Springs!!!

[Busdriver 6209]

I think I'm about to open a worm hole or a split in the time continium I got back ito the hobby in the late part of of 2018 and joined this forum in early 2019. I started with a CC01 Defender ( a good example of what I'm about to bring up) I didnt know anything about crawlers, trail trucks, SCT or anything else to be honest. But i spent money doing things to try and get my CC01 to do allsorts of things that it wasnt designed to do. Well I've given up doing that and my Defender is now an open topped Wrangler with new grill and bonnet. I have also amassed another 14 models since that time and frankly all but one suffer from the same problem. The one that doesnt is the Losi Baja Rey Raptor that seems so far to have an almost perfect spring/ damper set up, the rest although quite a few have quite decent Tamiya shocks (CVA's) have lousy springs In a thread recently @Carmine A mentioned about the amount of weight that would be needed to added to a CC01 to make the springs "work" was huge. My question is there must be 100's of millions of springs produced in possibly 1000's of diameters, lengths and compression weights ( not sure if this is the right term but I'm sure you know what I mean) Do Springs R Us not exsist where we could dial in all of the paremeters and come up with a spring, much in the way that RC bearings and various companies work.???? Perhaps my flux capacitor is broken.

[Bash 356]

I use the optional barrel spring set for the CC-01 with the stock shocks and oil and the suspension is much better than stock. It's still nowhere near a modern 1.9 crawler, but it is perfect for trail use and light crawling. My CC-01 is all stock except for electronics, so they should work well for you since it sounds like you've added a bit of weight to yours.  

[Busdriver 6209]

The barrel springs are a good idea. I must look at them. Most of the weight that has been added to mine is probably in the wrong place for trail running. Its all below the pivot points of the suspension. Keeps the wheels on the ground but the body doesnt follow it!

[BuggyGuy 1106]

Are you sure this problem is all to do with the springs - if things are too 'bouncy' then thicker oil can help - or visa versa if your not getting enough... 

Spring kits from competition cars can also be a relatively cheap and easy way to get a variety of springs in the same size, just pick a set from a kit with a similar weight to what your planning on running. 

E.G https://www.modelsport.co.uk/index.php?product_id=371768&gclid=Cj0KCQiAnb79BRDgARIsAOVbhRqC9g6vaoWgBCbxWQffWGNKRwYY8lRiFlOLvwCAGhioEy6_0Mnc6r8aAlAAEALw_wcB

Or at the more extreme end of the scale (not cheap but they do much smaller and cheaper sets as well... https://www.pbmracing.co.uk/products/spares/team-associated-b62b62d/_p_69966_team-associated-v2-12mm-big-bore-buggy-springs-full-set-front--rear-12-pairs/

[Lee76 638]

1 hour ago, Busdriver said:

Do Springs R Us not exsist where we could dial in all of the paremeters and come up with a spring

Yes, many many companies manufacture springs to order or have huge stock range. Lee springs.co.uk and Skegness springs are two I have used. You’ll need to know if you’re shaft or bore guided, what the ID is and working height and range. There will be a range of materials which will give you a variety of stiffnesses and then a range of wire diameters, you can tune the free height to give you the load required at working height and work out easily the range before coil bound. You can pretty much filter by all the parameters and come up with what you need. 

Lee spring website is pretty good, lots of drop down options, one more thing to consider is how the springs are finished, closed and ground, or just open etc.. closed and ground gives you parallel end faces but may leave you with a sharp edge, closed will be almost parallel, open will finish on the helix.

[Busdriver 6209]

Many thanks for the suggestions but maybe I didn’t express myself well enough. I’m looking for the generic spring manufacturer?  I accept that there is a balance between damping(oil wt) and springs.

[Busdriver 6209]

2 minutes ago, Lee76 said:

Yes, many many companies manufacture springs to order or have huge stock range. Lee springs.co.uk and Skegness springs are two I have used. You’ll need to know if you’re shaft or bore guided, what the ID is and working height and range. There will be a range of materials which will give you a variety of stiffnesses and then a range of wire diameters, you can tune the free height to give you the load required at working height and work out easily the range before coil bound. You can pretty much filter by all the parameters and come up with what you need. 

Are they prohibitively expensive?

[Lee76 638]

5 minutes ago, Busdriver said:

Are they prohibitively expensive?

Well... I confess to having bought them for work applications where price is irrelevant and typically have designed custom ones. If you’re picking std options, springs which are already available it should be just pence.. best thing to do is use the tools to pick the ones you want and give them a ring, see what they have closest or get a quote.. You may even get some samples if you’re lucky! You might be able to get a large batch and make some other TC members happy with the option to buy?

