Jon, As the most racy guy on this list or at least at the top, do you think the relative flexibleness in your old 355 chassis was a detriment to its overall performance. I notice that even with 355's on my twin post lift the door gaps open up. On your 355 the cage was not an 8 point with extra weld to the "a" pillers and door sills and tie-ins to the suspension towers which I guess would have made a big difference. How much of a difference do this think a proper cage would make and do you think the transference of stress to other points would have been able to take the extra load, I.e. full cage = more stress to say pick-up points welded to very thin box frame.
My engineering and technical background is somewhat limited (remember Tom Cruise in Day's Of Thunder............I just drive the car !!) But yes that is a very good assumption. The cage on 355 C's was nothing more than an OMP bolt in cage. In fact behind the seats they just welded in metal blocks that the cage bolted into. I have to think that a real welded 8 point cage would make a huge difference. The cage that came from OMP was minimal at best. A local friend of mine raced one at Summit Point a few years back and flipped his 355 C. The damage bent at least two bars, the one that goes across the front windshield and the one that goes down the driver's side A pillar. I was horrified to see this and SCCA immediately banned the cage from competition. I also seem to remember Doc. Steve Earle referring to his old 355 Challenge car as "Ole Noodles". I don't think the OMP cage makes any difference, or at most a very slight difference. I can't compare since I haven't driven a 355 C with a proper cage but I can tell you from experience that a good cage make a huge difference if designed properly. On my M5 I had a professionally designed 8 point (Speed World Challenge Spec) welded cage into the shock towers. This was on a 14 year old BMW 4 door sedan and the added structural improvements were quite amazing. I actually gained a few mph on the front straight because of less body roll. The guy to ask this question to would be Rob Schermerhorn at [email protected] . Regards, Jon P. Kofod www.flatoutracing.net
Jon - That's amazing! Do you figure the speed gain was from increased exit speed from the corner (as allowed by the stiffer chassis), or just superior straight tracking rigidity? Gary
Gary, I think it was entry speed and exit speed. At this stage the car had an upgraded street suspension (Dinan performance suspension vs. entirely stock OEM). Also keep in mind that this was a 14 year old car with 130,000 miles on the chassis (of which 20,000 were hard driven track miles). I think the benefit was pretty significant. It was 2mph at most but that's a huge difference and points towards increased exit speed. Everything else was the same on the car. However someone else once pointed out that maybe I was more confident of pushing the car with a full cage, but I am not sure that was a factor. Cheers, Jon
I Think your m5 impressions are pretty amazing considering the cage adds about 150lbs and the m5 is pretty stiff dispite the high mileage. I had taken for granted the flex in pre-360 ferraris since those cars end up in my garage 99% of the time...you just see it so much you don't think about it. I was working on a friends 928 non-caged driving event (DE) car (lowered suspension mods only) and we needed to jack the car just to get it on my lift. I lifted the car from one corner and was suprised at the relative stiffness compared to our noodle mobiles! The problem for all car designers is if you strengthen here you stress there! I bet that if you increased chassis rigidity with proper cages in pre-355's ferraris you would rip the pick-up pionts off the tack welds to the flimsy box frame. Compromises are difficult when you want to go faster. Regardless of how you got your speed confidence vs. something intrisic, extra speed is extra speed. I'd sure like to drive a 355 with a proper cage to see what that is like. The 360's are supposed to be really stiff but I have never had one on my lift. I wonder who you would make a proper cage in a fully aluminium car. You would have to bolt all the steel to aluminium and those joints flex. I could see some real problems there. the 360 is the fastest F out of the box for tracking but it does not make a good longterm track car IMO. I think the cage is a real issue because it is bolt in and longevity issues of steel on aluminium and all the SD2 needs just to do simple post trackday maintenance.
