teamking

Hi all, It's been a while since I've been on this board. I had a haybusa/birkin but ended up selling it as I don't do track days any more. But I've gone all-in on autocross and am a reasonable shoe at the National level in my CStreet ND2 Miata, where I've earned a couple of trophies at Nats. That said, I'm thinking about D Mod. And if I go that route, I'd like the car (perhaps with a "reasonable" amount of work) to be nationally competitive since my daughter and my son-in-law are both fully capable of winning in the right car (both finished 2nd in CSL/CS last year). In addition to Birkin, I've also owned a couple of S2000's. So, a WCM Ultralite has some appeal to me... and I wonder if it is a good platform for building a nationally competitive D Mod car. The advertised wait of 1240 is perfect for me and my son-in-law, and we'd actually have to add some ballast for my daughter to get up to the 1400lb minimum weight (with driver). But I see these cars in lots of configurations and I wonder how many of them actually tip this scales at 1240 with enough gas to avoid starvation. Also, is the outboard front suspension a non-starter at Nats. And it's hard to know what track width and wheelbase the top cars are running (and how the WCM compares). So, I'm very naive about all this and looking for input from those that know more than me about building a competitive D Mod car. Thanks in advance!

That makes sense: Einstein's theory of relativity dictates that if we drive fast enough, we never get old!

And for those rare lefts, I could just make three quick rights each time!!! :rofl:

Actually, top speed was really interesting. At one point I hit 128, but then realized that it was because I was getting a tow from a corvette. Without tow, I think 124 or maybe 125 was my top speed. Climbing esses: I think the camera (Garmin VIRB XE) showed me entering about 115 and keeping it in triple digits the whole way through. I think that the speed it shows is accurate, but it's only updated at about 1 Hz and there is a lot of averaging going on. (It's funny to use that speed on autocross videos, because it shows the speed moving up to about 10 MPH *before* you even start to launch the car). So, on a long straight, it's pretty accurate, but when you are accelerating or decelerating, you have to realize that it's showing you the average speed over about 5 seconds. I don't think I ever bothered grabbing the data out of my AIM solo, which gives a less averaged GPS speed. In any case, I wasn't pushing it hard through the climbing esses-- you'll note that I didn't use any curb at all. I think that was only my 10th lap in the car ever, so I'm still getting comfortable in it (even if it wasn't at all comfortable for my hip!) So, I really do think a 2:10 is very possible if I were to get some more seat time and some fresher tires. Thanks for the sympathetic words. It's funny, getting in and out of the cage is not an issue for me, as long as I am careful about which leg I use to carry most of my weight. And I had thought a year ago that it was the force of pressing the brake pedal that was problematic, but I've changed my mind on that. I think experience has taught me that sitting in the seat while I'm cornering is the real issue-- there is just a lot of bumping and loading going through the right hip as you're taking a left at nearly 1.5g's on an imperfect road surface. I think that is directly exacerbating my bursitis which is in turn causing extra stress on the tendons, particularly the gluteus medius tendon. (Although if there are any experts on hip anatomy that want to chime in, I would be glad to carry your suggestions to my PT or doctor, because we are all scratching our heads). And of course, you can imagine driving this car elicits a fair amount of adrenaline, so I felt great as I was driving it and when I got out. 30 minutes later... not so much.:banghead:

Hi all, I thought I would revive this thread with some good news / bad news. The good news is that I managed to take the Birkin to the track last month at VIR and it was an absolute blast! There was no fuel starvation, and I ran a 2:14 as my best lap. I definitely think that with some fresh 25 compound tires and more seat time, I could easily put down a sub 2:10 time. But that brings me to the bad news. My hip just wasn't up to it. I ran about 25 laps on Saturday, and that was all I could manage. I did about 5 laps in my friend's softer Cayman on the second day before I said enough is enough. I had some recent interest in the car, which has made me realize that I just need to let it go on to someone who can enjoy it. Unfortunately, there is no real end in sight for my hip issues (I've torn one of the tendons and those just don't heal quickly). And I'm finding that driving is extremely problematic. So, it's actually better for me to sell it on, and not be tempted to bring it to the track for at least a couple more years. At which point, it just doesn't make sense for it to sit in my garage when someone else could be enjoying it. It sure was a hoot to be back on track, brief as it was: I'm open to any reasonable offer at this point, so let me know if you are interested at 606BigOak AT comcast DOT net. Thanks!

