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harshnarayanin View Drop Down
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    Posted: Sep/16/2010 at 11:26am
What should be the appropriate spring rate for the front suspension?
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If you drop a check in my mailbox, I can help do the engineering of your car too :)


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Red_Beard Quote  Post ReplyReply Direct Link To This Post Posted: Sep/16/2010 at 12:13pm
Originally posted by RonGeorge RonGeorge wrote:

If you drop a check in my mailbox, I can help do the engineering of your car too :)




x2... your going to school to be an engineer....   Build something, test it, and if it doesn't work change it....  Technicians do what your asking, get out of that mind set, it won't get you far.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote RonGeorge Quote  Post ReplyReply Direct Link To This Post Posted: Sep/16/2010 at 12:16pm
Originally posted by Red_Beard Red_Beard wrote:

Originally posted by RonGeorge RonGeorge wrote:

If you drop a check in my mailbox, I can help do the engineering of your car too :)




x2... your going to school to be an engineer....   Build something, test it, and if it doesn't work change it....  Technicians do what your asking, get out of that mind set, it won't get you far.


I have to stop and do the Robert DeNiro face now. "Are you talkin to me?"
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Red_Beard Quote  Post ReplyReply Direct Link To This Post Posted: Sep/16/2010 at 12:19pm
Originally posted by RonGeorge RonGeorge wrote:

Originally posted by Red_Beard Red_Beard wrote:

Originally posted by RonGeorge RonGeorge wrote:

If you drop a check in my mailbox, I can help do the engineering of your car too :)




x2... your going to school to be an engineer....   Build something, test it, and if it doesn't work change it....  Technicians do what your asking, get out of that mind set, it won't get you far.


I have to stop and do the Robert DeNiro face now. "Are you talkin to me?"

No, the OP
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Post Options Post Options   Thanks (0) Thanks(0)   Quote harshnarayanin Quote  Post ReplyReply Direct Link To This Post Posted: Sep/16/2010 at 3:43pm
I know i'm here to learn but if u could give me slight hint whether i'm on the right path or not it would be great. I calculated spring rate by considering the g force that the suspension would experience after jumping from  a 6 feet height and also took into consideration the motion ratio , the weight distribution on the fornt wheels and the amount of spring travel that i want on my suspension. Please understand as my college is doing this for the 1st time i just wanted to be sure.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote EAD Motorsports Quote  Post ReplyReply Direct Link To This Post Posted: Sep/16/2010 at 3:58pm
Originally posted by harshnarayanin harshnarayanin wrote:

I know i'm here to learn but if u could give me slight hint whether i'm on the right path or not it would be great. I calculated spring rate by considering the g force that the suspension would experience after jumping from  a 6 feet height and also took into consideration the motion ratio , the weight distribution on the fornt wheels and the amount of spring travel that i want on my suspension. Please understand as my college is doing this for the 1st time i just wanted to be sure.
Why did you make two threads for one topic? Doing so clutters up the forum and makes it harder for future users to find usable information.

 

With respect to your question, you're leaving damping out of your formulas. Your calculated spring rate will likely be far too stiff when you don't account for damping.


Another problem is you are asking for spring rate. You start with wheel rate and back out the spring rate required to achieve the desired wheel rate. You can compare wheel rates reasonably well. You can't do so for spring rates because spring rates are dependent upon your motion ratio.

 

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Red_Beard Quote  Post ReplyReply Direct Link To This Post Posted: Sep/16/2010 at 4:25pm
Originally posted by harshnarayanin harshnarayanin wrote:

I know i'm here to learn but if u could give me slight hint whether i'm on the right path or not it would be great. I calculated spring rate by considering the g force that the suspension would experience after jumping from  a 6 feet height and also took into consideration the motion ratio , the weight distribution on the fornt wheels and the amount of spring travel that i want on my suspension. Please understand as my college is doing this for the 1st time i just wanted to be sure.


Do you have any idea what kind of shocks you plan on running?  Coil-over, air-shock, by-pass...  Any particular manufacturer you are planning on running?   Unless you plan on going to Works, or plan on making your own shocks, and have spring made for you/buying them off the shelf, your relatively constrained to what spring rates you can run.  There aren't many manufacturers out there that will make a shock specifically for our application, you can get close, but to get really close you have to be willing to dedicate some serious time to R&D and testing.

