Login    Forum    Search    FAQ

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




Post new topic Reply to topic  [ 45 posts ]  Go to page Previous  1, 2, 3
Author Message
 Post subject:
 Post Posted: Fri Oct 05, 2007 9:48 pm 
Offline
User avatar

Joined: Tue Apr 18, 2006 10:44 pm
Posts: 1507
Location: Tennessee
I also have the Bickel book and four link wizard. I have not seen the other book, but I know the Bickel book has helped me set my car up and understand what is going on.

This is a good thread, I really appreciate Mr.Shope coming on here and helping us understand this stuff.
Greg

_________________
Image


Top 
 Profile  
 
 Post subject:
 Post Posted: Fri Oct 05, 2007 9:54 pm 
Offline
User avatar

Joined: Tue Apr 18, 2006 10:44 pm
Posts: 1507
Location: Tennessee
George, I made a four link change this spring and now have that twist thing going on, I went out further than I was before and it really helped my 60s ( more consistant ) it took some hit out.

_________________
Image


Top 
 Profile  
 
 Post subject:
 Post Posted: Fri Oct 05, 2007 10:02 pm 
Offline
User avatar

Joined: Tue Apr 18, 2006 10:44 pm
Posts: 1507
Location: Tennessee
[quote="nlmsc33"]man reading all this makes me wish my roadster had good ol' ladder bars on it. #-o

Awww Mel, all you need is a good pair of leaf springs =;

_________________
Image


Top 
 Profile  
 
 Post subject:
 Post Posted: Fri Oct 05, 2007 10:11 pm 
Offline
Site Admin
User avatar

Joined: Tue Apr 18, 2006 7:28 pm
Posts: 1780
Location: Newport News, VA
StrokerCamaro wrote:
George, I made a four link change this spring and now have that twist thing going on, I went out further than I was before and it really helped my 60s ( more consistant ) it took some hit out.


I think that's what Rick was talking about earlier, more roll as you get further out.  One thing among several I learned from Dennis is that if it's rolling right, crank in more preload in the right rear.  That was not his first choice, I think moving weight was, but the preload change was on his list.

See Dennis, I do pay attention...sometimes. =;

George


Top 
 Profile  
 
 Post subject:
 Post Posted: Fri Oct 05, 2007 10:31 pm 
Offline
User avatar

Joined: Tue Apr 18, 2006 9:54 pm
Posts: 1619
Location: Western Illinois
gdmii wrote:
Bubstr wrote:
Here is a mind blower. On most Dirt Late models the 4 link is fitted to the housing on at least one side with a floating bearing. If not connected to the chassis it could swing in a full 360 on the tube. It still produces an IC, and can produce compression or separation. How does it do it? If you can figure this out it will help you understand the nature of force transmitted threw IC. Think on it and I will give the answer latter.


I think my mind is already blown, Dennis.  This sounds like the swing arm setup I've heard about but I've never gotten into the mechanics of it.

George


Ok George They have a multitude of different set ups. The 4 link, 4bar , Zlink , Pull bar, 5th coil, 6th coil, Fast boys. They are all the new best thing, lol about 60 years ago. They all do the same things, some better than others but the same. I used the fast boys set up in the late 70s, it's the new hot set up a couple years ago.

Down to the reason this loose 4 link acts almost the same as if it was welded to the housing, is because them bars don't lift or push down on the chassis, directly. the transmit force threw the instant center line, and depending where the IC line pushes on the mass of the car, the car will try to go over top or bottom, thus you are not pushing at the mass center. When you don't push right at center the result is the separation or compression.  them bars compensate for the mis alignment. Where we run into trouble is when we get it backward and think the bars lift the car. they do but that isn't the force  that is the reaction, and it's only the rear of the car. Where the bars are pointed lifts the cars front.

Now try to apply this to a theory that says the farther out the point is the harder it will lift the car, when if it was not connected to the rear housing, what would it lift from? Answer is it lifts from the difference between the IC and COG, and compression or separation that lifts or lowers the rear only is a result of it.

