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Hontec
Lookin' good beerchug.gif Can't wait for the mockup....
plymouth37
I did a loose mockup this morning, everything is just held on with zipties but you can get a pretty good idea of how this is supposed to work. I ran it through its entire range of movement and it looks like I am free of interference and binding so the next step is building mounts for everything then connecting this assembly to the trailing arm.

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plymouth37
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Ferg
pray.gif Looking Good!

Hey you going to the Rod show in Denver Friday?

Ferg
plymouth37
I am going to be in Wyoming until Sunday night so it looks like I will miss it, too bad, looks like it will be a good show!
Hontec
Nice work, can't wait to see the rest of the construction!
plymouth37
QUOTE(jd74914 @ Nov 21 2010, 03:32 PM) *

One suggestion though. You might want to look into adding a bearing at the bellcrank's pivot point. While the car weights and hence suspension forces are radically different, we found the stiction to be pretty [unacceptably] high on our FSAE car with only a bushing.


I think I will go with a bearing rather than the bushing I was planning on using. I just drilled a 1/2 hole at the pivot point for now to get the arm mounts placed, what type of bearings did you guys use on the FSAE car and where did you source them?
trojanhorsepower
OK I have a stupid question that I have wanted to ask you for a long time. Why does your car stay so shiny?? Did you clear coat it? I love this build and am just wondering since every thing I touch turns immediately to rust. Would you consider leaving it shiny with grinder marks.... I think it looks cool.

Eagerly awaiting more pictures

-Pete
plymouth37
QUOTE(trojanhorsepower @ Nov 24 2010, 06:16 PM) *

OK I have a stupid question that I have wanted to ask you for a long time. Why does your car stay so shiny?? Did you clear coat it? I love this build and am just wondering since every thing I touch turns immediately to rust. Would you consider leaving it shiny with grinder marks.... I think it looks cool.

Eagerly awaiting more pictures

-Pete


The main factor is the fact that I live in Colorado and we have almost no humidity, any bare steel takes a good long time to gather even a dusting of surface rust. As far as the body goes I shot it with a layer of clear coat about 4 years ago and it has kept the rust at bay pretty well over the years. I did run the car for a couple years with just the clear coat, works pretty well when you can't afford a fancy paint job!
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McMark
I'm not sure I understand. Seems like that orientation will achieve very little shock compression, because the pivot point is not between the trailing arm attachment and the shock attachment.

What am I missing?
plymouth37
The trailing arm will push up on what is now the open bolt hole in the pivot arm. That upward motion will cause the trailing arm to rotate in a counter-clockwise direction (on the passenger side). The upward force of the trailing arm is counteracted by the vertical and horizontal forces of the shock, given the angle of the shock about 392 pounds of its force will be acting horizontally on a point that is 5" above the pivot point while around 75 pounds of the shock resistance acts vertically on a point 7.5" off of the pivot point. These leverage points are counteracted by the trailing arm that attaches at a point 10" off of the pivot point. Since the trailing arm has a mechanical advantage on the shock the 400lb/in in the shock gets reduced down to about 250lb/in at the trailing arm which is just about what I want. Not sure if that clears anything up, I won't know for sure exactly how this thing will react until I get everything done and jump around on it wink.gif
MDG
QUOTE(plymouth37 @ Nov 25 2010, 02:07 AM) *

The trailing arm will push up on what is now the open bolt hole in the pivot arm. That upward motion will cause the trailing arm to rotate in a counter-clockwise direction (on the passenger side). The upward force of the trailing arm is counteracted by the vertical and horizontal forces of the shock, given the angle of the shock about 392 pounds of its force will be acting horizontally on a point that is 5" above the pivot point while around 75 pounds of the shock resistance acts vertically on a point 7.5" off of the pivot point. These leverage points are counteracted by the trailing arm that attaches at a point 10" off of the pivot point. Since the trailing arm has a mechanical advantage on the shock the 400lb/in in the shock gets reduced down to about 250lb/in at the trailing arm which is just about what I want. Not sure if that clears anything up, I won't know for sure exactly how this thing will react until I get everything done and jump around on it wink.gif


Halfway through reading that I had to take a nap. I said it before, pages back - mad scientist at work here.

