Front tire pressure adjustments
 

Will lowering my front tire air pressure slow my reaction time down. I run 40 lbs. is that normal or high or low.?

Re: Front tire pressure adjustments
 

should!- pressure compared to what?

Re: Front tire pressure adjustments
 

3200lb stocker 98 camaro.

Re: Front tire pressure adjustments
 

That's pretty high, but not crazy. Lowering the pressure will slow your reactions, but there isn't a ton there if you are keeping the pressure within reason.

I run 32-35 psi in my 3600# Super Street car. I typically bracket race it, and use starting line RPM to adjust reaction rather than tire pressure.

I can't tell if your question is:

1. I run 40 psi in my tires and I think it might be too high, but what will happen to my reaction times if I lower the pressure?

2. I need to slow my reaction times. Will lowering the pressure in my front tires accomplish this?

If #1, I'd probably drop 5 psi and you likely won't notice the difference. If #2, I'd still drop 5 psi, but you'll get more change in R/T through RPM adjustment or rear tire pressure.

Re: Front tire pressure adjustments
 

More in lowering rear tire pressure so they wrinkle more.

Re: Front tire pressure adjustments
 

I am trying to slow my reaction time down. When I am green it is is about a 015-020 But I go red alot by about .012-.015. Don’t win many races when you go red. Just trying to slow down reaction time without changing my spot on the tree. I might need to lower both front and rear tire pressure. I know I could lower my starting line rpm some as well. Just try to see what you guys think the best way to do it is.

Re: Front tire pressure adjustments
 

Put a taller front tire on, if you have the room.

Re: Front tire pressure adjustments
 

Drop leave rpm down just a tad.

Re: Front tire pressure adjustments
 

Not sure what size front tire you run but I run a 28" with 25 to 30 psi depending on roll out but as Lee stated don't overlook the rears. There's alot you can do there especially if you run bias ply tires.

Re: Front tire pressure adjustments
 

I’ve generally just lowered the RPM to slow RT, doesn’t seem to affect ET as much plus you can adjust that or not “on the fly” if you see everyone spinning like crazy or you’ve just packed in 50 pounds of lead. You can add some shock extension too and of course what Hacksaw said but probably don’t have much room on a late Camaro. Assume you’ve verified the car isn’t periodically pulling straight up out of the beam?

Re: Front tire pressure adjustments
 

I have 28 inch tall tire on it. Car went 1.33 60 ft this past weekend. Just didn’t know what other B/SA cars run for tire pressure. I run radials on rear.

Re: Front tire pressure adjustments
 

Are you "blocking"?

Re: Front tire pressure adjustments
 

Blocking, or bias slicks should help.

Re: Front tire pressure adjustments
 

Blocking? Are you talking about some sort of a blinder? If so , I really don’t know how to do that. I have seen and heard of people doing that. Are they blocking out the top 2 bulbs ? Do you then use the bottom bulb like a pro tree? What kind of device do you use to block out the top 2 bulbs? I also do not use a 2 step. I just lean on the converter. My 2step button is on my brake pedal. I have always been afraid I would hit the button and activate my 2 step at the finish line. Do you set the low side 2 step low enough where your brakes can safely hold the can without pushing it out of the beams. ?

Re: Front tire pressure adjustments
 

Blocking? Are you talking about some sort of a blinder? If so , I really don’t know how to do that. I have seen and heard of people doing that. Are they blocking out the top 2 bulbs ? Do you then use the bottom bulb like a pro tree? What kind of device do you use to block out the top 2 bulbs? I also do not use a 2 step. I just lean on the converter. My 2step button is on my brake pedal. I have always been afraid I would hit the button and activate my 2 step at the finish line. Do you set the low side 2 step low enough where your brakes can safely hold the car without pushing it out of the beams. ?

Re: Front tire pressure adjustments
 

Okay, if you're not blocking or blinding, let's leave that for another day.
Now, by your own description, you're swinging across .000 by about 35 thou.
So let's say you slow your vehicle reaction down .035. Your - .020 now becomes a +.015
Great.
But what happens when you hit what used to be a +.015? It now becomes a + .050.
Not going to win too many that way either.
My friend, I think you need to work on something other than the car right now.
Just my opinion. I don't consider myself to be a bracket racer. I did win a couple of track championships, but I think I'll let the experts take it from here.
Later ,we can get back to the technical items.

Re: Front tire pressure adjustments
 

Yes mark you are correct in determining that my slower lights would be less than stellar. I would rather have more ‘50’ lights and less red lights. Most people would rather have a 50 light than a red light. Most people are not as consistent as you on the tree. We all wish we were but we are not, at least I’m not.i I can read between your lines and I will continue to work on my driving as hard as I can. Hopefully I can get my cars reaction time to go along with my ‘human’ reaction time and get a win one day. Thanks mark.

Re: Front tire pressure adjustments
 

KD,

I would highly recommend using your 2 step. If you can lower the launch rpm that would be a great help to you. Also, I would it would be more consistent leaving at the same RPM each time. The converter can move a little with air changes and trans temps.

Hook up a micro switch that will only allow the 2 step to be activated in low gear. I have mine on my shifter.

