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Author
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Topic: Spinning slicks when launching.
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70coupe
Gearhead Posts: 483
From: Toronto,Ontario,Canada
Registered: Aug 2000
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posted 08-28-2002 07:52 PM
  
I'm running 26x10x15 M/T full drag slicks and since I put in my C4 tranny the launch has been quite a bit harder. My 60's are in the 1.63-1.64 range. I set my tire pressure at 14.5lbs all the time but lately I've been spinning them on the launch. I can feel it as well as verifying it on video tape. When it spins I get a 1.69-1.70 60'. Should I lower the tire pressure? On the M/T site it states cars over 3000lbs should have around 17-18lbs! My car is on the fence it weighs 3170 without me in it. Should I try 13 or 13.5lbs? I just didnt want to go under the safe zone.
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kid vishus
Gearhead Posts: 6590
From: middle of NC
Registered: Oct 2000
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posted 08-28-2002 08:38 PM
"Safe" all depends on how much the tire sidewalls move around once you lift past the lights. If the car is real stable now during shutdown, I wouldnt be afraid to let another pound or two out of them, (but I would do it a half pound at a time). I always ran my M/T at 12 lbs. But, I also had a bigger tire than you (I ran 28x10 M/T's, and I have also ran 29x11 Hoosiers on my 70). It also might be time for you to look into getting a little bigger slick, at least a touch taller to increase the footprint.
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70coupe
Gearhead Posts: 483
From: Toronto,Ontario,Canada
Registered: Aug 2000
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posted 08-28-2002 10:08 PM
I will try 13.5lbs to start and then go down in 1/2lb intervals. I will be trying out my transbrake as well this weekend! Should be fun.
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Boss302
Gearhead Posts: 841
From: Coleman, Wisconsin
Registered: Jan 2002
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posted 08-28-2002 10:23 PM
i have zip experience in the drag racing field, but how about considering doing a longer burnout...??? thats what i would try, but thats just me.------------------
Max
-1989 Mustang GT (MaxTang)
225/50R15 tires
BBK Strut Brace
K&N Filter
4 cats, no muffs
180* stat
Member 1,861 "My Best Friends Are My Dog, and My Car"
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steve'66
Gearhead Posts: 9533
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 08-28-2002 11:02 PM
I can help you out with this one! We've been working on the '66 with Alex's help and tonight with a "Wednesday night track prep" which isn't great, the car 60'd at 1.56 twice with 12 psi in the slicks, after pumping them up to 16 psi it went 1.517 twice, the last run I added another pound to 17 psi and it went 1.512. The same slick that you're running BTW!! The car was squirelly with 12psi, too. Not to bad with 17 psi. The '66 is a stock leaf sprung, clamps on the front half of the springs, Rancho shocks set on 3, 26-10" et streets, 90 pounds of ballast, 90-10 shocks on the front. It's pulling the front tires about 6" off the ground. The converter stalls at 4500 and she's leaving off the two step set at 3600 rpm. Hope this helps you out.  SteveW
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Moneymaker
Administrator Posts: 27499
From: Lyons, IL, USA
Registered: May 99
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posted 08-28-2002 11:02 PM
Pick the air pressure up to 17-18 lbs. 
You just have to trust me on this one.  ------------------
Alex Denysenko
Co-Administrator and Moderator/ non 65-66 Mustang owner sensitivity co-ordinator NHRA/IHRA/SRA member
NHRA and IHRA SS/LA National Record Holder '00, '01, & '02
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Part time secret agent license #0089
Professional Manwhore
The Barry of BarrysGrrl
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kid vishus
Gearhead Posts: 6590
From: middle of NC
Registered: Oct 2000
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posted 08-28-2002 11:21 PM
I stand corrected. I would have had you going the wrong way on air pressure.
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steve'66
Gearhead Posts: 9533
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 08-29-2002 12:08 AM
Kid,It's cool, not all combos react the same to tire pressures. I can't tell you how many racers tell me to drop tire pressures to 8#s.
It's not a 16" wide tire'd engine stand, is my response. SteveW
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Moneymaker
Administrator Posts: 27499
From: Lyons, IL, USA
Registered: May 99
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posted 08-29-2002 12:18 AM
Amen brother. ------------------
Alex Denysenko
Co-Administrator and Moderator/ non 65-66 Mustang owner sensitivity co-ordinator NHRA/IHRA/SRA member
NHRA and IHRA SS/LA National Record Holder '00, '01, & '02
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Part time secret agent license #0089
Professional Manwhore
The Barry of BarrysGrrl
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kid vishus
Gearhead Posts: 6590
From: middle of NC
Registered: Oct 2000
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posted 08-29-2002 10:03 AM
quote:
Originally posted by steve'66:
I can't tell you how many racers tell me to drop tire pressures to 8#s.
I only run between 6 1/2 and 7 on my racecar. And it is not a motor on a stick.
