Brianj5600
TJ Expert
Maybe - but it certainly doesn’t work that way the first time.
(And on this forum - I certainly would not tell anyone the length of those arms….)
Or your shock split.
Or your shock split.
I love everything about this statement. It took me a long time to understand what you have explained very concisely and succinctly here and it has been very valuable. It really does apply in every single place where we modify the vehicle - another nice example is seeing where the rear drive shaft on the Rubicon models starts binding and how that limits what can be done in terms of setting up useful rear travel in a typical lifted setup. Likewise for belly skid setup with 241/auto. The list goes on, but the message is very clear.
Just so it does not get taken out of context, it is a reply to Nashville to help him understand that the calculator will give you locations for stuff that you may NOT want if you guess at things and then try to stick to the "numbers". You should temper that with what the rig is for.
I know of a couple of builds where they were after different things and there are large channels in the rear cargo area that are boxed in to give the uppers room to move upwards. I'd rather shorten the lower arms a tad, pull the uppers back some and keep everything under the cargo floor. The caveat needs to be that we are building recreational rigs that do recreational things by folks who enjoy recreating with our rigs offroad. We aren't racing, we aren't hill climbing, we aren't rock bouncing, and we aren't building purpose built narrow function vehicles. We want all around rigs that are very good at most things.
When I recently started learning about geometry I read the college boy paper and the Gods of Suspension thread, some other online articles about 4-link and 3-link suspension designs, and finally the Dave Kishpaugh GC thread. One of the things the college boy paper stated was that the platform was being built around the suspension rather than the suspension around the platform. That statement means a lot because the platform has limitations. However, I was still under the impression from other articles on crawlpedia and elsewhere that I needed to plug numbers in a 4-link calculator. I asked about the best one and got mostly shunned. Ok, well, you don't know what you don't know. I felt it was pretty hard to get anywhere. I did get a calculator and played with numbers for a couple of hours on a computer that wasn't mine (which slowed me down). I did find it helpful to at least see what manipulating the numbers did to AS and IC, but, of course, it doesn't tell me what the rig will do on the trail (and articles out there such as Crawlpedia state that 140%+ AS is good for rock crawling, which is discrepant information). I haven't punched any numbers in the calculator since that day. I eventually did realize that most of this was looking at it statically, which renders the numbers irrelevant for offroad performance. As I read more here I finally started to understand that it was really about experimenting with various length arms (which changes the arc travel radius of the axle) and mounting locations (changing the IC and centering the axle when triangulated properly). Of course, in the practical real world performance of a TJ I don't have the resources to do testing, so I came to accept that I have to trust those who have. That is probably where a lot of us are. The main thing is understanding that you can work out all the numbers, but it is basically meaningless apart from an academic exercise. What works on the trail is what counts and when you're talking about TJ's/LJ's you are looking at that platform, so bringing buggies in doesn't help the conversation go anywhere. I'm sure I screwed up something in this post, so I am ready to receive my lashing.
Thanks to those who have given out eggs to help me get a little ways down the road to understanding.
As long as it understood that the calculator is a tool for collecting and processing data it will be useful. But as Blaine points out it is very easy to suffer from target fixation and ignore that what you may want still has to work withing the platform you are working on. It is also why I tell people to read the God of Suspension thread on Pirate. If you do you should come away with two things, first is a basic understanding of what makes for an ideal link suspension, and two stuff is only going to fit where it is going to fit and that ideal is the best of what you can make of it.
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I think if more people would just grab a yardstick and crawl under their rig and start holding it up before even thinking about calculators and whatnot they would maybe start to understand. But that does require effort.
(And on this forum - I certainly would not tell anyone the length of those arms….
The arms fit where they need to. The fixation and too many arguments about arm length come from equating a bolt on long arm with well thought out custom four link. The bolt on stuff make too many compromises for the sake of convenience when they really did not have to.
Talking about shock split does not have to become pretentious. Like I mentioned earlier in this thread there is no reason to not discuss why something may or may not work from a different platform to a TJ. Do I think the comical 20up 80down splits some buggies run would be good for a TJ the answer is no. I think that if you want a well balanced rig that can drive to the trail, run all day and drive home you need to have a bit more balance. Does that mean that if your current spring/shock setup gives you a 40/60 split that it is the end of the world absolutely not it is still all about acceptable ranges.
This is what probably gets lost in these discussions more times than we can count.
I am curious where the 20/80 split trend came from. Is it that they cannot fit more up because they are trying to stay low? Is it because that is their desired ratio? I’ve heard some mention that uptravel is not important for rock crawling specifically, but I have had many instances where I am balanced on a few boulders and the tires are stuffed way up in the wheel well. Without that uptravel, the body would undoubtedly have leaned over more. The 50/50 split is undoubtedly better for a well balanced multi task rig because it also unlocks go fast ability. But I would argue that I use uptravel a lot even while slow crawling.
