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Old January 4th, 2005, 03:39 AM   #51
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True, but as stock you are not putting the load member in compression with any force vector. The radial component is a tension load.

With the modified version, you are incorporating a radial vector that is a compression load. My concern is that this compression load may exceed the bending stress that can be sustained by the trailing arm. Yes, I may be unduly concerned, but I can't think of a single application on any suspension system that uses a "leading" arm loaded radially in compression.

I only want to make sure you guys are safe and to play devil's advocate so we explore all sides of a design.

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Old January 4th, 2005, 05:00 PM   #52
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i think people think far too much about 'ohhh-streess on this, stress on that' theyre forgetting that there is now no spare wheel well, valance, half of the inner arches, complete bumper and brackets and mount panels, the spare wheel itself, and even the fuel tank in a lot of our cars. so that might just make the front end a little bit lighter, thus reducing the stress on anything front suspension related. [img]style_emoticons/<#EMO_DIR#>/wink.gif[/img]

and griznat, what about the oh-so fashionable ford i-beams eveyone want to nail to the front of thier rides??? they are, in theory, with where the pivot point on a split 'bone or hairpin setup is, a leading arm system. ever seen a bimota motorbike??? they are too, as well as a lot of vintage dirtbike setups- leading link suspensions. its by no means a bad thing. and, have you seen the size of a vw trailing arm- you aint gunna go bending one of those with the type of compressive forces were talking about here!!
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Old January 4th, 2005, 05:54 PM   #53
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Dez, I agree with the lightened load making a big difference. We build offroad buggies here in Missouri and have watched these trailing arms go through some crazy shit. The only thing I can stress is that you run a light shock with this design. With the lightening of the front end as on a buggy, will use very little of the suspension on pavement. If you use too stiff of a shock it will just be a rigid front end. [img]style_emoticons/<#EMO_DIR#>/thumbsup.gif[/img]

It'll work!

[img]style_emoticons/<#EMO_DIR#>/smokin.gif[/img] [img]style_emoticons/<#EMO_DIR#>/smokin.gif[/img]
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Old January 5th, 2005, 03:53 AM   #54
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Quote:
Originally posted by dez@Jan 4 2005, 06:00 PM
and griznat, what about the oh-so fashionable ford i-beams eveyone want to nail to the front of thier rides??? they are, in theory, with where the pivot point on a split 'bone or hairpin setup is, a leading arm system. ever seen a bimota motorbike???
<div align="right">Quoted post</div>

Don't get me started on the Ford axle setup. I know it's done for looks, and it definitely looks the part of an old-school hot rod. I just can't bring myself to trade an independent front suspension design for a solid axle leaf-sprung setup. Something about going back in time on that one that I can't bring myself to do. However, they do look cool. [img]style_emoticons/<#EMO_DIR#>/cool.gif[/img]

I think the difference with those lies with the axle spreading the load across a larger area (both radius rods take the load since they are always tied together), and the fact that there is a certain amount of *give* to the leaf spring itself that helps to lessen the shock when force applied.

My biggest worry would be hitting a pothole and jacking everything out of shape. My brother recently snapped a strut on a Miata by hitting a pothole, including bending two rims, blowing one tire, and wiping out the drag link on the sway bar. [img]style_emoticons/<#EMO_DIR#>/sad.gif[/img]

These are BIG holes around here sometimes. For you guys in warmer climates, or that don't salt the shit out of the roads you probably can't relate. [img]style_emoticons/<#EMO_DIR#>/confused.gif[/img]

Later,

G
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Old January 5th, 2005, 04:06 AM   #55
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i can guarentee our roads are some of the worst in the world!!
i live in rural england, they dump salt by the ton, the roads have no kerbs, just bloody great big holes in em!!!
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Old January 5th, 2005, 08:13 AM   #56
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Quote:
Originally posted by mkparker@Dec 29 2004, 11:24 PM

<div align="right">Quoted post</div>
I've been looking at this drawing since it was posted and pic 4 has been bugging me.

More than likely I'm just missing something, but it appears to me that (in the drawing) if you were to rotate the pan down to put the tire back on the ground line, then your caster angle would be reduced, at zero, or (worst case) back where you started.

