Had a pair of racers that i consult for. One has learned to trust in us and he makes the changes we need to do. The other is very stubborn and wants to strictly adhere to the chassis builders setup even tho he wants to change 30 things between hot laps to the heat and heat to A or B main. That chassis builder calls for a very low rate on RR. This guy keeps throwing more rounds in and stuffs the poor spring full of rubber but wont let me talk him into trying a 25 pound heavier spring. Lol. Yall need to listen to Jay here and dont be afraid to try something different than the builder suggests. This is all very good information that many of us, me included, has paid a lot to get. A few YT ads and yall are getting it free.
Thanks Jay, I'm new to the IMCA Stock car scene and I have built all my own cars over the years IMCA Mods and Sportmods and with building my first IMCA Stock car its hard to get information from other chassis builders which I understand so you have been a tremendous amount of help. Thanks You!
Jay a few thoughts. I wouldn’t recommend anyone add lead to add load, these load numbers are arbitrary and should only be meant to get you close to balanced. I would be careful saying that rebound holds load in a spring. Rebound is not in the weight transfer equation. Only track width, mass, acceleration, and height of center of mass. Rebound actually takes weight off of a corner as it yields a lower average ride height. Ride height (in most cases) means wheel weight (raise a ride height in the scales and the corner gets heavier).
RR is getting a lot hotter then all other tires. Is my RR load to much or to little? Is the hotter tire doing the work or the colder tire? Thanks for all of the great video's Jay.
The answer is more detailed than I am going to give but, when the tire gets to around 160 degrees it is at it’s best performance level for making grip. (the tire is softer than it was)
Am I correct in saying that less RR load makes you looser on entry but lacks drive off the corner while more RR load creates tighter entry but gives you drive? Would something like lowering load to help create looser corner entry but putting a spring rubber in so that at 3/4 inch spring collapse it picks up the load through the corner again to help with drive off be something worth trying?
Load in the RR will help the car not over-travel the RR on entry, keeping it somewhat on all 4 tires. Rebound and lateral loads keep it from being loose on the exit, without load the car will lose the RR tire as you accelerate the car.
What is your opinion on putting a RR 150lb spring on a crusa street stock in place of the 225lb spring and adding load? Would that add corner entry side bite/ grip through the whole corner?
The short answer is Yes; the problem is how to do it. The soft spring needs to build enough load to control the 2” load number so in this case you would need about a 550 to 600 load at ride height. But you need to be at ride height when the car is sitting there, having the car high on RR is only going to cause problems for you as it slicks off. The other way is to run a bump stop which you can’t do in CRUSA but others could. The soft spring should make more grip for you but you have to hit the 2” number or you will hurt the car center off, and that will kill your lap times.
When you say "at ride height". Does that mean with the weight of the car on the coil over it should be 11.25 inch or whatever load number you are looking for? If so. How to i raise ride height without adding load
Had a pair of racers that i consult for. One has learned to trust in us and he makes the changes we need to do. The other is very stubborn and wants to strictly adhere to the chassis builders setup even tho he wants to change 30 things between hot laps to the heat and heat to A or B main. That chassis builder calls for a very low rate on RR. This guy keeps throwing more rounds in and stuffs the poor spring full of rubber but wont let me talk him into trying a 25 pound heavier spring. Lol. Yall need to listen to Jay here and dont be afraid to try something different than the builder suggests. This is all very good information that many of us, me included, has paid a lot to get. A few YT ads and yall are getting it free.
Thanks
Thanks Jay, I'm new to the IMCA Stock car scene and I have built all my own cars over the years IMCA Mods and Sportmods and with building my first IMCA Stock car its hard to get information from other chassis builders which I understand so you have been a tremendous amount of help. Thanks You!
If you need anything call me and we will get it worked out.
Jay a few thoughts.
I wouldn’t recommend anyone add lead to add load, these load numbers are arbitrary and should only be meant to get you close to balanced.
I would be careful saying that rebound holds load in a spring. Rebound is not in the weight transfer equation. Only track width, mass, acceleration, and height of center of mass. Rebound actually takes weight off of a corner as it yields a lower average ride height. Ride height (in most cases) means wheel weight (raise a ride height in the scales and the corner gets heavier).
Great information. Thank you sir.
Very welcome
Good info thanks!
Glad it was helpful!
World you say this is correct theory for a Northeast dirt modified(2400lb w/drive). Solid front axle, all for corners coilover,
Yes I would start at this point for sure and build some data.
RR is getting a lot hotter then all other tires. Is my RR load to much or to little? Is the hotter tire doing the work or the colder tire? Thanks for all of the great video's Jay.
I also am curious on the science behind the tire temps.
The answer is more detailed than I am going to give but, when the tire gets to around 160 degrees it is at it’s best performance level for making grip. (the tire is softer than it was)
@@jaynealgofast is the hotter tire doing more work or is the cooler tire? LR to RR that is
Thanks for the video. What kind of RR spring load do you think you need on an IMCA northern sport mod?
225 or 250 to start , we have a 230-250 that works well.
Am I correct in saying that less RR load makes you looser on entry but lacks drive off the corner while more RR load creates tighter entry but gives you drive? Would something like lowering load to help create looser corner entry but putting a spring rubber in so that at 3/4 inch spring collapse it picks up the load through the corner again to help with drive off be something worth trying?
Load in the RR will help the car not over-travel the RR on entry, keeping it somewhat on all 4 tires. Rebound and lateral loads keep it from being loose on the exit, without load the car will lose the RR tire as you accelerate the car.
What is your opinion on putting a RR 150lb spring on a crusa street stock in place of the 225lb spring and adding load? Would that add corner entry side bite/ grip through the whole corner?
The short answer is Yes; the problem is how to do it. The soft spring needs to build enough load to control the 2” load number so in this case you would need about a 550 to 600 load at ride height. But you need to be at ride height when the car is sitting there, having the car high on RR is only going to cause problems for you as it slicks off. The other way is to run a bump stop which you can’t do in CRUSA but others could.
The soft spring should make more grip for you but you have to hit the 2” number or you will hurt the car center off, and that will kill your lap times.
@@jaynealgofast so would you think that I might achieve better results going to your 230-250 VRT spring for a slick track?
I know in the video you said for modifieds 375-400 load, but for an Imca stock should I shoot for 600+?
That 600 number has been what we call high (500) but I think it maybe okay from some testing that has been done.
When you say "at ride height". Does that mean with the weight of the car on the coil over it should be 11.25 inch or whatever load number you are looking for? If so. How to i raise ride height without adding load
Yes at ride height and if you want to raise the ride height you will need to add turns to all 4 corners of the car.
Wouldn't we need to figure out how to do the math in reverse to determine our actual rr spring load?
We use a principal that states that 2/3 of the weight of the RR corner should be on the spring.