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DRR S/Pro
posted
SO I assume its a spin grab spin thing but what causes it and what's the best way to fix it? 4 link dragster


J.R. Baxter

""Fathom the hypocrisy of a Government that requires every citizen to prove they are insured ..but not everyone must prove they are a citizen."

2024 Miller
Rolla Competition Engines
ProCharger
Hoosier Tires
Abruzzi
 
Posts: 1530 | Location: Waxahachie | Registered: July 04, 2005Reply With QuoteReport This Post
DRR Trophy
Picture of Rodney Pryor
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On my 4.80 - 4.90 door a combination of these wil fix that issue depending on how much bite the track has:

1 - lower the wheelie bar
2 - lower the tire pressure
3 - raise starting line RPM

I would assume it would work the same on a dragster.
 
Posts: 119 | Location: Richmond, VA | Registered: December 07, 2002Reply With QuoteReport This Post
DRR Pro
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I thought you had that Goethe shaft?
 
Posts: 1431 | Location: united states | Registered: January 16, 2006Reply With QuoteReport This Post
DRR S/Pro
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I do but it still shows a check mark. Have always had the check mark


J.R. Baxter

""Fathom the hypocrisy of a Government that requires every citizen to prove they are insured ..but not everyone must prove they are a citizen."

2024 Miller
Rolla Competition Engines
ProCharger
Hoosier Tires
Abruzzi
 
Posts: 1530 | Location: Waxahachie | Registered: July 04, 2005Reply With QuoteReport This Post
DRR S/Pro
Picture of "The Bender"
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Doesn't a check mark usually mean that everything is OK? HMMMM Laughing Hard


272" Spitzer
540 Chevy
The Blower Shop XR1
FTI XPM Series Converter
FTI Level 6 Powerglide
3.69@199
.916 60'

2017 Bradenton Heads Up Madness
Open Outlaw Champ

2018 PDRA T/D #5
2019 PDRA T/D #2

2020 Retired From T/D Competition....

2020 Bradenton NMCA Hemi Shootout Winner

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Posts: 3100 | Location: Yes | Registered: July 08, 2009Reply With QuoteReport This Post
DRR S/Pro
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quote:
Originally posted by seabass:
SO I assume its a spin grab spin thing but what causes it and what's the best way to fix it? 4 link dragster


Post a picture!
 
Posts: 2161 | Location: Tewksbury, MA,USA | Registered: November 03, 2000Reply With QuoteReport This Post
DRR S/Pro
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quote:
Originally posted by "The Bender":
Doesn't a check mark usually mean that everything is OK? HMMMM Laughing Hard


Nice reply!!!!! Not worthy
 
Posts: 2161 | Location: Tewksbury, MA,USA | Registered: November 03, 2000Reply With QuoteReport This Post



DRR Sportsman
Picture of 369dragster
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quote:
Originally posted by seabass:
SO I assume its a spin grab spin thing but what causes it and what's the best way to fix it? 4 link dragster


Who says you have to fix it? If the car is consistent why chase something. Do you have a 2 or 4 magnet collar?


Ken
 
Posts: 321 | Location: Massachusetts | Registered: March 15, 2007Reply With QuoteReport This Post
DRR S/Pro
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18 on the sensor.....

Not saying its a problem just trying to improve things and maybe learn. Its usually consistent as it is


J.R. Baxter

""Fathom the hypocrisy of a Government that requires every citizen to prove they are insured ..but not everyone must prove they are a citizen."

2024 Miller
Rolla Competition Engines
ProCharger
Hoosier Tires
Abruzzi
 
Posts: 1530 | Location: Waxahachie | Registered: July 04, 2005Reply With QuoteReport This Post
DRR S/Pro
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J.R. Baxter

""Fathom the hypocrisy of a Government that requires every citizen to prove they are insured ..but not everyone must prove they are a citizen."