Is that right, or am I missing something? [img]style_emoticons/<#EMO_DIR#>/Idunno.gif[/img]

I'm not an engineer, nor am I a mechanic. I'm asking because I don't know.
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Old January 5th, 2005, 05:22 PM   #57
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I think its 'cus the wheel is floating off the ground it looks odd. That and the trailing arms are drawn at stock height. Its just deceiving.

Quote:
Originally posted by dez@Jan 5 2005, 08:06 AM
i can guarentee our roads are some of the worst in the world!!
i live in rural england, they dump salt by the ton, the roads have no kerbs, just bloody great big holes in em!!!
<div align="right">Quoted post</div>
Try going for a cab ride in rural China, or hell a Rickshaw is even scarier.
Nothing like a million people riding bicycles, MC's and Rickshaws in every direction while your driver is darting back and forth with no apparent traffic laws of any kind. The roads looked as though they haven't had any maintenace since they where built in 30's. just gorooves and cracks and holes big enough to fall into. Its almost like rural offroading with human obstacles. [img]style_emoticons/<#EMO_DIR#>/funny.gif[/img] I have seen some of the worst Bike accidents I have ever seen there such as MC's plowing into bikes and just keep going. Saw a kid while pissing in the street get hit by a bike...... Insane I tell you.
All this fun can be had for like $1. [img]style_emoticons/<#EMO_DIR#>/thumbsup.gif[/img]
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Old January 5th, 2005, 06:43 PM   #58
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<div class='quotetop'>QUOTE</div><div class='quotemain'>More than likely I'm just missing something, but it appears to me that (in the drawing) if you were to rotate the pan down to put the tire back on the ground line, then your caster angle would be reduced, at zero, or (worst case) back where you started.
[/b][/quote]

The drawings are not to scale or neccessarily "accurate", they're just to explain the cut frame head technique.
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Old January 5th, 2005, 07:36 PM   #59
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STAY AWAY FROM FRICTION SHOCKS! These were originaly designed by Barney Rubble for the Flintstone car. I had a pair on a T-Bucket and you have to tighten them every 200 miles and they don't work for crap.
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Old January 6th, 2005, 06:38 AM   #60
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I know "jack squat" about front end geomatery, but if pushing the front end forward messes with the way the car will handle as shown in

Then couldn't you simply widen the front end and in efect line all points back up? I'm not sure, that's why I ask.
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Old January 6th, 2005, 11:22 AM   #61
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im looking forward to the how to article on this one, to find out just how much work is involved in the extending of the tierods and bending of the spindles.


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Old January 6th, 2005, 04:35 PM   #62
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I think widening the ft. end would look kinda dumb. I am actually thinking of using my narrowed ft. end.

Can't decide on either an extended or flipped. I have flipped the ft. end in mock up form but I won't be using that beam so it can become a donor for an extension very easily.

Anyone have an opinion, I have been kinda indesicive lately. [img]style_emoticons/<#EMO_DIR#>/Idunno.gif[/img]
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Old January 6th, 2005, 09:25 PM   #63
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<div class='quotetop'>QUOTE</div><div class='quotemain'>Then couldn't you simply widen the front end and in efect line all points back up? I'm not sure, that's why I ask.[/b][/quote]

First off widening the frontend wouldn't be "simple". Second, it would not bring the the intersection of the two angles, kingpin/steering arm, back towards the rear of the car. It would just widen the "base" of the triangle. Third, having perfect Ackerman isn't a big deal. It only affects the car when it turns. Perfect Ackerman isn't required, but "ballpark" Ackerman will make the car turn much better than one with no or reversed Ackerman.

<div class='quotetop'>QUOTE</div><div class='quotemain'>Can't decide on either an extended or flipped. [/b][/quote]

