Shorter rr spring

[ZERO25]

In Mike Nuchols latest video, a 10" rear spring avgd 25 more lbs of spring load over the standard 12" one! It was pretty well linear as well!

Side note......he uses a 2" spacer instead of screwing down the top nut!

[MasterSbilt_Racer]

What are you trying to say, exactly?

[billetbirdcage]

If one spring has 25 more pounds of load then the other at a certain amount of compression, then that spring is a different spring rate. I could likely pick another brand of spring and get a similar result, it's not because of the length of the spring but the rate is not exactly the same or is more or less linear then the other.

[Burke1118]

I hope I can recover the brain cells I lost reading the original post………

[ZERO25]

Have we not discussed the spring table theory many times?

Mike said he just ignored the theory, until his Swift spring rep encouraged him to experiment on the smasher!Go to Race Know How and see it for yourself!

[MasterSbilt_Racer]

Have we not discussed the spring table theory many times?

Mike said he just ignored the theory, until his Swift spring rep encouraged him to experiment on the smasher!Go to Race Know How and see it for yourself!

Are you doing a commercial for race knowhow or having a discussion?

Spring table refers to the point the springs support and interact with the chassis, the sprung part of the assembly. I don't see how a smasher has any relationship to that dynamic at all.

I can't watch the video, but if I'm following the FB conversation correctly, Nuchols ran both springs on an automated spring smasher and read higher loads on the shorter spring. If that is the case, this is simply because the natural frequency on the shorter spring is higher and so as the smasher is unloading it, the spring expands more quickly to keep more load on the load cell.

That said, there are reasons to be concerned about your springs natural frequencies, but to adjust loose/tight balance is absolutely not why you would ever make that change. And honestly, most corners of our cars are so overdamped, the shock is really running the show on the dynamic response when the spring unloads.

[Burke1118]

Have we not discussed the spring table theory many times?Mike said he just ignored the theory, until his Swift spring rep encouraged him to experiment on the smasher!Go to Race Know How and see it for yourself!Lolololol the spring table changing because you changed the spring height on a COILOVER. That’s a good one. If you’ve read any material that swift spring rep has put out, you would know he’s an idiot too. As billet said, if you take 2 springs that are the same RATE but different HEIGHTS, compress them the same amount (not coil binding), and they don’t read the same, then they aren’t the same rate. By definition. If they are saying things other than that on raceknowhow, probably time to unsubscribe and stop wasting your money

[MasterSbilt_Racer]

Burke,

Unfortunately, there is a lot of very bad science sold in our sport.

[ZERO25]

45 or 12 gauge?

[ZERO25]

Are you doing a commercial for race knowhow or having a discussion?

Spring table refers to the point the springs support and interact with the chassis, the sprung part of the assembly. I don't see how a smasher has any relationship to that dynamic at all.

I can't watch the video, but if I'm following the FB conversation correctly, Nuchols ran both springs on an automated spring smasher and read higher loads on the shorter spring. If that is the case, this is simply because the natural frequency on the shorter spring is higher and so as the smasher is unloading it, the spring expands more quickly to keep more load on the load cell.

That said, there are reasons to be concerned about your springs natural frequencies, but to adjust loose/tight balance is absolutely not why you would ever make that change. And honestly, most corners of our cars are so overdamped, the shock is really running the show on the dynamic response when the spring unloads.

How does the smasher unload the spring? Ive nevr used one so i dont understand!

Even though the 2 springs were the same rate, their construction was quite a bit different. Wire diameter and coil spacing were easily pointed out. This was his reasoning for the rate increase!

[MasterSbilt_Racer]

How does the smasher unload the spring? Ive nevr used one so i dont understand!

Even though the 2 springs were the same rate, their construction was quite a bit different. Wire diameter and coil spacing were easily pointed out. This was his reasoning for the rate increase!

The smasher compresses the spring, then it goes in extension. The spring isn't causing the motion, the machine actuator is. It can go faster than the spring.

In that case you are not measuring rate. Rate can really only accurately be measured by stoping at each measurement.

Auto smashers have done a lot of harm when it comes to understanding shocks and springs.