In case anyone is wondering after Brian's comment - I'm at 6 up / 8 down. What's that, 43/57?
As with anything else, shock splits are nothing more than tech and an understanding of how shocks work in relation to the rest of the rig. Several things can be derived from a build by knowing about the shocks and how they are positioned. This is a reason why it comes up so often in the spring threads.
42.8, at least get that part right.
It is much easier to build in a way that results in a disproportionate amount of down travel, as shown in your recent efforts to build the opposite and maintain up travel. Very few will go through the effort of moving mounts. Far fewer will go through the effort of understanding why there would be a benefit to moving them in the first place.
It's easier to bolt on a longer shock and pretend that long reach down is functionally awesome. But then you come along using your rig in a way many fantasize about where experience shows the opposite is true.
Brianj5600
TJ Expert
Depends how many groceries he’s got in there
Post 219 and I have not read any of those resources you referenced. I just know how it works.
When I recently started learning about geometry I read the college boy paper and the Gods of Suspension thread, some other online articles about 4-link and 3-link suspension designs, and finally the Dave Kishpaugh GC thread. One of the things the college boy paper stated was that the platform was being built around the suspension rather than the suspension around the platform. That statement means a lot because the platform has limitations. However, I was still under the impression from other articles on crawlpedia and elsewhere that I needed to plug numbers in a 4-link calculator. I asked about the best one and got mostly shunned. Ok, well, you don't know what you don't know. I felt it was pretty hard to get anywhere. I did get a calculator and played with numbers for a couple of hours on a computer that wasn't mine (which slowed me down). I did find it helpful to at least see what manipulating the numbers did to AS and IC, but, of course, it doesn't tell me what the rig will do on the trail (and articles out there such as Crawlpedia state that 140%+ AS is good for rock crawling, which is discrepant information). I haven't punched any numbers in the calculator since that day. I eventually did realize that most of this was looking at it statically, which renders the numbers irrelevant for offroad performance. As I read more here I finally started to understand that it was really about experimenting with various length arms (which changes the arc travel radius of the axle) and mounting locations (changing the IC and centering the axle when triangulated properly). Of course, in the practical real world performance of a TJ I don't have the resources to do testing, so I came to accept that I have to trust those who have. That is probably where a lot of us are. The main thing is understanding that you can work out all the numbers, but it is basically meaningless apart from an academic exercise. What works on the trail is what counts and when you're talking about TJ's/LJ's you are looking at that platform, so bringing buggies in doesn't help the conversation go anywhere. I'm sure I screwed up something in this post, so I am ready to receive my lashing.
Did you have some caffeine Jeremy?
When I recently started learning about geometry I read the college boy paper and the Gods of Suspension thread, some other online articles about 4-link and 3-link suspension designs, and finally the Dave Kishpaugh GC thread. One of the things the college boy paper stated was that the platform was being built around the suspension rather than the suspension around the platform. That statement means a lot because the platform has limitations. However, I was still under the impression from other articles on crawlpedia and elsewhere that I needed to plug numbers in a 4-link calculator. I asked about the best one and got mostly shunned. Ok, well, you don't know what you don't know. I felt it was pretty hard to get anywhere. I did get a calculator and played with numbers for a couple of hours on a computer that wasn't mine (which slowed me down). I did find it helpful to at least see what manipulating the numbers did to AS and IC, but, of course, it doesn't tell me what the rig will do on the trail (and articles out there such as Crawlpedia state that 140%+ AS is good for rock crawling, which is discrepant information). I haven't punched any numbers in the calculator since that day. I eventually did realize that most of this was looking at it statically, which renders the numbers irrelevant for offroad performance. As I read more here I finally started to understand that it was really about experimenting with various length arms (which changes the arc travel radius of the axle) and mounting locations (changing the IC and centering the axle when triangulated properly). Of course, in the practical real world performance of a TJ I don't have the resources to do testing, so I came to accept that I have to trust those who have. That is probably where a lot of us are. The main thing is understanding that you can work out all the numbers, but it is basically meaningless apart from an academic exercise. What works on the trail is what counts and when you're talking about TJ's/LJ's you are looking at that platform, so bringing buggies in doesn't help the conversation go anywhere. I'm sure I screwed up something in this post, so I am ready to receive my lashing.
You have come a long way grasshopper. In all the reading you have done sometimes you have to look at when the information was written. Like Crawl saying 140% AS is good. Well there was a point were folks were running high AS with center limit straps thinking that they would get more bite. And they were right except if the traction is high enough even with the constraint of the limit strap they still hopped.