_________________
Older I get the less I know for sure Dennis


Top 
 Profile  
 
 Post subject:
 Post Posted: Fri Oct 05, 2007 10:55 pm 
Offline
Site Admin
User avatar

Joined: Tue Apr 18, 2006 7:28 pm
Posts: 1780
Location: Newport News, VA
Believe it or not but I actually understood that.  I surmized as much but wasn't sure enough to say.  It's still the same old "Where do you push on the refrigerator" deal sounds to me like.

George


Top 
 Profile  
 
 Post subject:
 Post Posted: Fri Oct 05, 2007 11:42 pm 
Offline

Joined: Sat Jun 10, 2006 5:28 pm
Posts: 1744
Location: Colorado
First off thanks for watering down that mud a little Dennis.

Just out of curiosity, what would keep the axle from rotating in the bearings? Or is one side still welded?


Top 
 Profile  
 
 Post subject:
 Post Posted: Sat Oct 06, 2007 12:54 am 
Offline
User avatar

Joined: Tue Apr 18, 2006 9:54 pm
Posts: 1619
Location: Western Illinois
slow72velle wrote:
First off thanks for watering down that mud a little Dennis.

Just out of curiosity, what would keep the axle from rotating in the bearings? Or is one side still welded?


On the full floating set ups you have a bar just to the left of center that runs forward to about tail shaft area. There it is connected to a bell crank, on the other end of the bell crank is two coil overs with about 600 lbs springs that cushion the hit and the let off the gas .This is also adjustable to soften the hit. that bar also will preload the right rear, counteracting torque induced roll. They have to mount the brakes off the four link.  On the fast boys set up they use a very well arched spring on the left and a floater on the right when you hit the go peddle the rear end steers to the left by pushing that side to the rear. on them they usually just use one 5th coil for acceleration help to the leaf, and to control spring wrap up. The funny thing is most of these concepts was thought of way before any of us where born, some before my father was born, 1905. They just keep coming back. The first 4 link I saw was on a pre WW2 sports car. I've seen links with spring inside them that collapse under acceleration, ones called J bars that wrap around connecting point and collapse to lengthen them.

If you ever get a chance look under a Dirt car, they have some of the most bizarre set ups you have ever seen. It's tech meets the mad scientist. It's never dull.

_________________
Older I get the less I know for sure Dennis


Top 
 Profile  
 
 Post subject:
 Post Posted: Sat Oct 06, 2007 1:11 am 
Offline
User avatar

Joined: Tue Apr 18, 2006 9:54 pm
Posts: 1619
Location: Western Illinois
gdmii wrote:
Believe it or not but I actually understood that.  I surmized as much but wasn't sure enough to say.  It's still the same old "Where do you push on the refrigerator" deal sounds to me like.

George


Yep Same refrigerator they pushed when on stone wheels and the same one they will use when we are riding on a magnetic field. Just put the beer on the bottom shelf if you have a lot of horsepower.

_________________
Older I get the less I know for sure Dennis


Top 
 Profile  
 
 Post subject:
 Post Posted: Sat Oct 06, 2007 7:47 am 
Offline

Joined: Sat Sep 22, 2007 7:05 am
Posts: 88
Location: Orlando, FL
I wish you guys could see me wave my hands and hear me yell as I talk. I'm sure everything would be clearer.

Seriously, what I've related is simply that which is found in reference books found in the office of every suspension engineer. And, of course, it was taught me in school. If you'd be interested in buying a reference book which, at the same time, strongly relates to racing, I'd recommend "Race Car Vehicle Dynamics," by Doug and Bill Milliken. You can buy it through the SAE, but it's cheaper through Amazon.

Short of that, you could read the "Getting Started" section on the first page of my site.

What I can't understand is the reluctance to use the traction dyno! Why waste your time and money on repeated trips to the strip and video analysis when you can measure everything at your shop without even starting the engine? Do you have equal rear tire loading on launch? The traction dyno will tell you. How much rise at the front and how much squat or rise at the rear? The traction dyno will tell you. What happens when you preload this link? The traction dyno will tell you. What happens when I move the links to this hole? The traction dyno will tell you.

Which makes more sense: A dozen trips to the strip or one afternoon with a traction dyno?

(I'm now waving my arms AND yelling.)

