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C5Z's don't hit 3rd gear on big courses and need to lug 2nd on small ones? Maybe I'm just both really slow and really fast at the same time, but in my C5Z I was pegging the rev limiter for several seconds at the NEPA Pocono event and end up lugging it making no power in 2nd on the smaller lots.
If you think that the Pocono events are in any way normal, they aren't. And fwiw, when there this past year I NEVER even topped 2nd gear in my C6Z with a stock rev-limit on Hoosier's.
As for reaming 1st. Sure people can and do. I don't and tend to beat them. The cars have torque, all of them have torque. Again if you think that NEPA's other events on the smaller lots are "normal" they aren't. I'd probably consider 1st in my FRC with it's taller gearing and lesser power but not in a C5Z.
Feel free to disagree, I somehow suspect you will. Maybe I'm just really slow and really fast at the same time too. But I'm not making this stuff up, nor am I clueless.
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Sorry I didn't know that NEPA is a unicorn region, I have heard from anyone and everyone that "nationals courses are always fast" so I assumed that they would be similar to the "fast" NEPA course - which means lots of 2-3-2 shifts in a C5Z. If that's wrong then my apologies, you're right.
Is there a region around here that is actually representative of national courses?
Can you advise is the OS Giken dual core aimed at cars on R tyres say doing autocross and some road course work versus your existing Superlock or would this differntial also suit a World Challenge spec type car
I guess maybe I should start a new thread on this but the winding out 1st vs lugging 2nd gear thing interests me quite a bit.
Since the z06 is the first car I've owned which has long enough gears to do some of our tight local courses in 1st gear (or at least a majority of the course in 1st) We did a bit of 1st vs 2nd gear testing running the whole course in 1st vs running the whole course in 2nd. even lugging it through the tightest slow corners we were on average .8 seconds faster around a 30 second course and the course was approx 100-150' shorter vs running the car in 1st gear.
This test was done on BFG Rivals with 2 different drivers finding almost identical results in the same car on the same day.
Interestingly both my codriver and I felt faster in 1st gear but, the clock/data doesn't lie.
I'd be happy to start another thread for discussion and upload my datalogs from this test this evening if anybody else has different findings they'd want to share!
I guess maybe I should start a new thread on this but the winding out 1st vs lugging 2nd gear thing interests me quite a bit.
Since the z06 is the first car I've owned which has long enough gears to do some of our tight local courses in 1st gear (or at least a majority of the course in 1st) We did a bit of 1st vs 2nd gear testing running the whole course in 1st vs running the whole course in 2nd. even lugging it through the tightest slow corners we were on average .8 seconds faster around a 30 second course and the course was approx 100-150' shorter vs running the car in 1st gear.
This test was done on BFG Rivals with 2 different drivers finding almost identical results in the same car on the same day.
Interestingly both my codriver and I felt faster in 1st gear but, the clock/data doesn't lie.
I'd be happy to start another thread for discussion and upload my datalogs from this test this evening if anybody else has different findings they'd want to share!
Basically the car feels faster, and sounds faster. You have revs and wheelspin, etc., but typically isn't faster and usually slower for one reason, wheelspin. You can't get the power down as well in 1st as 2nd, and that's more the case with street tires vs. R-comps.
The folks who like 1st better are usually those that overdrive a little (or a lot) on the way in because the extra engine braking helps the car turn when they've overrun the front tires, same thing applies for the power if they drive a push the gas pedal can transition that to oversteer....eventually. Mind you that'd be too late and you'd already be offline but it's kind of a damage control thing.
Look I'd be lying if I said I never ever got the urge to dump 1st sometimes. But it's rare and always out of frustration with having already made a mistake in the run, or if I'm just not having an "at the top" day. Neither are good excuses mind you, just being blunt.
FWIW I was thinking a full-on SSP car (he did ask about being nationally competitive) with 345 A7's on all 4 corners, trick diff, maximum weight redistribution/reduction, and fully sorted aero+suspension package. How much more grip that would generate I don't know, but it would be more than an SSR car. The 345's are also 26.8" tall, lengthening the effective gearing of 1st a bit.
If none of that actually matters and SSP cars handle just like SS(R) cars then nevermind - I've never driven a car prepared for SSP.
FWIW I was thinking a full-on SSP car (he did ask about being nationally competitive) with 345 A7's on all 4 corners, trick diff, maximum weight redistribution/reduction, and fully sorted aero+suspension package. How much more grip that would generate I don't know, but it would be more than an SSR car. The 345's are also 26.8" tall, lengthening the effective gearing of 1st a bit.
If none of that actually matters and SSP cars handle just like SS(R) cars then nevermind - I've never driven a car prepared for SSP.