If you look at the 355's that were built ground up a racecars in europe, they have substantial cages integrated into the car. Integrated into the subframes, it can make a huge difference. This goes for like any car really. A properly seam welded chassis with a well designed and built cage can do wonders. http://rpi.edu/~jaffes/Cage/Cage.htm That is something I did in cad one night for a fellow bmw club racer who wanted to see what his cage design would look like in 3d. I drew it on paper, and I converted into cad from generic dimensions. Thats a very basic cage when it comes to professional touring/gt class racing. Heres a gallery of the cage in my BMW racecar, its based off the factory motorsports design, with some added benefits. Integrates into front and rear subframe, center jackpoints, goes through firewall in 6 places, very close to frame and welded along each tube as well as the sweet gussets http://gallery.underclockers.net/gallery/Cage-Pics
Formula Racer, I agree 100%. Problem is that all 355's built post 1995 at Gestiva Sportiva had omp cages. They were not done well. The feet at bottom of A piller did not tie into the tub corners, the rollhoop was o.k. but the rear points did not tie to the shock towers, there was no knee bar, and IMO poor door bars, there was no tie in forward of the apillers! I have seen one proper cage in a 348/55 and that was in the IMSA flag car 348 that Dave Nelms put back together in Boulder Co. There may be others but I have never seen one. It seems like such an important thing for safety and chassis ridgitity but no body does it. Flatout had the last documented 95 355 converted car all to Ferrari specs and it did not have a proper cage either because that was not Ferrari spec at the time. I think it is too bad because Ferraris are giving up free laptime by not having a proper cage IMO. But then the cheap buggers would have to have better pick-up point attachment points and that would cost them 10 bucks in metal. Geez in 1997 the corvette Z06 was the stiffest production car made one of its claims to fame which contributed to its superior handling and it was a $60 car!
I've been on the track for over 2 years with a 355ch (95) that was fully updated for the later ch series. The cage they put in them is not for structural rigidity, its merely an added safety device, not to aid in retaining the stock suspension pickup points. I have seen 3 or 4 355's that were prepared for either scca, or WC. Some really nice work, but a waste since the cars were not competitive
We went back and forth with Rob Schermerhorn on this before, he claims it's absolutely not true. SCCA has a minimum tube width requirement now and doesn't consider the quality of the metal. Rob Schermerhorn claims the spec cage to be as safe than a standard width SCCA cage. You might also want to talk with speedmoore as he still races another users 355 C that his shop installed a custom cage that is as nice as it comes. He's also very engineering minded like Rob and knows his stuff. I never knew my car had a nick name. Of course #104504 got a brand new tub since Steve raced it.
Very true. I have a good SCCA cage for it sitting in the garage, but not worth installing as the car is 10 yo anyway and wasn't competitive ever in T1. Maybe in the rain it had a chance.
Rob, Is that SCCA T-1 the same class dominated by the near stock Z06 corvettes? Also, you may want to re-read the SCCA manual. SCCA does have very specifc requirements for cages and does take into account the metal. For example they distinguish between chromoly and mild steel and tube diameter and thickness based on chassis weight and ERW vs DOM tubing and demand inspection holes for tube thickness. Also there is a huge difference in a weld-in cage VS my 348 I want to look like a racecar bolt in OMP cage also used in 355's. A proper cage can stiffine that old chassis and make your new tube last longer. The real question is where all the stresses will go and can those points take the new load.
Yes. Challenge can't hang with the Z06's or even the old Vettes. I haven't seen any 360 C's in T-1 yet, they might do OK.
Yes Rob, It is amazing the performance in the Z06. There is alot of technology in there besides the stiff chassis. They have a funny fibreglass spring board to work the suspension like a swaybar design almost. The cool thing is the lack of unsprung weight as an advantage over the coilover shock design. Additionally vs the 360 the vette has no aerodynamics any more sophisticated thatn the old 1970's 308's. The Z06 body has a low CD and that's it. Most guys who race these cars don't even use "real" wings. Contrast that to 355/360c's and these wings are extremely functional and adjustable. Finally, the 360 takes all that to the next level where the 360 has real aerodynamic undertray which is also its shortcoming for the rookie race drivers that most of us are. We rookies are much safer and have potentially more fun with a wing ala the 355c even at the expense of the added aerodynamic drag. If you think the 355c has problems keeping up the 348 is significantly worse. I get lapped so may times I get dizzy. But geez the 348 costs me nothing to run and it is totally reliable. One other thing I have not figured out yet in driving a midengine ferrari is that when your back end breaks lifting makes it worse. Lifting then hitting the gas does not stick the front then stick the rear. All I seem to have is front coubter steering grip to handle the oversteer. In the nose heavy cars like the Z06 if the back breaks you can lift and the tail tucks/nose grips then you can power on again plus you have counter steering. To me these cars are easier to drive. Did you get that in the RX7?
