B-Max 2 Kit springs - lb?

[Danosborne6661]

Had a look around a few different places but couldn't find the info, whats the rating of the kit front and rear blue springs on the B-max 2?

[DrPaul]

Yok havent published them anywhere, I think thats why everyone uses Associated plus the Yok range is limited. I still like the look of the Core spring kits.

[Danosborne6661]

Hmmm whats the next spring up and the next spring down from the standard Yok springs? From that we might be able to make a guestimate if people know what one stage lighter/harder is?

[neallewis]

Hmmm whats the next spring up and the next spring down from the standard Yok springs? From that we might be able to make a guestimate if people know what one stage lighter/harder is?

Rear yellow is softer than rear blue.

Front red is harder than front blue.


I use AE red or yellow front springs, and keep returning to the Yok kit blue XL springs, having tried all the lower rate AE BB rears... green, black, grey, white blue.

I'd love to understand the Yok BB spring rates. Looks like the BMAX 4III has different set of coloured springs, different versions of "soft", again not mentioning the soft ones on the Bmax2. Why is it so hard to get a published spring rate?

Even the Japanese team drivers seem to be using AE BB springs.

[Danosborne6661]

Ahhh ok, those grades don't seem to be covered in the Petit spring chart either. Can understand why people haven't been using the Yokomo springs now :P I'll take the springs off and compare them to some of my others to give a rough lb rating.

[mes]

Here is a chart with the B-Max4 small and big bore spring rates. Maybe it helps a little at least.

[OneKiwi]

Why is it so hard to get a published spring rate?

Even the Japanese team drivers seem to be using AE BB springs.

I don't know why they dont release them as Id rather run the yok springs than the AE ones or others I have ran.

Whats "measured" on that chart?

[luniemiester]

I'm sure roger mills has a machine to check springs - maybe its worth asking him if he can and what it would entail etc?

[mes]

I don't know why they dont release them as Id rather run the yok springs than the AE ones or others I have ran.

Whats "measured" on that chart?

AFAIK Arn0 measured the spring rates himself instead of sneaking into Yokomo's top secret database. That was back when he had access both to the necesssary device and the springs. ;)

[Arn0]

A little correction need to be done about the chart and the measurement: Roger did all measurement and all credits must go to him in this sense. The chart in attachment is only a small extract of a larger chart I put together. You can find those spring charts on petit, there is one for small bore shocks and another for bib bore shocks.

All the best in your racing!

[neallewis]

A little correction need to be done about the chart and the measurement: Roger did all measurement and all credits must go to him in this sense. The chart in attachment is only a small extract of a larger chart I put together. You can find those spring charts on petit, there is one for small bore shocks and another for bib bore shocks.

All the best in your racing!

Arn0,

Your charts:
http://www.petitrc.com/reglages/BuggyBigBoreSpring.pdf
http://www.petitrc.com/setup/yokomo/BigBorevsSmallBore/Chart.pdf

Do not cover the following Yokomo BMAX2-MR springs:

#BM-1165X - Front "X" shock spring（medium/red）
#BM-1170X - Front "X" shock spring（soft/blue）
#BM-1175X - Front "X" shock spring（super soft/yellow）
#BM-1180X - Rear "X" shock spring（soft/blue）
#BM-1185X - Rear "X" shock spring（super soft/yellow）
#BM-1190XL - Rear "X" shock spring （soft/blue/long）

The BMAX4 springs are covered however.

[Arn0]

Gentlemen,

After getting some data, some mathematics were done to get the rating and the result can be found here (link) (http://www.petitrc.com/setup/yokomo/BigBorevsSmallBore/Chart.pdf) but for now I'm doubtful about the ratings.
Consequently, this need more work and revise some hypothesis.

[smokes]

Arno what is the referance equation used?

thanks

Sammy

[Arn0]

Ok Gentlemen

I sorted out the problem and I have only to blame myself to do some of those stuff a bit to late sometime. Now it make way more sense. Both links given by Neal are up-to-date.

Regarding the equation, it's the standard one for compression spring: Gd^4/[8nD^3]

where:
G = modulus of rigidity of spring material
d = wire diameter
n = number of active coils
D = mean coil diameter

[smokes]

what value are you using for G?

[neallewis]

looks a lot better now Arno. Cheers.

[mes]

Arn0, s it possible that you might have mixed up fronts and rears in several cases?

[neallewis]

Arn0, s it possible that you might have mixed up fronts and rears in several cases?

What makes you say that?

[mes]

Check the measured and theoretical rates for black, pink, orange and purple, and you will notice that front theoratical and rear measured values are more similar than the rear/rear and front/front values. The measured/theoretical values of the greens seem to be reasonable, though. :confused:

[luniemiester]

I'm a bit puzzled too as I know that the green rear springs from the bmax4 are a lot stiffer than the kit blue ones from the bmax 2 but the chart says there the almost the same. Also a rear kit spring of 3.0 seems high?

[Arn0]

Hi everyone,

Markus, I double check and there is no mismatch between some front and rear spring.
I get a bit confused too but if you look in the column left of the theoretical rate, you'll see the theoretical rate match the description and that get me confident about the mathematics.

I'm waiting for some data but this won't be far from reality.

[mes]

No worries! I am just a little confused about the huge differences between measured and theoretical rates of the above springs. With the greens, there is a difference of 0.2/0.3 ibs/inch, but e.g. for the purples, the front theoretical rate is much closer to the rear measured rate than to the front measured rate and vice versa.
I've got the blues, blacks and purples f/r and red and orange f springs at home, i.e. currently some 200 km away from me, and their feel rather resembles the theoretical values. I'd never use the blacks or purples on a buggy on an outdoor track, I bought them for carpet racing with an SC10 with 800/750 cst shock oil and </=1 cm droop/ground clearance - it'll drive like a touring car! :p