_________________
http://home.earthlink.net/~whshope


Top 
 Profile  
 
 Post subject:
 Post Posted: Sat Oct 06, 2007 8:31 am 
Offline
Site Admin
User avatar

Joined: Tue Apr 18, 2006 7:28 pm
Posts: 1780
Location: Newport News, VA
Billy,

Point taken on the arm waving. =;  =;

I want to thank you for being here and sharing with us your vast knowledge even though it may take a few times for you and Dennis to get points across to hard heads like me.  Usually, once I can visualize something, it sinks in pretty fast.  It's just getting to that point that takes time. =;  I have been to your website.  There's a LOT of info there and it will take several visits for it to soak in.  

I'm happy with my car right now.  It's working well although that's not to say it can't be made better.  But I don't think one can have enough understanding of why it does what it does.

And I promise I will try out your dyno!

George


Top 
 Profile  
 
 Post subject:
 Post Posted: Sat Oct 06, 2007 11:12 am 
Offline
Moderator
User avatar

Joined: Tue Apr 18, 2006 3:20 pm
Posts: 1457
Location: Missouri
BillyShope wrote:
What I can't understand is the reluctance to use the traction dyno! Why waste your time and money on repeated trips to the strip and video analysis when you can measure everything at your shop without even starting the engine? Do you have equal rear tire loading on launch? The traction dyno will tell you. How much rise at the front and how much squat or rise at the rear? The traction dyno will tell you. What happens when you preload this link? The traction dyno will tell you. What happens when I move the links to this hole? The traction dyno will tell you.

Which makes more sense: A dozen trips to the strip or one afternoon with a traction dyno?

(I'm now waving my arms AND yelling.)


I heard you yelling that time but couldn't see the arms waving.  =;

I think there are 2 things keeping me (and others) from using the traction dyno.

1. Lack of scales. They are not cheap and most don't have them.

2. Lack of a good place on the car to pull from at the correct height. On most door cars the sheetmetal is in the way over most of the rear of the car.

Maybe a full understanding of the process too. :-k

With an automatic car am I correct that you have the trans in Park to hold the driveshaft while pulling on the chassis? It says in the article to hold engine so I assumed this is how to do it for automatic.

Rick


Top 
 Profile  
 
 Post subject:
 Post Posted: Sat Oct 06, 2007 11:30 am 
Offline
User avatar

Joined: Tue Apr 18, 2006 9:54 pm
Posts: 1619
Location: Western Illinois
Billy If I was still racing I'd be on that Traction Dyno in a New York Minute. That thing sounds like the best idea I've heard in a long time. I think there may be two things that deter some. One access to scales and two how to hook it to a door car with a rear body panel in the way. I wonder if you could build a car on one of these? Maybe I'll find out, if my son in law ever gets done building his new house so we can play.

_________________
Older I get the less I know for sure Dennis


Top 
 Profile  
 
 Post subject:
 Post Posted: Sat Oct 06, 2007 12:36 pm 
Offline

Joined: Sat Sep 22, 2007 7:05 am
Posts: 88
Location: Orlando, FL
Rick360 wrote:
2. Lack of a good place on the car to pull from at the correct height. On most door cars the sheetmetal is in the way over most of the rear of the car.


It is often possible to pass the chain under an open trunk lid, open an access hole in the center of the car, and then "Y" out to the cage. The spreadsheet allows for a chain height different from the CG height. The program simply adjusts your results to take this into account.


Rick360 wrote:
With an automatic car am I correct that you have the trans in Park to hold the driveshaft while pulling on the chassis?


That's correct. With a manual, it's often possible to engage two gears at once.

_________________
http://home.earthlink.net/~whshope


Top 
 Profile  
 
 Post subject:
 Post Posted: Sat Oct 06, 2007 1:43 pm 
Offline
User avatar

Joined: Tue Apr 18, 2006 9:54 pm
Posts: 1619
Location: Western Illinois
Maybe build a big L shaped hook, like body men use to straighten these areas with out removing the rear body panel.
I have seen guys using a couple bathroom scales, bridging them with a two by twelve, then adding the numbers. I'm not sure how accurate that would be.

_________________
Older I get the less I know for sure Dennis


Top 
 Profile  
 
Display posts from previous:  Sort by  
 
Post new topic Reply to topic  [ 45 posts ]  Go to page Previous  1, 2, 3

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