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Thread: Dumb questions about drag slicks

  1. #1
    Senior Member NiceGuyEddie's Avatar
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    Dumb questions about drag slicks

    https://www.youtube.com/watch?v=s4fe...tu.be&t=23m38s

    My family is pitching in money for my birthday and the rule is I have to buy something I would normally not buy. So I thought about some drag radials and possibly inexpensive rims to boot. Worst (best) case, I’ll keep the tread off my normal tires when I go drag racing.

    I don’t do very well off the line. I currently run Nitto NT-05’s. I lowered them to 18psi my last time out. I am not a good enough driver to have noticed the difference with the lower pressure.

    1. Compared to my Nitto's, would slicks offer considerably more traction on a prepped drag strip? I currently do a light burnout only, just to clear the rocks off the tires.

    2. What might be the difference between Street Legal drag slicks (slight tread) and true slicks? I consider the chance of getting a ticket on the way to the track for having slicks completely negligible, as long as the drag slicks are black-walled.

    3. I see they sell Street Legal drag slicks in my low-profile tire size of 315/35/17. For a better flexing sidewall, is there big advantage to a separate set of wheels and 16" or 15" tires? I am certain my rear brakes will clear 16" rims, possibly not 15".

    My setup is a 347 with about 450hp, 3.55 gears, 5-link, and 2.95 1st gear. Zoom Racing billet aluminum flywheel, Zoom Racing Kevlar Clutch.

    By the way, I have never adjusted the Watts links on the 5-link for drag racing.
    Last edited by NiceGuyEddie; 11-09-2018 at 04:29 PM.

  2. #2
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    Need more info ! What RPM do you leave the line at ? How much wheel spin do you get ? Slicks in general will allow you to leave the line at a higher RPM (sweet spot of engine) and have less wheel spin. All slicks have different compounds (soft to hard) . Depending on the compounds and air pressure allows different results. Most pro's will try many sets before they
    pick a "permanant" tire. The taller the tire the more it raises your top end speed. The smaller the tire(height) the more it lowers your rear end gearing giving a better off the line start.
    For an ocasional racer todays drag radials are the way to go as they are more forgiving and allow you to be "legal" There are several racing classes just for Drag radial cars. True slick with no groves have more contact patch than Street groved slicks. The difference (in the same size) is minor. Any Drag or race slick will give an improvement over your Nitto's.

  3. #3

    Steve >> aka: GoDadGo
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    Things To Think About:

    1. Do you have a log book to document the variables?
    2. What RPM are you launching at?
    3. Are you launching at the same RPM or are you varying your launches?
    4. Are you shifting at the same RPM?
    5. What are you 60' times?
    6. Have you tried launching at different RPM's & comparing your 60' times?
    7. Could you possibly just soften up the compound?
    8. The NT05-R is a lot softer than the standard NT05.

  4. #4
    Senior Member NiceGuyEddie's Avatar
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    Above is my best time and the only time I got into the 7's. I ether have to launch VERY soft (roll) or I spin almost the entire 1st gear.

    Usually goes like this:

    1. Light burnout to clean the tires
    2. Launch at about 3500, otherwise I'll spin and over-rev immediately (I don't have a rev limiter)
    3. I keep the throttle FLAT until the wheels stop spinning
    4. Mash the gas, shift into 2nd at or near redline
    5. Shift into 3rd at or near redline
    6. 1 or 1/2 seconds later it's over, and I am at or near redline at the trap (about 90mph)
    7. With the above exception where I had a nice launch, I am almost always at about 8.2 seconds

    I've only done this 25-30 times so that's all the info I have. My first few times out were with my Sumitomos and the tires spun almost the whole way down the track.

    I tried launching in 2nd but the end result is still almost the same.
    Last edited by NiceGuyEddie; 11-09-2018 at 05:38 PM.

  5. #5

    Steve >> aka: GoDadGo
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    Have you tried launching at a lower RPM, say 2,250 or maybe even 2,500?