Best of luck!

For Sale – Track Ready Hayabusa-Powered Birkin S3 Charlottesville, VA http://www.usa7s.net/vb/attachment.php?attachmentid=13063&stc=1 With great regret, I am selling the Hayabusa-powered Birkin S3 I purchased in May of 2016. Not to go into too much detail, but I had a total hip replacement on my right hip in November and am not having the outcome I had expected. I am finding that braking with my right foot in autocross is causing me enough problems that I know I would be unable to attend a track day with the Birkin for the foreseeable future. I’m not trying to make this a pity party, I intend to purchase a VW Golf R with a dual clutch transmission and teach myself to left foot brake. I will be back to the track! But I want to make it clear that the Birkin is not the fault for the short ownership, it’s just that my circumstances have changed dramatically and it makes no sense to own a vehicle that I can no longer drive. Alas. Enough about me, now to the car that I absolutely fell head over heals with a little over a year ago… PICTURES: I’ve created a youtube video with pictures here: https://www.youtube.com/watch?v=aCfy4hxGN8M. THE BIRKIN: I purchased the vehicle from Dick Brink, who had originally sold the kit in the early 2000’s to a gentleman in San Antonio. This gentleman raced it successfully for a number of years before retiring from racing sometime around 2008. Last year, he commissioned Dick to get it running and sell it. The engineering work that he put into the car is unbelievable. My understanding is that he is a mechanical engineer that owned a machine shop—this is not the work of a shade tree mechanic or a weekend warrior. Rather, this car is the work of a professional as a present to himself toward the end of a long career. Included with the sale is a banker’s box full of meticulously detailed files covering every aspect of the build by system. The car is currently set up for me at 5’9” and around 150 lbs. But my understanding is the previous owner was 6’4” and I think around 230 lbs. With some pillows behind her, my daughter has autocrossed it and she is 5’2”. It’s got a quick release steering wheel that aids entry and exit, although I have no issues getting in and out with the steering wheel in place (even with my bad hip). I weighed the car this winter at 1100 lbs. without driver. I was told by the previous owner that the engine should be making around 197 horsepower, although I have not verified that. I will say that in either first or second gear with hot 35-compound Hoosiers on concrete and pointed in a straight line, the car produces wheelspin at full throttle in second gear. And that’s with the tall gearset. It has a quick change gearset and I have shorter gears, but I just don’t see the need. What’s interesting is that even while spinning the rear wheels, the car was controllable—there was no real attempt by the car to swap ends. I don’t know if this is a function of a solid rear axle (I know nothing about drag racing, but I know they favor solid rear axles over independent rear suspensions). I have not driven another 7 will IRS to compare but you would never know that this car has a solid rear axle just from driving it. It’s certainly nothing like a Mustang with a solid rear axle where every bump around a corner causes the rear end to skip. I’ve been told that it is a much bigger deal to have the wide front end on these 7’s (which this car does) than an IRS. And at least as far as I can tell, there may even be some advantage to the solid axle. I did have issues last year with fuel starvation in the first autocross, and in turn 4 at Virginia International Raceway. The car has a 5 gallon main tank as well as a swirl tank. I replaced the rear fuel pump and rerouted and replaced all the rubber fuel lines and did not have problems when I subsequently autocrossed it (although I have not returned to VIR due to my hip). It’s my belief that the old rubber fuel lines were kinking and reducing fuel flow, hence the new fuel lines fixed the issue. I've also not had success using the paddle shifters, but manually operating the sequential transmission has been delightful. The reversing mechanism is trouble free (although sometimes the car has to roll forward/backward an inch or two to engage it). The installed harnesses are 6-pt Schroth ASR, and are street legal and can be used as 4-pt as well. They are out of date, so for HPDE’s they are fine (check your group’s rules), but would need to be re-webbed for racing. The fire bottle is just below the green zone on pressure. The condition of the vehicle is “track ready”. In other words, it’s no garage queen. I’ve tried to do the best I could in the pictures to point out any flaws. There are chips in all of the fenders, and a cone caused a three inch split in the middle of the right rear fender. The aluminum panels are scratched in numerous places. Like I said, “track ready”. STARTUP / DRIVE / WALKAROUND: Here is a video of me starting it up yesterday cold after it had been sitting for about 6 weeks and taking it for a spin (note that the car is not titled so I should not be driving it on public roads. I do have a Manufacturers Certificate of Origin and it was my intent to put headlights and turn signals on it and get it titled). It normally fires up immediately on the first crank, but I think the battery was a little flat from having sat so long, so it took an extra fraction of a second to catch. (I know I should have it on a trickle charger, but I never intended to be going so long between drives): https://www.youtube.com/watch?v=bUuzANPGXYc. ASKING PRICE: $22,000 or best offer. I also have an open trailer with brand new tires, bearings, and electrical connector that I could throw in for another $1000. Please PM me if interested and make an offer. I'm in Charlottesville, VA. MORE VIDEOS: VIR: Autocross: https://www.youtube.com/watch?v=Tt4dX6NtTDQ.

