12-03-2013, 09:38 AM | #21 | |
Suck it up! Join Date: Mar 2008 Location: Arkansas
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| Re: Another 4 Link Thread Quote:
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12-03-2013, 09:57 AM | #22 |
I wanna be Dave Join Date: Oct 2007 Location: Castle Rock, WA
Posts: 8,786
| Re: Another 4 Link Thread
Duuuuuuuude, you didn't touch on swaybars, mainly sway bars in the rear of the truck and how they effect traction. I have used several to combat chassis roll on heavier trucks. There is no way my 15lbs CXT rig could crawl or handle the way it does with out it. Also, alot of guys run them on the Terra-X or Ultra-4 type rc trucks these days.
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12-03-2013, 10:17 AM | #23 |
Suck it up! Join Date: Mar 2008 Location: Arkansas
Posts: 11,652
| Re: Another 4 Link Thread
Sway bars are literally another spring in the system, added to keep the chassis and axle parallel to each other. They can be used to compensate for a relatively low RC in relation to the CG, or to keep a vehicle 'flat' when cornering without having to go to stiffer springs. They will also keep TT down because they are not allowing the chassis to roll. Most of the time you can tune out body roll by making RC and spring rate adjustments, but depending on the design and mass of the vehicle, you may not have the ability to do so. When you run out of options there, add a sway bar. The down side is that sway bars can inhibit articulation, after all, their sole purpose is to keep the body from rolling away from parallel to the axle. When setting up my race trucks, I do it without sway bars. I get my spring rates right, get my instant centers in a happy place, and if I think it needs a little more, I will add a sway bar. I have not yet applied my race tuning method to a crawler yet, but I will be soon. I'm very interested in what the results might be... |
12-03-2013, 10:34 AM | #24 |
I wanna be Dave Join Date: Oct 2007 Location: Castle Rock, WA
Posts: 8,786
| Re: Another 4 Link Thread
So with that explaination it would be safe to say that sway bars also help control unsprung weight on uneven ground? Which I think I kinda answered my own question. And yes, I think sway bars are truck weight specific. Ie, not every rig needs them. And I am referring to go-fast crawlers. I am probably side tracking this thread. |
12-03-2013, 10:59 AM | #25 | |
Suck it up! Join Date: Mar 2008 Location: Arkansas
Posts: 11,652
| Re: Another 4 Link Thread Quote:
With the increased popularity of 'go-fast' crawlers, I think its a perfectly valid discussion. Crawlers are designed with a specific purpose, and race vehicles are designed with a specific, but different purpose. The give-and-take rules still apply to both, and both will compromise one area of performance to achieve a gain in another area. Crawlers that go fast or race vehicles that crawl are doing double duty, so the compromises change towards the goal of having a well rounded rig. A pure crawler will race horribly, a pure racer will crawl horribly. To make them improve in an environment that they were not designed to handle, you will end up removing performance in the environment that they were designed to handle. Last edited by Duuuuuuuude; 12-03-2013 at 11:06 AM. | |
12-03-2013, 04:04 PM | #26 |
I wanna be Dave Join Date: Aug 2006 Location: under a rock and a hard place
Posts: 5,443
| Re: Another 4 Link Thread
So what if leaf srings are thrown in the mix ? Obviously they wont be adjustable like a 4 link, can anything be done other than shock tuning ? What about adjusting your CG with placement of the other components and it effects on the leafer...
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12-03-2013, 04:14 PM | #27 | |
Suck it up! Join Date: Mar 2008 Location: Arkansas
Posts: 11,652
| Re: Another 4 Link Thread Quote:
Hopefully tonight I can get started on post #5, which will be a sort of 'how do I apply all of this'. I may also get into panhards as well. | |
12-03-2013, 08:01 PM | #28 |
RCC Addict Join Date: Jul 2008 Location: San Diego
Posts: 1,144
| Re: Another 4 Link Thread
Thanks for all the info.... now my head hurts.
