Manticore

progressive springs only work on cars with longer suspension travel. for on-road or touring car, suspension travel is so little that the progressive spring will always work on the soft side.

Taylor-Racing

Hmmm . . . that's nearly right.
Actually, progressive springs are a good way of understanding how the number of coils affects the rate - the spacing of itself doesn't affect the rate.

Here's how they work:
When you start to compress a progressive spring, all coils start to compress at the same rate, however within a short distance, the closer spaced coils will contact each other and thereafter cannot play a part in the spring action.
As you further compress the spring, the remaining coils are doing all the work and the spring becomes stiffer.
That's why they're called "progressive rate springs"

Taylor-Racing

Yes, but in the original post you were suggesting that the increased coil spacing would compensate for the difference in wire diameter and yeild springs of the same rate. The HPI rear springs will be softer (as you would expect) because they are made of a thinner wire. Coil spacing is irrelevent.

Yes, but this is just introducing an additional parameter into the equasion.
It doesn't affect how springs are rated.

The Sleeper

Sorry Taylor but I disagree.

The original question I thought I was trying to answer was will two springs with the same color but different length have the same rate. I answered yes so long as the springs were made by the same manufacturer.

I was using the silver spring made by HPI for the R40 as an example. Unfortunately I did not see what the spring rate was. But I'm positive both springs have the same rate even though the front spring has a thicker wire.

And to add more confusion, HPI also sells a gold front and a gold rear spring for the R40. Again the gold front spring has a thicker wire but is 3mm shorter than the gold rear spring. Both have 6.5 coils. But by design, the longer rear spring with the thinner wire will have the same rate as the shorter, thicker wired front spring.

Now would HPI paint these springs the same color if their rate wasn't the same? I really don't think so.

sbmon

Taylor racing
i am sorry but i do not think that is how dual rate springs work
the coils do not all compress at the same rate, and then the completely compressed coils are taken out of the suspension equation
There is no way you can tell me that on real size cars, motorcycles, or rc applications theywere designed to work like this.
dual rate springs were not designed to bottom out on one end of the spring , if that happened you would be severly upsetting the suspension of the vehicle. I am not saying they can't bottom out just that they were not designed to work in the manner you described above.

Bobby Flack

Progressive springs are progressive because the coils that are close together touch each other as the spring compresses. In effect the spring has fewer colis working, so it gets stiffer. And yes that is how car manufactures make them. It does not bottom out with a big change in rate, the spring simply gets stiffer and stiffer because fewer coils are left to do the work.

The rate of a spring is due to length and diameter of wire, not the distance between coils. If you take a long spring and cut it down it will be stiffer.

As far as the HPI springs go, if the spring is a bigger diameter and the number of coils is the same it will not be the same rate. The example of the silver spring being a bigger diameter and the same length must make it stiffer.

Don't confuse the length of the spring with the length of wire. You can have a spring several length's but the same rate if the overall lenght of the wire is the same.

Not real clear but we will keep trying!!


Ted

The Sleeper

Ok, I went back to HPI site and got the following info:

6763 2 Shock Spring 13 x 20 x 1.7mm x 6.5 coils (Silver/2 pcs) (Front)
6767 2 Shock Spring 13 x 20 x 1.7mm x 5.5 coils (Gold/2 pcs) (Front)
6773 2 Shock Spring 13 x 23 x 1.6mm x 6.5 coils (Silver/2 pcs) (Rear)
6777 2 Shock Spring 13 x 23 x 1.6mm x 5.5coils (Gold/2 pcs) (Rear)

These shocks are for the R40. And if I'm reading it right, the 13 means the spring is 13mm wide, the 20 means it's 20mm high (front), the 23 means it's 23mm high (rear) and the 1.7 and 1.6mm is the thickness of the wire.

Now, this is a question from me. Do the silver springs have the same spring rate? Also, do the gold springs have the same rate?

I say yes...

Taylor-Racing

That's quite OK.

You answered yes, but did not put forward any basis for the assertion.

How could you be positive if you don't know the rate?

Again, you have not put forward any basis for the assertion.
Specifically, what part of the "by design" suggests they will be the same rate?

Yes they would paint them the same colour. The reason is that they are considered a set of front and rear springs and that most would use them this way - the rears would typically be softer.
I gave an example of Kyosho doing exactly this. The Kyosho Gold, Silver or Black "sets" all contain softer rears and the front and rear springs are all the same colour.

Taylor-Racing

OK, then you tell me how they work.

The Sleeper

Is there any way you can give us the specs on these Kyosho springs?

Specifically their coil diameter, number of coils, length, and spring rate.

Just to let you know, I'm asking in a polite, conversational way

Taylor-Racing

I agree with how you read the dimensions.

6.5 coils = Number of coils
13 means the spring is 13mm wide = Coil diameter
20 means it's 20mm high (front) = Free length
23 means it's 23mm high (rear) = Free length
1.7 and 1.6mm is the thickness of the wire. = Wire O.D.

I have previously posted the spreadsheet that will work out the rates for you.
You will need to change the suffix ".txt" to ".xls".
This spreadsheet expects you to enter imperial measurements but will work fine with the metric ones because we only want to look at comparative spring rates. Put those dimensions into the spreadsheet and tell me what you come up with. Also notice the what happens when you change the free length field.

Taylor-Racing

I can supply the Kyosho spec's , but let's look at the HPI ones since they are the subject of discussion and the spec's are posted. The Kyosho ones will work out similarly - probably Mugen, Serpent and every other brand also.

Yep, polite and conversational at this end, too.

The Sleeper

Well the reason I'm asking for the specs is so we can see the difference between the Kyosho springs even though they are the same color.

I'm going to try your speadsheet thingy if I can get it to work.

Taylor-Racing

V-One R Springs: Active coils. Wire O.D


Front
Silver 3.5 active coils 1.7mm
Black 3 active coils 1.7mm
Gold 2.5 active coils 1.7mm

Rear
Silver 4.5 active coils 1.6mm
Black 4 active coils 1.6mm
Gold 3.5 active coils 1.6mm

sbmon

I only disagree with the point about the spring being designed to bottom out completely(i don't think that they would be designed to actually contact each other)
I will admit this is just what i think and not what i know to be fact and from the view of your posts you are much more knowledgeable about this than I

Very interesting topic