I lost you at "lifting". Sorry, I don't know what that is? Seriously, I'm not the best at describing vehicle dynamics and especially what my brain is telling my feet and arms to do. They just kinda do it. I know one thing a really really good instructor (Randy Aust) told me in the Challenge car as compared to the Rx7 is that it likes to be under power. The car grips much better when under power. The Rx7 is a momentum car and I just kinda dive bomb it into the corners as fast as I can and through drifting (scrubbing) I get the speed where it needs to be and then nail the gas as early as I know I'll survive the corner. That is way different than the Challenge as it wants to be under throttle and SMOOTH. So Randy was working with me on getting the speed down in the braking zone vs. trail braking/skidding and thus allowing you to throttle earlier and take advantage of that grip through the corner. Anyone know why the Challenge has so much grip under throttle? I mean, I know why any car has more grip under throttle, thus why most spins in corners are the result of someone lifting. However, with the Challenge does it have something to do with aligning the car and setting it up for when the back is squatting under throttle? One thing I do know is your car has more steering input the heavier the front is. So when you lift, you're shifting weight to the front and will have more steering input. Works well for autocross, but on the road course it's probably a little too much steering input with the back light.
Rob and Bob, A couple of things: 1) First off, a 355 C will only have problems hanging with a T1 Z06 on something like a high speed oval (TMS). And this is mainly due to the Vette's superior aerodynamics (no wing and better cd). At most tracks the 355 C can more than hold it's own against T1 ZO6's. At Summit Point the T1 record is 1:20 flat by Speed World Challenge regular Tom Oates. I've been in the 18's and Ferrari Challenge champion Jim Kenton has seen 17's. At Lime Rock the 355 C record is half a second quicker than the T1 record. Ditto at Mid Ohio where Shearer has run faster than either Bobby Archer in his T1 Viper, or the current record holder in T1 John Heinracy. At the Glen which is a real power track, Shearer holds the Challenge record at 2:04. Fastest T1 time is in the 2:07 range. All these comparisons are between T1 cars with R rated rubber and Challenge cars with slicks. I think given equal tires the cars are equal. Jeff Stahley did 1:21's in T1 with his 355 on Hoosiers and he isn't a front runner. If a ZO6 is significantly faster than a 355 C than the 355 C isn't being driven fast. The ZO6 will have a slight edge on power to weight (410/3100 vs. 390/3000) but the Challenge cars brakes and handling more than make up the difference. With R rated tires on both cars I'd call it dead even. A 360 C would destroy any T1 car, even on equal rubber. At the Glen a 360 C does a 1:59. R rated tires are not going to be nearly 9 seconds per lap slower. 2) In regards to the cage, I know Rob S. knows more about these cars than anyone here, but the fact of the matter is that I saw with my own two eyes, Stahley's 355 cage all mangle up. The center section across the windshield was bent downward and the A pillar bar was crushed and compacted. the bolts on both sides of the driver side (front foot well and behind the seat) were loosened enough to cause grave concern among SCCA. There is no way a bolted in cage will ever hold up to the same impact of a fully welded cage. 3) I am taking a wild guess here on your suspension question (RX7 vs. 355) but you have to remember that in "stiff" setup form the 355 has 2200 lb springs and that in order to get the most out of this stiff setup you have to be at 10/10ths through the corner. This means either on the gas at turn in or even left foot braking while feeding in gas. If you get on the gas late or drive it 8/10th's the springs do not compress enough to get maximum grip form the slicks. 4) In reference to why lifting causes problems in a mid engine or rear engine, just picture where the weight of the car is...........the rear. When you are already oversteering, the rear doesn't have enough weight over the rear tires and this causes loss of traction. Then you lift and what is happening. You are transferring an already inadequate amount of weight to the front of the car and de-compressing the rear springs. This is worst on early 911's. Think of the pendulum effect. The only thing that can save a 911 in terminal oversteer is to get the wheels with drive (rear wheels) to grip the pavement. When you lift in this situation you do two things that are counter productive to what you are trying to achieve. One, you are now cuttting power to the drive wheels and TWO you are transferring weight from the rear to the front which is the opposite of what you want. 5) Lastly, I am not sure if Steve Earle was referring to his old car (not your new tub but the old one) in terms of comparison vs. the 360 C (it was in the first Forza test for the 360 C unveiling) or if he meant the car had seen a lot of useage. Regards, Jon
