Login    Forum    Search    FAQ

Board index » Racing Forum » Drive Train, Suspension and Brakes




Post new topic Reply to topic  [ 150 posts ]  Go to page Previous  1, 2, 3, 4, 5, 6, 7, 8 ... 10  Next
Author Message
 Post subject: Re: Suspension Dynamics.
 Post Posted: Wed Apr 08, 2009 7:12 pm 
Offline
User avatar

Joined: Wed Apr 19, 2006 8:20 pm
Posts: 5852
Location: N.J.
Elkyman wrote:
Ok Barry, obviously, you may think you have a problem with your springs, now, you have two sets of springs, and my question is what springs came on your chassis when you picked it up from the chassis shop???? were they these progressive springs?, or a regular style spring? If, they were the reg. style spring, ask the shop(unless you already know) what the rates were when you got the chassis, I would think this would put you back into the game with a new set, but, if you have these progressive springs, hmmmm, we still will need some help on these questions you have.

Can you call or visit on a web site of a spring company and find someone who can send you a graph of what an extremely well setup chassis graph should look like and then mention what you have and are getting for a plot on your graph and get some insight from a tech guy? I just don't know enough about this whole suspension system yet, but, I am on a mission to figure it all out and if I have to I will pay for the help to understand it all even better. I am a (SEE) person, and if I see it, and then do it, I can usually figure it out from there, but many variables come into play with suspensions and power and C/G to get the results we would like to get. Maybe your just at the max of what your car can produce with your power for your best or lowest 60foot time Barry????!!!
I am not sure, myself, but a 1.20 60foot time is one hell of a fast start to me when we compare to MY 1.40 hits!!!! Next :-$




John, The car came with 125lb springs in the rear and he told me that it may or may not need a softer one.......So when the short times were not constant I just tried a softer spring........Well that didn't work.....So I tried a different front spring to get some stored energy...... Well that didn't work....Then tried a different tire.......Well that didn't work....... Hope to get it working before I run out of $$$$$$$$$$$$$$$.....

_________________
Image
running E85
Best ET 8.07
Best MPH 170.71
Barry


Top 
 Profile  
 
 Post subject: Re: Suspension Dynamics.
 Post Posted: Wed Apr 08, 2009 8:45 pm 
Offline

Joined: Tue Feb 05, 2008 6:45 pm
Posts: 248
Do you have a video of the car leaving? A shot from the back, from the back and about 45° to the side and directly from the side? That would help alot. If you're intrested then I wouldn't mind talking on the phone. PM me here and I'll send you some contact info.

Don

_________________
GOODSON Tools & Supplies For Engine Builders


Top 
 Profile  
 
 Post subject: Re: Suspension Dynamics.
 Post Posted: Wed Apr 08, 2009 10:38 pm 
Offline

Joined: Tue Dec 02, 2008 9:03 pm
Posts: 87
Location: Texas Panhandle
Keep going shrinker......please.

_________________
Image


Top 
 Profile  
 
 Post subject: Re: Suspension Dynamics.
 Post Posted: Wed Apr 08, 2009 11:15 pm 
Offline
User avatar

Joined: Sat Feb 07, 2009 4:12 pm
Posts: 1215
Location: Adelaide Australia
Hi to All; I hope you don't think I'm trying to undermine anyone's efforts, it's just that there are many ways to skin a cat. I have considered all the ways that I have seen taught in the past and I can find situations where the methods dont fit. I know that when i set a car up I do it differently than any chassis shop or other person I have come across. But the differences are not much. Small details of what you pursue alters the car a lot. In drag racing a small amount is a lot and its hard to do. But that's the fun of it all. I have been involved in chassis setup longer than I've been making carburetors. Its always been my passion but people wont pay for a chassis setup like they do to purchase a carburetor.
The example of the monkey toy is a good representation of the effects of CG location. Whats important in analyzing physics is to visualize everything as an entity on paper first. It gets very complicated and confusing trying to deal with 3 dimensional forces at the beginning of learning. So lets start a conversation on just a 4 link drawn in a side view on a piece of paper.
Can a cad drawing be posted on here?
We need to set up a four link and then we can analyze what it does.


