launch issues ( update and a new pb )
#1022138
06/28/11 07:30 PM
06/28/11 07:30 PM
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I have just swapped over to rms upper control arms and calvert 90/10 shocks to improve 60ft times. Last weekend i took the car out , the launch was a lot more aggresive, front end rises very quickly but car is loosing 60ft. I managed to find a pic of the car on the net and it appears to be squashing the tyres a lot. Car runs 9 way ranchos and ss springs, new 31X10.5 Hoosiers, 4.56 gears. Car was running 1.53 60 ft's down from 1.48-1.50. What pressures should i try, have been running 8 to 10, i'm thinking of going to at least 12 and stiffening the rear shockers up a lot.
69 Dart GTS 440 mopar .590 cam, Edelbrock heads, 3200# best et 6.45, 106.78, 10.14, 132.88 mph, 1.47 60ft best 60ft 1.36
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Re: launch issues
[Re: VernMotor]
#1022142
06/29/11 03:27 AM
06/29/11 03:27 AM
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HI Don I have frame connectors, footbrake off the converter, around 3000 i think, ss springs with clamps on the front, yes i run tubes, car with me 3200lbs 1st Run on sunday tried shocks set on 5, 10psi, second and third, 8 psi shocks on 3 and 4 psi respectively. Points of note, when i fitted the dana, i moved the axle back an inch and dropped the rear down, also my old M/T slicks were stiffer side walls. Vernmotor I'm thinking of trying at least 12psi and shocks around 7, what 60ft and times does your car run?. ab7fh I have around 5" of travel, the lower bump stops are cut right down to around 1/2". Ideally i want to be were you are, between 1.40-1.42. Mick
69 Dart GTS 440 mopar .590 cam, Edelbrock heads, 3200# best et 6.45, 106.78, 10.14, 132.88 mph, 1.47 60ft best 60ft 1.36
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Re: launch issues
[Re: 493_DART]
#1022144
06/29/11 09:29 AM
06/29/11 09:29 AM
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Yeah, i always follow your posts for that reason. Has it gone 1.41 footbraking it.? I haven't had a snubber on it for 15 yrs, do you think it would help?. Mick
69 Dart GTS 440 mopar .590 cam, Edelbrock heads, 3200# best et 6.45, 106.78, 10.14, 132.88 mph, 1.47 60ft best 60ft 1.36
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Re: launch issues
[Re: deaks]
#1022145
06/29/11 03:33 PM
06/29/11 03:33 PM
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AS soon as i get video, i will post it, in the mean time more advice would be appreciated. Mick
69 Dart GTS 440 mopar .590 cam, Edelbrock heads, 3200# best et 6.45, 106.78, 10.14, 132.88 mph, 1.47 60ft best 60ft 1.36
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Re: launch issues
[Re: 493_DART]
#1022148
06/29/11 07:30 PM
06/29/11 07:30 PM
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Joined: Aug 2003
Posts: 2,401 Tucson, Arizona
MRMOPAR
top fuel
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Tucson, Arizona
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I wonder if your losing time with front end lift vs moving the car forward.
68 RR 528" INDY MAXX
07 2500 CTD
Southwest International Raceway - IHRA - Tucson, AZ
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Re: launch issues
[Re: MRMOPAR]
#1022149
06/29/11 08:05 PM
06/29/11 08:05 PM
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Posts: 3,675 Akron, Ohio U.S.A.