I just had a total hip replacement on my right hip in November. I've had no issues getting in and out of my 7, and climbed in after about 3 weeks. I've been doing lots of autocrossing (although in my S2000 to get ready to take it to nationals). However, I just want to caution you that I am not ready to do track days and am not sure at this point (8 months) when I will be. I am beginning to think that I'm the cautionary tale of the fact that not all total hip replacements are successful. From a flexibility standpoint, I have no issues and am in better shape in that regard than before the surgery. But in terms of strength/endurance, I'm in worse shape than before the surgery and do not think that pressing a brake pedal all day at the track is something that I'm ready to handle. If it were my left hip, I might feel very differently, since the clutch requires less pressure (and I don't left-foot brake). I guess the bottom line is that you should expect to not have any issues with continuing to enjoy your 7, but be prepared for the small possibility of a different outcome.

All, I am starting to formulate plans to make my Birkin street legal over the winter, and am trying to figure out what to do about tires. Currently, I am running Hoosier 20.0 x 7.5-13 A2500 front and 22.5 x 10.0-13 A2500 rear in a 35 compound as my track tires. I think at some point I will switch to 25 compound, and that will be my dry track configuration. I'd like to find a setup that is street legal and doubles as a wet track setup. I'd like to not have to make any other modifications to the car if it suddenly starts to rain while I'm at the track-- I'd like to just throw on the new wheels/tires and be ready for the wet. So, I'm thinking Toyo RA-1's are probably ideal. They're street legal, durable, and I understand they are quite good in wet conditions, particularly when they are at full tread depth. So, what sizes to choose-- I'm thinking: 205/60/ZR13 front and 225/50/ZR15 in the back. The stagger of tread widths is identical at 23% more in the rear (the Hoosier fronts are 8" wide and the rears are 9.8" wide. The RA1 fronts are 6.9" wide and the rears are 8.5". Both ratios are 1:1.23). So, the handling balance of the car should be close to identical with the two types of tires. Also, the narrower RA1's should be less prone to hydroplane. The stagger of the circumferences is a little different. The Hoosier circumferences are 20.6"f and 22.6"r, or about 10% more in the rear. The RA1 circumferences are 22.7"f and 23.9"r, or about 5% more in the rear. So while the gearing will be longer in the street/wet setup, I'm not too worried about that. But the brake bias will also be affected, and this is where I need some help thinking this out. Let's say my current Hoosier setup is ideally biased front to rear in terms of the braking, with the rears being 10% greater circumference. Now, I throw the RA1's on, where the rears are only 5% greater circumference. Essentially, I've made the fronts 5% bigger compared to the rears with the RA1s. If the front circumference is 5% bigger, that means the front tires will exert 5% more torque on the front brakes, which means that I will have just biased the brakes by 5% to the rear. Now, since I'll be driving in the wet on this setup, I won't be able to brake as hard in the limited traction, and there won't be as much weight transferred off the rears onto the fronts, so the 5% effective rear brake bias increase of the RA1's is exactly what I want compared to the Hoosiers. Does that logic make sense? Next question: other than aesthetics, will there be any compromise in performance for the RA1's since they will be on 13" rims on the front and 15" rims in the back? On the Hoosiers (mounted on 13" rims all around) the rear sidewalls are much taller than the fronts. On the RA1's, the front sidewalls will actually be a little taller. Thanks in advance for any advice you have for me!