God I love this thread.
plymouth37
QUOTE(MDG @ Nov 25 2010, 06:24 AM) *

QUOTE(plymouth37 @ Nov 25 2010, 02:07 AM) *

The trailing arm will push up on what is now the open bolt hole in the pivot arm. That upward motion will cause the trailing arm to rotate in a counter-clockwise direction (on the passenger side). The upward force of the trailing arm is counteracted by the vertical and horizontal forces of the shock, given the angle of the shock about 392 pounds of its force will be acting horizontally on a point that is 5" above the pivot point while around 75 pounds of the shock resistance acts vertically on a point 7.5" off of the pivot point. These leverage points are counteracted by the trailing arm that attaches at a point 10" off of the pivot point. Since the trailing arm has a mechanical advantage on the shock the 400lb/in in the shock gets reduced down to about 250lb/in at the trailing arm which is just about what I want. Not sure if that clears anything up, I won't know for sure exactly how this thing will react until I get everything done and jump around on it wink.gif


Halfway through reading that I had to take a nap. I said it before, pages back - mad scientist at work here.

God I love this thread.


That was quite possibly one of the most boring things I have ever written. biggrin.gif
The shape of the pivot arm is deceiving, the shock is given a lot more leverage than it looks like it should have.
And since the trailing arm has a mechanical advantage on the shock the spring needs to move less to counteract it. The spring will only have a 2-3 inch range of compression.
While I am on here: Have a Happy Thanksgiving Everybody! beerchug.gif
MDG
QUOTE(plymouth37 @ Nov 25 2010, 10:26 AM) *

QUOTE(MDG @ Nov 25 2010, 06:24 AM) *

Halfway through reading that I had to take a nap. I said it before, pages back - mad scientist at work here.

God I love this thread.


That was quite possibly one of the most boring things I have ever written. biggrin.gif
The shape of the pivot arm is deceiving, the shock is given a lot more leverage than it looks like it should have.
And since the trailing arm has a mechanical advantage on the shock the spring needs to move less to counteract it. The spring will only have a 2-3 inch range of compression.
While I am on here: Have a Happy Thanksgiving Everybody! beerchug.gif


To be clear, Dana, my sudden case of narcolepsy had nothing to do with boredom. In fact, I found your explanation to be enlightening. The nap was to give my brain a rest before continuing.
scotty b
QUOTE(MDG @ Nov 25 2010, 04:24 AM) *

QUOTE(plymouth37 @ Nov 25 2010, 02:07 AM) *

The trailing arm will push up on what is now the open bolt hole in the pivot arm. That upward motion will cause the trailing arm to rotate in a counter-clockwise direction (on the passenger side). The upward force of the trailing arm is counteracted by the vertical and horizontal forces of the shock, given the angle of the shock about 392 pounds of its force will be acting horizontally on a point that is 5" above the pivot point while around 75 pounds of the shock resistance acts vertically on a point 7.5" off of the pivot point. These leverage points are counteracted by the trailing arm that attaches at a point 10" off of the pivot point. Since the trailing arm has a mechanical advantage on the shock the 400lb/in in the shock gets reduced down to about 250lb/in at the trailing arm which is just about what I want. Not sure if that clears anything up, I won't know for sure exactly how this thing will react until I get everything done and jump around on it wink.gif


Halfway through reading that I had to take a nap. I said it before, pages back - mad scientist at work here.

God I love this thread.



A NAP ?? REALLY ? Half way through it I had to jerkit.gif
PeeGreen 914
QUOTE(scotty b @ Nov 25 2010, 11:39 AM) *

QUOTE(MDG @ Nov 25 2010, 04:24 AM) *

QUOTE(plymouth37 @ Nov 25 2010, 02:07 AM) *

The trailing arm will push up on what is now the open bolt hole in the pivot arm. That upward motion will cause the trailing arm to rotate in a counter-clockwise direction (on the passenger side). The upward force of the trailing arm is counteracted by the vertical and horizontal forces of the shock, given the angle of the shock about 392 pounds of its force will be acting horizontally on a point that is 5" above the pivot point while around 75 pounds of the shock resistance acts vertically on a point 7.5" off of the pivot point. These leverage points are counteracted by the trailing arm that attaches at a point 10" off of the pivot point. Since the trailing arm has a mechanical advantage on the shock the 400lb/in in the shock gets reduced down to about 250lb/in at the trailing arm which is just about what I want. Not sure if that clears anything up, I won't know for sure exactly how this thing will react until I get everything done and jump around on it wink.gif


Halfway through reading that I had to take a nap. I said it before, pages back - mad scientist at work here.