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70coupe
Gearhead Posts: 483
From: Toronto,Ontario,Canada
Registered: Aug 2000
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posted 08-29-2002 10:17 AM
Thanks guys, I always like a bunch of opinions. I will try raising it first as that seems safer to me and it seems Alex is running 60's fairly close to mine. I have tried a longer burnout but it didnt help.
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Moneymaker
Administrator Posts: 27499
From: Lyons, IL, USA
Registered: May 99
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posted 08-29-2002 10:20 AM
Rob, small tire "hook" is a very precise science that I have spent years developing.
Traditionally, big tire, light cars like yours always prefer lower air pressure. All of the cars I ever had with big tires we ran at 6-8 lbs of air. By big tires I mean 14x30 or larger. ------------------
Alex Denysenko
Co-Administrator and Moderator/ non 65-66 Mustang owner sensitivity co-ordinator NHRA/IHRA/SRA member
NHRA and IHRA SS/LA National Record Holder '00, '01, & '02
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Part time secret agent license #0089
Professional Manwhore
The Barry of BarrysGrrl
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kid vishus
Gearhead Posts: 6590
From: middle of NC
Registered: Oct 2000
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posted 08-29-2002 10:28 AM
quote:
Originally posted by Moneymaker:
Rob, small tire "hook" is a very precise science
There used to be a guy at Eddyille that had a small tire small block Malibu, it ran 9.60's in the qrtr, and only had a 9" wide slick. His car worked real well, but, if the track wasnt real good, it didnt work. But it still impressed me that a car with such small tires could go so fast. I did good getting a 30x11 slick to hook consistently on a car that wasnt near as fast.
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67Coupster
Gearhead Posts: 189
From: Fortson, GA, USA
Registered: Oct 2001
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posted 08-29-2002 11:05 AM
Just to add another setup into the mix, my car likes 10-11psi in the MT ET Streets 28 by 12.5 on a 10" rim. This is a 4 speed car that shocks the tires pretty hard. I think the ET streets have a stiffer sidewall than ET Drags. I've tried up to 15 psi and the car just spins out of the hole. My best 60' is a 1.52 and it is normally around 1.55. I have the rear shocks set on #5 with spring clamps both front and rear. Cal-tracs set in bottom hole with one turn of preload. Front shocks set on 90/10. I'm going back to the track tomorrow night and will by trying it out uncapped and with an airpan and no filter on the carb. A friend of mine will also be bring his fourwheeler so I can shut off going through the lights and tow me back to the pits so I can try out some plug reading(threads of course). Hoping to improve on my 7.0's in the 1/8 mile. PS: Alex I got the new strange spool installed and it was a very nice piece of work compared to the cheap one I bent. ------------------
James
67 Coupe
393W, 4 Speed,
7.07 @ 98MPH 1/8
1.52 60'
'66 Fairlane 500XL
Daily Driver
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Moneymaker
Administrator Posts: 27499
From: Lyons, IL, USA
Registered: May 99
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posted 08-29-2002 11:17 AM
Glad to hear you appreciate nice high quality products James. ------------------
Alex Denysenko
Co-Administrator and Moderator/ non 65-66 Mustang owner sensitivity co-ordinator NHRA/IHRA/SRA member
NHRA and IHRA SS/LA National Record Holder '00, '01, & '02
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Part time secret agent license #0089
Professional Manwhore
The Barry of BarrysGrrl
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n2oMike
Gearhead Posts: 2831
From: Spencer, WV
Registered: Jan 2001
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posted 08-29-2002 11:38 AM
James,How stiff are those leaf springs of yours? Those (Rancho?) shocks are pretty stiff when set on 5. I would think a softer rear suspension would absorb more shock, and allow you to run more air in the tires. Have you always used the Cal-Trac's bottom hole? The top hole puts more leverage on things and plants the tires harder. The bottom hole generally works best on cars with an abundance of traction. The only reason I could see using the bottom hole on your car is if you had a problem with the rear end bouncing. Other thoughts???? His car is similar to mine, so I'm interested... Good Luck! ------------------
Mike Burch
66 mustang real street
302 4-speed 289 heads
10.63 @ 129.3
http://www.geocities.com/carbedstangs/cmml_mburch.html
http://www.fortunecity.com/silverstone/healey/367
http://www.mustangworks.com/cgi-bin/moi-display.cgi?220
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Rory McNeil
Gearhead Posts: 1687
From: Surrey, B.C. Canada
Registered: Nov 2000
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posted 08-29-2002 12:45 PM
I think most guys run thier slicks too soft. On my high 12 second, 302, T5, 3.55 geared street Fairmont, I normally run my 8 1/2x26-15 M/T slicks at 18 lb`s, with a best 60 foot of 1.74. On my low 10 second 428, 4 speed Fairmont drag car, which uses 14x32 slicks, I normally run 10 1/2 lbs of air, best 60 foot of 1.32.Years ago, when I ran a C6(with trans brake) in the 428 car,the tires liked much less air, 6 1/2-7 lbs.In photo`s, the tires were all buckled up on launch with the low pressures, but that was how the best 60 foots were obtained.However the stick works much better with more air pressure to hold the sidewalls more stable.Running really low pressure also adds a lot of rolling resistance, not to mention the pontential for top end sway.------------------