What they measured (no real value as you are fighting the shock and spring, just a reference point to tell your friend) was directly a result of the natural frequency, as I said. Weight, rate, and diameter of the spring wind all affect that natural frequency. When you make a spring taller and bigger diameter, both of those things lower the natural frequency.

[ZERO25]

Thanks for the info!

That explains alot. I have heard Mike and Kirk Loudy claim an auto smasher was more accurate due to the shock and spring on a car was in constant motion as well!

How could they be so wrong, esp Kirk? smh

Side note......when I make a post about a video, obviously i have paraphrased their words. Theyre not mine! Dont shoot the messenger, just post why you disagree and why!

[MasterSbilt_Racer]

Thanks for the info!

That explains alot. I have heard Mike and Kirk Loudy claim an auto smasher was more accurate due to the shock and spring on a car was in constant motion as well!

How could they be so wrong, esp Kirk? smh

Side note......when I make a post about a video, obviously i have paraphrased their words. Theyre not mine! Dont shoot the messenger, just post why you disagree and why!

As a guy who spent half his life working for a high end testing laboratory, and has a racing and an engineering background, I'm going to tell you it's terrible measurement practice. Springs are displacement dependent. You measure the loads at a static point. Shocks are velocity dependent. You measure them with a shock dyno. Now, you need to know what your forces are on the car, you add the travel forces and speed forces together for the correct moment in time on the track.

I apologize if I can across as a jerk, but I honestly couldn't understand what you were trying to say about the video. And without being able to watch it, I had to surf FB and piece the story together.

[ZERO25]

He ran the test to 2.5 inches of compression, wouldnt that be a static measurement?

Ill loan you the $9.99 to watch all their videos for a month......so we/i can get the real info! lol

[MasterSbilt_Racer]

He ran the test to 2.5 inches of compression, wouldnt that be a static measurement?

Ill loan you the $9.99 to watch all their videos for a month......so we/i can get the real info! lol

If he stopped the machine and then recorded his number, yes.

[phenom08]

It appears they took that video down

[ZERO25]

If he stopped the machine and then recorded his number, yes.

So, would that make his test accurate then?

Whats the difference in construction of the two different smashers? I was told the standard machine uses an electric trailer jack!

[MasterSbilt_Racer]

So, would that make his test accurate then?

Whats the difference in construction of the two different smashers? I was told the standard machine uses an electric trailer jack!

I have a standard manual machine with a trailer jack actuator.

Higher end machines have electric actuators that are a ball screw with brakes.

Before I left my testing job, I used a servo hydraulic fatigue testing machine that was computer controlled and cost about 70k.

[cjsracing]

video is now gone - i watched it Friday

[ZERO25]

So his test was accurate, since he had stopped the smasher at 2.5 inches?

[95shaw]

Only if the test was started at equal preload.
A 2 inch shorter spring with a 2 inch spacer may not be exactly the same.
The 2 percent that most guarantee the spring rate comes into play. Plus or minus.

If they start at the same load, travel the same 2.5 inches, and end 25 lbs different, springs are a different rate.

[crownman25]

I have ben hearing some huge rr springs at some tracks....

[Lizardracing]

Racers are full of junk science.
A few weeks ago I was arguing on FB about this spring hysteria stuff. A rep from Swift posted and how important is it was and why their springs are better than other brands because they understand it and no one else does.
I asked for the data, not to argue, but to learn something and even called the guy on the phone. I still don't have data or straight answers.
Just another example of racers making things more complicated than it needs to be and being sold a promise your too stupid to understand so buy our stuff and trust "the science". I've watched a lot of the tech videos from many of the so called chassis schools and I still haven't seen a magic trick. Not that generic info is bad thing.....I just don't like the idea of being sold a magic bean, and getting a fern.

[ZERO25]

Talked to one of the house car drivers, from one of the popular modified chassis's, and was told that theyre running a 6" rr spring. The only drawback was a lack of rubbers that work well with the tight coil spacing!

[MasterSbilt_Racer]

Talked to one of the house car drivers, from one of the popular modified chassis's, and was told that theyre running a 6" rr spring. The only drawback was a lack of rubbers that work well with the tight coil spacing!

If they running a screw jack deal, that would make a lot of sense.

But, then again, how much spring do you really need for 3" of total travel. Not much. The rest is just weight you are carrying around.