Scaling cars?

jjones752 · 3/17/14, 2:21 PM

Dad,

I'm with you 100%; my primary goal every time I'm at a race is pure enjoyment, whether I'm behind a wheel, behind a wrench or behind a catch fence in the stands.
In an efort to un-hijack this thread, Dave, you and I are probably in somewhat the same boat as far as asking for hard setup numbers; you have a chassis that few others run, and I have one that is modified far beyond the original constructor's design. I'm going to start with bars and ride heights that seem to make sense for me based on available information (asking people who have cars "close" to mine, watching Jimmy sills' video over and over). I have a set of matching Taylor digital bathroom scales that I intend to use as you're suggesting, just to get a baseline that I can go back to if (when?) the chassis gets a little tweaked. I also want to take readings when I crank weight into the corners, just so I know how much things change when I put that 1 to 1-1/2 turns in, and hopefully I can use that data for repeating setups in the garage. But mostly, I plan on getting out there and having a ball. When I was crewing on TQ's for me the most fun was watching the track and seeing how close I could come in helping my guy keep up with it; I can only imagine it will be even more fun to make those changes from a more informed positon, i.e. with the seat of MY pants in the seat of the car.

jjones752 · 3/17/14, 2:51 PM

Something else that occured to me is the we shouldn't be so much concerned with where the weights "should be" from a theoretical standpoint as where they "are" after you get your car squared and blocked; if you start out with a preconceived number that you think, say, your left rear should be, what do you do if your actual reading is nowhere near that figure, but the car "looks" right? I think that's where Dad's idea comes into play, that this dirt track thing is more feel and finesse than facts & figures.
Gary B. would probably attest to that; in fact, I think he may have finally made it around Turn 1 at Syracuse flat yesterday...

DAD · 3/17/14, 2:52 PM

Jim

I represent that hijack remark!!!

You are about to take a trip to the twilight zone. Been there done that, have at it, can you imagine confused.

First off bathroom scales are going to be a little light for the left rear unless you leverage them.

Then them dumb old shocks will absorb and confuse all your weights.

Even tire pres will affect the scales.

Bar and Spring rate will change things.

Then by moving the wheel in or out all the numbers will go south on you.

Pretty soon you will be a babbling idiot just like me and all because you wanted to scale a race car.

After several decades of racing my best advice is "KISS".

Every time you second guess the race track it will come back and bite you.

Your set up has to change for the season, I herd that Btown was full of holes and rutts this weekend, that's a spring thing, goes with dirt in the spring. Next thing it will be dusty and black, that's a summer dirt thing, and sometime that darned stuff will mix up the results,

Been chassen them old race tracks for years and the only thing I know for sure is " I ain't no Karl Kinser", BUT I do got a little Steve Kinser driving for me and we are still having fun and messin with people.

Honest Dad himself

jjones752 · 3/17/14, 3:02 PM

I was referring more to me, with my "knob in the cockpit" joke, but hey if the foo...
I doub't I'll get too concerned about the scaling part of it, mainly why I only spent about 2.50 a crack on the scales at Goodwill. if they give me useful info, great but if not, I'm only out a ten-spot. My main goal, as I think Dave's is, is to have a "starting point" something I can go back to in the shop so I know where I am when I make those inevitable changes over the course of a night, a climatic season, and a racing season.

DAD · 3/17/14, 3:13 PM

Jim

Then you got ride height, tilt, etc, etc. that play a lot in the way a car responds to the race track. You do need a base line. Heck it does not have to be spot on base line, and I would be worried if it was. With a base to start from every race you adjust to the race track and even to the driver. Just because it works for us doesn't mean it will work for you. My son Doug likes the car so tight anymore not many people could drive it with his set up.

If you are just getting into driving a race car keep try to keep it just a little on the tight side also. It is much easier to stay on top of a car that has a push than it is with the ass end all bent out of shape. And Tight is fast. If you can push a tight car hard enough it will probably loosen up for you.

Honest Dad himself

jjones752 · 3/17/14, 3:22 PM

Dad,
All good, and accurate info; I'm not a raw rookie, having seat time in TQ's and a 360 Sprint Car, just never in actual competition. I know how to get the back end to come around when I need it to, and how to drive it in when that's the correct technique. I know it's better (and easier) to overcome a tight car with judicious application of brake and throttle than to try to save a car that's rotated beyond the critical point. I sure hope Dave is getting something useful out of this...

DAD · 3/17/14, 3:37 PM

Quote:

Originally Posted by jjones752

Dad,
All good, and accurate info; I'm not a raw rookie, having seat time in TQ's and a 360 Sprint Car, just never in actual competition. I know how to get the back end to come around when I need it to, and how to drive it in when that's the correct technique. I know it's better (and easier) to overcome a tight car with judicious application of brake and throttle than to try to save a car that's rotated beyond the critical point. I sure hope Dave is getting something useful out of this...

Jim

I hope so. He said he has experience with the 270 micros. WE raced with them things one time and they was picking the right front wheel of the ground on turn exit. I Been trying to do that for years just can't seem to pull it off.

I just throw this stuff out there for general consumption, wish somebody would have written down some of this stuff for us back when. It would have saved us a whole lot of time and money. And if I told some people at the race track they would probably think that I was a know it all busy body. This way it just might help somebody.

My 9th grade Biology teacher wrote on the black board a quote for the day. "A word to the wise is sufficient".

Honest Dad himself

badcoupe · 3/17/14, 10:35 PM

We always scaled before we left and when we came home with all notes of conditions changes etc through the night that way we had a decent idea of where to be for any given condition. We've had a "bible" for every car we've owned. It helps you have an idea of what to do certain nights when conditions are adverse for a given track.