Good luck out there and keep trying, it will come.

Ryan

Re: Front tire pressure adjustments
 

Thanks Ryan. I think you are correct. I’ll check into hooking up that switch.

Re: Front tire pressure adjustments
 

You have some good suggestions here.

Just to complete the logic circle, you do have a brake pressure gauge in the car and know what brake pressure you are staging at correct? Don't have time to look, etc, get a go pro and video the gauge. If your not consistent with that then there you go.

Two step, could help, depends on your carb and how it works when floored, you may also want to upgrade to a brake pressure switch, instead of the brake pedal piece.

Log books should give you a clue too. Time trials versus competition etc.

Change one thing at a time.

Eric

Re: Front tire pressure adjustments
 

What’s the best source for a brake pressure switch? I’ve also avoided a button on the brake petal, just another thing to put in the starting line procedure.

Re: Front tire pressure adjustments
 

Sorry but I do not have a brake pressure gauge. Sounds like I need to install one. My car is fuel injected. Will I need to change my tune up while I am on the 2 step. My car work really good running off the foot brake. Im very new to stock and the fuel injection game. Thanks.

Re: Front tire pressure adjustments
 

What benefit is there to the brake pressure switch over the brake pedal switch two step? Thanks for the help in advance.

Re: Front tire pressure adjustments
 

Do you use a practice tree? I found that it helped me narrow down the range of the lights I was cutting. Then I was able to zero in on when to leave.

Of course, if they eliminated reaction time, none of this would matter. :-)

Re: Front tire pressure adjustments
 

At the least it would require the same brake line pressure each time you stage. Eliminates a variable.

Re: Front tire pressure adjustments
 

So then you prestage bump in and check brake pressure then look at the tree and get on the two step? I don’t mean to sound synical, just want to make sure of the process and if this would help me

Re: Front tire pressure adjustments
 

ok this is gonna sound stupid but try ankle weights used them on my stick super stocker was going 10-15 red try 5pd weight

Re: Front tire pressure adjustments
 

You can microadjust the brake pressure switch to release at a higher or lower pressure as your needs and car may like.

Everyones staging method is different, I don't look at the gauge, I listen for the two step if I am running it. My dakota fuel injected two step process is totally different than the footbrake gremlin(I don't run the pressure switch two step on it, just a gauge)

Two step is just faster for some cars/trucks. I like footbraking more.

Even better is a stick, now that is where the fun factor really comes in, lots of variables you can tweak to adjust RT, but don't ask me specifics, I'm a novice.

Eric

Re: Front tire pressure adjustments
 

Good advise here. Your car if set up the same each run is going to react in just about the same amount of time each run, the variable is the driver. I worked my super gas car down to decent repeatable lights on a Pro tree. I then ran it in super street and was consistently early. (I needed to adjust the car to the slower light) That was accomplished with making changes to the car. Then I went and ran some full tree classes and I was all over the place. The car was still the same and I knew it could cut decent lights on either Pro tree. The difference in the full tree races was squarely with the driver, me. I needed to find a way for the driver to be better at reacting to the full tree, blocking or leaving on the top bulb are some of the ways to accomplish that.

Re: Front tire pressure adjustments
 

Drop front to 17psi

Re: Front tire pressure adjustments
 

I think that would be taken as loose ballast (illegal).You would need a MD's cert.calling it some form of prosthetic...lol

Re: Front tire pressure adjustments
 

damn! never thought of that!


I gotta try it;)

Re: Front tire pressure adjustments
 

would it be any different if it was 5lbs of lead in a shoe?

Re: Front tire pressure adjustments
 

I would think there is grounds to consider that the whole front tire pressure affecting RT's might be somewhat of an urban legend. As a test, I put my car on a flat floor in the shop and put a 3" block in front and behind the front tire at the 40PSI that I normally run and measured the distance between the blocks. I then started lowering the pressure in increments and remeasured the distance. I got all the way down to 15 PSI (which I thought was probably an unsafe pressure to actually race at) and the distance between the block had barely changed. Maybe the 3" height wasn't quite right but it has to be pretty close to the correct height for the photocell. Based on that, I kind of wonder if the real life change in RT is in the drivers head and not a result of the rollout. If you doubt my test, try it yourself.

Jim Caughlin
SS6019

Re: Front tire pressure adjustments
 

Someone has a detailed mathematical analysis of this online that reached the same conclusion. I think you need to focus on other parameters rather than tire pressure.

Re: Front tire pressure adjustments
 

A brake pressure switch will work for some, not for others. When I tried one on my Skyhawk, I found out I don't pull my foot up consistently off the brake pedal. Way too much variable with reaction times, went back to button in pedal. Was between .008 and .036 in six runs today testing.

Re: Front tire pressure adjustments
 

Trust me from 40-17 works. It's worth about .012-.015

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yep -- it does work ---not sure how much on everyone's car but on 3 specific cars I have seen it will slow down the reaction time--- not going to give you any numbers but it did change the RT

Re: Front tire pressure adjustments
 

I would make sure that 17 psi tire was on the inside at the turn off.

Re: Front tire pressure adjustments
 

Was told to do this many many years ago by Tony Cowell.