God I love this thread.



A NAP ?? REALLY ? Half way through it I had to jerkit.gif

laugh.gif
McMark
Will the trailing arm connect to the lever arm via a rod? Or will it be a direct connection. Your explanation makes sense. It seems like a small range of motion, but you sound like you've done your math and I'm just armchair speculating. It's cool looking, regardless. drooley.gif
rick 918-S
Be careful you don't build in a metronome effect with the vertical connecting rod from the trailing arm to the rocker. Could cause a weird vibration at speed. Just an arm chair observation. biggrin.gif
jd74914
Cool. I like that shock placement.

One more observation: your new rocker is the perfect place to add attachment for a sway bar arm for fine tuning. Just think if it; you could have a blade arm with cabin stiffness adjusters... laugh.gif
roadster fan
Hey Dana thanks for posting all the progress on your project. I love learning along the way and am fascinated by suspension design. I drew up your arm and shock into a simple CAD program as I was skeptical that you could compress that that shock 2.5"-3" with the geometry you designed in.

I discovered (and i will attempt to upload a pic of my drawing but have to convert it i think) that you can compress your shock and spring 2.5" with a vertical trailing arm motion of 4.25" which I believe is possible in a 914. But I noticed that the actuator rod between the trailing arm and the cantilever arm has to be 6.25" long. This is due to the cantiliver arm moving on an arc away from the trailing arm so the mounting hole on the cantilever arm gets further away as it moves vertically.

It is probably hard to visualize without my drawing but I think your design would work fine as long as the actuator rod is at least 6.25" long which means it probably would have to mount an 1" to 1.5" below the shock bolt hole on the trailing arm. Your drawing shows the actuator rod to be 5" long I think but that would try to pull the trailing arm inboard causing a binding issue. This is all a novices observations, I could be completely off my @$$ and confused, that has happened before dry.gif

I love your project and cant wait for more pics of the progress,

Jim
geniusanthony
39k views. keep it up Dana, great work.
plymouth37
QUOTE(roadster fan @ Nov 25 2010, 05:57 PM) *

Hey Dana thanks for posting all the progress on your project. I love learning along the way and am fascinated by suspension design. I drew up your arm and shock into a simple CAD program as I was skeptical that you could compress that that shock 2.5"-3" with the geometry you designed in.

I discovered (and i will attempt to upload a pic of my drawing but have to convert it i think) that you can compress your shock and spring 2.5" with a vertical trailing arm motion of 4.25" which I believe is possible in a 914. But I noticed that the actuator rod between the trailing arm and the cantilever arm has to be 6.25" long. This is due to the cantiliver arm moving on an arc away from the trailing arm so the mounting hole on the cantilever arm gets further away as it moves vertically.

It is probably hard to visualize without my drawing but I think your design would work fine as long as the actuator rod is at least 6.25" long which means it probably would have to mount an 1" to 1.5" below the shock bolt hole on the trailing arm. Your drawing shows the actuator rod to be 5" long I think but that would try to pull the trailing arm inboard causing a binding issue. This is all a novices observations, I could be completely off my @$$ and confused, that has happened before dry.gif

I love your project and cant wait for more pics of the progress,

Jim


Thanks for drawing that up, I look forward to seeing it! Totally agree about a potential binding issue with the connecting rod, I went old skool and replicated each component from my diagram on trace paper last week and simulated its movement, the 5" rod does tweek out a good amount as the suspension reaches its outer limits of rotation. I was going to tack in the suspension mounts and then really dial in the position and length of the rod, thanks for the tip about the length, longer is definitely better, luckily the shocks and the connecting rod will be adjustable so I should be able to fine tune within reason once everything is in position and making a mount that adds a couple inches to the connecting rod should be pretty doable. Luckily since the motion of the connecting rod is fairly vertical I can make the connecting rod any length I need to without effecting the suspension geometry too much.
plymouth37
QUOTE(McMark @ Nov 25 2010, 03:36 PM) *

