How to Size and Strengthen Double Wishbone Suspension Struts for an ATV?

[harpreet singh]

I want to make double wishbone suspension struts for an ATV. Please guide me what should be the size of A's used in it and also how much should be their strength...

 

[Mech_Engineer]

What exactly do you plan to accomplish with the suspension? You should probably analyze the stock A-arms on the atv first to decide what your baseline performance characteristics will be.

 

[harpreet singh]

I m not getting wat r u saying.. And my aim is to construct an off road vehicle.. I need these suspensions for that...

 

[Mech_Engineer]

Sorry, I was under the impression your were designing replacement A-arms for an already existing ATV's suspension.

If you're designing the system from scratch, your fist step will be to decide how much suspension travel you want. After that, you can decide on a type and length of coil-over shock (assuming you use coil-over shocks) and travel-limiting devices like bump stops. I would recommend studying suspensions on ATV's that are currently available for ideas.

We can't easily answer questions about required strength of the arms and components without know a lot more about your application. If this is truly an off-road application, speed and overall weight will tend to dictate how strong components have to be.

 

[harpreet singh]

Maximum speed will be 50 kmph and overall vehicle weight(including driver) will be around 330 kgs

 

[ank_gl]

Maximum speed will be 50 kmph and overall vehicle weight(including driver) will be around 330 kgs

this is like throwing away your work at others. No offense, but how much have you designed so far??

 

[harpreet singh]

I am not getting from where to start.. I read about the basic structure online but didn't was not able to understand on what parameters it should be designed..

 

[ank_gl]

everything is designed on the basis of loads it will have to bear, & the kind of load, static, transient etc.
An ATV has a fate of jumping up and down, get all the forces acting on the structure. Do you know structural FEA??
For the spring & damper, make sure you design(or calculate) spring constant & damping coefficient respectively, that system gets a nice damping(far from resonance). For that you must know how much the system is going to vibrate, in turn this depends upon the speed and surface, the system is going to work in.
By the way, I am not a complete engineer by now, it ll take an year more, so, sometimes, I do make things sound easier than they really are!

 

[harpreet singh]

Sorry but i know nothing about structural FEA... Have just completed my second year of engineering

 

[Mech_Engineer]

I would guess that off-road suspension design is equal parts up-front analysis and real-world prototype testing. As I said before, your best bet for a starting point is to see what already exists out there in terms of ATV suspensions; there is no magic set of equations that will tell you exactly what the suspension will look like or how it will perform in all situations.

 

[ank_gl]

Do you plan to make one?? I mean cast those A's, get those springs, dampers, bearings & all?? Or is it that you need to get the calculations for a project??
In case you need a real one, Mech_Engineer is right, you better go & see what is out there.

 

[harpreet singh]

I am planning to make it.

 

[harpreet singh]

I checked on many sites but everywhere I m getting about the standard models available in the market. No site is providing such deep specifications. I have searched about the dampers etc. but the problem is with double A structures. I don't have any idea about how thick rods should I use which can sustain the severe off road conditions.

 

[ABHIdAVIATOR]

i guess u asking all this stuff for SAE baja, INDIA. rite? @harpreet

in that case i wud advise u to use maruti 800's suspension arms. modify them accordingly. i don't think u've got much time to decide.

gud luck!

 

[harpreet singh]

Ya that's true.. I was asking for SAE BAJA only.. R u sure that maruti 800's suspension arms would be strong enough for the off roading conditions??

 

[ABHIdAVIATOR]

ya it is.
ppl used it in the last year's competition
performance was gud enough, though they had to cut and modify the arms with a lot of effort.
do consult someone else before u go for it.

 

[ank_gl]

I am planning to make it.

Do you have the facilities??

Your best bet is to go with what the other guy is saying.