For example, if you go with a Fox, like 50% of the teams out there, you adjust the knob on the outside of the body, and thats about all you can you do (depending on which model you get).  If you go the air-shock route, you can tune it to be much closer to your needs, but you have to invest a substantial amount of time into testing, and a ridiculous learning curve.  Coil-overs are slightly simpler, and *if* you can determine what your optimal spring rate is, and have your drivers buy in on it, then you can get a shock that will meet that rate.  The issue with this is you have to go to Works, or someone like works to get your shocks custom made; or if your bad ass like OSU you can make your own shocks.


Edited by Red_Beard - Sep/16/2010 at 4:31pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rob71zilla Quote  Post ReplyReply Direct Link To This Post Posted: Sep/17/2010 at 8:00am
Being a first year team, I would suggest using some sort of air shocks unless you have someone that is highly educated in the topic (which it sounds like you don't)  Air shocks will give you any spring rate you want (within reason) and are easy to design around. Fox Floats have a 0-150psi range, they are only compression adjustable but for a first year team I think that is a great starting point. Being a first year team, you probably don't have a large budget so they will help with that too. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Red_Beard Quote  Post ReplyReply Direct Link To This Post Posted: Sep/17/2010 at 9:01am
Originally posted by Rob71zilla Rob71zilla wrote:

Being a first year team, I would suggest using some sort of air shocks unless you have someone that is highly educated in the topic (which it sounds like you don't)  Air shocks will give you any spring rate you want (within reason) and are easy to design around. Fox Floats have a 0-150psi range, they are only compression adjustable but for a first year team I think that is a great starting point. Being a first year team, you probably don't have a large budget so they will help with that too. 


I am going to strongly disagree with you on this one.   Call up works and send them all your design parameters, and let them build a shock for your application.  We did that for 5+ years, and the cars that we still have around the shop with works shocks are awesome cars, mostly due to the shock set-ups they have.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote collinskl1 Quote  Post ReplyReply Direct Link To This Post Posted: Sep/17/2010 at 9:16am
This may not be what a lot of more established teams do, but I know my team got the Polaris discount special Fox Podium X shocks with a few different spring combinations and called it good.  We did some analysis and testing to ballpark the rates we liked, and mainly focused on engineering a robust car before we spent a lot of time on tuning suspension... 
 
I think there is much more to a first year car than designing the perfect shock package... one of our cars rode somewhat like a dumptruck, but it was very stout.
 
All this is to say yes, suspension dynamics are important, but a strong car that will last the whole event so you can utilize the suspension is more important for a new team.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Rob71zilla Quote  Post ReplyReply Direct Link To This Post Posted: Sep/17/2010 at 2:38pm
Originally posted by Red_Beard Red_Beard wrote:

Originally posted by Rob71zilla Rob71zilla wrote:

Being a first year team, I would suggest using some sort of air shocks unless you have someone that is highly educated in the topic (which it sounds like you don't)  Air shocks will give you any spring rate you want (within reason) and are easy to design around. Fox Floats have a 0-150psi range, they are only compression adjustable but for a first year team I think that is a great starting point. Being a first year team, you probably don't have a large budget so they will help with that too. 


I am going to strongly disagree with you on this one.   Call up works and send them all your design parameters, and let them build a shock for your application.  We did that for 5+ years, and the cars that we still have around the shop with works shocks are awesome cars, mostly due to the shock set-ups they have.
 
Ok, fair enough.  I don't know anything about Works but I don't think you can argue that using air shocks to save some design time and money is a bad idea for a new team.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Red_Beard Quote  Post ReplyReply Direct Link To This Post Posted: Sep/17/2010 at 2:47pm
Originally posted by Rob71zilla Rob71zilla wrote:

Originally posted by Red_Beard Red_Beard wrote:

Originally posted by Rob71zilla Rob71zilla wrote:

Being a first year team, I would suggest using some sort of air shocks unless you have someone that is highly educated in the topic (which it sounds like you don't)  Air shocks will give you any spring rate you want (within reason) and are easy to design around. Fox Floats have a 0-150psi range, they are only compression adjustable but for a first year team I think that is a great starting point. Being a first year team, you probably don't have a large budget so they will help with that too. 


I am going to strongly disagree with you on this one.   Call up works and send them all your design parameters, and let them build a shock for your application.  We did that for 5+ years, and the cars that we still have around the shop with works shocks are awesome cars, mostly due to the shock set-ups they have.
 
Ok, fair enough.  I don't know anything about Works but I don't think you can argue that using air shocks to save some design time and money is a bad idea for a new team.