Will the trailing arm connect to the lever arm via a rod? Or will it be a direct connection. Your explanation makes sense. It seems like a small range of motion, but you sound like you've done your math and I'm just armchair speculating. It's cool looking, regardless. drooley.gif


It will be a heim joint connection to compensate for the various crazy directions the different parts of the suspension will be going.
roadster fan
Well I slept on this, and like I suspected I was wrong headbang.gif

Attached below is a bitmap of the drawing as corrected this morning. Looks like a 5" actuator arm will work fine, and you would get the 2.5" compression with a vertical trailing arm movement of 4.22". Like I said I like learning along the way, and as I should have suspected YOU had it worked out right from the beginning chair.gif

Here is the drawing:




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plymouth37
Nice rendering! It is so much easier to understand this drawing than anything I have created, thanks for the help!
I may still need to make the connecting rod a little longer, as the suspension unloads the pivot arm kicks out over the trailing arm and there is a potential binding/contact issue between the trailing arm and the connecting rod there, still won't know for sure until I can tack in the mounts and run the suspension through its entire range of motion though.
wingnut86
......Got Milk?

chowtime.gif chowtime.gif chowtime.gif
db9146
Okay, I'm going to go ahead and stick my neck out.....

The trailing arms pivot from the front of the arms so any compression will tend to ultimately move the rear wheel forward given enough travel, correct? However, it looks like the planned mounting point for the horizontal shocks is going to be behind the wheel centerline. This makes it seems to me that there will be a twisting motion on the linkage and shocks.

Takes a lot more time to "conduct class" while doing the work rather than just forgetting about "schooling" all of us and completing the project, huh?
stownsen914
Really cool stuff. I actually am in the middle of redoing the suspension on my 914 track car, and am currently modeling my ideas using susprog, a suspension analyzer. It's extremely helpful to test out stuff that i otherwise would probably discover only after building the parts smile.gif I haven't read your whole thread, but it might be worth trying something like that if you haven't already done so. Susprog also has an option to visualize your design while moving the suspension through it's full range of motion.

Edit -- modified post after I realized that your design already has a push rod. That part should be OK. Only other thing a lot of bending forces on the rocker. I would think the push rod would try to push the rocker forward and rearward (relative to front/rear of the car). Would a wider base help where it mounts to the chassis?

Scott
plymouth37
There is a potential for bending in the arms but I would think that since the entire cantilever component moves on a single plane and is connected to the trailing arm with a heim joint the chances of significant off axis movement occurring would be minimal. To counteract any twisty forces that do appear I had planned on making wide reinforced attachment points on the chassis and the arms have already been built with additional reinforcement points at that point.
plymouth37
I decided to take a break from the suspension to wrap up a couple little projects on the car.
A year or so ago I pieced up this intercooler system but since I was in an apartment couldn't weld it up.
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Now that I have my house I can play with welders all I want so I decided to weld up the intake system, I also welded in a bung for the boost gauge sender and a ground stud for the sender.
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plymouth37
Then I sprayed the parts with high heat paint and hung them in front of my trusty Reznor heater to bake.
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This is starting to look like progress!
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plymouth37
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Gint
Very nice!

Hey Dana... got a tig machine? Can you weld aluminum? My Audi has a crack in the oil pan.
plymouth37
I do have a tig but it is in storage up in Wyo, never been great at welding aluminum either, wish I was though.
plymouth37
I finally finished this semester yesterday so I decided to spend some of my new found freedom working on the car. I wanted to start nailing down details like exhaust but I had to get the engine in a fixed position before I made any more progress on the drivetrain. I fabbed up an engine mount cross member, this one is almost identical to the Renegade one I used to run on my car, just the ends are at a slightly different angle.
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Here is an under side view of the engine mount setup.
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And a shot from the top, I am going to weld in threaded mounting holes into the chassis but everything is just hose clamped together until I can pick some up.
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Hontec
Lookin' good, as usual!!! piratenanner.gif
wingnut86
Dana,

I'm most impressed young Jedi...