I'm considering making my Birkin street legal in Virginia this winter. You think this will work? http://www.usa7s.net/vb/attachment.php?attachmentid=11929&stc=1

This was my sixth run (and my daughter had warmed the 35-compound Hoosiers on two previous runs), and the tires were getting stickier on each run... Nevertheless, it was guaranteed wheelspin at full throttle in either first or second gear. I am amazed at how straight it tracks while the rear wheels are spinning. You can hear it hitting the rev limiter right before the right hand 180 at the top of the course-- not because of vehicle speed but because of wheelspin. I guess the LSD is helping to keep it straight... Enjoy!

RE71R's are very good tires on my S2000 for autocross, but they hydroplane easily so I would say not acceptable for wet weather tracking.

http://www.brr-scca.org/forum/viewtopic.php?f=1&t=16574

Hi all, So, I wanted to give an update. I spent the 4th of July weekend underneath the car replacing and rerouting all the fuel lines (see the diagrams for the original routing and the new simplified routing). I guess I'll make the big event next year-- sorry I missed it. Anyway, I must have done something right. I took it out yesterday to an autocross and got FTD! Fuel system was great-- not a hiccup! Dick did put me in touch with the original owner and he was very helpful in getting me up to speed on the system. Thanks to you both!

So, I had an idea of simplifying my fuel delivery system by feeding the surge tank passively through a check valve. In my current system, the surge tank is sitting just to the left of the main tank in the back of the vehicle. Currently, it is fed by a low pressure pump and I'm not sure why I'm getting starvation. The simplified idea uses just a check valve and a T in the hose routing. I'd like to get some reactions to see whether this would work well: While on a level surface without cornering, the surge tank fuel level is the same as the main tank: http://www.usa7s.net/vb/attachment.php?attachmentid=11279&stc=1 The surge tank is filled above the level of the main tank by the cornering forces during a right turn: http://www.usa7s.net/vb/attachment.php?attachmentid=11280&stc=1 During a leftt turn, the check valve prevents the surge tank from draining into the main tank: http://www.usa7s.net/vb/attachment.php?attachmentid=11281&stc=1

Yes, I'm intrigued. I'm not sure exactly how I would run the plumbing, though. I need to do some more research and plan on calling a talking with someone at Holley just so I can ask a bunch of dumb questions. Yes, that thread was very helpful. I should have pointed out that I do have a surge tank after the pump, although I *think* my problem happens before the surge tank. You are thinking of the right car. I bought the car from TMW, and either Dick has not put me in touch with the original owner, or the original owner has not contacted me, after several requests. I will try again through Dick, I feel awkward about just looking the guy up in the phonebook-- like I would be pestering him.