Jon, on the oversteer issue yes I understand that. I guess what I don't understand or know how to do is recover when I am at terminal oversteer. I cannot ride the edge between 10/10ths and "in the dirt". Maybe I need to to have more off track excursions to learn the edge. But that is an expensive way to learn. And in regards to T-1 I do not dispute any of your times. However, it is my understanding that the T-1 Vettes hold all the titles and or dominate the class. Even the super powerful vipers are not the top of the heap in T-1. In my personal experience in low level club racing the Z06's are always at the front or near it. What I see does not compare with what you see. One club's documented track records @ laguna Seca 360C drivien by a pretty hot challenge driver 1:46.7 and at the same event M3 1:46.2 , 993TT 1:41.2 so not all that dominant? There are many results such as these.
I had a nice response to you yesterday, but deleted it out of Word before I had copied and posted back to FC by mistake. Here's another attempt... There just isn't enough data on the 355 C in T1 on R tires. I think you're giving the R tires too much credit, I think it makes a huge difference. FC user Bob Meyer or something like that was immediately faster in T1 when going to the Z06 from the 355 C. There just aren't enough facts to compare, we'll just leave it that my opinion is the Z06 is faster at most tracks, even technical ones. I'm the first person in internet history to be arguing against the car they actually own. At minimum you'll have to admit in racing (not going for lap times) that it's better to have the power down the straight than any handling advantage. I do agree the 360 should be very competitive in T1. Racing a full season without any damage would be a "challenge" though. I think what Steve was talking about is intrinsic to all 355 C's. However, he did beat up the #104504 pretty bad and then Ed raced another two years after that. If there were issues with the wear on the chassis, that was solved in 2002 when a completely new tub was installed.
Bob, I looked over some stats for you. At Laguna for this years Challenge race the fastest lap was 1:36.XX (see: http://www.motorsport.com/news/article.asp?ID=165069&FS=FCS) If you go to the SFR SCCA website the T1 record is still held by a 355 C. It lists the track record for race as a 1:40 by a 355 C (see: http://www.sfrscca.org/RoadRacing/Records/index.html) and it lists the Qualifying record as 1:40 by someone in a Vette this year. I also pulled up Road Atlanta which is another fast track and found the following: SCCA T1 track record is a high 1:35 in T1 (see: http://www.atl-scca.org/AtlSCCA-Club%20Racing.htm) Darius Grala did a 1:30 at the same track in 02 at the Challenge Series (see: http://www.motorsport.com/news/article.asp?ID=92128&FS=FCS) Again, we can't really decipher from websites the quality of certain drivers. There is no question that the ZO6 is the dominant car in T1 because of it's performance and price. We both know what a 355 or 360 costs, and a Viper is now in the 90K range (the older model not the new one). At this years Run offs there was only one non-Vette in T1 and that was Freddy Bakers Porsche GT3, which sat on pole but finished 3rd or 4th. At Mid Ohio, John Heinrecy hold both the race and qualifying records (1:35 and 1:33) http://www.scca.org/Event/Event.asp which is above Steve Earle's 1:29 at Mid Ohio in a 355 C (no race rubber not R compound). To my knowledge the 360 C's never raced at Mid Ohio. I think that the number of people running a Ferrari in T1 is very small. I am not aware of any Ferrari in T1 here on the East Coast or even in the mid-West. I would gather that any serious racer would be running a Vette since it's 1/3rd the cost and as fast as a 355. So we have a large scarcity of Ferrari's in T1 and then I would gather that if at most 4 or 5 are running in T1 in the country probably none of them are driven by world class drivers. I think it makes little sense to race a 355 or a 360 in T1 because there is little perofmance advantage, and as you have pointed out may even be a handicap at some tracks. Even with equal race rubber the 360 C is going to be