[Lee76 638]

Just ran through a random made up spring 10mm ID 35mm long for 1 off was about £3

[Busdriver 6209]

I was thinking that if there was a decent supplier quite a few members  might be happy. Now they they all know the possible!!!

[Lee76 638]

2 minutes ago, Busdriver said:

I was thinking that if there was a decent supplier quite a few members  might be happy. Now they they all know the possible!!!

Yes, I’ve thought of changing the ones on my monster beetle as it has no droop, thought if i ever had the time I’d put some longer dampers on and pick some springs that have a lower rate. Just make sure to pick a material which is corrosion resistant! 

[Lee76 638]

Let me know how you get on with those two suppliers, I can have a look on Monday if there are any others our buying department recommend, once you have a spec. I can also make the enquiry to the contacts I’ve used before, see if they’ll give a better response!

[Lee76 638]

Just looked at the MB, the springs are not ground, just ‘closed’ they also look plated or highly polished, but this isn’t a must so long as you’re corrosion resistant.

[Busdriver 6209]

Thanks for the info. Apologies but some of the descriptions don’t mean much🤔 for instance are not ground?? Could you perhaps do an idiots (specifically me) guide to spring terminology . I’m sure others would appreciate it it 😀

[Lee76 638]

No need there’s one on the lee springs site

https://www.leespring.co.uk/learn-about-compression-springs

Lots of other types of springs but most of the ones you’d find on RC dampers are basic compression.

It’ll say ground or unground, basically, whether or not it’s been on a grinding machine to flatten the last coil, which can be closed or open see pic.

The terminology closed and squared are pretty much the same thing for small springs, looking at the RC market I think they are just closed/squared to make the ends parallel, grinding would add another level of cost, so manufacturers wont bother.

Personally, I favour springs with a relatively low rate (force per unit length to compress N/mm) this means you can have more variation in length for very little deviation in force. Provided you have an application where the working height (static installed) has enough difference to coil bound (compressed to solid) to ensure the working range doesn’t hit the limit, though this method is more suited to an application where you want a controlled load and the response time for a spring to expand is proportional to it’s load. To specify a spring you will need to know what the solid height is as well as the maximum travel and the free height of the spring. So if you’re fitting to a damper unit, measure the fully extended height and the fully compressed height, the range is the difference between the two. You’ll want to make sure the Free height of the spring is larger than the fully extended damper so it doesn’t become unloaded (unless you’re limiting the range by other means) the spring you select will need a solid height less than the fully closed damper so you don’t go coil bound. The rest is up to you to pick the correct load. Another spring term is working length, or force at L1. You can have more than one loaded height reference, but lets assume you’re fitting to a 50mm travel damper and you want the damper to sit midway when loaded and use the full travel, the damper must be long enough to accommodate a compressed spring at L2 (in this case full compression) so lets say the damper length is 75mm (body length). This gives you a maximum solid height of 75-50=25mm, you’ll need some safety on this so right off the bat, lets assume you’ll be limited to springs where the solid height is less than 25mm, lets go for 20mm. Next we want to know where the damper sits mid travel and at what load so we can pick the height. If you pick a spring that has a free height of 100mm and a rate of 1N/mm  it will have 25mm compression at damper fully open and a load of 25N (25mm x 1N)  when you compress to L1 (mid travel) you’re now at 50mm compression and 50N and so on until you hit max compression (75mm and 75N). If you want more load at L1 you can either pick a spring with a higher rate, either a material change or wire diameter change, but you can also put in a longer spring or add some spacers, provided you don’t end up breaching the solid height limit you set. The spring data sheet will give you other useful information, like the solid load, the force required to coil bound the spring. So if you know the mass of the car you can quickly work out if the springs are strong enough to stop it going coil bound, you’ll also be able to work out if your car will go coil bound after taking a jump by adding an acceleration multiplier to the force. You’ll also get the ride height if you know the car mass and the spring rate and free height.. so in our previous example,  a mass of 3kg is (rounded up a little for easy maths) 30N,  at damper free height you’ve already got 25N force acting against that so 30N-25N=5N, rate was 1N/mm so 5x1=5mm travel. This is 20mm higher than the desired mid travel position.. so you’ll either need a lower rate, but this would change the response, (F=ma) or a shorter spring. going 20mm shorter now means you have a free height of 80mm, a fitted (installed length) height of 75mm a working height of 50mm a load at L1 of 30N and a perfectly balanced mid limit car..