    You want to get off the line at the lowest possible RPM and drive into the power so that the tires have a chance to stick.
    Even if you launch with a little bogging or none at all preferably then I'd bet money that your 60' times will drop significantly.
    Also, if you practice just the launch and driving through 1st gear, then the rest of your run will come much, much easier.
    Your car is fast, you just need to get off the line and even if it bogs a bit, the car will likely give up some much quick 60' times.
    Stopping the wheel spin in 1st gear and likely 2nd gear too is what you need to do.
    Also, if your tires are 2-3 years old, replace them with some new Drag Radials please.
    Tires get hard over time and don't stick Worth A S---! (Slang Word For Excrement)

    Hope this helps.
    Last edited by GoDadGo; 11-09-2018 at 05:51 PM.

  6. #6
    Senior Member BEAR-AvHistory's Avatar
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    The NITTO 05's are 200 treadwear & the NITTO 555R are 100 treadwear. Better traction but they are still traction limited with our cars. Have had no issues driving them on the street since the car was plated in March of 2015. Personally I think you could do better just coming down on the launch RPM the feeling your way to maintain traction. Think your car should be a lot quicker & faster.

    Comparison this is my listing in DragTimes for my old lightly tuned 2011 BMW 335IS 7DCT @ 3570lbs. Car was dynoed at the time at 370WHP factory stock 321WHP. 2nd gear was used for launching on summer street tires

    195) 12.583*^ 114.529 8.062 90.430 2.070 BMW 335i 335IS 2011 BEAR-AvHistory

    195 is the listing # first two numbers are 1/4 mile time & speed. Second two are 1/8th mile which matches your 7.9 seconds & 90 MPH while your 60ft time, third number set, is a lot better then mine was by .25 seconds.

    This suggests although you would put a hole shot on an even launch the cars would be pretty much tied at the 1/8 mile finish. Think you are loosing a lot of time after the launch

    Have not taken the COBRA to the strip but have launched against some quick cars including a Lamborghini with launch control & bikes with a lot of success by maintaining traction at the launch with a 2000/2200RPM or so launch on the 555R. They just go & don't slip at the lower RPM. At 3500RPM can put down black 11's as long as I hold the throttle down.
    Last edited by BEAR-AvHistory; 11-09-2018 at 10:39 PM.
    Kevin
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    I love the smell of 100 octane in the morning.
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  7. #7
    Senior Member CraigS's Avatar
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    I agree w/ dropping the launch rpm. I run autocrosses on Hoosier A7s, so a little different but I still try for a good launch. I come off the line at maybe 1500-1800 and can not use full throttle in first. If I spin the tires more than a second or so I figure I screwed that launch.
    FFR MkII, 408W, Tremec TKO 500, 2015 IRS, DA QA1s, Forte front bar, APE hardtop.

  8. #8
    Seasoned Citizen NAZ's Avatar
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    Low profile tires built to go around corners are not a good choice for drag tires. Even with the softer compounds the construction of the tire doesn't allow the sidewall to flex. This limits your footprint and the tires ability to absorb the shock of a hard launch. A tire designed specifically for drag racing is much thinner than a DOT tire. It has a taller, more flexible sidewall that allows the tire to absorb the shock of the launch and the deformation adds footprint to the tire. A larger diameter drag tire adds even more footprint as it flexes. Bias ply drag slicks are much more forgiving than DOT drag radials. Once a drag radial spins it's not as likely to recover as a bias ply tire. Bias ply tires grow (some 1.5" or more at 150 MPH) so you have to have enough room to accommodate that growth. Drag radials don't grow and take less friction to roll so may produce slightly higher MPH in the traps. DOT drag radials are a lot heavier than bias ply drag slicks and run with more air pressure than the bias tires. If you're serious about running a tire made for drag racing with a stick I suggest you look at a true bias ply (15" rim dia) slick the largest size you can fit on that little car.

