Can someone who understands the science of launching on slicks explain it? I am not asking "What slicks should I get?" or "What RPM should I launch at?", I would just like to understand how they work. I have been told that even when the slicks are spinning, they are getting traction and the car is still accelerating; unlike street tires that are going nowhere fast when they are spinning. I would just like to get a better understanding of how they work. Get as technical or in depth as you care to

 

you know what I think

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b19coupe &raquo;</TD></TR><TR><TD CLASS="quote">Can someone who understands the science of launching on slicks explain it? I am not asking "What slicks should I get?" or "What RPM should I launch at?", I would just like to understand how they work. I have been told that even when the slicks are spinning, they are getting traction and the car is still accelerating; unlike street tires that are going nowhere fast when they are spinning. I would just like to get a better understanding of how they work. Get as technical or in depth as you care to </TD></TR></TABLE>

This one would be hard to explain, because you are getting into the tech part of it and that is behind closed doors.

The only tech info I can give you is, you have to have the right compound, compound is the #1 key. Now on a slick you have a full contact batch to the ground, and on a street tire you do not, I hope the helps.

Good Luck

John@M&H-Hashim's

 

Yeah but on a slick doesn't it expand at like twice or 3 times the rate? I thought you had to allow for ab expansion of 3 inches because when you go to burnout the tires will expand up to 3 inches as the wheels spin. Wouldn't you loose some of the contact patch as you spin the tires?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Redlineracer &raquo;</TD></TR><TR><TD CLASS="quote">Yeah but on a slick doesn't it expand at like twice or 3 times the rate? I thought you had to allow for ab expansion of 3 inches because when you go to burnout the tires will expand up to 3 inches as the wheels spin. Wouldn't you loose some of the contact patch as you spin the tires?</TD></TR></TABLE>

Hi (Redlineracer); M&H only requieres a 1/2 " around the slick for expantion. Now yes you will loose a little, because the car lifts up on a fwd.

John@M&H-Hashim's

 

only a half inch? I like it

I'm new school age but taught the old ways. 3" is what I had to allow for my olds back when I 16. I was the only kid in high school with a ride that was cut and tubbed

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Redlineracer &raquo;</TD></TR><TR><TD CLASS="quote">

I'm new school age but taught the old ways. 3" is what I had to allow for my olds back when I 16. I was the only kid in high school with a ride that was cut and tubbed </TD></TR></TABLE>

A man after my own heart! I was the only one at my high school who used to roll up on Mondays in my 79 Malibu with 10.5" slicks out back that I was too lazy to take off on from the weekend before. I thought it would get chicks, but I don't think they noticed.

Care to tell me about your old car, I'm a big fan of tubbed out, old school iron.

 

hehe chicks hated my car. "Its too loud!", "why does it jerk like that?!?", "whats that smell!?!" I didn't care. I loved my car but unfortunately she was stolen and brutalized by some guy that used to own the Mustang I had recently "aquired". She was a 1984 Olds cutlass supreme with a 455 squeezed into her. A Weiland big chevy blower and a radical *** cam helped her breathe. She was on the verge of not being streetable and my father was getting pissed. The last time I ran her she did a 9.93 and I don't recall the mph. I miss her but she went with honor and I still have her heart

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SlicksMH &raquo;</TD></TR><TR><TD CLASS="quote">

This one would be hard to explain, because you are getting into the tech part of it and that is behind closed doors.</TD></TR></TABLE>

Aw ! C'mon John, I want you to get into the tech part of it
Let us in on some of your secrets.

P.S. thanks for your help on Saturday (Green Civic coupe with the 22X8X13's).
Could not find you after my run to get your input.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b19coupe &raquo;</TD></TR><TR><TD CLASS="quote">

Aw ! C'mon John, I want you to get into the tech part of it
Let us in on some of your secrets.

P.S. thanks for your help on Saturday (Green Civic coupe with the 22X8X13's).
Could not find you after my run to get your input. </TD></TR></TABLE>

Sorry I missed you (b19coupe) I must of helped 20-racer with their ? and had alot of fun doing it, let me know when you are going to race again and I will be hands on with you.

John@M&H-Hashim's

 

Thanks for being there for all of the racers, John. See you at the next race

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b19coupe &raquo;</TD></TR><TR><TD CLASS="quote">Thanks for being there for all of the racers, John. See you at the next race </TD></TR></TABLE>



John@M&H

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b19coupe &raquo;</TD></TR><TR><TD CLASS="quote">Can someone who understands the science of launching on slicks explain it? I am not asking "What slicks should I get?" or "What RPM should I launch at?", I would just like to understand how they work. I have been told that even when the slicks are spinning, they are getting traction and the car is still accelerating; unlike street tires that are going nowhere fast when they are spinning. I would just like to get a better understanding of how they work. Get as technical or in depth as you care to </TD></TR></TABLE>

You still accelerate when you spin your tires, whether they're slicks or street tires. You will read in physics books that the coefficient of friction is higher when there is no relative motion (spin), and lower when there is spin. This doesn't mean that it's 0 when you're spinning your tires...it's just less, and so you will still accelerate. Just slower.

