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Could a gear change induce wheel spin at launch? #3021687
03/07/22 09:05 PM
03/07/22 09:05 PM
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J_BODY Offline OP
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Coming off my dismal showing at March Meet has given me time to ponder the impossible or improbable…. I spun 2 out of three passes. This is something I have not had an issue with at this track. While the temps were cool (50s) we had some sun shine so I can’t imagine the track temp was too bad. 1.34, 1.24, 1.33 were my hits. The only change I’d made was dropping from a 4.56 to a 4.30. In the past I’d basically printed out 1.22/24 slips there. I guess I’m going to have to add track temp to Daves duties (my right hand man) and log that. Either way, I’m putting the .56s back in before Vegas.

Re: Could a gear change induce wheel spin at launch? [Re: J_BODY] #3021690
03/07/22 09:12 PM
03/07/22 09:12 PM
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It depends ? IF the car has enough power , less gear will calm launches down , but 60 the same or sometimes better ….. maybe your power/converter works better with more gear ? It’s hard to say for sure , do you any data logging ? An rpm trace would show a lot here


....BAD A$$ STREET CAR.....
Re: Could a gear change induce wheel spin at launch? [Re: n20mstr] #3021720
03/07/22 10:10 PM
03/07/22 10:10 PM
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I have Racepak data from all three and would love to post them but that seems to be quite the task for me anymore. We we’re running 9.2 to 9.4. I’ll go back and see if it affected stall speed. Less power or bigger tire would cure this smile

Re: Could a gear change induce wheel spin at launch? [Re: n20mstr] #3021721
03/07/22 10:12 PM
03/07/22 10:12 PM
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The 4.30 has more wheel speed and the converter will be looser which could further cause traction problems early in the runs. Same tire and same or similar condition?


"Any fool can know. The point is to understand"

- A. Einstein
Re: Could a gear change induce wheel spin at launch? [Re: EvilB1Dart] #3021733
03/07/22 10:51 PM
03/07/22 10:51 PM
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Fulton County, PA
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You can absolutely spin the tire from not enough SLR if you are not planting the tire.

That said, I find it hard to be convinced that a small step like that gear change is could make a car go from good to junk. Assuming a 3 speed, that's around a half point of gear ratio. Go back to the old set up and see.

I can tell you that running on a track that is prepped for fuel cars, along with the clutch dust and oil they leave behind, is not typically going to be the best situation for 9 and 10 second door cars.


If the results don't match the theory, change the theory.
Re: Could a gear change induce wheel spin at launch? [Re: CMcAllister] #3021787
03/08/22 06:37 AM
03/08/22 06:37 AM
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Tulsa OK
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I think with a taller gear once you lose the tire it might be harder to get it back, but you didn't make that drastic of a change. It will be interesting to see how it does when you go back.


68 Barracuda Formula S 340
87 "Chrysler" Conquest
Re: Could a gear change induce wheel spin at launch? [Re: Bad340fish] #3021802
03/08/22 07:58 AM
03/08/22 07:58 AM
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1.22 at that ET level is pretty stout. You are talking good NHRA S/S numbers. How did the 330 times look? Were they off the same amount? You're hitting the tire with less torque, all else being equal. Might need a looser rebound/tighter compression setting in the rear.
Doug

Re: Could a gear change induce wheel spin at launch? [Re: dvw] #3021820
03/08/22 09:02 AM
03/08/22 09:02 AM
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pittsburghracer Online work
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We race in a lot colder temperatures than that around here but my quickest 60 foot was 1.21 in my Daytona and 1.25 in my Duster. I also have a lot more tire than you do. Even at that when the temps did drop I had to do a longer burn out.


1970 Duster
Edelbrock headed 408
5.984@112.52
422 Indy headed small block
5.982@112.56 mph
9.42@138.27

Livin and lovin life one day at a time




Re: Could a gear change induce wheel spin at launch? [Re: pittsburghracer] #3021918
03/08/22 01:04 PM
03/08/22 01:04 PM
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Las Vegas
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I know a guy that's free in a couple weeks that could help at the Vegas race grin

How old are your tires?

Did you change the shocks at all to compensate?

Do you have any good video of the runs?

Can you email the run files?


"I am not ashamed to confess I am ignorant of what I do not know."

"It's never wrong to do the right thing"
Re: Could a gear change induce wheel spin at launch? [Re: Al_Alguire] #3021942
03/08/22 02:00 PM
03/08/22 02:00 PM
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Did you heat the tire just a hair more to overcome the cooler temps? Could have made them a bit
greasy.

Last edited by FurryStump; 03/08/22 02:02 PM.

best of 11.39 at 117 mph 1.60 60’. 68 340 S Barracuda Fastback F.A.S.T [IMG]http://i67.tinypic.com/2mnnnnt.jpg[/IMG]
Re: Could a gear change induce wheel spin at launch? [Re: FurryStump] #3021953
03/08/22 02:18 PM
03/08/22 02:18 PM
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What ignition box do you have?

Re: Could a gear change induce wheel spin at launch? [Re: J_BODY] #3022070
03/08/22 07:28 PM
03/08/22 07:28 PM
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Bend,OR USA
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Do you know the difference in the density altitudes for both tracks?
Did you change the jets to run Famosa ?
I'm wondering if it picked up enough power due to the altitude and better air out there in the groves to make it spin the tires: work:


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Could a gear change induce wheel spin at launch? [Re: J_BODY] #3022105
03/08/22 08:39 PM
03/08/22 08:39 PM
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Livermore, CA
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Check Your Racepak files and see if You are spinning the tires on the 1-2 gearshift as well? I suspect a shock adjustment is in order as well. Keep going. Did You pick up mph with the rear end ratio change?

Re: Could a gear change induce wheel spin at launch? [Re: Dduster] #3022529
03/09/22 11:44 PM
03/09/22 11:44 PM
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Slicks have 22 passes. 14psi as always
Prior to this weekend I hit that test day in Vegas back in December. Was very cold that day and we loosened the front 4 clicks extension, left the rears alone. I put the turns back into the shocks prior to the 1st pass and took 2 out for pass 2.
Burnouts…. yeah probably over did that perhaps…. It was “cold”
Ignition….. old school 6AL timing locked at 32. Been that way forever.
We went up 4 jet sizes since Vegas was the last run. Was 12.4 afr so we let it be.


Starting to wish I’d stayed with my 4150 carb and 727 trans…. Fun consistent combo that definitely ran the number. smile
I’m sure the softer barometer in Vegas might work my way.

Re: Could a gear change induce wheel spin at launch? [Re: J_BODY] #3022720
03/10/22 06:57 PM
03/10/22 06:57 PM
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I had a nostalgia pro stock racer tell me that if the track was crappy they would add more gear, not less, to reduce the wheel speed. Never tried it myself as I was locked into the one gear ratio I could get in a pro gear.


I raise chickens, so I am literally a chicken tender.

The Scamp is sold, now just two old trucks and one newer one.
'92 D250 Club Cab CTD, 47RH conversion, pump tweaks, injectors, rear disc and hydroboost conversion.
'74 W200 Crew Cab 360, NV4500, D44, D60 and NP205 divorced transfer case.
2019 1500 Long Horn Crew Cab 4WD, 5.7 Hemi.






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