faster. A 360 C weighs nearly 500 pounds less than a Z06 and has nearly the same power. I also think that the quality of drivers, nationally, in T1 is much greater than in the Challenge series. In referrence to your oversteer question, much depends on the situation but the main requirement of correcting out of a potentially terminal oversteer situation is to properly recognize it's happening immediately and to make the proper correction the first time. At the club level and most DE's/Track days, the majority of accidents happen because one of two things (or both happen). One, students/racers react or recognize the situation after it occurs, NOT when it occurs. And two many students/racers make a "saveable" event even worse by over correcting, thereby increasing the terminal aspect of the situation. Every situation calls for different responses so it would be silly of me to tell you what to do. You obviously know that in a 911 you never lift even the tiniest bit, and in a mid engine car (like your 355) you barely lift at all (feather the throttle very lightly). I think, and this is just my opinion, that the biggest obstacle for most people in a terminal oversteer situation is to recognize it at once and to calmly slow the event down in their mind and not over react. Most good racers, both professionals and club guys can react with blinding speed to such a situation but when it occurs and when they react everything is in fact happening at a slower pace for them because their brains process everything much faster. I remember when I was a novice and got into such situations I would panic and jerk the wheel. I would then replay the event in my mind and swear that it happened in a plit seconds and there was no time to react. Now I review my in car video from races and see things (corrections, and big moments) I don't even remember doing. Only one thing can teach this and that is seat time and the willingness ($$$'s) to push to the edge. I think that unless you have buckets of money and a penchant for excitement, it won't happen at a DE. I learned most of what I know in terms of driving on the limit from racing low cost cars. I learned more this season in driving over the limit than I had in the previous 4 or 5 years. I had to race for a Championship and every race I was either in front of my rival or behind him be inches. This cannot be taught in DE's. Hope this helps. Regards, Jon
You are correct that there is little "equal" data to compare since very few raced a 355 C in T1 and all the data I am using is from the Challenge series which uses a different tire. Part of the problem is that the ZO6 is a street car on street tires. In T1 the suspension is still a street suspension on a Vette and the brakes are still stock (save for pads, lines and fluid). As you know the suspension in a 355 C has nothing in common with a street 355 and the brakes come from the 333 SP LeMans endurance racer. I think the R rubber cannot cope with Challenge suspension and therefore is a handicap on our cars. I think that if you put race rubber on the Vette and raced it against the 355 Challenge you wouldn't see the domination by the ZO6's. Look at some of the track records above. There is no way switching from R compound to slicks is going to yield 5 seconds per lap at Laguna, Mid Ohio and Road Atlanta. I think on real race rubber the ZO6 is not any faster or not significantly faster than a 355 C and against a 360 C it's slower. Just my opinion and of course we will never know because T1 makes them use crappy R tires. It will be interesting to see if more people step up to the Porsche GT3. Baker had pole at Mid Ohio but got a bad start against Henirecy. Regards, Jon P. Kofod
Jon wrote:I learned most of what I know in terms of driving on the limit from racing low cost cars. I learned more this season in driving over the limit than I had in the previous 4 or 5 years. I had to race for a Championship and every race I was either in front of my rival or behind him be inches. This cannot be taught in DE's." Jon, I totally agree. I also would like to see more GT3's...the cup car not the street gt3. Personally, I think it is a better car than the 360C. Again $ are an issue. Those cars are 360C priced and Z06's are maybe 50% (cages,cell,big brakes,race springs etc) by the time you add all the race gear that the gt3 has stock. If I get a chance and buying a cheap gt3 I will probably jump on it. The GT3 has the added advantage of sheer numbers such that when you make a change to the car someone has an opinion as to what will happen. With a Ferrari every change is an expensive guess since basically no body races them.
