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

Re: Front tire pressure/Reaction time
 

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

Re: Front tire pressure/Reaction time
 

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.

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.

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.:D
When you tech in, if wheelbase left to right is measured, it is with the vehicle in a static condition.:cool: 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:)
Dissident

Re: Front tire pressure/Reaction time
 

The wheelbase can be + or - 1" of the factory spec. The max. diff in stagger is 3/4".

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

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

Re: Front tire pressure/Reaction time
 

Hacksaw. Think the rule is the opposite. +-3/4 with max variation 1" side to side.

Re: Front tire pressure/Reaction time
 

* 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.

Re: Front tire pressure/Reaction time
 

We used to have three sets of front tires and wheels, three different size and would run the size that gave the right reaction times at a particular track. Never played the fron tire pressure game.

Re: Front tire pressure/Reaction time
 

I am thankful for all the info and
insight on things to try.
There nothing like the racing community
helping out a competitor
Where else would you find this

Thank You

Re: Front tire pressure/Reaction time
 

You Sir, are 100% correct.

Re: Front tire pressure/Reaction time
 

Tech guy told me one inch side-to-side. I use 3/4 inch. Been checked a couple of times.
And pressure effected my foot brake cars more than the trans brake car. Testing would be required to determine how much, IMHO.

Re: Front tire pressure/Reaction time
 

The tire height makes a significant difference in reaction time.

5 or 10 Lbs pressure in the tire = very little that I can find.

Maybe if I took the front runners from 40 to 10 it might make a observable
difference. Someone can tell me = I am not going to try it!

My Blood Sugar level makes a lot more difference = Of Course - I am old!

Re: Front tire pressure/Reaction time
 

I'm not sure of the exact height of the stage beam but as an experiment, I put a 3" tall block in front and behind my 26" tall tire, the measurement at 40 PSI and 10 PSI was exactly the same. Based on that, I think the change in reaction time is a mental thing and not real.

Jim Caughlin
SS 6019

Re: Front tire pressure/Reaction time
 

Many different opinions from many great drivers but in my personal opinion I don’t feel front tire pressure is very important. I normally don’t check front tires after I leave the house unless one or both look like they’re leaking for some reason. And pretty similar with rear tires. I’ll usually check them every morning as they can vary quite a bit with outside temperature. And sometimes I’ll give them a check to make sure they’re about the same throughout the day. But whatever works for you or makes you feel most confident and comfortable is what’s most important!

Re: Front tire pressure/Reaction time
 

We check all four each morning and the rear
most times in the staging lane unless we are
rushed.

Re: Front tire pressure/Reaction time
 

[QUOTE=GTX JOHN

My Blood Sugar level makes a lot more difference = Of Course - I am old![/QUOTE]

From a fellow diabetic..... yes it does. I keep good check on mine because it makes a HUGE difference in react and driving the stripe.

I check my tires in the morning and thats about it lol. 38frt & 19rear is my bracket tune
Rpms will change react the most, mine is 200 for .010 up to a certain point

Re: Front tire pressure/Reaction time
 

I feel the same way. I typically check mine before the first and second passes of the day, and that's about it.

With the dragster I pay a little more attention and check before each pass, but I buy the cheapest gauge that is in the range needed.

Re: Front tire pressure/Reaction time
 

I check mine every run. I`ve seen front tire pressure drop 2 to 3 pounds after the sun drops. Same scenario during the day as it gets warmer. Do the same with both my V6 Stocker and 11 second S/P car.

Re: Front tire pressure/Reaction time
 

Well I didn't get to try anything at Indy today.
We had a tire hooking problem.
Like eye to the sky problem.On 2nd pass tried to
Kill some power,took 14 degrees out at the start line
and dropped the 2 step 400 rpm. Then I keep my
foot in it. Hung the front end way up. Busted the pass
Side shock and think it messed the top ball joint up.
Loaded up and went back home
To say Indy was hooking today was a under statement.
Hope someone got a good picture.
Lol

David