Hi all, Wanted to give an update. I took the car to VIR Wednesday/Thursday and had a real challenging time. I struggled with fuel starvation the whole time. I had chalked up my fuel starvation in the autocross to the fact that the tank only had 1.3 gallons in it. So I filled the tank for VIR and went out. After about 3 laps, it started to starve in turns 4 and 5. 4 is a 90* left, whereas 4b and 5a are a nearly 180* right. Note that Oak Tree is a 180 degree right and that Hogpen is a left followed by a long right (but with significant compression), but it was 4/5 that was giving me the problem. My starvation at the autocross had only happened on the run where I got a little offline and took a jink to the left before my 180* right. Hmmm. Anyway, it gets worse on the successive laps and I decided to go in after 5 laps. Also, my mirrors were not adjust properly (and I couldn't reach them with my arm restraints), and twice my AIM solo had come off it's magnetic mount (and I actually caught it in midair both times-- wish I had video of that!). So, I figured I'd bring it in, get the mirrors right, put some zip ties around the solo, and out I'd go. Except that it wouldn't fire up. Crank crank crank, but no catching. Got some advice from the Wisko guys (they build/maintain hayabusa-powered Radicals out of their shop at VIR and seem to be really sharp) and put the car up in the air and took out the sponge from the tank that was 8 years old since it was probably deterioriated, and removed the fuel filter. The sponge was deteriorating just a little, but they cut open the fuel filter and it was fine. But now I needed a new filter so went into town and got a new filter at Advance (20 minutes each way). Since the next step after reinstalling the filter was to test the pump, I thought about getting one while in town but decided that that would just be throwing parts at it and headed back to the paddock. Sure enough, although it clicked and I could feel pulses in the hoses, there was absolutely zero flow. So I went back to Advance and got a replacement pump. Hooked it up and it was flowing. I'd thrown away the sponge but figured if I kept the tank full, I should be OK. Got everything put back together by 8:15 pm and took a shower (rinsing out the gasoline from my hair and at this point I will mention that gasoline doesn't taste good, stings the eyes, and is a significant irritant on little cuts and scrapes on your hands...). Dinner and a beer at a crowded Oak Tree Tavern and back to the room by 10:15, exhausted an hoping for better things in the morning. Woke up and got out on track by 9:00. Five laps and starvation in turns 4/5. Came in and filled the tank (with two gallons). Five laps and fuel starvation in 4/5. Went out again and started getting starvation after 3 laps. Came in after 4 laps and filled up and went out and started getting starvation after two laps, and was starting to get it in the climbing esses (not a great place to lose control of the throttle!)! Came in and parked the car in front of the trailer and tried to decide what to do. Hmmm. Decided enough was enough and I'd just call it a day (it was 2:30 by then). Went to start the car to put it on the trailer and crank crank crank, no catching! Just like yesterday. Fortunately, I have a winch on the trailer and the car was already in position, so up it went. I'm 99% confident that I burned up another fuel pump. I guess my thinking is that a fuel pump has a lifespan of about 15 seconds, in total, or pumping air before it's dead. And that fuel starvation at the engine is both a cause and an effect. Sloshing in the tank is causing starvation *to* the pump, which causes it to start to overheat, which causes it to overheat, which causes starvation *from* the pump as it pumps less and less fuel. Until you get starvation with a nearly full tank and then it won't start at all. So, what is causing the starvation in the first place? Clearly running without the sponges isn't helping. But let me describe my fuel system because I think there are some issues there that should be addressed. The tank is a 5 gallon cube, maybe 15" in each dimension. There is section cut out at the bottom left to act as an additional accumulator, and this is where the hose to the fuel pump is attached. Rear View: _____________ | | | | | | | __________| |_/ The hose to the fuel pump flows down and and toward the front of the vehicle, and then bends to be on a transverse and horizontal path toward the fuel filter. The filter is a cylinder with an inlet on one end and an outlet on the other, and is mounted horizontally such that the inlet and outlet are at the same height off the road. This is the first issue. My belief is that air is accumulating inside the filter (how would it escape) when it is mounted in this configuration. It should be mounted vertically with the outlet directly below the inlet to prevent air accumulation. The fuel pump looks similar to the fuel filter and it is mounted next to the filter and at the same height such that the hose from the filter outlet to the pump inlet makes a 360* decreasing radius bend at the same height off the ground to get from the filter to the pump. In other words, the hose from filter to pump is a big circle sitting parallel to the ground. My belief is that a left hand turn is causing fuel to slosh in the tank and air gets to the outlet of the tank. As fuel is pumped, the air makes it's way into the filter where it stay in a little bubble in the top of the filter. Now we immediately transition to a right turn. Now the air in the filter moves to the outlet side of the filter and as the pump continues to work against fuel it is drawing air into the hose and eventually it runs out of fuel and into air. Now it starts spinning wildly and begins to burn itself up. Now it pumps less efficiently and the problem gets worse and worse. Eventually, it won't start the car. So, my thinking: 1. Get new sponges for the tank. 2. Mount the filter vertically so it can't hold air. 3. Move the pump so that the loop of hose is removed and there is a continuous downward path from the filter. Not sure if the above is possible without moving the tank higher. Another thought is to find a filter that has it's inlet and outlet at the top. I am going to re-read the thread mentioned above on fuel starvation. Any thoughts appreciated. ******************* As to driving the car: It took an afternoon session with a literal back-to-back session (with only refilling the tank in between) to get the tires heated up. Even so, I was lacking rhythm/confidence. I managed a 2:18.2 (my best in the 944 turbo at VIR was a 2:13). Top speed was 124.4. I could have taken the turns leading onto the straights a little better, but it seems like I'm pretty close to top speed by the end of the straights. 130 may be possible but that would be it. I struggled a little bit with the sequential shifting. I only used second gear in the 944 coming out of Oak Tree and it's up to go from 2nd to 3rd. Guess what I tried to do twice coming out of Oak Tree... up! Which the tranny was kind enough to reject before I floated any valves. Argh. Old dog... new tricks. I just decided to use 3rd for Oak Tree rather than risk blowing up the engine after I realized why I was making that mistake. I'll fix it with visualization before I go back. But otherwise the car was well balanced and a delight to drive. Very visceral. I'd never experienced an open cockpit so the helmet trying to pull off of my head at speed was an experience! I think that a 2:10 is possible with the fuel starvation solved and a chance to build some heat in the tires and get a rhythm going. Here's video: Enjoy!

