it shut off when I hit full throttle or play with some other variables.
I run a total loss system so it might be too much current draw. I have enough weight that I have to add to the car so I may just end up with another huge battery to feed it.
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Old 04-02-08, 01:03 AM
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The S5 TII's basically have an S4 power steering unit, so you really can't get the fast ratio and the simpler setup, unless maybe the internals from an S4 rack fit in an S5 housing? I've had both apart, and they're definetely similiar, but I couldn't tell you if it'd work because I wasn't paying attention to the valving at the time, since I was ripping it out. Might be worth a shot since you've already got an S4 rack and you'd need an S5 rack to do the swap.
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Old 04-02-08, 04:51 AM
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I saw you out there, man that car sound good
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Old 04-02-08, 10:48 AM
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Originally Posted by Black91n/a View Post
The S5 TII's basically have an S4 power steering unit, so you really can't get the fast ratio and the simpler setup, unless maybe the internals from an S4 rack fit in an S5 housing? I've had both apart, and they're definetely similiar, but I couldn't tell you if it'd work because I wasn't paying attention to the valving at the time, since I was ripping it out. Might be worth a shot since you've already got an S4 rack and you'd need an S5 rack to do the swap.
So without having any of the original ps wiring or sensors, the S5 NA seems the only way to proceed, right? I don't want to retrofit any of that junk
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Old 04-02-08, 11:37 AM
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I think so, but it may not actually be that difficult to put in the speed sensing system.
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Old 04-03-08, 08:02 PM
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manual rack

I'd try a stock manual rack first. you can get them for 100 bux and it works in my car just fine. See you in BW in a few weeks. We''l have three FCS there. you shouldn't miss us
Attached Thumbnails My 20B FC Redline Time Attack experience-bw1007sm.jpg  
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Old 04-04-08, 05:04 PM
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Sounds like quite the shakedown of a weekend. What course configuration were they running and what did your best lap end up being?
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Old 04-06-08, 05:56 PM
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Originally Posted by Flynbryn View Post
I'd try a stock manual rack first. you can get them for 100 bux and it works in my car just fine. See you in BW in a few weeks. We''l have three FCS there. you shouldn't miss us
I really like the look of your car, looks close to mine! I tried making a hood like yours with the same vents, but I didnt think it matched the fc body lines as well.
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Old 05-02-08, 08:03 AM
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Congrats

I am really glad to see that this engine worked out, because otherwise it would still be sitting around doing nothing. I'd like even better to see it in real life
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Old 05-02-08, 09:58 AM
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Wink

Unfortunatly, the car is on Ebay. and on the NASA Forums posted for sale. I hope everything is well with thetech. I was suprised not to see him at the track last week either. I was really looking forward to running with this car in SU or ST1 so someone buy it and keep it in Socal!
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Old 05-02-08, 11:33 AM
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Originally Posted by Flynbryn View Post
Unfortunatly, the car is on Ebay. and on the NASA Forums posted for sale. I hope everything is well with thetech. I was suprised not to see him at the track last week either. I was really looking forward to running with this car in SU or ST1 so someone buy it and keep it in Socal!
I'm still here, everything is fine but some days I crave my Spec Miata back and think about selling this expensive machine

Flynbryn which track day were you at recently? Assuming I don't sell it, I'll probably be at the Speedventures event at California Speedway ROVAL on May 16-18. Would love to share some setup info as your config sounds very close to mine minus the extra rotor!
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Old 05-02-08, 11:28 PM
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Nasa. I got up to BW around 3:00 on Friday. I heard today from my freind at JMC Motorsports that there was a dark blue winged FC that broke on Friday. Was that you? They said that it looked like the diff broke and the car got the one wheel peel action going. then the motor gave up the goat. My car and me are a work in progress faster every trip out though. I'll be at WS 05.24 & 25 w/ NASA. Hope to see you there. I'll be in TTU. I haven't run with SV in a few years. They are a fun group to
Regards.
Brian
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Old 05-15-08, 10:31 PM
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It was great to see other FC's at BW a few weeks ago. We'll be out again for the 6-hour enduro on June 7. I hope it won't be too hot!
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Old 05-17-08, 01:23 AM
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Doesn't look like I am going to make the event this weekend or the event on the 24th. Currently battling a few issues, see my blog in signature if interested!
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Old 05-17-08, 03:15 AM
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thats ok, man that car sound good
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