PDA

View Full Version : rear cantilever suspension.



v1c10us
05-28-2008, 10:10 PM
I remember reading a magazine and someone had put a cantilever suspension in either a fit, ep3, or ek.
now for those of you who don't know what this is, although you all probably do, the simplest(and not the way I would do it, i would probably use thick billet aluminum) way to do this would be to replace the spring with a rod, attached to another rod, making an upside down L, the stick of the l would go into the car where it would be attached to a pivot point with the strut/shock on the other end, with the end of the strut attached to some sort of joint allowing it to change angles.
in theory you could go as low as possible with this by just adjusting the length of the fabricated piece that would go where the strut/shock were without running into camber issues if you made the point that the strut/shock replacing rod mounts to the pivoting rod adjustable, such as by using several holes that could be chosen at any given time.
This would also allow you to adjust the stiffness if you used a progressive spring since changing the mount point would compress or uncompress the spring
I'm very tempted to do this in the rear of my ep3.
excluding shocks and springs I'm fairly sure I could get this done for under 1500 bucks total.

It would just be a matter of measuring everything out very well and then sending it off to be machined out of a massive block of aluminum, this would bolt up to the remaining stock suspension with no modifications. You would then need to find a place to mount one end of the shock/spring and you would also need to reinforce its mount points because I wouldn't feel comfortable just having it bolted to the thin chassis metal.
http://i45.photobucket.com/albums/f88/joshcivic/Rear%20Suspension/hatch.gif
http://i45.photobucket.com/albums/f88/joshcivic/Rear%20Suspension/Untitled-16.gif
http://images.superstreetonline.com/featuredvehicles/130_0702_09_z+extreme_dimensions_2007_honda_fit+in terior_view_honda_cbr_600rr_shocks.jpg
something like that, but with the pivoting piece longer and with adjustable mounting locations on both sides.
instead of a triangle I would use something long like an LCA and have it mounted further away from the hole the stock tophat mounts to. and the springs would be mounted vertically instead of at an angle such as these.
I do understand that these diagonal springs would serve to make the suspension stiffer and have less travel though.

I'm under the impression that you could run ridiculously stiff springs but due to the amount of leverage you would have on them you're travel could still be fairly significant.
input?

edit: i would end up elongating the hole that the rod comes out of into a rectangle to allow it to pivot to mount into a new hole, if you look at the last pic, it has 3 holes on each triangle, you could move it to a hole closer to the pivot point, and then on the opposite end, mount the spring on either a further or closer hole to the pivot point, allowing the suspension to be adjusted in stiffness and travel.

MugsyTheGr8
05-28-2008, 10:16 PM
for a race car go for it, but i dont think that re-engineering a cars suspension will be that simple.

v1c10us
05-28-2008, 10:20 PM
it isnt that complicated, a guy on honda tech did it quite simply
http://i45.photobucket.com/albums/f88/joshcivic/Rear%20Suspension/Untitled-15.gif
replaces shock/strut

http://i45.photobucket.com/albums/f88/joshcivic/Rear%20Suspension/Untitled-16.gif

http://i45.photobucket.com/albums/f88/joshcivic/Rear%20Suspension/hatch4.gif
fabricate those other pieces but with my modifications in mind and mount the shocks/struts.
I mean I know i could do it with the help of a few companys and welding shops etc.

twep
05-29-2008, 05:21 AM
that piece of rod holding the calipers doesn't look too strong lol

but it looks SO cool in the hatch

Drew1d
05-29-2008, 07:06 AM
It looks like a lot of work.

civiKSiborg
05-29-2008, 09:19 AM
Also looks like a good way to protect your shocks and springs from corrosion.

civictype_r04
05-29-2008, 10:31 AM
That is a crazy set up!:meek: I have never heard of or seen this before.

Tnhatch03
05-29-2008, 10:44 AM
wouldn't be hard to steal.

keep that in mind. haha

but anyways, i think it would be dope. go for it and let us know how it turns out.

!@#$%
05-29-2008, 11:19 AM
I think what mugsy meant by "not be so simple" is that the suspension that is manufactured is made at certain length to be a replacement for a car that is weighed to have support at each corner in different ways.

I'm sure when the Ford GT was made they didn't just say, "We'll take the mustang gt suspension and move it into the upper rear."

MugsyTheGr8
05-29-2008, 01:22 PM
I think what mugsy meant by "not be so simple" is that the suspension that is manufactured is made at certain length to be a replacement for a car that is weighed to have support at each corner in different ways.

