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Old 10-09-2020, 01:11 PM   #1
Willyracer
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Default Front tire pressure/Reaction time

Does the front tire pressure effect your reaction times?
(stock) foot brake racing

If so how much?
Looking for ways to slow the car reaction
to have more constant reaction time
I have to delay my reaction to the last bulb
some i can tell when i am late
Takes me several passes to get where i need
to be. Then the next week i am lost again
and start over

thanks
david
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Old 10-09-2020, 01:36 PM   #2
Stan Weiss
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Default Re: Front tire pressure/Reaction time

Quote:
Originally Posted by Willyracer View Post
Does the front tire pressure effect your reaction times?
(stock) foot brake racing

If so how much?
Looking for ways to slow the car reaction
to have more constant reaction time
I have to delay my reaction to the last bulb
some i can tell when i am late
Takes me several passes to get where i need
to be. Then the next week i am lost again
and start over

thanks
david

If the change in tire pressure changes the tire rollout then it will effect your reaction tire. Depending on how fast or slow your car is. Adding a 1/2" of rollout if your rollout is around 12" is anywhere from .0045 (faster car) to .0065 (slower car) of a second change.

Stan
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Old 10-09-2020, 02:32 PM   #3
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Default Re: Front tire pressure/Reaction time

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Originally Posted by Willyracer View Post
Does the front tire pressure effect your reaction times?
Yes it does. How much depends on your car. If you are very consistent at your local track and are a little off somewhere else, this is a great tool. Rear tire pressure and track prep are also a factor to consider in reaction times.
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Old 10-09-2020, 04:57 PM   #4
Jeff Stout
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Default Re: Front tire pressure/Reaction time

For the life of me I can't find the example with drawings from a bracket website. Stan is correct on the slight amount of change. When the tire gets flatter the distance of the tires curvature in the beam, the rollout when the curvature of the back of tire becomes such a small distance it makes for a very small reaction change. The drawing I had seen explained it perfectly.
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Old 10-09-2020, 05:33 PM   #5
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Default Re: Front tire pressure/Reaction time

Staggering the wheelbase left to right is an easy way. So is choosing larger diameter front wheel/tire combinations. Some cars can also be creatively manipulated with the front suspension (extension) on launch.
When you tech in, if wheelbase left to right is measured, it is with the vehicle in a static condition. Of course check the rulebook to see the allowable tolerance on the wheelbase one side vs the other.


Regards to All that like this kind of stuff,
HB2
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Old 10-09-2020, 05:56 PM   #6
Hacksaw
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Default Re: Front tire pressure/Reaction time

The wheelbase can be + or - 1" of the factory spec. The max. diff in stagger is 3/4".
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Old 10-09-2020, 08:03 PM   #7
gmonde
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Default Re: Front tire pressure/Reaction time

here is an example : my lights where terrible in the first part of the double header @ epping divisional and went out first round because of it ,, made a whole sale change with tire pressure fronts and back (up the pressure) i had some very consistent light's from time trials to when i went in third round in the sports nationals .035-.019 ,, the .019 was against buba linke and resulted in a double breakout .002 mov for buba
just my 2 cents
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Old 10-09-2020, 09:26 PM   #8
e vassar
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Default Re: Front tire pressure/Reaction time

I see a lot of racers checking and maybe adjusting front tire pressure in the staging lanes.
I wished I was consistent enough on the bottom bulb to adjust my RT,s with 4-5 lbs of front tire pressure. I set mine to about 38lbs at the beginning of the day and forget about it
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Old 10-09-2020, 10:07 PM   #9
Stewart Way
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Default Re: Front tire pressure/Reaction time

Hacksaw. Think the rule is the opposite. +-3/4 with max variation 1" side to side.
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Old 10-10-2020, 08:19 AM   #10
Myron Piatek
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Post Re: Front tire pressure/Reaction time

Quote:
Originally Posted by Willyracer View Post
Does the front tire pressure effect your reaction times?
(stock) foot brake racing

If so how much?
Looking for ways to slow the car reaction
to have more constant reaction time
I have to delay my reaction to the last bulb
some i can tell when i am late
Takes me several passes to get where i need
to be. Then the next week i am lost again
and start over

thanks
david
* Get consistent on the tree through practice to establish a baseline that's "comfortable". A practice tree will help and you can usually adjust the "rollout" to be similar to the track. Then you can start making "mechanical" changes with the vehicle, which are "set". Trying to vary your reactions with any consistently is obviously difficult.

* Stage as shallow as possible.

* Go to a taller tire, but watch for fender interference. Then experiment with lower tire pressures, but not below a safe minimum.

* You'll likely slow RT's with bias ply slicks over radials and traction will be more consistent on marginal tracks. Radials tend to be faster with RT's & ET's, but more sensitive to track conditions.

Then there is varying launch RPM and the other suggestions, like staggered front suspension.

As a bonus, more rollout also helps ET!

Some tracks can have slightly different rollouts, but how you see the tree at different tracks (distance, background, etc.) as well as your mood from day to day can also affect overall reaction times.
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