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!!

[keeks]

Where else would a bump stop go?

[Jking24]

15d i think your over complicating it. Just as mb racer said nothing has changed except how we look at things. if you don't have known numbers from your chassis builder to start with. Setup car traditionally measure ,smash to those cc than record data do not change it race it and adjust accordingly.

[Jking24]

I will add this that 3.75 number is petty high on average that doesn't mean it's wrong though

[cjsracing]

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!!

Haha. The first thing Randy said to me at the Tipton Deery show during pre-race tech was "You don't have any bump stops or stacked springs on the car right?"

[hunterracing]

What’s a good number for standard rr spring 225 at static ride height or the fronts for smash numbers

[billetbirdcage]

You can't just give numbers for every car as motion ratios and % are different between a lot of cars so they can't be used as a general number for all cars.

The static RF numbers between a blue/grey rocket maybe be an easy 100# difference from an XR1 and more on other cars. Fronts will typically be way closer between different cars then the rears can be. Some may be really similar and others could be 200# different at static.

Just to show you on the RR you asked about, I've been as low 175# and as high as 700# so.....

[15D]

Haha. The first thing Randy said to me at the Tipton Deery show during pre-race tech was "You don't have any bump stops or stacked springs on the car right?"

Hmm......I might have to come up with a convenient mis-statement of the truth should I bump into Randy.

[hunterracing]

You can't just give numbers for every car as motion ratios and % are different between a lot of cars so they can't be used as a general number for all cars.

The static RF numbers between a blue/grey rocket maybe be an easy 100# difference from an XR1 and more on other cars. Fronts will typically be way closer between different cars then the rears can be. Some may be really similar and others could be 200# different at static.

Just to show you on the RR you asked about, I've been as low 175# and as high as 700# so..... I was just curious kinda figured wouldn’t be same for every car or driver

[15D]

15d i think your over complicating it. Just as mb racer said nothing has changed except how we look at things. if you don't have known numbers from your chassis builder to start with. Setup car traditionally measure ,smash to those cc than record data do not change it race it and adjust accordingly.

If I run any less the nose starts plowing. I set the car up old school last week and it was slightly tight according to the driver, but sitting in the stands it looked slightly loose (an ongoing, decades worth, of discussion between us, was it actually loose or did you over compensate and it felt tight.)

[riddle28]

so just so im straight. my car is an 09 so no smash numbers. I set my car up conventionally, lets say rf wheel weight is 500 lbs. do i take that spring off the car, put it in the smasher and run the smasher to 500 lbs and that is my center to center or do i run the smasher to my static center to center #s i measure on the car and let the static smasher number just end up where that is?

[fastford]

If I run any less the nose starts plowing. I set the car up old school last week and it was slightly tight according to the driver, but sitting in the stands it looked slightly loose (an ongoing, decades worth, of discussion between us, was it actually loose or did you over compensate and it felt tight.)

a simple piece of white tape wrapped around the top of the steering wheel with the tires strait will help solve your debate on the tight loose thing........

[MasterSbilt_Racer]

so just so im straight. my car is an 09 so no smash numbers. I set my car up conventionally, lets say rf wheel weight is 500 lbs. do i take that spring off the car, put it in the smasher and run the smasher to 500 lbs and that is my center to center or do i run the smasher to my static center to center #s i measure on the car and let the static smasher number just end up where that is?

The second option is correct.

[7uptruckracer]

Take your race ready setup. Go over to it with your tape measure. Measure every coil over center to center aka eye to eye aka pin to pin. Write down those measurements. Take each spring off one at a time. Load it into the smasher and smash it to your written down pin to pin. Write down the spring load number the smasher gives you. That is your static spring preload. Lets say this for example is your RF. At Race ready your RF Pin to Pin is 18" You load it into the smasher and it reads 600lbs. Write that down. You know your car travels say 4.5". So take your machine and write down your spring load at 13.5" pin to pin or eye to eye whatever you want to call it. That is your spring load at dynamic. Lets say its 2100lbs. YOu can with that info change your spring. Take a softer one. Smash it down to 18" and make sure you set the collar until it reads 600lbs you could then if you wanted bolt it back onto the car and if you put it back on the scales all your numbers will be exactly how it was when you did it" old school" what you will find is if you put that softer spring in the smasher reset it to 600lbs at 18", and then take it to 13.5" you won't have at much dynamic load because you went softer. So what you can then play with is spring rubbers, Bump stops, etc. You have a static and dynamic baseline. You can do alot of manipulation once you have those two.


so just so im straight. my car is an 09 so no smash numbers. I set my car up conventionally, lets say rf wheel weight is 500 lbs. do i take that spring off the car, put it in the smasher and run the smasher to 500 lbs and that is my center to center or do i run the smasher to my static center to center #s i measure on the car and let the static smasher number just end up where that is?