Top 
 Profile  
 
 Post subject: Re: Suspension Dynamics.
 Post Posted: Thu Apr 09, 2009 5:31 am 
Offline
User avatar

Joined: Wed Apr 19, 2006 8:20 pm
Posts: 5852
Location: N.J.
nlmsc33 wrote:
Beretta wrote:
Mel the short times have been up and down...Can't seem to get them consistent..
It will hook good and have 1.22 short time maybe once and then go to 1.24/1.23/1.25 then back to 1.22 O:) O:) O:) ...Dialing the car is a crap shoot..



Barry another dumb question just popped into my head.

Are the splits from 60 to 330 consistent??

Do you feel a VERY VERY slight shudder about 15-20 ft out? ... maybe sometimes worse than others?

sorry...that was 3 dumb questions =;




No shudder and splits differ .004 in three runs....The track was cold and lot's of wind...but the splits have always been good and usually only vary .002 or less..

The problem is on the starting line.......

_________________
Image
running E85
Best ET 8.07
Best MPH 170.71
Barry


Top 
 Profile  
 
 Post subject: Re: Suspension Dynamics.
 Post Posted: Thu Apr 09, 2009 5:43 am 
Offline
User avatar

Joined: Wed Apr 19, 2006 8:20 pm
Posts: 5852
Location: N.J.
want-a-be wrote:
Do you have a video of the car leaving? A shot from the back, from the back and about 45° to the side and directly from the side? That would help alot. If you're intrested then I wouldn't mind talking on the phone. PM me here and I'll send you some contact info.

Don




I don't have Video but I will try to get one next time out but I don't have any Idea
how to post it ](*,) .....No puter guy here so ay have to send it to you :-s ....
The track I go to is very strict on letting anybody on the starting line but I do know the track owner and the security guys so I will talk to them and try to get some one to get some Video....

_________________
Image
running E85
Best ET 8.07
Best MPH 170.71
Barry


Top 
 Profile  
 
 Post subject: Re: Suspension Dynamics.
 Post Posted: Thu Apr 09, 2009 12:21 pm 
Offline
User avatar

Joined: Tue Apr 18, 2006 9:54 pm
Posts: 1619
Location: Western Illinois
Shrinker, I think we are closer to the same train of thought on this than either of us think. The difference is in wording. The force line is different from how it effects the center of gravity, or should I say the center of mass. This is the whole car's weight. The line of force never changes it is ground level for practical purposes going straight forward. How it effects the center of mass COG is what changes. Now every car has a COG above ground level. True? So all cars have a COG that to achieve an equal and opposite force, ( Newtons Law of motion), have to rise or attempt to because they can't go down or straight to the rear as they would prefer to. Take IC out of this for now. To visualize this balance a broom on your finger against the wall. The wall is the track. To raise COG, bring the top of the broom away from the wall. It's COG is no longer in the direct line of force. The farther you move the broom top away from the wall the easier or faster it will make gains to get to the starting point of force. It wants to be where it started. ( things in motion tend to stay in motion and things at rest tend to stay at rest) Newtons law of motion. This and very little torque from ring gear climbing pinion gear is weight transfer.

Now add An IC of suspension. All sprung suspensions have one, with out exception. This IC just modifies weight on rear contact patch. That may change spring rate and even give faster initial weight, that effects traction. Traction is part of the power/ traction combination that increases or decreases forward force. This is the only effect it has on weight transfer, because COG and force line never change. Sure once transfer starts, the COG will get higher and make it easier to transfer weight. this is where the balance of power/ traction and COG come in.

In both Monster truck tires and go kart tires, we change COG height by changing ride height. When COG height changes the instant center has to change to get the same Effect. To get a neutral IC the higher the COG is, the higher the IC will be. and vice verse. So you are right the bars shouldn't be at the same angles for both. For every inch a COG goes up, the IC will go up a fraction of that inch depending on the wheel base.

_________________
Older I get the less I know for sure Dennis


Top 
 Profile  
 
 Post subject: Re: Suspension Dynamics.
 Post Posted: Thu Apr 09, 2009 1:04 pm 
Offline
User avatar

Joined: Sat Nov 03, 2007 4:44 pm
Posts: 1423
Location: Clawson, Mi.
Beretta wrote:
Elkyman wrote:
Ok Barry, obviously, you may think you have a problem with your springs, now, you have two sets of springs, and my question is what springs came on your chassis when you picked it up from the chassis shop???? were they these progressive springs?, or a regular style spring? If, they were the reg. style spring, ask the shop(unless you already know) what the rates were when you got the chassis, I would think this would put you back into the game with a new set, but, if you have these progressive springs, hmmmm, we still will need some help on these questions you have.