I can argue that exact point because I was the teams "shock guy" for 4 years, and that whole time we ran air-shocks....  Not externally adjustable ones, but true air shocks where you had to take them apart to tune them.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote dillon_b12 Quote  Post ReplyReply Direct Link To This Post Posted: Sep/17/2010 at 4:50pm
Be prepared for a 3+ hour conversation if you call Works and speak with a guy named "Sandy". LOL
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Oddly enough, the guy to talk to at Ryde Fx is also named sandy.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote RonGeorge Quote  Post ReplyReply Direct Link To This Post Posted: Sep/18/2010 at 3:52pm
Originally posted by Red_Beard Red_Beard wrote:

Originally posted by harshnarayanin harshnarayanin wrote:

I know i'm here to learn but if u could give me slight hint whether i'm on the right path or not it would be great. I calculated spring rate by considering the g force that the suspension would experience after jumping from  a 6 feet height and also took into consideration the motion ratio , the weight distribution on the fornt wheels and the amount of spring travel that i want on my suspension. Please understand as my college is doing this for the 1st time i just wanted to be sure.


Do you have any idea what kind of shocks you plan on running?  Coil-over, air-shock, by-pass...  Any particular manufacturer you are planning on running?   Unless you plan on going to Works, or plan on making your own shocks, and have spring made for you/buying them off the shelf, your relatively constrained to what spring rates you can run.  There aren't many manufacturers out there that will make a shock specifically for our application, you can get close, but to get really close you have to be willing to dedicate some serious time to R&D and testing.



Just did a quick search for Works Shocks. Well what do you know. People are pissed off with their products. http://www.horizonsunlimited.com/hubb/equipment-reviews/works-shocks-dont-work-23959

I dont know about others but with Fox Shocks, you get to choose your own "spring size" but by size, I'm assuming they mean rate, free length and so on.




Edited by RonGeorge - Sep/18/2010 at 3:53pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Red_Beard Quote  Post ReplyReply Direct Link To This Post Posted: Sep/18/2010 at 8:19pm
Originally posted by RonGeorge RonGeorge wrote:

Originally posted by Red_Beard Red_Beard wrote:

Originally posted by harshnarayanin harshnarayanin wrote:

I know i'm here to learn but if u could give me slight hint whether i'm on the right path or not it would be great. I calculated spring rate by considering the g force that the suspension would experience after jumping from  a 6 feet height and also took into consideration the motion ratio , the weight distribution on the fornt wheels and the amount of spring travel that i want on my suspension. Please understand as my college is doing this for the 1st time i just wanted to be sure.


Do you have any idea what kind of shocks you plan on running?  Coil-over, air-shock, by-pass...  Any particular manufacturer you are planning on running?   Unless you plan on going to Works, or plan on making your own shocks, and have spring made for you/buying them off the shelf, your relatively constrained to what spring rates you can run.  There aren't many manufacturers out there that will make a shock specifically for our application, you can get close, but to get really close you have to be willing to dedicate some serious time to R&D and testing.



Just did a quick search for Works Shocks. Well what do you know. People are pissed off with their products. http://www.horizonsunlimited.com/hubb/equipment-reviews/works-shocks-dont-work-23959

I dont know about others but with Fox Shocks, you get to choose your own "spring size" but by size, I'm assuming they mean rate, free length and so on.





What I know is they have worked us in the past.  We ran their shocks for something like 5 years with no issues.  Always good service, and a quality product, but I can't speak for their current service since we don't use them anymore.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ErikHardy Quote  Post ReplyReply Direct Link To This Post Posted: Sep/20/2010 at 7:35pm
Originally posted by Red_Beard Red_Beard wrote:


What I know is they have worked us in the past.  We ran their shocks for something like 5 years with no issues.  Always good service, and a quality product, but I can't speak for their current service since we don't use them anymore.
 
Which shocks from Works were you running? We have some old coil-overs (roughly 5.5" travel to the bump stop)  I found in the closet that I am considering using for the front suspension.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Red_Beard Quote  Post ReplyReply Direct Link To This Post Posted: Sep/21/2010 at 9:05am
Originally posted by ErikHardy ErikHardy wrote:

Originally posted by Red_Beard Red_Beard wrote:


What I know is they have worked us in the past.  We ran their shocks for something like 5 years with no issues.  Always good service, and a quality product, but I can't speak for their current service since we don't use them anymore.
 
Which shocks from Works were you running? We have some old coil-overs (roughly 5.5" travel to the bump stop)  I found in the closet that I am considering using for the front suspension.


We have two styles, but I couldn't tell ya what length they are, but that sounds about right 5"-5.5".  I'm sure the guys still at school are reading this and will chime in what lengths we have.
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