[billetbirdcage]

Take your race ready setup. Go over to it with your tape measure. Measure every coil over center to center aka eye to eye aka pin to pin. Write down those measurements. Take each spring off one at a time. Load it into the smasher and smash it to your written down pin to pin. Write down the spring load number the smasher gives you. That is your static spring preload. Lets say this for example is your RF. At Race ready your RF Pin to Pin is 18" You load it into the smasher and it reads 600lbs. Write that down. You know your car travels say 4.5". So take your machine and write down your spring load at 13.5" pin to pin or eye to eye whatever you want to call it. That is your spring load at dynamic. Lets say its 2100lbs. YOu can with that info change your spring. Take a softer one. Smash it down to 18" and make sure you set the collar until it reads 600lbs you could then if you wanted bolt it back onto the car and if you put it back on the scales all your numbers will be exactly how it was when you did it" old school" what you will find is if you put that softer spring in the smasher reset it to 600lbs at 18", and then take it to 13.5" you won't have at much dynamic load because you went softer. So what you can then play with is spring rubbers, Bump stops, etc. You have a static and dynamic baseline. You can do alot of manipulation once you have those two.

I'll add to this:

1. You will also want the other compression (or rebound loads on LR) travels besides just the static (18") and the max dynamic (13.5")

2. The other travel numbers: (non 18" and 13.5") Early 1" increments are fine as long as the spring assembly is linear, but once it goes non linear: You will want at least in 1/2" increments and most likely way finer like 1/4" or 1/8th's if possible. Non linear: just means when rate changes due to rubbers, dual stage, or bump spring/stop engagement.

3. On certain coilovers, you will want to get an idea of rounds to change loads a certain amount so you don't have to pull just to make an adjustment at the track. Others you may want to install rubbers and have a basic idea where that takes the dynamic loads.

[7uptruckracer]

Great info! I just didn’t want to fry his brain lol! It’s astounding how much you can manipulate things. Especially tech rules with the smasher now that’s I’ve gotten involved heavily with it. I wouldn’t be surprised if we end up with a minimum ride height or block height soon. I take 1” just to make sure everything is kosher then when I get to a “secondary spring rate” I mark every 1/8-1/4. The funny thing is you can do all this work and still not know what it needs in race conditions it’s just more tools


I'll add to this:

1. You will also want the other compression (or rebound loads on LR) travels besides just the static (18") and the max dynamic (13.5")

2. The other travel numbers: (non 18" and 13.5") Early 1" increments are fine as long as the spring assembly is linear, but once it goes non linear: You will want at least in 1/2" increments and most likely way finer like 1/4" or 1/8th's if possible. Non linear: just means when rate changes due to rubbers, dual stage, or bump spring/stop engagement.

3. On certain coilovers, you will want to get an idea of rounds to change loads a certain amount so you don't have to pull just to make an adjustment at the track. Others you may want to install rubbers and have a basic idea where that takes the dynamic loads.

[billetbirdcage]

Yep, it's just info what you do with it is what matters.


Note: So you might know the max travels your getting but do you have any idea when and where on the track it's at that point........how long it stays there.....how far is the RF coming up.....when and where is it doing that.

Most don't have a real idea and are guess's and usually it's wrong

All I'm saying is: unless you know this, it's hard to make an educated guess on what number to change if you don't know what the actual load or travel is at the point on the track you have an issue.

[Matt49]

Not to make this more confusing but I think it is also important to make a distinction between know what the load is at a certain amount of travel and knowing what the travel will be at a certain amount of load. Those are different things. Just like with shocks, we get the dyno that tells us force at a certain speed but we really care about speed at a certain force.
And I agree that travel indicators are giving us limited information. It only shows us the max travel for the entire time we were on the track. So if you hit one hole in the track the wrong way, the indicator could be off by a significant amount from where were normally max traveled to in the corners. Short of real data acquisition systems, GoPro cameras may be the best way to go on this stuff.

[15D]

a simple piece of white tape wrapped around the top of the steering wheel with the tires strait will help solve your debate on the tight loose thing........

reason and facts with a driver in an argument? Hell, being a ex-7th Fleet Sailor I'm always up for an adventure!!!!

I can see he is turning to the right while exiting, classic loose to me

[15D]

So, I just took the RR shock and spring and put it into the smasher after racing Friday night. I was surprised to see that it only gained 160#s in dynamic. The driver was complaining about a lack of side-bite which makes me think I need to soften up the spring and lower the J-Bar on the pinion.

[Jking24]

J bar could help but has most effect at center of corner. softening the rr spring will remove side bite. You say only gained 160 in dynamic ? What do you mean by that ? it was 160 at your c+c measurement ?

[fastford]

reason and facts with a driver in an argument? Hell, being a ex-7th Fleet Sailor I'm always up for an adventure!!!!

I can see he is turning to the right while exiting, classic loose to me

but can you see that split second that he may be turning left then when rear breaks loose , he whips it right to catch it? harder to see with plain un marked wheel than you think.......and being a sailor , you should be accustom to detail.......