Wow, I wouldn't have expected it to get that hot! I am used to it-- my previous track car was a 944 turbo that I had removed all the HVAC and insulation. With only two windows, it used to get baking hot in there. My data acquisition would run at 118* (although it produces some heat of its own so I don't know how accurate that is for the actual temp in the car). I was debating whether or not to install the cooler for the cool suit-- finding space for the cooler means removing a cross brace that is running from the center of the rear bulkhead across to where a passenger's right knee would be. You just helped me make the decision! And anyway, that brace wouldn't be there if I had a passenger.

Oh, and another (dumb) question: how do I obtain the "shroud" that goes over the peddle box assembly? (My car didn't come with one and I'm thinking it would be helpful in the event of an engine fire to keep my feet protected) Thanks!!!

Thanks for the help with the tires and starvation issues. I'm getting ready for the track so I thought I'd post some pictures of me in the car. Everything is set from a safety standpoint, except I forgot to put the gloves and the arm restraints on prior to the pictures. Anyway, I'd love to get some feedback on any safety issues you see.

Definitely!

So I had my first shakedown yesterday at a Triad Sports Car Club autocross and the Danville airport yesterday. Overall, the car did really well! What an amazing chassis! I had fuel starvation on my second run, which I need to spend some time figuring out. But the biggest impediment to fast times was lack of heat in the front tires. I am running 35 compound Hoosiers, 7.5f and 10r. It was a cool (low 70's) and dismal day, if it wasn't raining it was about to. Nevertheless, 5 of my 6 runs were in the dry so I can't complain. I was experimenting with tire pressures and found that 18f and 15r worked best. It seemed that all the time I spent spinning the rears got a little heat in them, the fronts were never more than lukewarm to the touch. I ended up 4th fastest out of 61 cars, and about 2-4 seconds faster than I likely would have been in my S2000 (just judging by times from other folks). Let's not talk about the results on PAX index, though... Unless the SCCA SEB ever decides to class motorcycle-engined 7's in DMod, this will always just be for fun when it comes to autocross, but I'm wondering how the succesful drivers deal with the heat issue when the ambients are below 75 degrees. A co-driver would have helped. 25 compound would have helped. Are there better tires for autocross, or do people use a narrower tire to build heat? Here's a link to the fastest run I recorded (I left the camera on after this run and used up the entire memory card): https://www.youtube.com/watch?v=bIHsnpJonzY. Just amazing how well the car did while I was spinning the rear tires at full throttle. This car is going to be a lot of fun!

Thanks for the video, although I'm struggling a little bit with the 173 MPH part.

So that's really interesting. I'm used to driving a 944 turbo with a modified suspension but stock drivetrain. Figure about 210 hp. On R6's, I could enter the climbing esses as fast as 122 but would exit about 102, having to lift in both the rights. Top speed on both the front and back straights was 132, but still accelerating. The car weighed about 2800 with me in it. I was told this Birkin is geared for 142 as it sits and makes just under 200hp. So do you think I'll get up to that speed or be drag limited beforehand? Here's me in the 944 turbo:

I'll look into it! Haven't been to NJMP yet!