Hopefully that makes sense and I’ve not messed up the maths trying to watch Trolls with my 4YO and using a small tablet... and i know i didn’t factor tolerance for top limit full travel but you get the idea... I normally do all this in an excel spreadsheet and don’t have to keep track of my ramblings..

If you start to pull in some of the parameters we can discuss the various pros cons of spring selection,  perhaps we do it from a practical side and pick a long spring with a low rate and a shorter spring with a high rate and performance test them...

 

[Lee76 638]

For reference...

[Busdriver 6209]

Thanks I think!! May take a little while to sink in🤔

[Juggular 4964]

2 hours ago, Busdriver said:

Thanks I think!! May take a little while to sink in🤔

Ditto.

I just wish Tamiya off-road springs are softer. (M-chassis are fine)  Frankly speaking, 2kg RC cars don't need 900 weight oil.  I wish Tamiya engineers drive the off roaders without any oil in the shock.  See if springs work well.  Like 20% compression when loaded, bottoming out when landing --- I think 2 feet jump not resulting in full compression is unnatural.  Then add light oil to dampen the whole thing, so that the oil would barely prevent fully bottoming out when landing.  Seriously, my Hornet's one O-ring does dampen the front suspension just fine.  Not in stock form, I cut one loop off the spring.  

Tamiya engineers seem very afraid of dirt.  They choose the spring setting that could never bottom out because if you bottom out, the earth will turn flat and people on the other side of the earth would fall off!!  They just can't be responsible for that, oh-no!  

I should experiment with some soft spring sets one of these days...

 

[ACCEL 2014]

Sounds to me like Spring is in the air

now how many piston holes if any to use? and what diameter are these holes and who's oil's viscosity is really correct ? CST's and Weights

The expression for dynamic viscosity, or absolute viscosity of the oil and is the measure of the fluids resistance to flow. cst is the expression for Kinematic viscosity, which is the ratio of a fluids viscous force to it's interial force.

External/Internal limiters, cups, stroke, rebound, eyelet length, even ball stud distance.

Ok now what position do you put your shock at ?, given if it has options for the tower holes, and thus experimentation can be quite endless.

 

 

[Lee76 638]

5 hours ago, ACCEL said:

Ok now what position do you put your shock at ?, given if it has options for the tower holes, and thus experimentation can be quite endless

Yes, I’m not even sure I’d know which experiment is the right one... A static drop like @Juggular suggested, or running on rough terrain or running on the flat and doing lots of sharp turns to see how the unloaded wheels react (the MB goes into spasm when I do this :)) I’m beginning to have a little more appreciation for what the F1 trackside mechanics go through at each race, they have teams of engineers with simulation, accelerometers to measure vibration, driver feedback and a million options to tinker with.. and still get it totally wrong when the weather changes and they put a new tyre on.. The RC dampers I have experience of even though simple, would still take a fair while to alter, taking them off to change the damper fluid or add/remove some holes put a longer spring in etc.. not only would it take time but unless you’ve made some mods the self tap screw bores would soon wear out... One day.. I will make some changes to my MB and feedback how awesome it drives out on the flat grass pitch I drive on... then someone on here will make the same change on theirs, run it on a jump track and have the worst drive of their life...It now occurs to me the reason there is no static drop on my beetle and the car sits full height (extended shocks) is because as Juggular said.. the engineer is probably afraid of it bottoming out when kids jump them off the roof of their house.. so over protective drivers like me on flat ground.. have it set up totally wrong.. So on this note.. I’m not going to do any intricate damper characterisation.. I will just get a different spring and adjust the ride height through car mass and see what happens..

[Juggular 4964]

I feel like sometimes Tamiya is forgetting the goal.  

The purpose is to keep the tires on the surface.  Absolutely minimum air time (except when jumping).  How I get there is less important than getting there.  So the popular test for the shock is the bounce test.  I have no problem with the Grasshopper's springs, but the front suspensions are absolute pogo sticks.  

The Hornet is how most Tamiya suspensions are like; a little too strong. 

If the springs are too stiff, they don't conform to the ground as well.  If the shocks are too stiff, they don't conform to the ground as fast.  Sometimes they act like they are almost the same thing, but they are not. 

(1) when the spring is too stiff, the front will jump up from a small pebble, even if it has no oil in the shock.  In this case there would be oscillation. Because even the stiff spring would bounce.  

(2) when the oil is too heavy, piston holes are too small, the front will jump up with a small pebble, even if the spring is soft. Because it can't react fast enough.  The suspension would not oscillate, it would feel like a dead body. (not that I've seen one)  

Now if you add some oil (even light oil) to case (1)? Then both (1) and (2) would work similarly stiff.  Which is why I think it's important to find the right spring rate first, then work on the shocks.  