Jon and Rob, I have never been on a track in anything but a Ferrari. Rob made some interesting observations about the RX7 vs the 355...i.e. Rx7 momentum car dive late scrub off speed....355c more brakes gass after turn-in. What can you guys say about the handling charactor like Rob described above in Front engine almost 50/50 weight balance like Z06 and True front weight bias like RX7 60F/40R and Front weight bias 60F/40R with front drive? Are there general statements or is every car just an individual? I have driven 911's and they are very Mid engine Ferrari like after 1980...a trait I suspect in all rear weight bias cars.
I dont quite agree here, but Im with ya. In 1997 on a 1.6 mile flat road course, the difference between the DOT Hoosier and Pirelli Challenge spec slick was 7 seconds with a good (not great) club-level driver. Big difference. Totally agree. IMHO a big part of this issue is not having a truly great pro-level driver campaigning a 355C in T1. The Z06 does actually have a dynamic performance advantage, and in spite of better brakes and low friction control arm bushings, maybe better aero, its still an underdog to the Corvette. Again, as hard to believe as it may seem, the C5 is a better overall package in T1 dynamically. The 355C handicaps are torque and weight distribution (too much rear bias). All other variables equal, the Corvette is easier to drive fast. They are. SCCA disapproved the cage design before your friends shunt (and I totally believe the damage, though not inherently unsafe, it does meet FIA standards). The SCCA objected based on design of the bolted joints specific design not that its unsafe, but that it was different from their specification, and wanted nothing to do with rewriting the GCR just for one homologated car. And yes, the rear-facing down tubes were under size for their spec. Agreed. The F355C cage design facilitates the Challenge series (read that as cost). Building Challenge cars with integrated cages, while superior for performance and safety, would add too much cost to the cars. Look at the price difference between a 360C and Michelotto FIA GT chassis. Agreed. Polar moment of inertia. Which is the biggest difference between the Z06 and 355C, vastly different moment of inertia in roll, pitch and yaw. Chassis stiffness is critical for cornering performance. Your BMWs suspension was more efficient, and you as a driver were better able to sense the accelerations and act accordingly. Good thread. Best regards, Rob
RX-7 is very close to 50/50 weight distribution. Yes, every chassis is different. However, here's a general statement and close to overgeneralization, but...53% to 54% rear weight bias is ideal, assuming you've got the right tire sizes front vs. rear. This is how TransAm and V8 Supercars with heavy front engine designs handle so well. This is how the Panoz LMP car worked, weight distribution, chassis rigidity, suspension geometry and moment of inertia. Rob
I have to agree with this. I recently raised the ride height on my M3 track car slightly to give it a little more rear weight bias (as well as to get a little bit more front suspension travel) and it made a WORLD of difference on track. It is much easier to glide on track---meaning it just flows from corner to corner much better, and allows me to brake a little harder & deeper with balance. It is much more fun to driver, and a lot less work---which is saying alot for an easy to drive car like an M3!!
Just for what its worth, R- Compound tires are nowhere NEAR 9 seconds a lap slower at a track like Watkins Glen on a 360C. Everything I have ever experienced indicates that VIR and Watkins Glen are VERY similar in terms of outright lap time for a car like the 360C, as well as laptime imrpovements based on setup changes and tire compound. At VIR, we ran a 360C with Hoosier Grand-Am Cup spec R-Compound tires a little over a year ago in the Grand-Am VIR 400k. My fast time was a 2:01.3. Cort Wagner (undisputed PRO who can squeeze every last bit out of the car) did around a 2:00.5 when trying the car in practice for a few laps. Compare this to the outright 360C pole time of a high 1:59.xx IIRC. I would be VERY confident that a 360C could do AT LEAST a 2:03.xx on R-Compounds at Watkins Glen, if not better. So much for the 9-second gap from Pirelli slicks to "R-Compund"... As for the rest of this thread and argument, I don't know. But I DO know about running a 360C on R-Compounds, and the lap time drop off isn't anywhere NEAR as much as some people might imagine given equal drivers and track conditions. Maybe this adds fuel to the fire... Maybe not... -Jeff
