Working on a project at work, to add suspension to a product that doesn't have a suspension. I only have around 10" to fit a compact little shock/strut assembly. Is there any sites that I can search based off of the overall dimensions and weight instead of by vehicle? Or, can you recommend a vehicle that would have a compact shock/strut assembly? Thank you!
Does it need to be a strut? or can it be a shock/spring combo?
If the latter is possible, mountain bike or motorcycle. Most motorcycles have a shock slightly longer than that, but you could cut the spring and compress it more favoring more droop/less bump travel. There are a few under 10" though.
Mountain bike shocks are easily under that length.
Can you share any more about the application?
Application is steel wheels on steel tracks. I bought some mountain bike shocks to try, but I think the strut is going to be needed to not have this thing bouncing down the tracks.
I think you are misunderstanding what "strut" means. A strut is a shock absorber that also doubles as a structural element of the suspension. It will not necessarily have more or less "bouncing" (damping) than a shock absorber that is not structural. The shock part is what takes care of the damping.
10" total length sounds like mountain bike territory and not much else. A lot of mountain bike shocks are installed at really bad motion ratios and are actually pretty stiffly sprung/damped as a result
[Edit: industrial gas springs have some damping, IDK if those are any option. McMaster is the easy place to start, gas springs or dampers]
Like everyone has been saying, mountain bikes or pitbikes (sub-125cc dirt bikes) are good places to start.
A low-tech way to get some ideas is go on Amazon and repeatedly search for "250mm shock", "240mm shock", "230mm shock" etc. to get a sense of what is common, and also typical prices. There's going to be a big range on cost from "it has some damping until the oil leaks out past the single rubber o-ring" all the way up to "professional race-ready 4-way adjustable with rebuild kits available".
Beyond that, some online bike shops can let you filter shocks by length, and also give a drop-down list for different spring rates:
In reply to Keith Tanner :
I responded to that incorrectly. The ones I bought from Amazon were springs only, with the strut not actually functioning other than a guide. I need either a shock or a strut, and not just a spring like I purchased. A spring alone isn't going to work. A shock/spring would absolutely work.
In reply to Oapfu :
That is super helpful. I haven't found where you can buy different spring rates before. Thank you!
Came here to say sportbike or mountain bike. Mountain bike air shocks allow the rate to be adjusted by changing the pressure with a high-pressure shock pump, however an air spring setup is inherently progressive.
How much weight is it holding, how much suspension movement are you looking for, how critical is damping control, what style of suspension is it, and what's the motion ratio?
I mean, I could recommend hydraulic RC car coilovers as technically fitting the stated requirements so far. I mean, it doesn't get much more 'compact' than this but I'm guessing that might be a bit lighter duty than you need. Or perhaps just urethane pucks, damped by the internal hysteresis, as used on Formula 440/500/600 race cars... As well as basically being how the old 'elastomer' mountain bike forks worked.
In reply to Driven5 :
Yeah, I was going to come back to this thread and instead of trying to answer the question as it was asked, go way overboard brainstorming the design/engineering problem behind it...
Again depending on production volume, lifecycle maintenance support, etc etc etc: maybe rather than MTB springs it makes more sense to look for equivalent industrial die springs (again, McMaster is one place to start) , or even custom wound springs (e.g. Lee Spring, or past GRM threads), or (as Driven5 already said) try something other than steel coil springs (gas springs? airbags? urethane/ MCU?)
springs w/o any damping at all are probably unacceptably bad, but how much damping, how messy can it be (in normal use, or if it fails), how much maintenance, easily adjustable or set it up once and forget it...?
If you are honestly looking for steel wheels on steel tracks, why have shock or struts at all?
No suspension is definitely the smallest suspension possible. That what go karts have.
In reply to SV reX :
Because not all tracks are smooth, and axles break without anything to absorb the impacts. This is about taking those impacts and not snapping steel components when they hit. Suspension travel doesn't need to be much. Two inches would be more than adequate. Weight is around 800 lbs per axle.
Im not at the point where I'm looking into production yet. The idea is to modify our current product, add suspension to it, send it to our roughest track and video to see if there's improvement. Amazon or anywhere else is fine for this.
I would probably use rubber blocks here, both to get integrated damping and likely more weight capacity than MTB suspension. And lower cost.
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