I run 345's in the back, and they aren't short being 345/30-19's. An SSP car would also have more power, and typically stiffer springs as well (depending who builds it). Aero doesn't typically do much of anything below about 50 mph at best, which is where power down is hardest. Weight distribution won't change much at all, it can't. A C5 you can move the battery but it's already in the right rear of a C6Z or Grand Sport.
Can't you take 100+ lbs out of an SSP car (mostly from the middle and front) that you can't take out of an SSR? Seats, stereo, steering wheel+airbag, emissions stuff, air conditioning.
You're probably still right anyway, I didn't realize you already ran the tall tires and there probably isn't thaaaat much grip to be gained from wider wheels and a better suspension+diff setup since the car is pretty good stock. I guess the LS7 simply has more power than you can use at low speeds even on hoosiers, not too surprising I suppose.
Still, the C6 is only one possible SSP competitor. What about GTR track edition, Gallardo superleggera, 911 Turbo S? I haven't seen an autox build for any of those but they sound scary on paper.
Getting back to the STU build, do you guys have any more info on the dual core diff? I'm researching what I want to use in my build and am interested in the availability of the product as well as what it does differently from your current line up. Thanks in advance!
Getting back to the STU build, do you guys have any more info on the dual core diff? I'm researching what I want to use in my build and am interested in the availability of the product as well as what it does differently from your current line up. Thanks in advance!
I'm curious about this as well. Though my build will have triple the power, grip and aero. (not STU )
I've heard good things about the OSG from other vette sources.
Differential Section OS Giken TCD Dual Core LSD
The Dual Core helical side gears are a new technology from OS Giken utilized to further expand potential grip out of Limited Slip Differentials. It allows for gradual lockup in wheel speed difference while cornering. Japan and USA have been testing these gears in one-way LSD configurations with great success in both track and autocross sanctions with improved lap times. We hope further testing into the C5/C6 platform will achieve similar results!
Why bother with an aftermarket differential?
Probably the first question in regards to differentials would be "why would I need a new one if my car already came with one from the factory?" To be blunt, the difference between stock and our OS Giken Super Lock is night and day. This difference can be greatly seen when comparing both differentials to each other on the bench. As you can see in the photos, the stock clutch plates are smaller than our discs and only total to 16 plates. Our LSD unit for the C5/C6 utilizes 20 clutch plates and have more surface area per disc than stock. Approximately 156% more surface area per disc for a total of 220% increase over the stock unit in total surface area.
During testing this significant increase in lockup greatly showed at the track. There was more confidence in the car and we were able to put power down everywhere. This is the pure benefit of the Super Lock in general. We keep 100% lock up by utilizing all the plates activated and change the lock timing so we can control when 100% lock happens. That is how our diffs work: Open while turning, 100% achieved gradual lock when we want it. The Dual Core is most noticeable in slaloms and corner entries into fast sweepers. It provides minimal lock in situations where you would either have too much lock or not enough in comparison to other diffs. This greatly inspires confidence to carry more speed in a controlled manner through these elements.
What is the benefit of Dual Core?
Improved Turn-in
. When converted to a one-way configuration turn-in ability improves due to the decrease in static decel lock from the pressure ring. The benefit of the variable deceleration lock provides the stability under trail braking and corner entry.
Variable Deceleration lock
. Decel lock is now determined through the difference in wheel speed. This compensates for the lack of initial decel ramp angle by going to a one-way configuration and allowing the helical side gears to engage the differential lock during cornering. The greater the wheel speed difference, the more the differential will provide locking. This lock can start at 0% utilizing our new zero preload option for Dual Core use.
Smoother Acceleration Lock
. The transition from deceleration locking to acceleration lock is seamless. This is due to the helical side gears being active during cornering. As there is difference in wheel speed; the clutch plates are locking mid-corner at about 30% total lock. As you pick up throttle there is no abrupt action caused by differential locking. On some Super Lock applications slight wheel spin may occur during curb hopping maneuvers or when one wheel is off the racing surface. The Dual Core cures that and stays locked even when the vehicle is temporarily airborne.
***Our LSD's are fully tune-able; however, I must disclose that all tuning is done in house here at OS Giken USA. This is similar to how one would submit their shock absorbers (Penske, Moton, etc) in for service. Tuning parts are not sold to the general public. The reason for this is for the customer's ease of mind. We have the experience and data to be able to achieve the characteristics you want from your differential. Also the complexity of reassembly is much more complex than your typical clutch type differential. There are many little details that need to be followed in order to have a proper working diff. We have seen many units come back to us due to improper tuning that we would like to protect our customers by providing a service linked to us directly. We want our customers to be fully satisfied with their unit and tuning is a daunting task especially for our units.***
MSRP for LSD Tune when purchasing a new differential is $150. MSRP for LSD upgrade will be $150 plus cost of parts. Please note that Dual Core will be available for the C5/C6 sometime late in the year transitioning to 2016 once full development and extensive testing (Track and Autocross) has been performed.