The reality though is much more complex. Apparently for tires the coefficient of friction is actually highest when there is about 15% slipping. I'm sure it's different with slicks and street tires and different compounds, etc, but the idea remains the same. To get the highest acceleration, you actually do want some spin, but not very much. Just a little...just the right amount

 

^^ would that mean that full traction (no spinning at all) is bad? or in some cases bad?

 

If you've got full traction, you should get a little bit more power, because you obviously have too much tire

 

I know on ABS system, the controle unit allows 30 % slip for braking, thats what many manufators have mensured. That should be the best for braking, so i can´t see why it should´t be the best for a good start.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nerdsports &raquo;</TD></TR><TR><TD CLASS="quote">^^ would that mean that full traction (no spinning at all) is bad? or in some cases bad?</TD></TR></TABLE>

It just means that traction is not what's slowing you down, and like raene said, you need more power.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Lsos &raquo;</TD></TR><TR><TD CLASS="quote">

You still accelerate when you spin your tires, whether they're slicks or street tires. You will read in physics books that the coefficient of friction is higher when there is no relative motion (spin), and lower when there is spin. This doesn't mean that it's 0 when you're spinning your tires...it's just less, and so you will still accelerate. Just slower.

The reality though is much more complex. Apparently for tires the coefficient of friction is actually highest when there is about 15% slipping. I'm sure it's different with slicks and street tires and different compounds, etc, but the idea remains the same. To get the highest acceleration, you actually do want some spin, but not very much. Just a little...just the right amount </TD></TR></TABLE>

Just curious, where did you find this "15% slip" #? Is this something you can back up? Are there theory's on why 15% is optimal?

 

no, i can´t back it up. It is just something i learned on a technical school once. So.. But i think there is something about it..

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by DIRep972 &raquo;</TD></TR><TR><TD CLASS="quote">
Just curious, where did you find this "15% slip" #? Is this something you can back up? Are there theory's on why 15% is optimal?</TD></TR></TABLE>

No I can't back it up and as I said I'm sure it varies with compounds, heat... everything. I just remember reading it somewhere. The point I was trying to make is that maximum grip is not when the tires are not slipping, but slightly above that. What the exact value is I don't know, but is not of critical importance in this discussion.

 

Here's one page where they state the slippage to be 4-10%....

http://www.turnfast.com/tech_h...shtml

Here's a 5-15%

http://users.pandora.be/elvo/c1/index.htm

Anyways, everyone will tell you different values but the point remains. Why there needs to be slip...has something to do with adhesive forces and friction and bonds breaking and molecules stretching and black magic and basically I and probably no-one else knows. Either way I'm sure it's beyond the scope of this, and probably any, discussion



Modified by Lsos at 2:21 AM 5/6/2006

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Lsos &raquo;</TD></TR><TR><TD CLASS="quote"> Either way I'm sure it's beyond the scope of this, and probably any, discussion
</TD></TR></TABLE>
Especially because I doubt anyone will ever know if they're getting a 10% slip with their tires on the strip.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Lsos &raquo;</TD></TR><TR><TD CLASS="quote">

No I can't back it up and as I said I'm sure it varies with compounds, heat... everything. I just remember reading it somewhere. The point I was trying to make is that maximum grip is not when the tires are not slipping, but slightly above that. What the exact value is I don't know, but is not of critical importance in this discussion.</TD></TR></TABLE>

Oh I'm not disagree'ing with you. I'm with you on the physics of it. I thought you made a good post. I was just curious about slip # because that is something that could be helpful for me personally. thanks for the links though.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SovXietday &raquo;</TD></TR><TR><TD CLASS="quote">
Especially because I doubt anyone will ever know if they're getting a 10% slip with their tires on the strip. </TD></TR></TABLE>

There are ways of knowing. It just takes a little more computer then what most people are running. The hard part would be tuning it to run at optimal slip.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SovXietday &raquo;</TD></TR><TR><TD CLASS="quote">
Especially because I doubt anyone will ever know if they're getting a 10% slip with their tires on the strip. </TD></TR></TABLE>

I think it's something that seasoned racers feel, or know. Maybe they don't know the exact slip pecentage, but they know when they have the most grip available. I'm sure it's also easier to feel with racing tires as opposed to street tires.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Lsos &raquo;</TD></TR><TR><TD CLASS="quote">

You still accelerate when you spin your tires, whether they're slicks or street tires. You will read in physics books that the coefficient of friction is higher when there is no relative motion (spin), and lower when there is spin. This doesn't mean that it's 0 when you're spinning your tires...it's just less, and so you will still accelerate. Just slower.
</TD></TR></TABLE>

Exactly. If there is gravity, there'll be friction in the tires, whether spinning or not.