[15D]

J bar could help but has most effect at center of corner. softening the rr spring will remove side bite. You say only gained 160 in dynamic ? What do you mean by that ? it was 160 at your c+c measurement ?

Smashed number at ride-height was roughly 620. At what I thought was max travel by looking at the tattletale the smashed number was 780. I thought it should of picked up more, but am inexperienced with this

[15D]

but can you see that split second that he may be turning left then when rear breaks loose , he whips it right to catch it? harder to see with plain un marked wheel than you think.......and being a sailor , you should be accustom to detail.......

Yep, just as you describe on exit. Kinda of hard to tell from the stands on entry though.

Attention to Detail; pounded into me from Day One at Boot Camp, nearly 37 years ago. This philosophy has served me well!!

[15D]

J bar could help but has most effect at center of corner. softening the rr spring will remove side bite. You say only gained 160 in dynamic ? What do you mean by that ? it was 160 at your c+c measurement ?

Your post made me re-think what is happening with the car. I want to restate what I think isn't happening, I don't believe we are shifting much of the weight. from the left side to the ride side from mid-corner off. Putting it in terms of "side-bite" may not be as accurate.

[billetbirdcage]

Your post made me re-think what is happening with the car. I want to restate what I think isn't happening, I don't believe we are shifting much of the weight. from the left side to the ride side from mid-corner off. Putting it in terms of "side-bite" may not be as accurate.

Softening the RR spring will make it travel farther but cause less weight to be put on RR so......

[15D]

Softening the RR spring will make it travel farther but cause less weight to be put on RR so......

If we are truly "loose" on entry and exit, softer RR might be what we need?

[Matt49]

If we are truly "loose" on entry and exit, softer RR might be what we need?

Forget about exit. If you are too loose on entry and you soften the RR you WILL get looser on entry. Fix entry first. 9 times out of 10, exit fixes itself if you can have a car that gets to and through the center good.

[7uptruckracer]

Just make a note he is talking about Softening RR spring will cause less wheel load. It can be confusing in a spring smasher thread where we have been talking about spring load. Springs absorb load that would otherwise be transferred into the tire. I was showing a fellow forum member this morning about how to manipulate loads and why it is important that once you know ideal travel to always shoot for that ideal travel to lessen compromises. You can end up with less spring load on a stiffer spring if you under travel then a softer spring traveling the right amount.


Softening the RR spring will make it travel farther but cause less weight to be put on RR so......

[15D]

Ran a softer RR Spring, 200 vs. 250#, and dropped the J-Bar down to the bottom slot on the pinion this last week and picked up a little speed and the driver thought the car had a little more side-bite. I see that we had another 3/4" of movement for the shock tattletale and thought the car did a better job of transferring weight onto the RR. The driver thought the car was still loose on entry, and I thought he was a tad loose on exit.

Looking at putting a softer spring on this upcoming week, probably a 175#

[Jking24]

Ran a softer RR Spring, 200 vs. 250#, and dropped the J-Bar down to the bottom slot on the pinion this last week and picked up a little speed and the driver thought the car had a little more side-bite. I see that we had another 3/4" of movement for the shock tattletale and thought the car did a better job of transferring weight onto the RR. The driver thought the car was still loose on entry, and I thought he was a tad loose on exit.Looking at putting a softer spring on this upcoming week, probably a 175# Make sure his belts are tight!

[a25rjr]

Make sure his belts are tight!

I think 99.9% of us would agree!

I think he has some driver communication issues.

[billetbirdcage]

I think 99.9% of us would agree!

I think he has some driver communication issues.

I'm to lazy to reread all this again but I'm gonna make a bet that he's describing lack of side bite as off the corner (IE once back into the gas and the back end is kicking out).

IMO, there is no side bite off the corner, it's a lack of LR drive

[a25rjr]

I'm to lazy to reread all this again but I'm gonna make a bet that he's describing lack of side bite as off the corner (IE once back into the gas and the back end is kicking out).

IMO, there is no side bite off the corner, it's a lack of LR drive

That's how I see it too!

I always equate side bite to....off the gas during corner entry!

[15D]

I'm to lazy to reread all this again but I'm gonna make a bet that he's describing lack of side bite as off the corner (IE once back into the gas and the back end is kicking out).

IMO, there is no side bite off the corner, it's a lack of LR drive

center-off is where I'm getting the feedback where the "side-bite" issue is. This sport is filled with a lot of slang that is misused or misinterpreted

[Jking24]

That's how I see it too!I always equate side bite to....off the gas during corner entry!Agreed! Weight transferring in different direction by that point

[Jking24]

That's how I see it too!I always equate side bite to....off the gas during corner entry!Agreed! Weight transferring in different direction by that point. And his softer rr spring is likely going to add to his tailing exit. if he makes it that far