We are still in the process of firming up applications with Japan. At this time we do not have a set cost on upgrading LSD units to Dual Core at this time as we are still in testing phase. You will see release of various applications towards the end of the year and enter 2016.
Interesting! I've been using your LSD for about 2 seasons now doing 30+ track days a year in my C6Z track car and it has been awesome. I should also add that it also has been completely problem free over that time and I'm running a Katech 463ci engine putting out 630+ RWHP. I use the recommended OS Giken 80w-250 fluid and change it twice per season just to be safe. During the intial break in there was a little popping which is typical but after break in and the first fluid change zero noise and the diff is extreemely smooth on track with how it locks. It's an awesome product so thumbs up on that
From reading your post it sounds like there is going to be an upgrade path available for people to bring their standard Super Lock up to Dual Core specs, correct? Do you have any eta on when conversion kits will be available?
I'd be curious to hear about maintenance intervals and streetability - last I knew basically all upgraded diffs were for "race only" cars and needed rebuilt often but I know little about any of them.
I'd be curious to hear about maintenance intervals and streetability - last I knew basically all upgraded diffs were for "race only" cars and needed rebuilt often but I know little about any of them.
Take a look at my comments 2 posts above yours. I've also ran the car on the street and the diff is completely street friendly
Thanks for the update Jon! Any chance you guys can share what "improved lap times" means (ie. a couple tenths, a couple seconds, etc)?
Hey Lane,
In Japan, on a 60 second track they've found .3-.6xx tenths of a second out of their Dual Core Turbocharged Toyota 86. For myself with my S2000, i found about .2xx tenths of a second in an autocross setting and about more than half a second at Buttonwillow. YMMV
Originally Posted by troyguitar
I'd be curious to hear about maintenance intervals and streetability - last I knew basically all upgraded diffs were for "race only" cars and needed rebuilt often but I know little about any of them.
Our OS units we always recommend the use of our OS 250R fluid. If you are using a differential cooler; Motul Gear Competition FF 75W140 is a suitable fluid for our units. We do not recommend Redline or Royal Purple as test have shown accelerated wear and poor locking.
For a new OS unit we recommend changing out the fluid after 500-1000 miles or 1 Track Event. After the initial fluid change intervals should follow the Recommended OEM Service Interval. Because our diffs are a negatively preloaded design, the diff spends most of its time unlocked if you are using it on the street which has little impact to disc wear.
The 2015 Road to Lincoln has officially begun and the first stop was held at Auto Club Speedway this past weekend.
For those not familiar with this site, it has been known to have low grip and feature slight elevation changes. We were pleased with the initial results, but are looking to make some adjustments to the rear bar to maximize the overall grip. All drivers felt that with our upcoming suspension/alignment tweaks they would have been able to find .6 to .8 out there.
"The Radium Competition Catch Can (CCC) was created to provide motorsports participants with a high quality product that meets the common 1QT minimum capacity requirements dictated by many organizing bodies including SCCA, NASA, and Formula Drift. It is CNC machined from solid 6061-T6 aluminum to provide the ultimate in function and finish. All of the CCC components are anodized to provide a long lasting durable surface finish." - Radium Engineering
From our experience in Solo 2 Autocross we have learned that many cars benefit from oil catch cans. My previous Honda S2000 was notorious for oil being sucked back into the intake manifold creating a smokescreen as I passed through the course. We did not want to take a chance with the C5 and reached out to our sponsor at Radium Engineering for a suitable solution.
"Stainless steel filtration media provides surface area for oil vapor to condense and drop out of suspension. A large chamber for the media will not create a flow restriction. The media can be removed for cleaning." - Radium Engineering
The folks at Radium Engineering supplied us with their Universal Competition Catch Can as well as several add on pieces. One neat feature in particular is the drain peacock. It is a great optional add on as it makes for emptying the catch can a simple affair. As you can see in the photos every port is sealed tightly with o-rings to keep things a sealed unit. Anytime when dealing with oils things can get messy quite quickly. A leaking catch can is a horrible cleanup job in general and Radium does a fine job in making sure it doesn't happen.
The installation was basic just like any other catch can install. Due to time restraint and lack of materials on hand we had to utilize the can in its short version. Once we have more time to work on the car we will figure out a mounting to fully utilize the full can configuration. For now we simply took some aluminum sheet and made a mount for the catch can mounting bracket.
01-14-2015, 05:46 PM
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