    If you decide to stay with a street radial I suggest you DO NOT burn out as this generally does not help a street tire and may make them greasy. It's best to drive around the water box and launch them without a burnout. As others have stated above, launch RPM is important and will require testing to find the optimum RPM. But what I didn't notice mentioned is slipping the clutch to prevent slipping the tires. It's a difficult skill to master this manually but there are devices that help with slipping the clutch on launch. The first is a Borg & Beck style clutch designed for drag racing that you can adjust the amount of slip. Ram makes a good one but it won't work with a hydraulic T/O bearing. Next is flow controls for hydraulic clutches that you can also adjust the slip for launch. These have an electrically controlled by pass that operates the flow control to slow the clutch engagement only at launch and all other gears the clutch works normally.

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    I wouldn't go to much trouble without being aware that you're supposed (required) to have an approved 5 point roll bar for any convertible under 8.25 - 1/8 or 13.49 - 1/4 (both NHRA + IHRA).

    And you'll find it very impractical to comply with those specifications in a FFR roadster.

  10. #10
    Senior Member CraigS's Avatar
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    About drag radials and the cold. I understand that they won't grip as well but are they like some of the tires that can't even be driven under 40deg because they will crack? Different brands better than others? I think about them for regular street tires but need to be able to drive all year around.
    FFR MkII, 408W, Tremec TKO 500, 2015 IRS, DA QA1s, Forte front bar, APE hardtop.

  11. #11
    Senior Member Mike N's Avatar
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    Eddie. You aren't really giving yourself enough credit for your driving, your 1.743 60ft time is really quite good for the tires you are using. With practice and a good track you should be able to get into the 1.6XX range with those tires. Drag radials with a similar short sidewall will not give you a significantly better 60 ft time as they will not be able to absorb the shock of a high rpm launch. Using a smaller diameter rim and a tire with a taller sidewall will help however keep in mind that right now your tires are protecting the weakest link in your drive train. Yes it's a real kick in the pants to launch at a higher rpm and full throttle but being able to use higher rpm and getting it to hook off the line might just help you find your weakest link. That always equates to $$$$$.

    By the way for the mph you are running your times are really very good. MPH is a very good indicator of rear wheel horsepower. You might see a tenth or two with slicks but from looking at your numbers to go much faster you need more HP not so much more traction.
    Mike............

    FFR2100 - 331 with KB supercharger - T5 - 5 link rear 3.08's and T2 Torsen.

  12. #12
    Seasoned Citizen NAZ's Avatar
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    Craig, good question about cold weather use of drag radials. I run 29x18.00x15 M/T ET Street DOT drag radials on the rear for street tires. M/T has nothing on their website about cold just a comment about dry traction. I have a set of Toyo Proxes R888 (315/30ZR18 on the back) and there is a caution about wet pavement and temps below 15-deg F. The Proxes are very sticky tires and throw gravel all over the car -- they stick to the gravel like flypaper. And they stick around corners like the car is on rails. The M/T drag radials not so much. However, the short stiff sidewalls of the Proxes are easy to spin on the street and the M/T drag radials barely slip for a few feet. But for the track I use 28x11.5x15 M/T ET wrinkle wall slicks and these dead hook on a prepped surface. My car is set-up for drag racing, 2500lb with me in it, and 550HP SBC with a Glide and transbrake. I'll submit to all reading this that a transbrake leaves just as violently as any clutch car and those small drag slicks dead hook.

  13. #13
    Senior Member 3yearplan's Avatar
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    I agree with the others, drop the launch rpm. I would launch my supercharged 360 Dakota at or near 1800 rpm and feather it until I shifted into 2nd. You think these cars are tricky, try a 450 horsepower pickup truck. Your time slip is cool, even tells us what radio station was playing...of course I'm kidding.

    Mike
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  14. #14
    Senior Member NiceGuyEddie's Avatar
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    Quote Originally Posted by NAZ View Post
    Bias ply drag slicks are much more forgiving than DOT drag radials.

    If you decide to stay with a street radial I suggest you DO NOT burn out as this generally does not help a street tire and may make them greasy..
    I had no idea there was such as thing as bias ply drag slicks. I thought the only bias ply tires were for nostalgic purposes. I'll read up on them.

    At Irwindale speedway, the entry is old and has lots of gravel. I drive around the wet box but the officials recommend a super-light burnout to clean the tires.