78 Fairmont 428 4 speed 10.20@130mph
80 Fairmont 302 5 speed 12.8@105mph
85 Mustang NHRA Stocker under construction, 302 5 speed
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67Coupster
Gearhead Posts: 189
From: Fortson, GA, USA
Registered: Oct 2001
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posted 08-29-2002 01:15 PM
Mike, my car had been hitting the tires too hard. After video taping the car then talking with Cal-trac I set it up per their recommendations. It was hitting the tires hard and then bouncing back up. The clamps, bar hole and shock setting was to try and limit the hit to the tires. It helped quite a bit and dropped my 60' times by a tenth. I may try a little less preload on the caltracs to try and delay the hit a little more. Less preload let's the tires rollout a little bit prior to smacking the crap out of them.I'm working with what I have right now. Would like to get an adjustable clutch in the future or a aluminum flywheel. I have access to the alum flywheel to test so will more than likely try that first. And some ET drags, that should probably be my first change though. Later!! ------------------
James
67 Coupe
393W, 4 Speed,
7.07 @ 98MPH 1/8
1.52 60'
'66 Fairlane 500XL
Daily Driver [This message has been edited by 67Coupster (edited 08-29-2002).]
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Buster
Gearhead Posts: 1635
From: Hurricane alley
Registered: May 2002
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posted 08-29-2002 03:33 PM
quote:
Originally posted by Moneymaker:
Pick the air pressure up to 17-18 lbs.
You just have to trust me on this one.
WoW, really... I've been runing 7 1/4 psi with M/Ts, same tire too *Edit* whoops 28X11's [This message has been edited by Buster (edited 08-29-2002).]
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capri man
Gearhead Posts: 7611
From: doerun, ga.
Registered: Nov 2000
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posted 09-01-2002 10:37 AM
i am looking for consistancy, not speed. 2900 lb car, 26x10 m/ts. my prob is that if the track is in good cond, i will 60 at 1.65-1.66 all day long. but if the track gets a little marginal, it will through a 1.71-1.75 60 in every few runs. i have tried from 14 to 21 lbs of air but it still does it. any suggestions???------------------
mike r
racing is real
everything else is just a game.
81 capri-7.51 @89mph 1/8
1.54 60 ft.
http://prestage.com/site/site_display.asp?SiteID=141
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Buster
Gearhead Posts: 1635
From: Hurricane alley
Registered: May 2002
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posted 09-01-2002 10:45 AM
Alex, I tried higher tire pressure once with a set of 9" tires, like 12 or so, and it was a hand full on the big end.... It felt like there was only 5" on the track.
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70coupe
Gearhead Posts: 483
From: Toronto,Ontario,Canada
Registered: Aug 2000
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posted 09-02-2002 04:12 PM
Heres what I figured out. I started the day on Saturday with my usual 14.5lbs and no tire spin,same thing all day long with no problems until around 8pm then what I figure is the dew sets in and makes the track a little greasy! I had the same thing happen 2 weeks in a row. I went to the 4th round and lost both times because of tire spin. I lost .04-.05 in the 60' which at the end of the 1/4 = .08 or so = a loss. Now, I still haven't figured out how to get rid of this other than trying some time trials later in the evening when those conditions exist.
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steve'66
Gearhead Posts: 9533
From: Sonoma,CA,USA
Registered: Mar 2000
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posted 09-02-2002 07:08 PM
Brian,Today I tried higher pressures (18) and it didn't work. Got the best 60's (1.51) with 16 psi and a 130* track temp at 95* air temp and 2700' of d/a. The car went a 10.885 @ 123 in the heat. Too bad it went red.  SteveW
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Moneymaker
Administrator Posts: 27499
From: Lyons, IL, USA
Registered: May 99
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posted 09-02-2002 07:08 PM
If there is dew on the track and it is that slick then everyone should be spinning. ------------------
Alex Denysenko
Co-Administrator and Moderator/ non 65-66 Mustang owner sensitivity co-ordinator NHRA/IHRA/SRA member
NHRA and IHRA SS/LA National Record Holder '00, '01, & '02
Fleet of FoMoCo products including 88 ASC McLaren Mustang #28
Part time secret agent license #0089
Professional Manwhore
The Barry of BarrysGrrl
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70coupe
Gearhead Posts: 483
From: Toronto,Ontario,Canada
Registered: Aug 2000
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posted 09-02-2002 07:44 PM
Just a guess as to what might be happening? Something else just came to mind. The air might be better in the eve and I'm getting a little more power to the wheels?
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