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12-04-2013, 12:30 PM | #29 |
No idea what I'm doing Join Date: Oct 2008 Location: Underground, CO
Posts: 4,529
| Re: Another 4 Link Thread
I like the Carpenter/Drill analogy |
12-04-2013, 12:54 PM | #30 | |
I wanna be Dave Join Date: Aug 2004 Location: Tri-cities, WA
Posts: 4,831
| Re: Another 4 Link Thread Quote:
Not exactly. Yes most people that run leaf springs just slap them on there and go with it. BUT there is lots of tuning to be done with leafs. Mounting the forward eye higher than the shackle end will make the axle move up and back when compressed. That makes for a nice ride but when climbing over a ledge the axle will attempt to drive out from under the vehicle. It also has massive amounts of antisquat. Mounting the forward end lower than the shackle end will induce a bit of squat but the axle will not try to drive out from under the rig either. I played around with most every way to mount leafs and I have always built my own packs from scratch. | |
12-04-2013, 12:57 PM | #31 | |
Suck it up! Join Date: Mar 2008 Location: Arkansas
Posts: 11,652
| Re: Another 4 Link Thread Quote:
Since this is a 4 link thread, I probably won't get too deep into them anyway...just cover the basic geometry. | |
12-13-2013, 09:49 PM | #32 |
Quarry Creeper Join Date: Nov 2013 Location: Huntsville
Posts: 222
| Re: Another 4 Link Thread
This is a great thread! I feel like I've been wasting my time reading Millken! I do have one question, though. In your 2nd post, you start using the acronym "IS" e.g., "Your IS is also the point where the suspension links apply force to the chassis. But there is a little bit more to it, in the form of Line of Force (LF). I will get to that shortly." and "To find the LF, draw a line through the bottom of the rear axle line and through the IS." Did you mean IC? |
12-14-2013, 12:00 AM | #33 |
Suck it up! Join Date: Mar 2008 Location: Arkansas
Posts: 11,652
| Re: Another 4 Link Thread Yes I did, thanks for the heads up. |
12-14-2013, 11:14 AM | #34 |
Quarry Creeper Join Date: Nov 2013 Location: Huntsville
Posts: 222
| Re: Another 4 Link Thread
So how do Anti-Squat and Line of Force play out if the planes containing the upper and lower links intersect aft of the rear axle, thereby establishing an IC that is located behind the vehicle? For that matter, what happens when the upper and lower link sets run parallel to each other (i.e., intersect at infinity?)
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12-14-2013, 11:40 AM | #35 | |
Suck it up! Join Date: Mar 2008 Location: Arkansas
Posts: 11,652
| Re: Another 4 Link Thread Quote:
I'm not entirely sure, and i dont know that I've ever driven a rig set up like that that handed particulary well. | |
12-14-2013, 12:08 PM | #36 | |
Quarry Creeper Join Date: Nov 2013 Location: Huntsville
Posts: 222
| Re: Another 4 Link Thread Quote:
Saying that setting up a suspension in the way that I suggested is impractical and unheard of is a good enough answer for me. I was asking out of curiosity. | |
12-14-2013, 12:23 PM | #37 | |
MODERATOR™ Join Date: Jul 2004 Location: Ohio
Posts: 18,928
| Re: Another 4 Link Thread Quote:
Exactly the same thing. You forgot one word (okay, two), though. 2. TT is NOT caused by pinion gears TRYING TO climb ring gears. Thus the resistance. | |
12-14-2013, 12:40 PM | #38 |
MODERATOR™ Join Date: Jul 2004 Location: Ohio
Posts: 18,928
| Re: Another 4 Link Thread
And I'm not comfortable about the sway bar stuff. Yes, it's the last bit of tuning to be done. But, the way it works is thusly: While cornering there's a weight shift to the outside from the chassis and body which compresses the outside suspension, the sway bar resists the twisting motion, and therefore lifts the inside tire, the chassis reacts with a weight shift to the inside and etc... It's the sway bar resisting the torsional twisting movement and doing work to the other tire that makes things happen. |
12-14-2013, 01:35 PM | #39 | |
Newbie Join Date: Jan 2013 Location: Here
Posts: 36
| Re: Another 4 Link Thread Quote:
This is the type of suspension you mentioned in use. Not something that would work well for crawlers persay. http://m.youtube.com/watch?v=gC3W9Zd...%3DgC3W9Zd_1Pg http://m.youtube.com/watch?v=pA9Sut0...%3DpA9Sut0umpY Last edited by Pixelfantasies; 12-14-2013 at 02:16 PM. | |
12-14-2013, 02:05 PM | #40 |
Quarry Creeper Join Date: Nov 2005 Location: Western, NC
Posts: 490
| Re: Another 4 Link Thread
Duuuuuude, huge thanks for taking the time to do all of this. I'll need to re-read it many times I'm sure. I'm just starting to learn about actually trying to tune my suspension to get my rigs to do what I ask of them, and all of this is a big help for sure. |
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