2024 Miller
Rolla Competition Engines
ProCharger
Hoosier Tires
Abruzzi
 
Posts: 1530 | Location: Waxahachie | Registered: July 04, 2005Reply With QuoteReport This Post
DRR S/Pro
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Heres another, even tho I blew the tires off on this one



J.R. Baxter

""Fathom the hypocrisy of a Government that requires every citizen to prove they are insured ..but not everyone must prove they are a citizen."

2024 Miller
Rolla Competition Engines
ProCharger
Hoosier Tires
Abruzzi
 
Posts: 1530 | Location: Waxahachie | Registered: July 04, 2005Reply With QuoteReport This Post
DRR Sportsman
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That’s pretty early. Typical check mark from a hook spin is much later (peak at 0.2 - 0.25 vs. that looks like less than 0.1). As early as that is and you have an 18 magnet collar I’m thinking you’re catching the tire winding up on the initial. If that’s it, there’s nothing to fix.
 
Posts: 936 | Location: my own little world | Registered: July 20, 2005Reply With QuoteReport This Post
DRR Trophy
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It may also be an interpolation error in rpak based on what was just mentioned about the initial "play/windup" in the driveline. The scan frequency is a moment in time measurement which may pick up X quantity of pulses from the pick up within that cycle. While it may have picked up the several ticks it takes to get the car moving it's more than the actual track speed causing a graphic mapping to look like what you are seeing. In simpler terms the graph is just connecting dots. Play with the smoothing in your settings and you'll see just how well rpak made their software.
BW
 
Posts: 190 | Location: Rock><Hard Place | Registered: February 20, 2010Reply With QuoteReport This Post
DRR Sportsman
Picture of Slick Vic
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As stated too early in the run. I have seen back to back passes with one check mark and no check mark and the car be deadly. 8 magnet collar. It depends on where the magnet is in relation to the sensor, as i believe it has to see 2 magnets in order to start. 18 obviously is going to make the distance from sensor smaller variances every time you stage compared to a 8, 4 or 2 magnet.


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Posts: 131 | Location: Delaware | Registered: June 12, 2008Reply With QuoteReport This Post



DRR Sportsman
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Gents... Do some research and you will find that check mark is normal. What you are actually seeing is the tires flatten, creating a smaller diameter, which rotates quicker (yes the system can detect this, it's hard for our brains to comprehend but these systems detect, as designed, very subtle differences in DS velocities). You will see the same thing but not as dramatic on shifts, and even bumps in the track.

My car shows that every run and it's within .00x in the 60ft. I believe the OP even stated his car is deadly.... That because it's not spin, it's the diameter of the tires changing as they are suppose to as the chassis drives the tires into the ground in the hit.

It's possible to fix it with more air pressure, but your just risking true spin and keeping the tires from going as flat.

Do some research on the subject you will find lots of info even from pro teams explaining this but the above explains it in the nutshell.



Configuration: 3350#, 582 C.I.,

60 - 1.24
1/8 - 5.53@ 126MPH
1/4 - 8.73@ 159MPH



3700#+210lb driver, FULL interior, through mufflers, 10.5 tire.
60'-1.333 (IN 4000ft DA! Joisy Math excluded; 1.25sec using JOISY MATH.) Wink
1/4 - 9.60@144MPH

 
Posts: 1451 | Location: St Marys | Registered: January 12, 2004Reply With QuoteReport This Post
DRR Top Comp
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My engine builder says the same thing. Tire wadding up, pretty much only shows up with collars with a bunch of magnets.


Clowns to the left of me, Jokers to the right. Here I am.......
 
Posts: 5321 | Location: stuck in the middle with you! | Registered: March 11, 2002Reply With QuoteReport This Post
DRR S/Pro
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quote:
Originally posted by Cashflow:
My engine builder says the same thing. Tire wadding up, pretty much only shows up with collars with a bunch of magnets.