Maybe I should just rack, stack and tow my 2 out to Colorado for skiing.

Hmmm, maybe drop by for a cup of cocoa, 3-weeks of body and chassis work and take in the big skies drooley.gif

2nd thought - I'll just freeze in the deep south and dream a little dream...


pray.gif popcorn[1].gif pray.gif

-- Dave

Aka Wingnut
PeeGreen 914
aktion035.gif Nice Dana. Can't wait to see what you are able to do over the break smile.gif
914Sixer
Really bad to the bone !!!!! Keep up the excellent work.
nsr-jamie
Excellent!! Always glad to see updates in this thread, its one of my favorites. Thanks!!
plymouth37
I had an hour or so to work this morning and pieced together an f-ing huge exhaust. I wanted to use oval tubing but since the exhaust had to follow a kind of complex path I decided to fabricate it out of 3" round tubing with a 1" spacer in the middle, the equivalent area is about that of 3.5" round tubing. Once I have a little more time I will weld it up, add an O2 sensor bung, and finish it smooth.
I think this should flow pretty well biggrin.gif. I will run this portion of the exhaust when I test the bare chassis, then eventually add on a full (but still muffler-less) exhaust once the body is on.
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KELTY360
QUOTE(plymouth37 @ Dec 18 2010, 11:06 AM) *
I had an hour or so to work this morning and pieced together an f-ing huge exhaust. I wanted to use oval tubing but since the exhaust had to follow a kind of complex path I decided to fabricate it out of 3" round tubing with a 1" spacer in the middle, the equivalent area is about that of 3.5" round tubing. Once I have a little more time I will weld it up, add an O2 sensor bung, and finish it smooth.
I think this should flow pretty well biggrin.gif. I will run this portion of the exhaust when I test the bare chassis, then eventually add on a full (but still muffler-less) exhaust once the body is on.

An hour or so? You make me sick Dana, I haven't accomplished that much all year.

The Anklebiter just gets better....and better....and better...and better...and.......................
plymouth37
Thanks! I used to build headers for Renegade so fitting tubing goes pretty quick for me, I can't wait to hear how this sounds, the turbo is going to scream!
KELTY360
QUOTE(plymouth37 @ Dec 18 2010, 11:43 AM) *

Thanks! I used to build headers for Renegade so fitting tubing goes pretty quick for me, I can't wait to hear how this sounds, the turbo is going to scream!


Looking forward to seeing how you'll set up the cooling system. Is that next?
plymouth37
QUOTE(KELTY360 @ Dec 18 2010, 01:48 PM) *

Looking forward to seeing how you'll set up the cooling system. Is that next?


I am going to wrap up the rear end first, amputate the back of the tub, then tackle the front end with the cooling system. I am going with my Renegade radiator mounted in the front of the car with a custom shroud.
KELTY360
QUOTE(plymouth37 @ Dec 18 2010, 06:08 PM) *

QUOTE(KELTY360 @ Dec 18 2010, 01:48 PM) *

Looking forward to seeing how you'll set up the cooling system. Is that next?


I am going to wrap up the rear end first, amputate the back of the tub, then tackle the front end with the cooling system. I am going with my Renegade radiator mounted in the front of the car with a custom shroud.


Does that mean we get to see the diffuser in place soon? drooley.gif
iamchappy
Sick, talk about zero restriction.......
TC 914-8
Hi Dana, I've been following your thread for quite a while (lurking) to say the least. Whats the chance of you making it to the WCR in June ?
At the rate you are going I think its possible.. welder.gif
Everyone needs to chime in cheer.gif
plymouth37
QUOTE(TC 914-8 @ Dec 19 2010, 09:18 PM) *

Hi Dana, I've been following your thread for quite a while (lurking) to say the least. Whats the chance of you making it to the WCR in June ?
At the rate you are going I think its possible.. welder.gif
Everyone needs to chime in cheer.gif

There is no way the body will be done but I am not opposed to driving a bare chassis!
I may show up looking like this:
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MDG
QUOTE(plymouth37 @ Dec 20 2010, 12:57 AM) *

I may show up looking like this:
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That would actually be pretty cool. Not sure about about a flathead for your car though.
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