Can you call or visit on a web site of a spring company and find someone who can send you a graph of what an extremely well setup chassis graph should look like and then mention what you have and are getting for a plot on your graph and get some insight from a tech guy? I just don't know enough about this whole suspension system yet, but, I am on a mission to figure it all out and if I have to I will pay for the help to understand it all even better. I am a (SEE) person, and if I see it, and then do it, I can usually figure it out from there, but many variables come into play with suspensions and power and C/G to get the results we would like to get. Maybe your just at the max of what your car can produce with your power for your best or lowest 60foot time Barry????!!!
I am not sure, myself, but a 1.20 60foot time is one hell of a fast start to me when we compare to MY 1.40 hits!!!! Next :-$




John, The car came with 125lb springs in the rear and he told me that it may or may not need a softer one.......So when the short times were not constant I just tried a softer spring........Well that didn't work.....So I tried a different front spring to get some stored energy...... Well that didn't work....Then tried a different tire.......Well that didn't work....... Hope to get it working before I run out of $$$$$$$$$$$$$$$.....




So how many passes do you have on the 125 lb springs total? they could be worn out!!!!!!! and maybe another set of the same will do it, or the next size up for a rate, and also put back the front springs you changed already and see what happens then, just trying to figure out where you lost your 60ft, maybe after changing your front springs...? Seems you may have went the wrong way with the rear springs, and maybe you should have gone with a stronger spring instead of a softer spring in the rear.
What does the front end do on the launch?, does it come up at all and how much?, does the rear just crunch and squat down and not lift the front tires at all???, do you think you are fighting the rears with the fronts? does is porpous off the line at all? Does it feel like it shoots off the line and then things start to change too much for your liking?

Yeah, we need some video Barry, and someone can just be behind the burnout box and do a closeup of the rear of the car, and still be safe. Got any still shots of the car from the front and rear on angles????? I think you posted some already somewhere didn't you? Your turn. =;

_________________
Image
Thanks To;
DART
Motor City Muscle
Induction-Solutions
Fuelab Fuel System
D & S Engines
My Wife & Family




R.i.p. Doug Cunningham, gone, not forgotten.


Top 
 Profile  
 
 Post subject: Re: Suspension Dynamics.
 Post Posted: Thu Apr 09, 2009 6:43 pm 
Offline

Joined: Tue Feb 05, 2008 6:45 pm
Posts: 248
I was just looking at the pic of your rear suspension. It just occured to me that your track locator is bottomed out. I realize that the car is suspended and the rear end is pretty much hanging on the shocks. But to me ,....from what I can see. The looks like a pretty good possibility for a bind there upon launch. Since it's on the botton of the rear end it will also promote the bind since the pinion rotates up,...thus closing up the gap on the slip joint. You could lengthen the 4 link bars if you need to give it some more room. Will onlt make the wheel base a bit longer. Doesn't look like the wish bone can be shortened much. That kind of bind, if it's happening, can really make your car very inconsistent. How much room do you have when everything is at ride height?

Hope this helps, would be an easy fix.

Don

Wayne County

BTW,...if you want to talk about it I'll be glad to send you the contact information. If you were closer I'd be glad to tune it for you.

_________________
GOODSON Tools & Supplies For Engine Builders


Top 
 Profile  
 
 Post subject: Re: Suspension Dynamics.
 Post Posted: Thu Apr 09, 2009 7:40 pm 
Offline

Joined: Sat Sep 22, 2007 7:05 am
Posts: 88
Location: Orlando, FL
Beretta wrote:
So by moving them closer to the CL of the axle what does this do????????

If the IC remains in the same location, all this does is increase the loads in the links. The car will behave exactly...repeat, exactly...the same. This is because the line passing through the rear tire patch and the IC defines the line of action of the force acting to accelerate the car.