I'm sure when the Ford GT was made they didn't just say, "We'll take the mustang gt suspension and move it into the upper rear."

exactly. there is a lot of complex geometry that goes into designing a suspension, and you would be hard pressed to design something that would be higher than the factory standard. im not saying don't do it, in fact i hope you do. it would be interesting to see what your feedback on it is when you complete it.

v1c10us
05-29-2008, 01:43 PM
well the guy on honda-tech did it and he said it was the nicest suspension he had ever driven.
It would be alot of work, but no more than an engine build, in fact probably less.
Installing all of the parts could be done quicker than swapping an engine provided you had all the materials and welding gear right there with you.

The reason I would make it adjustable is because as you said, I don't know about the suspension geometry, and allowing different mount points would make up for camber and stiffness and travel, which are the only things im concerned with since the rest of it would still be stock.
I think instead of that pushrod type thingy I would use a thick rectangular piece of billet with similiar mounting options at the top, basically it would be like the skunk2 LCA's cept a different shape.
When I get some funds and my streetbike I'll do this because In the event I fuck something up I cant be without transportation.

When/if I do ever get this underway I'll be sure to do a step by step of every stage of the build..
And I'll also do a before and after autoX time; haha!
see how much I improve without any additional practice just by changing the suspension to this wacko suspension.

Lucid Moments
05-29-2008, 02:56 PM
Interesting concept. It could work out to be pimp as hell, or it could suck enormously.

As you say the actual fabrication involved doesn't look too complicated. But getting the geometry right could be interesting. This would do all sorts of interesting things to your motion ratios and thus to your spring rates and damper rates.

One other aspect that might be worth thinking about is isolating the cabin from road noise. Not an issue in a race car of course, but in a daily driver you might want to think about it.

v1c10us
05-29-2008, 09:50 PM
yeah thats a good point on road noise.
I know that I could increase and decrease my motion ratio's by simply adjusting the point that the rod and springs are mounted to on the pivoting bar.
if you put the spring on the point closest to the pivot point and the push rod on the furthest point away from the pivot point you would have a large amount of torque on a very small area of motion. This would allow you to set it so that for every 5 inches the wheel travels up or down the opposite end could possibly move as little as 1 or 2 inches.
That would make the suspension very soft because you wouldn't have to compress the spring much for plenty of travel.
you could then do the opposite and require the spring to compress 5 inches for every 1 inch the wheel travels; thus making the suspension incredibly stiff regaurdless of the spring used.
Im fairly confident that with the adjustability I have in mind that I will be hard pressed to make the suspension worse than it is now.
Combine all this with adjustable shocks and adjustable height springs as well as possibly a threaded pushrod to replace where the shock/spring was to adjust the height and camber to make up for any modifications to mounting positions and you could have yourself a wicked track car that would only need to be jacked up for 20 minutes to be set back to soft and moderately low for daily driving

Tnhatch03
05-29-2008, 10:36 PM
go for it man.

i think it would be sick!

JCEM
05-29-2008, 10:42 PM
Huge props to whoever has he balls to do it...even bigger props if it actually handles decent.

v1c10us
05-29-2008, 11:00 PM
Im positive it will handle decent.
In fact I'm positive it will handle better than stock. the question is, how much better.
ima start savin up some cash and be one of the first(atleast the first I know of)people to put this sort of suspension in an Ep3

cow
05-29-2008, 11:17 PM
Super interesting concept. Subscribed for input from others.

Is there some sort of equivalent to what you've posted that would go in the front & address the EP's awful caster angles &/ or V'd steering rack?

Windchaser
05-29-2008, 11:27 PM
I have seen this type of suspension on a Toyota Yaris. It was built for racing (as expected). However, it got dominated by an Integra Type R with Ohlins DA coilovers.

v1c10us
05-30-2008, 12:10 AM
Super interesting concept. Subscribed for input from others.

Is there some sort of equivalent to what you've posted that would go in the front & address the EP's awful caster angles &/ or V'd steering rack?

unfortunately I have no idea how you could do anything in the front, with the space constrictions it wouldn't be easy and isn't anything Im up for trying to engineer.
Input for something for the front is welcome.

about the yaris, thats a yaris, you cant make a bad car perfect, but you can make a good car better.

Windchaser
05-30-2008, 12:15 AM
unfortunately I have no idea how you could do anything in the front, with the space constrictions it wouldn't be easy and isn't anything Im up for trying to engineer.
Input for something for the front is welcome.

about the yaris, thats a yaris, you cant make a bad car perfect, but you can make a good car better.