My M-06's front shocks are empty, for example. The nose is as light as the Hornet. And the Hornet is perfect with one o-ring.  Just because I have oil shocks doesn't mean that I should fill it with oil (mostly yes, but not in this case).  If you need them be softer, but even the lightest oil can't make it react fast enough because it already has one o-ring, just like the Hornet?  Then it shall have only a drop of oil for lubrication.  The shock should give me what I need. I shouldn't be swayed by the convention that shocks must have oil. If one o-ring inside gives me enough damping, then that's fine by me (until I need it to sharpen the steering).  

The Grasshopper's springs are good.  The Hornet simply added D1 part to add friction damping without shortening the springs.  Why create another part when kids can't tell anyway, right?  But it's a collar that makes the spring stiff.  

@shenlonco cut a loop off the spring to make room for that D1 part.  I did too, and that softened it up for sure.  The front works like the Grasshopper, just with some friction damping.  And the Grasshopper rear springs never needed damping, because of the angle.  The lesson I learned is that you have to make it work.  The manual includes shortcuts corporations have to make sometimes.  So if @Busdriver says CC01 (along with hundreds of others) needs better springs, I absolutely agree.  

 

[Big Jon 684]

Without getting into any of the engineering discussion concerning springs, to get the right springs for your applications, start hoarding (and properly sorting) springs. Save every "extra" spring, buy spring sets out of the bargain bin at the LHS, pick up those random boxes of spring and shock parts at the swap meet, order a spring set or two to round out an internet order. Springs are relatively cheap, so before long, you'll have a nice big assortment to choose from, and experimenting with shock tuning is definitely enjoyable. 

There's nothing wrong with hoarding RC parts! Springs, shocks, shock parts, hardware, extra plastics, gears of all sorts, body accessories, driver figures... All of that stuff has uses for the serious hobbyist.

 

[ACCEL 2014]

24 minutes ago, Big Jon said:

There's nothing wrong with hoarding RC parts!

That's my kinda guy, if you gottem', smokem'

i've been accumulating the various pistons now for a couple of weeks, VRP, Flash Point, AVID and a few others, mostly for my AE vehicles.

always just used that was available, but now i want to learn how and the why about true shock tuning.

 Nicadraus started a damper tuning thread and has some insight there.

when i build i just get the shocks to feel as they're supposed to feel and usually stay at the stock settings to start with, just because by then i'm already about to start another build, then usually electronics are next and wheels and paint and now i can just go back and update all the shocks i think might need attending to, truthfully if it bounces and flips over

immediately i did something wrong.

[Lee76 638]

1 hour ago, Big Jon said:

There's nothing wrong with hoarding RC parts!

Glad it’s not just me.. now if anyone can tell me why I need to keep all the plastic bushes I swapped out for bearings or has a clever use for them.. please let me know! I’m building quite a collection in my parts case... just in case...

[shenlonco 1156]

On 11/14/2020 at 9:49 AM, Busdriver said:

I think I'm about to open a worm hole or a split in the time continium I got back ito the hobby in the late part of of 2018 and joined this forum in early 2019. I started with a CC01 Defender ( a good example of what I'm about to bring up) I didnt know anything about crawlers, trail trucks, SCT or anything else to be honest. But i spent money doing things to try and get my CC01 to do allsorts of things that it wasnt designed to do. Well I've given up doing that and my Defender is now an open topped Wrangler with new grill and bonnet. I have also amassed another 14 models since that time and frankly all but one suffer from the same problem. The one that doesnt is the Losi Baja Rey Raptor that seems so far to have an almost perfect spring/ damper set up, the rest although quite a few have quite decent Tamiya shocks (CVA's) have lousy springs In a thread recently @Carmine A mentioned about the amount of weight that would be needed to added to a CC01 to make the springs "work" was huge. My question is there must be 100's of millions of springs produced in possibly 1000's of diameters, lengths and compression weights ( not sure if this is the right term but I'm sure you know what I mean) Do Springs R Us not exsist where we could dial in all of the paremeters and come up with a spring, much in the way that RC bearings and various companies work.???? Perhaps my flux capacitor is broken.

Tamiya CC-01 hop up springs the white barrel springs put the soft up front and you can put them in the rear..but I left my stock ones in the rear and it works much better...that is for crawling or trail running what I use mine for.

you can see the springs in this video plus I did a lot of mods to mine also see the video under this one.