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suspension design

FABRICATOR

Well-Known Member
#2
Cantilever: "a projecting beam or member supported at only one end"...
This is a great question but is a bit too broad to cover all at once here.
Can you explain what you mean by cantilever suspension?
(we'll assume it's rear only)
Are you thinking of moving the shock and spring forward to the end of the arm?
Are you thinking of not having a top link (like 3 link or 4 link) as in no link?
A true cantilever would involve both of these and is very possible.
And lastly, IRS or solid axle?
 

rdc

- users no longer part of the rdc family -
#3
I'm going to build a 127" wheel base truck to pre- run and looking to get at least 30" of traval. I was looking at the July issue of OFF-ROAD magazine and wanting to know if the Cantilever rear suspension that Martyn Atkins used on his 89 Blazer had any advantages over a 4 link trailing arm suspension, Or does a 4 link trailing arm rear suspension have an advantage over the other. Also would there be a cost big differance between the two?
 

rdc

- users no longer part of the rdc family -
#4
First off, WOW 30" of travel??? Thats huge! Why do you want so much? If you go for quality and get 20" you will be more than happy. Then what exactly are you trying to ask? I think you are confusing things. I am not an expert on this by all means. But I think what you are talking about is a cantilever shock set up, yes this could include coilovers. Advantages to this is you can put big shock under the bed of a truck and/or keep them up out of harms way. The only problems I see is you will have more moving parts and therefore more to break. I think you should keep things simple. You can run a cantilever set up with a leaf set up, i-beams, a-arms, straight axle and a link set up. You will always have to have links running to an axle. You must locate it somehow.... How much money are you looking to drop? from what you are talking about you have some serious cash burning a hole in your pocket!!!! Hope this helped some....

Tony
 

michael

Well-Known Member
#5
From looking at the article in Off-Road it appears that the cantilever that is being referred to is to place the spring(coilover) and shock(bypass)
behind the rear axle on an arm extending to the rear instead of a typical trailing arm that extends forward.. This seems to have been the rage
a few years back....mostly with 1/4 elliptic springs. It was said to make a short wheelbase truck handle more like a long wheel base.
So, referring to a solid rear axle......any tips for or against? I have no answers...just trying to add what I saw in the article. Thanks!

Michael <A target="_blank" HREF=http://jmartin.net/parker/goose.htm>jmartin.net/parker/goose.htm</A>
 

rdc

- users no longer part of the rdc family -
#6
That is imposible. You can not make a short wheel base work like a long wheel base. They way the handle bumps, i.e. whoops is timing. You can improve the performance of any wheel base but each has its pluses and miniuses.... If you take a short wheel base, lets say a bronco II, that has something like a 96" wheel base and drive through whoops you will find that when the front tires are going up a whoop the rear is going down one. This creates a wild bucking motion. You can make it go faster by improving wheel travel and shocks/spring. But you will never go as fast as a long wheel base car/truck with the same suspension.

Tony
 

FABRICATOR

Well-Known Member
#7
There's not much advantage to this type of cantilever suspension other than saving some bed space. It is relatively easy to layout and build. The extra weight won't be too noticeable on a full size street legal truck. A good 3 or 4 link will outperform it all around. As far as making a short wheel base truck act like a longer wheel base truck, this is because it adds a few hundred pounds to the rear end of the chassis. Some of Walker Evans dezert trucks took advantage of this characteristic with very short wheel bases. If you can build all or part of this system yourself and don't plan on racing it, it might be an O.K. way to go.
 

rdc

- users no longer part of the rdc family -
#8
Actually, cantiliver has a few advantages over traditional 3 or 4 link, it is easier to put the fuel cell in the middle of the car so the
constantly changing weight of the fuel cell effects the entire ride height not just the rear like it does when the fuel cell is way out
back and then you can move the constant weight of the shocks, springs, tires batteries out back for a more consistent weight
transfer of the truck which would make it easier too drive.
 

michael

Well-Known Member
#9
The key to the statement....Tigger....was "handle more like a long wheelbase"....not just like a long wheelbase. Apparently it is somewhat possible. Thanks for your concern.

Michael <A target="_blank" HREF=http://jmartin.net/parker/goose.htm>jmartin.net/parker/goose.htm</A>
 

rdc

- users no longer part of the rdc family -
#10
still impossible.... because if we are talking handling then you have to consider everything. Like cornering. And you have to be a very good driver to go fast in a short wheelbase on a curvey dirt road. But hey any car/ truck can be fast with the right person behind the wheel... And it is easy to make short wheelbases go fast. Thats why all them jeep ( CJ/ Wrangler) guys haul butt across the dez... This is just my opinion and is not meant to bash anyone.... If it works for you then thats all that matters, right?


Tony
 

Donahoe

Well-Known Member
#11
Everyone read Tricky88 post... He is the closest to being right. Everyone else gets a c-...... We did all the work on Martyn Atkins blazer. Even though in the artical it says differnt. A rear swing set up has its advatages.... Most of them being how the WHOLE car wieght transfers. later.

NEVER LIFT!!!!!
 

rdc

- users no longer part of the rdc family -
#12
I do agree with the weight transfer part. Better to have a constant wieght in the rear vs. a fuel cell that changes as you go...

Tony
 

Donahoe

Well-Known Member
#15
Klaus, Read chapter 3 in "engineering to win" there will be a pop quiz on friday. Wait a minute... They say the people that can do, do and people that cant teach.... I'm no teacher. here is something to ponder...check the attachment..

NEVER LIFT!!!!!
 

Chris_Wilson

Well-Known Member
#16
OK Kreg, I'll bite. Whatcha building? Prerunner? 1 car, TT? That's not your "TT"
development project is it?
 

Donahoe

Well-Known Member
#17
SHHHHHHHHHH top secret..... no its the back of our new trophy truck. The never ending project from hell.

NEVER LIFT!!!!!
 

rdc

- users no longer part of the rdc family -
#18
Well Kreg I told you awhile back about my project and its gettin real close now , I believe after hearing my description of it you said it sounded like a "screamer" Looking forward to takin it out and shakin it down a little! Heres a few pics
 

gary

Well-Known Member
#20
i don't know dirt about suspension design, but i've got a question. let's educate me a bit here. seems like your attachment pic's suspension would be harder to engineer than a standard type 4 link. don't the arc of the arms work better as "trailing arms" rather than reversed, as in your picture??? seems like the natural motion would be kinda backwards. i know yours isn't the only one ever with that set up, and i've always wondered. as the vehicle is traveling forward and hits a bump, wouldn't the tire want to go up and back?? i'm sure it's not that simple, but i'm just curious as to how that set up works, or works better, or is more space efficient, or whatever....please enlighten me.
 
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