4 Link Calculator

[fluidfloyd]

For you guys that really want to work out the laws of physics in rear suspension systems, here is a neat little calculator I ran across a while back. This program was written for guys designing off road or rock climbing systems but the design math is the same. You will see a lot of useful help in the fact that you can vary 4 link tube lenght, diameter, wall thickness and material choice. It will show you pinion angle change as you bump the axle height. I have played with it several times a while back and it seems to be pretty good. I guess I need to work with it a bit more in my next project. I usually use another software package that is more suited for our application so maybe I'll run the same numbers on both and get a comparison. Once you download it, you don't have to be online and that makes it very handy. Hope you find it useful.

George

http://mysite.verizon.net/triaged/files/4BarLinkV3.1d.zip

 

[Chris@whiterhino]

I use this on a daily basis. Great took and since I build rock crawlers I get to play with it a bunch =)

 

[Alfwulf]

For you guys that really want to work out the laws of physics in rear suspension systems, here is a neat little calculator I ran across a while back. This program was written for guys designing off road or rock climbing systems but the design math is the same. You will see a lot of useful help in the fact that you can vary 4 link tube lenght, diameter, wall thickness and material choice. It will show you pinion angle change as you bump the axle height. I have played with it several times a while back and it seems to be pretty good. I guess I need to work with it a bit more in my next project. I usually use another software package that is more suited for our application so maybe I'll run the same numbers on both and get a comparison. Once you download it, you don't have to be online and that makes it very handy. Hope you find it useful.

George

http://mysite.verizon.net/triaged/files/4BarLinkV3.1d.zip

I really liked this app. but since I have been more of a sports car kind of guy, fast in turns and slow down the road slow to speak some of this drag stuff was...foriegn? I am used to reducing roll in turns etc.

Besides reducing squat I wasn't completely sure of the goals with the four link but I know it is GOOD especially via adjustablility.

This link helped me alot:
http://www.dragstuff.com/techarticles/PB-4linktuning.html

Lee

 

[Alfwulf]

I really liked this app. but since I have been more of a sports car kind of guy, fast in turns and slow down the road slow to speak some of this drag stuff was...foriegn? I am used to reducing roll in turns etc.

Besides reducing squat I wasn't completely sure of the goals with the four link but I know it is GOOD especially via adjustablility.

This link helped me alot:
http://www.dragstuff.com/techarticles/PB-4linktuning.html

Lee

Thanks George!

 

[Bucketman]

I really liked this app. but since I have been more of a sports car kind of guy, fast in turns and slow down the road slow to speak some of this drag stuff was...foriegn? I am used to reducing roll in turns etc.

Besides reducing squat I wasn't completely sure of the goals with the four link but I know it is GOOD especially via adjustablility.

This link helped me alot:
http://www.dragstuff.com/techarticles/PB-4linktuning.html

Lee

Wow, this is over my head. Never knew the rear end did so much, and that small changes in suspension can make such a difference. I think if I read it a couple more times it'll sink in.

 

[Bucketman]

For you guys that really want to work out the laws of physics in rear suspension systems, here is a neat little calculator I ran across a while back. This program was written for guys designing off road or rock climbing systems but the design math is the same. You will see a lot of useful help in the fact that you can vary 4 link tube lenght, diameter, wall thickness and material choice. It will show you pinion angle change as you bump the axle height. I have played with it several times a while back and it seems to be pretty good. I guess I need to work with it a bit more in my next project. I usually use another software package that is more suited for our application so maybe I'll run the same numbers on both and get a comparison. Once you download it, you don't have to be online and that makes it very handy. Hope you find it useful.

George

[URL='http://mysite.verizon.net/triaged/files/4BarLinkV3.1d.zip[/QUOTE']http://mysite.verizon.net/triaged/files/4BarLinkV3.1d.zip[/URL]

Couldn't get the link to open. I've been thinking so hard about the rear suspension my head hurts. I think I'm going to take a break today and put the floor into the body. Maybe a couple of days. If you know of or find another site that explains a TRS in depth please forward it to me. There is a lot more to the suspension than I ever knew, and it needs to be right to be safe.

 

[fluidfloyd]

Bucketman,

Don't let this suspension design wear you out. These cars are so lite weight that you can be as complicated or simplified as you want. You might just look at a bunch of them as I'm sure you have and make your choice on that alone. As long as you stay fairly traditional and simple you have a pretty good chance that will be fine. Just pick one that is popular and that will probably be your design guide and safety net. To optimize suspension in these cars is more of a personal challenge then anything.Just build it safe and strong, use common sense design and good welding and you'll be roaring down the highway while others are still thinking about their suspension. Now go have fun and don't be afraid to ask any questions. Might not have the correct answers but we'll figure it out. Take Care.

George

 

[Bucketman]

This looks simple. Uses a pan hard bar but like I said I have nothing against them just thought I could get away from it.

 

[fluidfloyd]

Bucketman,

Not sure what I'm seeing or not seeing. The 4 link I understand but not sure how you are centering it. That appears to be a flat plate that looks like it rides against the inside of the upper tube. If that is the case then I see several problems. If that is not the case I don't see any centering devise. Guess I need some vision guidance here.

George

 

[choppedtop]

The pan hard will be the centering devise. I think the plate you see is holding up the rearend so that it is about ride height.
Lee

 

[Francis Blake]

I don't know how those different length rods are going to work out, I have never seen any just like this before

 

[T-Test]

I don't know how those different length rods are going to work out, I have never seen any just like this before

With unequal length rods like that I'm sure the pinion will tilt downward as the rear end rises, but no more travel than what it will have, not enough to hurt or cause a vibration IMHO.

 

[Hotrod46]

The axle bracket could be rotated back so that the angle of the holes matched the angle of the frame bracket. Two of the bars would need to be lengthened so that they are all the same. That will eliminate the pinion angle change.

I would make at least one of the bars on each side adjustable for length.

Mike

 

[409T]

With unequal length rods like that I'm sure the pinion will tilt downward as the rear end rises, but no more travel than what it will have, not enough to hurt or cause a vibration IMHO.

It is also only momentary.

 

[baddawgcustoms]

I had Ron cut me a set of brackets to put the top bar a couple inches behind centerline of the rear. That keeps both bars the same length even tho they are mounted on the kick at an angle as above. The bottom bars are even with axle centerline and the top 2" back.

 

[Bucketman]

Bucketman,

Not sure what I'm seeing or not seeing. The 4 link I understand but not sure how you are centering it. That appears to be a flat plate that looks like it rides against the inside of the upper tube. If that is the case then I see several problems. If that is not the case I don't see any centering devise. Guess I need some vision guidance here.

George

I'm pretty sure that flat plate is being used to hold the differential at 3 degrees. Optical illusion. It does require a pan hard bar.

 

[Bucketman]

Here is what I ended up with on mine. Pan hard bar hasn't been installed yet. More grinding (yuck).