The Yaris had a better lap time than 3 competition S2000, an ITB/Turbo WRX, and plenty of other cars. The ITR was just faster for some reason.

v1c10us
05-30-2008, 12:26 AM
strange, I would say that the cars that the yaris beat should have also beat the ITR though, so I'm not sure what to say about that one.

oldschoolimport
05-30-2008, 12:35 AM
by changing your lever arm ratio, you can raise your spring/damper rates, in a shorter stroke, and achieve the same results as a full length coilover in standard configuration. if you had a 1:1 lever ratio, you could just move the stock coilovers into position. the reason to do this is for packaging, and unsprung weight in open wheel race cars. the ability to change spring/damper rates with lever changes is another benefit. :mredface:

v1c10us
05-31-2008, 12:00 AM
by changing your lever arm ratio, you can raise your spring/damper rates, in a shorter stroke, and achieve the same results as a full length coilover in standard configuration. if you had a 1:1 lever ratio, you could just move the stock coilovers into position. the reason to do this is for packaging, and unsprung weight in open wheel race cars. the ability to change spring/damper rates with lever changes is another benefit. :mredface:

haha well I read that 3 times and got the jist of what you're saying, thats sweet, so basically its awesome and provided I make it all adjustable it'll be the bomb? I mean thats the layman's version of what you said haha

oldschoolimport
05-31-2008, 06:22 AM
you really can't make the rocker adjustable (edit: you can if the top of the strut will clear the mount inside the rocker). you will need to make several different rockers and change them out, to be able to adjust that part of the set-up. actually, if you make a pair that the arms of the rocker are the same length, and then make a pair that one leg of the rocker is 1.5 times the length of the other arm, you could rotate that rocker 180 degrees and it would be like having 3 sets. the long arm could be used for the strut or the hub link side, either one (if you build the entire set-up correctly).

the rockers are the black pieces that the top of the struts/coilovers are bolted to, and that bolt to the rod going down where the original strut was. these also look like rear shocks from a liter bike (busa, zx-12 or the like).
http://i45.photobucket.com/albums/f88/joshcivic/Rear%20Suspension/hatch4.gif

Nitrofaint
05-31-2008, 06:31 AM
The Yaris had a better lap time than 3 competition S2000, an ITB/Turbo WRX, and plenty of other cars. The ITR was just faster for some reason.

Your statement really has no validity to support the disadvantages of running this type of suspension.

Nothing against you.

Also there really doesnt seem to be an real advantage to run the coilovers horizontally. The only benefit I see is that you are spreading out the weight more evenly across the car. It is also easier to install and uninstall the springs for each track/condition. But that's about it.

You are also adding more wieght with the additional parts, that could hurt handling. Something to consider is that you will probably be using some type of steel alloy if you go through with this. I wouldnt use aluminum.

v1c10us
05-31-2008, 01:16 PM
you really can't make the rocker adjustable (edit: you can if the top of the strut will clear the mount inside the rocker). you will need to make several different rockers and change them out, to be able to adjust that part of the set-up. actually, if you make a pair that the arms of the rocker are the same length, and then make a pair that one leg of the rocker is 1.5 times the length of the other arm, you could rotate that rocker 180 degrees and it would be like having 3 sets. the long arm could be used for the strut or the hub link side, either one (if you build the entire set-up correctly).

the rockers are the black pieces that the top of the struts/coilovers are bolted to, and that bolt to the rod going down where the original strut was. these also look like rear shocks from a liter bike (busa, zx-12 or the like).
http://i45.photobucket.com/albums/f88/joshcivic/Rear%20Suspension/hatch4.gif

well I wouldn't be doing the set up like the picture
Instead of diagonal/horizontal coilovers like in that picture mine would be almost straight up and down and the rocker would be straight instead of an L shape, that way you would be able to easily just pivot the coilover and pull the rocker down to attach it to the coilover at any point on the rocker arm.
and yea, they are showa shocks from a honda actually.
the rocker arm could either be two plates spaced apart like in the picture, or I could use a strong thick piece of metal of some sort that was offset from the coilover mounting position and use a big ass bolt.. I think the first choice might be better though.

in the event that I would have to replace the rocker arms that wouldn't be too much of a hastle, since everything would be in the car changing things out would be quite easy considering the lack of rust and the amount of space I'd have to work with.
edit:
I know this picture is horrible out of proportion. but you can kinda get what I was thinking here.. The rocker arm is the straight piece with 3 thins connected to it.
The middle one would be the point on which it pivots and then the left and right pieces could be mounted at different points on the arm. Most likely only the coil would be able to be mounted on different points because pivoting the shock replacement rod probably wouldn't work without adjusting a camber arm as well..

JDMCivicEP3
05-31-2008, 01:35 PM
I don't see any benefit in this application in a street car.

Windchaser
05-31-2008, 01:44 PM
Your statement really has no validity to support the disadvantages of running this type of suspension.

Nothing against you.

Also there really doesnt seem to be an real advantage to run the coilovers horizontally. The only benefit I see is that you are spreading out the weight more evenly across the car. It is also easier to install and uninstall the springs for each track/condition. But that's about it.

