Spring smasher #s

[riddle28]

I’ve got an older car so all I have is ride height meaasurements and weight percentages to go off of. I’ve seen where ppl talk about with newer cars they just give you smashed #s and percentages to go off of. Do they take into account type of engine and track or just a general set? I’m trying to figure out what the common load #s are and also trying to figure out what brand car I wanna upgrade to. Thanks

[billetbirdcage]

The basic load numbers they give you is just like the basic set of old with scaling. They may have more then one set up for different tracks. Basically static load numbers is the same as scaling the car, instead of using a ride height to set the car you use a load number to set the ride hieght. The big difference is with loads you can set the dymanic, but everything needs to be the same to compare stuff. Alter the % some or a bunch of different things and it starts getting off.

Load numbers on one car on the RR maybe completely different then another car due to spring angles, birdcage location, and etc. So you can't really compare 2 different cars although they could also be close enough that they may match somewhat on some corners or even all of them.

[MidwestExpress]

What about driver weight? How is that calculated into it? If you have two cars that are identical but have two drivers that are separate weights how do you make that work with the same smash numbers?

[billetbirdcage]

What about driver weight? How is that calculated into it? If you have two cars that are identical but have two drivers that are separate weights how do you make that work with the same smash numbers?

54% left and 54% rear is still the same with a 200# driver or a 400# one, as they will give the left/rear% they want WITH driver. But yes, it don't work if they give a % without driver.

Above is also assuming the 400# drivers car isn't way over weight, like 2300 vs 2475

[15D]

Not having any smash numbers from a builder, I measured pin-to-pin distance at ride height
and used this distance to set weights in a spring smasher. When I put the car on the scales I notice some of the weights are considerably different then what I had in the smasher. Should this be expected?

[MasterSbilt_Racer]

Not having any smash numbers from a builder, I measured pin-to-pin distance at ride height
and used this distance to set weights in a spring smasher. When I put the car on the scales I notice some of the weights are considerably different then what I had in the smasher. Should this be expected?

Are you comparing smasher load to load on scale pad? Yes, they will not be the same.

[15D]

Are you comparing smasher load to load on scale pad? Yes, they will not be the same.

Yes, some numbers are up to 90lb different. I should say we went from a perpetually tight car to one that is slightly loose. Unless I'm mistaken, if I choose to, I could use the numbers I have and use traditional adjustments to tighten or loosen the car?

[Matt49]

Spring smasher numbers and scale pad numbers are never going to be the same. You're measuring spring load on the smasher and wheel load on the scales. Those are not the same because of motion ratios.

[MasterSbilt_Racer]

All adjustments are still the same. If you wanted to go from your old scale method to this method, you would have scaled normally. Then measure all shocks pin to pin. Then load all coilovers to the measured pin to pin and record the load output from the spring smasher.

[Jking24]

You say you went from a tight car to a loose car whay did you change ? Just measuring c to c and recording the smash numbers doesn't change anything. So what did you do ?

[billetbirdcage]

You say you went from a tight car to a loose car whay did you change ? Just measuring c to c and recording the smash numbers doesn't change anything. So what did you do ?

I think he took the pin to pin measurements while scaling and removed or changed coilovers and smashed them to his scale pad numbers, which would be completely different.

Or he is looking at the differences between the smash number and the scale numbers: like 50# different between RF smash # and Pad # but LR is 100# difference between the two.

Not sure but, least the way I read it.

[15D]

JKing

I calculated what I wanted each corner spring load to be at each corner at ride height. When I put it on the scales (old school way) I ended up with a 40 lbs of reverse bite, which probably explains why the car went loose, from perpetually tight. We run IMCA and this year we can run bump stops. With the bump stocks I set the RF for a smashed number around 2400 with 3.75" of shock travel from ride height, we are no longer bottoming out the right lower chassis rail and cross member (hurrah!!.) Running bump stops in the RR, but have backed off on them as the driver indicates the car has lost "side-bite." Will look at the shock tattletales after this Friday nights run to understand the dynamic forces there and adjust the ride height and spring accordingly, maybe.

[15D]

Billet, your first thought on what I did was right. I mistakenly thought the chassis is centered on all 4 wheels and I could take a guess at setting smash numbers based upon 54% of rear and 53% of left weight. I'll set it up old school way for tomorrow night with about 70-80 lbs of bite then take a look at the smash numbers after we race, if we like the handle on the car.

Looking at a way to more easily record shock travel rather then the O-Ring on the shock rod

[cjsracing]

JKing

I calculated what I wanted each corner spring load to be at each corner at ride height. When I put it on the scales (old school way) I ended up with a 40 lbs of reverse bite, which probably explains why the car went loose, from perpetually tight. We run IMCA and this year we can run bump stops. With the bump stocks I set the RF for a smashed number around 2400 with 3.75" of shock travel from ride height, we are no longer bottoming out the right lower chassis rail and cross member (hurrah!!.) Running bump stops in the RR, but have backed off on them as the driver indicates the car has lost "side-bite." Will look at the shock tattletales after this Friday nights run to understand the dynamic forces there and adjust the ride height and spring accordingly, maybe.

We can't run bump stops in IMCA Late Models - see rule #7

[15D]

We can't run bump stops in IMCA Late Models - see rule #7

evidently I'm cheating then. I don't have a bump stop on the suspension, I have one on the shock rod. Guess next time I see Randy Anderson at the track I'll get his take on this.

Thanks for pointing it out!!