  15. #15
    Senior Member NiceGuyEddie's Avatar
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    Quote Originally Posted by Mike N View Post
    Eddie. You aren't really giving yourself enough credit for your driving, your 1.743 60ft time is really quite good for the tires you are using.

    By the way for the mph you are running your times are really very good.
    This excellent 60' time was dumb luck and happened only once. I never got less than 2 seconds otherwise.

    Once the car starts moving it really really GOES. Unfortunately I'll never know a 1/4 mile time because I can't pass tech for California Speedway for 1/4 mile with a single rollbar. I also would need a proper jacket.
    Last edited by NiceGuyEddie; 11-12-2018 at 06:04 PM.

  16. #16
    Senior Member BEAR-AvHistory's Avatar
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    Quote Originally Posted by CraigS View Post
    About drag radials and the cold. I understand that they won't grip as well but are they like some of the tires that can't even be driven under 40deg because they will crack? Different brands better than others? I think about them for regular street tires but need to be able to drive all year around.
    No cracks with DOT drag radials over 3 winters. They will start to loose traction under 40 but not uncontrollable down to 30 in my personal experience. That said a hard shift but not WOT at 40*F with 555R will slip the tires. Think its like driving on snow with good tires.

    The 555R are 100 treadware tires.

    BTW the car is driven almost every day it does not rain & the temp is in the 40's & up. Temp is due to driver comfort not tires issues. Our local COBRA club meets once a month all year round.
    Last edited by BEAR-AvHistory; 11-13-2018 at 10:20 AM.
    Kevin
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    I love the smell of 100 octane in the morning.
    NITTO NT01 275X40X17ZR - 315X35ZRX17
    Delivered 2/7/14 - Plate "COYOTE NC1965" 3/25/15

  17. #17
    Senior Member BEAR-AvHistory's Avatar
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    Quote Originally Posted by NiceGuyEddie View Post
    This excellent 60' time was dumb luck and happened only once. I never got less than 2 seconds otherwise.

    Once the car starts moving it really really GOES. Unfortunately I'll never know a 1/4 mile time because I can't pass tech for California Speedway for 1/4 mile with a single rollbar. I also would need a proper jacket.
    Rough estimate for speed would be to add 25mph to your 1/8 speed. No guess for time.
    Kevin
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    I love the smell of 100 octane in the morning.
    NITTO NT01 275X40X17ZR - 315X35ZRX17
    Delivered 2/7/14 - Plate "COYOTE NC1965" 3/25/15

  18. #18
    David aka Ducky2009 Ducky2009's Avatar
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    Cold weather and soft tires don't mix. Took a short ride on a cold day (55 degrees). Zero traction.

    https://youtu.be/7oHaXhmEFS0

    Also, as someone mentioned, your tires are presently the weak link. Slicks will make something else the weak link. Believe me, I've blown several clutches and trans while racing (not my MK4).
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  19. #19
    Senior Member Mike N's Avatar
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    Quote Originally Posted by NiceGuyEddie View Post
    I had no idea there was such as thing as bias ply drag slicks. I thought the only bias ply tires were for nostalgic purposes. I'll read up on them.

    At Irwindale speedway, the entry is old and has lots of gravel. I drive around the wet box but the officials recommend a super-light burnout to clean the tires.
    You need more practice. Go find an empty lot or industrial complex on the weekend and practice launching up through the first to second shift. I have lost count of how many test launches I've made in my car, certainly well into the hundreds. If you can get the weight transferred to the rear tires without shocking them loose you should be able to get consistent 60 ft times in the 1.7 range. Without trying to launch really hard practice rolling off the clutch and into the throttle smoothly. You should be able to feel the weight move to the rear of the car as you come off the clutch. Once you can do this consistently at lower throttle / rpm start gradually dialing it up to more aggressive with the throttle and clutch. You will need to make fine adjustments long the way. I have found that holding the throttle somewhere round 2000 rpm on the line is enough to allow me to not bog the engine but still leave smooth enough to not shock the tires loose.
    Mike............

    FFR2100 - 331 with KB supercharger - T5 - 5 link rear 3.08's and T2 Torsen.

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