Bingo, it is the tire sidewall wrapping up at the hit which shows up as false tire spinning! And you only see this with 8 magnets or more on your DR ring.

In the big picture here, if you are trying to go FAST, controlled tire spin is your friend, work the DS speed graph with ACCEL and you will see.
 
Posts: 2161 | Location: Tewksbury, MA,USA | Registered: November 03, 2000Reply With QuoteReport This Post
DRR S/Pro
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Thanks.. Its pretty fast most of the time, just wondering why I have this and others don't. What was said does make sense, as I don't run much air and do see a decent of squat on my travel sensor on the chassis.


J.R. Baxter

""Fathom the hypocrisy of a Government that requires every citizen to prove they are insured ..but not everyone must prove they are a citizen."

2024 Miller
Rolla Competition Engines
ProCharger
Hoosier Tires
Abruzzi
 
Posts: 1530 | Location: Waxahachie | Registered: July 04, 2005Reply With QuoteReport This Post
DRR Sportsman
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quote:
Originally posted by ski_dwn_it:
Gents... Do some research and you will find that check mark is normal. What you are actually seeing is the tires flatten, creating a smaller diameter, which rotates quicker (yes the system can detect this, it's hard for our brains to comprehend but these systems detect, as designed, very subtle differences in DS velocities). You will see the same thing but not as dramatic on shifts, and even bumps in the track.

My car shows that every run and it's within .00x in the 60ft. I believe the OP even stated his car is deadly.... That because it's not spin, it's the diameter of the tires changing as they are suppose to as the chassis drives the tires into the ground in the hit.

It's possible to fix it with more air pressure, but your just risking true spin and keeping the tires from going as flat.

Do some research on the subject you will find lots of info even from pro teams explaining this but the above explains it in the nutshell.


Just to be argumentative, in most cases what is perceived as “flattening” of the tire is really wind up. The tire gets shorter (i.e. axle CL gets closer to track) because the id is moving relative to the od. The footprint is stuck to the track. I was able to prove this to myself by LOWERING air pressure and ADDING power on the initial until the tire all of a sudden didn’t get as short at the hit (because it could slip the footprint). That was a very hard setup to repeat though and I eventually gave up on it.
 
Posts: 936 | Location: my own little world | Registered: July 20, 2005Reply With QuoteReport This Post
DRR Trophy
Picture of Rodney Pryor
posted Hide Post
quote:
Originally posted by BJs Wild Ride:
quote:
Originally posted by ski_dwn_it:
Gents... Do some research and you will find that check mark is normal. What you are actually seeing is the tires flatten, creating a smaller diameter, which rotates quicker (yes the system can detect this, it's hard for our brains to comprehend but these systems detect, as designed, very subtle differences in DS velocities). You will see the same thing but not as dramatic on shifts, and even bumps in the track.

My car shows that every run and it's within .00x in the 60ft. I believe the OP even stated his car is deadly.... That because it's not spin, it's the diameter of the tires changing as they are suppose to as the chassis drives the tires into the ground in the hit.

It's possible to fix it with more air pressure, but your just risking true spin and keeping the tires from going as flat.

Do some research on the subject you will find lots of info even from pro teams explaining this but the above explains it in the nutshell.


Just to be argumentative, in most cases what is perceived as “flattening” of the tire is really wind up. The tire gets shorter (i.e. axle CL gets closer to track) because the id is moving relative to the od. The footprint is stuck to the track. I was able to prove this to myself by LOWERING air pressure and ADDING power on the initial until the tire all of a sudden didn’t get as short at the hit (because it could slip the footprint). That was a very hard setup to repeat though and I eventually gave up on it.


I found the same thing out in my testing - less air pressure and more power. The biggest change for me was a new tire gauge. The older moroso gauge read 1.5 pounds higher than my new intercomp. I gained more consistency after eliminating the early check mark.
 
Posts: 119 | Location: Richmond, VA | Registered: December 07, 2002Reply With QuoteReport This Post
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