I personally dislike the whole "flipped" beam/arm setup. I think ( like griznat) that it is potentialy dangerous (especially in the hands of unskilled "artists") and somewhat unnatractive. There is obviously a lot more engineering in a proper front end setup than most people apprecitate. I think a lot of this gets back to the "ratrod" mentality that has been brought up before, "Screw it that's it's unsafe and drives like crap! I'm too cheap or too uninformed to do it right."
I think this and other threads are trying to help get information out, but ya gotta be careful when ya start "re-engineering" front ends.
So, in sumary....I like the extended beam setup, with a nicley designed extension....not two beams welded together.
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Old January 7th, 2005, 05:04 AM   #64
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Thanks. I was just wondering, and after further thought, I figured that it wouldn't work. The reason that I asked is that the pan I am starting with came with 2x3 trairing arms attached. If widening the front to match the rear would help, then I would have investigated further.
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Old January 7th, 2005, 06:01 AM   #65
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Quote:
Originally posted by mkparker@Jan 7 2005, 01:25 AM
I personally dislike the whole "flipped" beam/arm setup. I think ( like griznat) that it is potentialy dangerous (especially in the hands of unskilled "artists") and somewhat unnatractive.
I'm with you here. IMO it's just an easy way out to get an extended front end. Nothing against people trying it, but not my cup of tea.
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Old January 7th, 2005, 04:18 PM   #66
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I don't think its an easy way out. As far as I am concerned its gotta be done right either way.

As far as the 2 beams welded together I just don't know how else to describe it. Kinda like JimW's extension but with out the bolt on section. Done right, yes it would be. It would just simply be welding a spacer to the back of the beam, that sapcer would consist of a section of another beam so that it cradles just right into the chassis's frame head.
Oh yeah it would be all built onto a narrowed beam that I did myself as well.

I don't see where its the "wrong way" of doing it. Unless I just stacked the beams up and didn't trim off the ends of the donor one and also didn't factor in the Castor angle ............

How else would you get the the bolt on section to cradle perfectly inot the frame head ? Fab your own using 2 1/16" O.D. tubing and brackets with the correct holes drilled in them to match the stock beams holes ? Just sounds like a lot more trouble than cuting what you need out of a donor beam. I guess if you don't form all your filler pieces for a chopped roof then you did it wrong ?

Sorry I just don't understand what is wrong about my idea. The only thing I have is this thing in my mind that makes me worry about things like that breaking so I would have to go the overkill route just so I could sleep at night. I don't know if you noticed but I tend to over think things to the point of all details and what if scenarios are worked out before I even consider doing something. Thats what all this is and what the damn forum is for as far as I am concerned.
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Old January 7th, 2005, 08:29 PM   #67
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<div class='quotetop'>QUOTE</div><div class='quotemain'>Anyone have an opinion, I have been kinda indesicive lately. [/b][/quote]

Don't ask for opinions then whine when you're not ageed with. As I said, I don't like the whole flipped beam/arm setup. I prefer the extension if it is done safely. You don't appear to have enough experience or confidence to construct one youself, so in my opinion(you asked remember) you, Jon, would be better off buying from someone who does have knowledge and experience. Perhaps if you could draw up what you are talking about with your double beam idea I could follow better. You've already stated you have little confidence in your welding abilities so it just seems logical for you to consider a route other than fabricating your own.
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Old January 8th, 2005, 06:23 PM   #68
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Look what I was saying is that I would just simply feel more comfortable having a certified welder do it. Actually thats easy to do. Just tack and have one do it. Hell even Charlie could help me out with that.
I am not whining about a damn thing I was discussing this and someone decided to try and insult me.
I was basically saying that I have more than one possibility and was trying to weigh my options as to which one I should go with.

I just wanted to know if anyone was seeing a need for some sort cross bracing or whatever ... that I might have been missing with extending the beam forward option.
As far as being to cheap or too uninformed I am neither I just like to do as much of it myself as I enjoy that sorta thing.


With out the "bolt on section"

And those 4 horizontal sguare tubes welded directly to the back of actual beam with torsion bars .... this would be exactly what I was describing. Forget the plates with the half circles cut out and the flat bar going across the back for the bolts .... Just 4 tubes directly to the forward beam and the donoer beam being the bolt up section with ends cut off. Got it.

So in conclusion, it would work. Just trying to decide which I want thats all.
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Old January 8th, 2005, 08:02 PM   #69
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Jon, I apologize if you think I was "insulting" you. I wasn't refering to you with this quote - "Screw it that's it's unsafe and drives like crap! I'm too cheap or too uninformed to do it right." It is just a general observation of some of the attitudes I've seen with the current "Rat Rod" craze and is not limited to this forum or VWs. You seem to have a good handle on what you want to do and how you want to do it. Good luck with your project.
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