It follows then, that there exists an infinite number of IC locations which provide exactly the same performance. That is, there are an infinite number of points on that line. That line defines a certain percentage of antisquat. Your 4link software should provide that percentage. If not, there's a spreadsheet at my site.
http://home.earthlink.net/~whshope
over 140,000 page views


Top 
 Profile  
 
 Post subject: Re: Suspension Dynamics.
 Post Posted: Thu Apr 09, 2009 8:38 pm 
Offline
User avatar

Joined: Wed Apr 19, 2006 8:20 pm
Posts: 5852
Location: N.J.
[quote="want-a-be"]I was just looking at the pic of your rear suspension. It just occured to me that your track locator is bottomed out. I realize that the car is suspended and the rear end is pretty much hanging on the shocks. But to me ,....from what I can see. The looks like a pretty good possibility for a bind there upon launch. Since it's on the botton of the rear end it will also promote the bind since the pinion rotates up,...thus closing up the gap on the slip joint. You could lengthen the 4 link bars if you need to give it some more room. Will onlt make the wheel base a bit longer. Doesn't look like the wish bone can be shortened much. That kind of bind, if it's happening, can really make your car very inconsistent. How much room do you have when everything is at ride height?

Hope this helps, would be an easy fix.

Don





Don, That was a picture when I was assembling the rear...It has a good inch before it bottoms out and from looking at it it looks like it only moves less than a half inch..

You have a PM Don......

_________________
Image
running E85
Best ET 8.07
Best MPH 170.71
Barry


Top 
 Profile  
 
 Post subject: Re: Suspension Dynamics.
 Post Posted: Thu Apr 09, 2009 10:13 pm 
Offline

Joined: Tue Feb 05, 2008 6:45 pm
Posts: 248
Sent you some info

Don

_________________
GOODSON Tools & Supplies For Engine Builders


Top 
 Profile  
 
 Post subject: Re: Suspension Dynamics.
 Post Posted: Fri Apr 10, 2009 6:58 am 
Offline
User avatar

Joined: Wed Apr 19, 2006 8:20 pm
Posts: 5852
Location: N.J.
BillyShope wrote:
Beretta wrote:
So by moving them closer to the CL of the axle what does this do????????

If the IC remains in the same location, all this does is increase the loads in the links. The car will behave exactly...repeat, exactly...the same. This is because the line passing through the rear tire patch and the IC defines the line of action of the force acting to accelerate the car.

It follows then, that there exists an infinite number of IC locations which provide exactly the same performance. That is, there are an infinite number of points on that line. That line defines a certain percentage of antisquat. Your 4link software should provide that percentage. If not, there's a spreadsheet at my site.
http://home.earthlink.net/~whshope
over 140,000 page views




Thanks Billy.........Keep going and tell us more =;

_________________
Image
running E85
Best ET 8.07
Best MPH 170.71
Barry


Top 
 Profile  
 
 Post subject: Re: Suspension Dynamics.
 Post Posted: Fri Apr 10, 2009 7:14 am 
Offline

Joined: Sun Nov 11, 2007 10:33 am
Posts: 1293
Location: Montgomery, Alabama
I'm glad yall at least moved off the springs. He could have 90's or 150's on the car and it wouldn't matter in this case.

If the shocks are fine and the suspension is not binding then it is either A, The IC is too high, B, not enough starting line gear, or C both.


Top 
 Profile  
 
 Post subject: Re: Suspension Dynamics.
 Post Posted: Fri Apr 10, 2009 7:25 am 
Offline
User avatar

Joined: Wed Apr 19, 2006 8:20 pm
Posts: 5852
Location: N.J.
Scott Smith wrote:
I'm glad yall at least moved off the springs. He could have 90's or 150's on the car and it wouldn't matter in this case.

If the shocks are fine and the suspension is not binding then it is either A, The IC is too high, B, not enough starting line gear, or C both.






Good to see your back =; ........I can lower the IC to between 3 to 5 inchs but it will be 47 to 50" long :-s .......I know that you wanted mid 50s......All this stuff makes me crazy cause I don't understand most of it but now getting some of it and glade most have kept on posting =; =; ........

_________________
Image
running E85
Best ET 8.07
Best MPH 170.71
Barry


Top 
 Profile  
 
Display posts from previous:  Sort by  
 
Post new topic Reply to topic  [ 150 posts ]  Go to page Previous  1, 2, 3, 4, 5, 6, 7, 8 ... 10  Next

Board index » Racing Forum » Drive Train, Suspension and Brakes


Who is online

Users browsing this forum: No registered users and 1 guest

 
 

 
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to:  
cron