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Mick We've gone over my combo before however, I run 29.5x11.5 with 12-12.5psi (works best for my combo). Looking at your photo seems to me you do need more air in the rear tires. Also what kind of angle is your rear shackle at? I run an agressive layed down angle. From my experience this hepls promote dynamic rise in the rear, thus planting the tires. JOM though Oh, one more thing, don't think a snubber is going to help with your issue. Really not needed. Best thing I ever did was pitch the snubber and put QA-1 shocks on the rear, footbrake 1.389 60' @ 3325#
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Re: launch issues
[Re: deaks]
#1022150
06/29/11 08:18 PM
06/29/11 08:18 PM
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Joined: Jan 2003
Posts: 2,933 A shed in England
Tig
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Mick, we were tuning our launch a little at the weekend at the pod (not a good thing to do when your running in brackets I know) We had 12.5 psi cold and we need more looking at the photos. We got it down to a 1.37 when the front touched before the 60ft lights and 1.48 when they didn't. Car wants less ext damping and more compression damping at the front along with more rear tyre pressure, lots of wadding on launch and darker at the edges on the contact patch. We're just creeping up on it as a friend of ours with caltracs got all 4 wheels off the floor this weekend and had some damage
'74 Challenger..9.46 @ 145.9 1/4, 6.001 @ 118 1/8 so far. 4023lb !!! # N/A, Marsh performance 655ci, Indy Maxx, T/R, Indy 600-13 X's, Street legal, pump gas, full interior, Cal-Tracs, mufflers, 3:73's and real 10.5 radials. 9.51 @ 142.4 1/4, 6.003 @ 114 1/8 with our old mule KB, 572-13, 580 wedge. RHD '68 Barracuda Fastback 323ci street/strip. Best ET 13.88 @ 99.03
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Re: launch issues
[Re: Tig]
#1022151
06/30/11 04:28 AM
06/30/11 04:28 AM
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The hoosiers are definitely softer than the M/T's, however they were at least 8 yrs old but still ran a 1.46 on the car last year. Since fitting the control arms and calvert shocks, it's dramatically improved the front end rise. Greg I was always led to believe ss springs dont need a snubber because of the short front section. The angle of the rear hangers, is as shown in the mopar chassis book. Tig I am going to the pod in a couple of weeks, i am going to stiffen the shocks up to at least 7 and start with around 12 psi. Your car is making far more power than mine, i cant see all four wheels coming off the ground on mine, oh and well done on the 60ft improvement. Mick
69 Dart GTS 440 mopar .590 cam, Edelbrock heads, 3200# best et 6.45, 106.78, 10.14, 132.88 mph, 1.47 60ft best 60ft 1.36
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Re: launch issues
[Re: deaks]
#1022152
06/30/11 05:06 AM
06/30/11 05:06 AM
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Joined: Jul 2004
Posts: 4,384 Worst Weather USA
493_DART
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Id like to post some real track data (im not a keyboard racer) ---this is my experience , i race and keep a log book. MY car DID improve with a snubber. it was going around 1.49 - 1.51 or so on an average day ....... and after the snubber was installed it was going 1.46-1.49 . It seemed to help and make the 60 more consistent. the weather was similar--no other changes. Thats the end of the story--no argument needed--it worked. most of the above passes were in crap weather (normal in iowa) . My point is , a pinion snubber may or may NOT work on YOUR car-----its worth a try . It sure seemed to help MY car. I wouldnt sit here and say so if i couldnt offer a possible enhancement to your car . (and no--i dont sell pinion snubbers--i made mine)
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Re: launch issues
[Re: 493_DART]
#1022153
06/30/11 06:09 AM
06/30/11 06:09 AM
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I'm sorry Kevin, i was just making an observation and i do value your contribution to this thread along with everyone else who has replied. If i had all the answers i wouldn't be on here asking for help. BTW, Judging by the time difference you must have match sticks holding your eye lids open. It's 10 am here Mick
69 Dart GTS 440 mopar .590 cam, Edelbrock heads, 3200# best et 6.45, 106.78, 10.14, 132.88 mph, 1.47 60ft best 60ft 1.36
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Re: launch issues
[Re: tboomer]
#1022156
06/30/11 04:55 PM
06/30/11 04:55 PM
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Posts: 4,384 Worst Weather USA
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Quote:
Quote:
yes-my hours are weird plus i get insomnia on top of that
Usually on the starting line!!
i went home the last 2 races due to RED lights.....YOU know all about those --dont ya ?
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