You are also adding more wieght with the additional parts, that could hurt handling. Something to consider is that you will probably be using some type of steel alloy if you go through with this. I wouldnt use aluminum.

I was not trying to disprove the advantages. I do not see any benefit in this application in a street car nor is it necessary to use it in a semi-race car, especially when the driver has never competed. It just goes to show that there is more to it in competitive racing.

v1c10us
05-31-2008, 10:04 PM
There isn't much purpose for it in a street car you are correct there sir, although spending a couple grand on suspension as many people do here for street cars hasn't much purpose either.
I feel this is no more futile than putting a set of $1000 coilovers in a street car, as well as sway bars strut bars x bars H bars c bars v bars and whatever else kinda fuckin bar the manufacturers wanna sell us.
This I feel will be tuneable to my preferences, so if i feel like driving a car that ride like a cadilac, I will have that choice, as well as setting it to stiff as shit for a track day if I want..
It is kind of silly, you got me there, but I wanna do it, if not for function but at least for form, although I bet this will be a bit of both.

Windchaser
05-31-2008, 11:48 PM
I'm not going to say, "don't do it." I would like to suggest that you should spend the money on some driving lessons before you even consider anything..

v1c10us
05-31-2008, 11:56 PM
Thats a nice suggestion, but how do you know how I drive or that I need driving lesson?
Did you take driving lessons? Or did you start off as a beginner and go to the track and run laps untill you got better and learned the fun, gritty, real way?
Even then, who's to say I plan on doing anything that would require me to drive better than I already do?
for what I do with my car I'm quite content with being able to heel toe and correct understeer, because thats all my car is capable of.. When my car is better than me, then I will get better for it.

Windchaser
06-01-2008, 12:12 AM
I took driving lessons and I am pretty sure that most people that compete in auto-cross took driving lessons as well. I still am taking driving lessons. You are correct to state that I do not know how you drive, but throwing down money on some suspensions with no expectation with what the turn out would be is ridiculous. There is a huge difference between pro drivers and an amateur. I took lessons, I practiced, took more lessons, practiced some more, and etc.

Do what you want, I'm done with this thread.

v1c10us
06-01-2008, 12:19 AM
dont have a hissy fit man, I'm just saying, i dont have ambitions to be a pro driver OR an amateur, I want to have fun.
This mod doesn't really reflect a want to be the best at autox.
I have an expectation of te turnout of the suspension, not having one and doing it would indeed be ridiculous, you are correct sir.
But that doesn't have anything to do with my driving, that has to do with the performance of this modification.

Windchaser
06-01-2008, 12:28 AM
dont have a hissy fit man, I'm just saying, i dont have ambitions to be a pro driver OR an amateur, I want to have fun.
This mod doesn't really reflect a want to be the best at autox.
I have an expectation of te turnout of the suspension, not having one and doing it would indeed be ridiculous, you are correct sir.
But that doesn't have anything to do with my driving, that has to do with the performance of this modification.

You want performance, but yet you have never felt the limit of your car. I thought my car being stock was slow. However, when the instructor drove my car, it was completely different. I have done several open track events before taking lessons, but he managed to drive the car 20 times faster and 20 times better than I did and I thought I was good being able to take top 5 in my class.

v1c10us
06-01-2008, 01:01 AM
You want performance, but yet you have never felt the limit of your car. I thought my car being stock was slow. However, when the instructor drove my car, it was completely different. I have done several open track events before taking lessons, but he managed to drive the car 20 times faster and 20 times better than I did and I thought I was good being able to take top 5 in my class.

did you read the part of my post earlier that said, "if not for function, then at least for form"?
I'm not doing this to GO FAST AT THE TRACK.
I said in my most recent post, I just wanna have fun.
I am sure that I have not felt the limit of my car, I have felt the limit of its traction though many many times, I'm sure i could pick better lines, learn to manage when I shift better and a few other things, but thats not the point of it for me.
I want to have fun, i want to learn, I want to go, man i bet if I had done blah blah blah I'd have gotten a better time.
I dont want some guy telling me what I'm doing wrong, so that I can go out and all I can think about is correcting my problems, its not about that for me.
This mod is just because I think it would be very cool, It would be different, new, unusual, functional.
It doesn't matter if i cant use it to its full potential.

also you say, you thought you were good being top 5 in your class.
Why would you want to feel that that is no longer good?
If I was top5 in my class i'd be damn happy, i'd enjoy myself and I'd have a grin for a month.
You go take lessons from some hotshot and now what are you, nothing, and the fun is gone.. so you take more and more lessons till you're as good as him, and then what the fuck do you do, you're an amazing driver with a shitty car..
I understand your logic and I'm not trying to say you're wrong, just that its not for me.
If I was really adamant about autocross and it was all i ate and slept and breathed then that'd be different.