Mbarnes72 · 3/18/14, 4:03 PM

Here you go Dave, an actual answer to your original question. 60% Left side, 60-64% Rear. The number we really adjust to is the LR-RF cross which is 48-50% depending on what you want. The first two numbers are more a function of the chassis build and ballast when we get the cross correct.

DAD · 3/18/14, 5:42 PM

M

Would those be the percentages for dirt or pavement racing set up?

What do those cross weight percentages affect and how?

Do you just stick with those numbers?

Do you scale car with or without shocks being attached?

Do you use blocks for the basic set up and adjust from there?

Honest Dad himself

3/17/14, 2:21 PM	#11 Re: Scaling cars?
jjones752 Senior Member Race Count This Year: 19 Race Count Last Year: 22 Join Date: Jul 2011 Posts: 2,259	Dad, I'm with you 100%; my primary goal every time I'm at a race is pure enjoyment, whether I'm behind a wheel, behind a wrench or behind a catch fence in the stands. In an efort to un-hijack this thread, Dave, you and I are probably in somewhat the same boat as far as asking for hard setup numbers; you have a chassis that few others run, and I have one that is modified far beyond the original constructor's design. I'm going to start with bars and ride heights that seem to make sense for me based on available information (asking people who have cars "close" to mine, watching Jimmy sills' video over and over). I have a set of matching Taylor digital bathroom scales that I intend to use as you're suggesting, just to get a baseline that I can go back to if (when?) the chassis gets a little tweaked. I also want to take readings when I crank weight into the corners, just so I know how much things change when I put that 1 to 1-1/2 turns in, and hopefully I can use that data for repeating setups in the garage. But mostly, I plan on getting out there and having a ball. When I was crewing on TQ's for me the most fun was watching the track and seeing how close I could come in helping my guy keep up with it; I can only imagine it will be even more fun to make those changes from a more informed positon, i.e. with the seat of MY pants in the seat of the car. __________________ Jim Jones Midwest Thunder Speed2 Midget #97

3/17/14, 2:52 PM	#13 Re: Scaling cars?
DAD Senior Member Join Date: Aug 2009 Posts: 5,957	Jim I represent that hijack remark!!! You are about to take a trip to the twilight zone. Been there done that, have at it, can you imagine confused. First off bathroom scales are going to be a little light for the left rear unless you leverage them. Then them dumb old shocks will absorb and confuse all your weights. Even tire pres will affect the scales. Bar and Spring rate will change things. Then by moving the wheel in or out all the numbers will go south on you. Pretty soon you will be a babbling idiot just like me and all because you wanted to scale a race car. After several decades of racing my best advice is "KISS". Every time you second guess the race track it will come back and bite you. Your set up has to change for the season, I herd that Btown was full of holes and rutts this weekend, that's a spring thing, goes with dirt in the spring. Next thing it will be dusty and black, that's a summer dirt thing, and sometime that darned stuff will mix up the results, Been chassen them old race tracks for years and the only thing I know for sure is " I ain't no Karl Kinser", BUT I do got a little Steve Kinser driving for me and we are still having fun and messin with people. Honest Dad himself _________________________________________________ Last edited by DAD; 3/17/14 at 3:02 PM.

3/17/14, 3:02 PM	#14 Re: Scaling cars?
jjones752 Senior Member Race Count This Year: 19 Race Count Last Year: 22 Join Date: Jul 2011 Posts: 2,259	I was referring more to me, with my "knob in the cockpit" joke, but hey if the foo... I doub't I'll get too concerned about the scaling part of it, mainly why I only spent about 2.50 a crack on the scales at Goodwill. if they give me useful info, great but if not, I'm only out a ten-spot. My main goal, as I think Dave's is, is to have a "starting point" something I can go back to in the shop so I know where I am when I make those inevitable changes over the course of a night, a climatic season, and a racing season. __________________ Jim Jones Midwest Thunder Speed2 Midget #97 _________________________________________________ Last edited by jjones752; 3/17/14 at 3:03 PM.

3/17/14, 3:13 PM	#15 Re: Scaling cars?
DAD Senior Member Join Date: Aug 2009 Posts: 5,957	Jim Then you got ride height, tilt, etc, etc. that play a lot in the way a car responds to the race track. You do need a base line. Heck it does not have to be spot on base line, and I would be worried if it was. With a base to start from every race you adjust to the race track and even to the driver. Just because it works for us doesn't mean it will work for you. My son Doug likes the car so tight anymore not many people could drive it with his set up. If you are just getting into driving a race car keep try to keep it just a little on the tight side also. It is much easier to stay on top of a car that has a push than it is with the ass end all bent out of shape. And Tight is fast. If you can push a tight car hard enough it will probably loosen up for you. Honest Dad himself

3/18/14, 4:03 PM	#19 Re: Scaling cars?
Mbarnes72 Member Join Date: Sep 2013 Posts: 14	Here you go Dave, an actual answer to your original question. 60% Left side, 60-64% Rear. The number we really adjust to is the LR-RF cross which is 48-50% depending on what you want. The first two numbers are more a function of the chassis build and ballast when we get the cross correct.

3/18/14, 5:42 PM	#20 Re: Scaling cars?
DAD Senior Member Join Date: Aug 2009 Posts: 5,957	M Would those be the percentages for dirt or pavement racing set up? What do those cross weight percentages affect and how? Do you just stick with those numbers? Do you scale car with or without shocks being attached? Do you use blocks for the basic set up and adjust from there? Honest Dad himself