Hi some of us are trying to get 1/4 scale cars going around here on a local dirt gocart track and have had a couple practice sessions with sprint cars and to our surprise they seem to be working with very little to no rollout in the rear unlike real sprints.

We were wondering what was normal for these cars and basic rollout theory for 1/4 scale cars.

Thanks for any advice or input....

Well i don't race on dirt with my 1/4 scale (used to with a street stock) but stagger and rollout are two very different things.

Rollout

Rollout is a calculation of pinion, Spur and the circumfrence of the right rear tire. The formula is: tire diameter X 3.14 divided by your final drive ratio

In other words Say you have a RR tire of 18 3/4 diameter
18.75 X Pi = 58.875

and your gear ratio is 14 pinion and 80 spur
80 devided by 14 = 5.714

(58.875) devided by (5.714) = 10.3036

Your rollout is 10.3036 or the motor spins 10.3036 times for the wheel to go around once.

Stagger

Stagger is the difference between the right and left tires. Either front or back. So if you have an 18 3/4 RR and a 17 5/8 LR, you would be running 1 1/8 stagger.

As for if you should be running more or less stagger, it all depends on the track size, car setup, weather, and how the car is reacting to all that. i have run as little as 1/4 inch to almost 1 1/2 stagger on ashphalt

Hi some of us are trying to get 1/4 scale cars going around here on a local dirt gocart track and have had a couple practice sessions with sprint cars and to our surprise they seem to be working with very little to no rollout in the rear unlike real sprints.

We were wondering what was normal for these cars and basic rollout theory for 1/4 scale cars.

Thanks for any advice or input....

I run about 1/4 to 1/2 inch rear stagger on a big 600 ft dirt track. I have ran no stagger when the track was really loose (dry, hard packed).

Plant the rear and make the front stear. :thumbsup:

Okay thanks for the reply..we are in the right area then running from 1/4 to even up as the track was kinda loose...

It just surprised to be so little...

Okay thanks for the reply..we are in the right area then running from 1/4 to even up as the track was kinda loose...

It just surprised to be so little...

Where is this track? Any pics or info?

It is a go kart track in Muskogee OK...Coody Creek Raceway.... The owner has wanted rc cars to run there on his off weekends for awhile but track is to big for 10th scale for most of us.

A few of us have gotten interested in 1/4 scale and it seems to be perfect for them just got to get things rolling. My racing bubby that used to run real sprints got a new WCM and we have been working with it and are starting to get other people interested.

As soon as I get the money I will have one they are very cool cars.

just found out they have a web site www.coodycreekspeedway.com

just found out they have a web site www.coodycreekspeedway.com

What is the run line around this track?

around 375 and it is egg shaped....curved front straight into a open 1 and 2 a little down hill then a long straight back straight into a tight uphill 3 and 4...real wide and seems to flow good when driving around it.

around 375 and it is egg shaped....curved front straight into a open 1 and 2 a little down hill then a long straight back straight into a tight uphill 3 and 4...real wide and seems to flow good when driving around it.

It looks bigger than 375. Looks good....The surface looks like clay..?, about the same as what I race on. Are you using the BRP checker board pattern rear tires? The 4 inch wide RR tire will help w/traction / side bite.

I agree on the looks bigger part but the guy that owns it says 375...LOL if it is it must be right down tight on the bottom all the way around.

As for the dirt it isn't clay it is a red fill dirt and it seems to hold water good and stay together.

As for tires yes on the checker boards and we have 4 inch right and 3 inch left but until we can get more tires the only way we could get the the car to really hook up was to go to even stagger and that ment running a 3 inch left off another car on the right so we ended up with a 3 inch...18 1/4 tire on both sides.

The only 4 inch tires we had would put us in the 1/2 to 3/4 stagger range and the car was way loose when you picked up the gas.

We also are running checker boards on front around 2 1/4 wide and the car has way to much steering at all times making it touchy to drive...that will be the next thing we work on next practice session.

I agree on the looks bigger part but the guy that owns it says 375...LOL if it is it must be right down tight on the bottom all the way around.

As for the dirt it isn't clay it is a red fill dirt and it seems to hold water good and stay together.

As for tires yes on the checker boards and we have 4 inch right and 3 inch left but until we can get more tires the only way we could get the the car to really hook up was to go to even stagger and that ment running a 3 inch left off another car on the right so we ended up with a 3 inch...18 1/4 tire on both sides.

The only 4 inch tires we had would put us in the 1/2 to 3/4 stagger range and the car was way loose when you picked up the gas.

We also are running checker boards on front around 2 1/4 wide and the car has way to much steering at all times making it touchy to drive...that will be the next thing we work on next practice session.

Keeping the frame ride height lower in the rear will help out with the (to much) steering. Try 1 inch in the front, 5/8 in rear. 20lb RF spring, 18 LF, 10 RR, 14 LR. Then move top wing around to fine tune.

Tip #1: Put a lexan guard in front of the pinion to keep the dirt (from LF tire) off the gear & belt.

Tip #2: Use a Belly pan from front to rear, also Outerwear covers on air filter and pull start are a must. :thumbsup: A little bit of dirt will junk a motor in a heartbeat. :cry:

Good Luck.

Thanks for the tips on spring rate...I will get with him about those and we figured out the belt guard and stuff the first run....LOL

MJS34,

I have one more race with my WCM sprint car and then I will be selling it. It has many new parts and I will be replacing a few more after this weekend. Let me know when you have your money and we can talk. This car has been great since day one, just wish my driving was as good.

Later Troy

cool Troy let me know when your ready to sell and we can see what we can do.

MJS34 you have a pm. - Troy