How's my numbers?

Treefrog said:
Huh. Fwd track car. That's a new one. Gonna have to think some.

What is the front suspension? If it is double wishbones could I get you to put the frame points in as the two ends of the links? It will give a good enough idea of what the front is doing.
Click to expand...
Front is a macpherson strut with 1 lower control arm & no sway bar. Ill grab some measurements this weekend and get it plotted out if that would help.
Treefrog said:
Your convergence angle may be a bit high. I have no feel for your set up. I'll look at some of how it acts later when I get home from work.

I'll have to think on the antis. Your setup is not one I have memorized. My inclination is that you have more front weight than expected and the rear becomes very sensitive to pitching.

Drop plates would not be treated as portals. The portal height is purely a visual display thing.

Do you have the ability to adjust the brake bias?
Click to expand...
Last time i took it to the weigh station i was 1500 on the front axle and 1000 on the rear with me in it. Didnt have the canopy on then but i did have a bunch of tools in the bed. probably about the same difference.

I have adjustable prop valves for each rear wheel. I dont have any adjustment on the front. I've tried all the adjustment the valves will let me i cant lock up the fronts without getting sideways because the rear unloads and locks up so fast. Doesnt matter if its full 100% open or 100% shut(57% pressure reduction based on the data sheet).

I tested at autox with both the canopy on and no canopy thinking maybe a little weight over the rear would help but no real change which is where i opened up the calc and started lookin harder.
 
brocolocoli said:
Front is a macpherson strut with 1 lower control arm & no sway bar. Ill grab some measurements this weekend and get it plotted out if that would help.

Last time i took it to the weigh station i was 1500 on the front axle and 1000 on the rear with me in it. Didnt have the canopy on then but i did have a bunch of tools in the bed. probably about the same difference.

I have adjustable prop valves for each rear wheel. I dont have any adjustment on the front. I've tried all the adjustment the valves will let me i cant lock up the fronts without getting sideways because the rear unloads and locks up so fast. Doesnt matter if its full 100% open or 100% shut(57% pressure reduction based on the data sheet).

I tested at autox with both the canopy on and no canopy thinking maybe a little weight over the rear would help but no real change which is where i opened up the calc and started lookin harder.
Click to expand...
Just the side view angle of the lower arm frame points and strut would go a long way.

Guess it isn't a weight issue then.
 
brocolocoli Just put some thought into it. It is different thinking about braking and the lowers being the ones offset from centerline. I also ran it through some of the other tools I have. First time I have seen a particular error message. Your tire radius is larger than half the diameter. In that calculator; diameter is purely a visual thing so nothing is affected. I didn't even know I had put that error in.

I think this is a case of anti percentages are not real. Under braking, the imaginary pinion is trying to go down. This puts the lower link in tension. But not nearly enough to make up the entire rear braking force, thus the upper is in tension as well. Both the upper and lower point below the CG. So their combined force (and the front's compressive force) are wanting to raise the rear. This has the effect of aggressive pro-lift in the rear.

Two solutions come to mind.

The quick check would be to put spacers in so the rear sits higher. Enough to get the uppers pointing over the CG by a bit. This will at least give you an idea if this is a potential improvement/fix.

The better solution would be move links to get the rear upper point over the CG and build in some anti-lift. It will involve some combination of lowering the axle end and moving the frame side back. Potentially moving the axles back as well if the arm length gets short.

Since you are doing some reading on 4 links, you will probably see the general guideline of vertical spacing being 25% of tire diameter. You application is one where the weight and forces involved are low enough that ratio can get lower, within reason. You have the luck of not having to work around axle shafts or a differential which opens up a lot of interesting options for link locations, toe, and caster.

I ran some 3d movement checks out of curiosity. Sorry if they seem difficult to read or are confusing.

First plot is a continuance of link convergence angle that shows what percentage of a links fore/aft forces are applied side to side. It also shows what percent of peak fore/aft link force could be handled when applied sideways.

Second plot is toe change though non-symmetric travel. It is pretty high for the amount of travel due to the steep links, but the limited travel keeps it in check. I know that the signs don't make sense, but it shows that the inside tire moves forward more as it rolls in a corner, causing geometric oversteer.

1767929964246.png

1767929977086.png
 
so one of the things i want to do this spring is get the number off my buddies buggy because it preforms in almost the worst way possible. example. every buggy with us had to go up said hill, dirt bit off mud. each one would grab traction and go. not his. his suspension would not have any of that. sure it flexs but does not transfer any weight like it should. zero..

1767991003588.png
 
Hi very new to the actual calculations of 3/ 4 link set up ,have done a few with my boss at work with the "looks about right " strategy and so far it's been pretty ok

Looking to do 4 link in the front of my tube chassis race / fun day 4wd

Goal is extremely light and basic

Zero road kms but if it was predictable at around 50kmh it would be great

I've punched some numbers i to the calc and just wanted to check i haven't messed up any of the initial measurements as the wording has tripped me up

Pic as follows

Ps is there any calculators that are based on the metric system?

Greg
 

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GregFromNz said:
Hi very new to the actual calculations of 3/ 4 link set up ,have done a few with my boss at work with the "looks about right " strategy and so far it's been pretty ok

Looking to do 4 link in the front of my tube chassis race / fun day 4wd

Goal is extremely light and basic

Zero road kms but if it was predictable at around 50kmh it would be great

I've punched some numbers i to the calc and just wanted to check i haven't messed up any of the initial measurements as the wording has tripped me up

Pic as follows

Ps is there any calculators that are based on the metric system?

Greg
Click to expand...
What sort of terrain / application? At a quick glance, the antis and roll slope are both high. But at the speeds you are looking at roll slope is not that important.

A picture that includes the links plot would be helpful.

Versions 6 and 7 have a metric mode. Use with caution, I am only mostly sure that metric works properly.
 
Treefrog said:
What sort of terrain / application? At a quick glance, the antis and roll slope are both high. But at the speeds you are looking at roll slope is not that important.

A picture that includes the links plot would be helpful.

Versions 6 and 7 have a metric mode. Use with caution, I am only mostly sure that metric works properly.
Click to expand...
Thanks for the reply much appreciated

It'll be used in winch challenge racing locally the tracks are mud/ rock and clay based

Just playing with angles etc at the mo trying to get a grasp on 4 link stuff

Loosely following the busted knuckle video on YouTube with level top links lowers at 7 deg upwards angle towards the chassis / frame

Again appreciate the help !

Greg
 
Sorry to be a pain again

I'm having trouble opening the latest version of the calculator ? It's come through as a file but my computer dosent seem to recognize it and open it sorry again if this is not the place to post this any help would be great !

Greg
 
GregFromNz said:
Sorry to be a pain again

I'm having trouble opening the latest version of the calculator ? It's come through as a file but my computer dosent seem to recognize it and open it sorry again if this is not the place to post this any help would be great !

Greg
Click to expand...
You more than likely need to unzip the file, then, when it brings up all the different files once unzipped, you have to scroll down and click on the main application
 
Hey guys, i am using the link calculator to try and improve at least pinion angle chage on my triangulated four link on my f150 prerunner and i wanted some other opinions. The truck does work well besides the vibration starting at about halfway to droop but i figured might as well try and make some other improvements while i'm here. here is my current set up, that has a lot of pinion angle change, I measured 2.9° pinion rotation up during droop physically on the truck, here are the numbers inputed into the link calculator with the trend graphs.


1000005941.jpg



Here is a few that i've been working on, it does seem to me that the upper link pockets need to go up, and the upper links probably need to be shortened here is a few what I think are improvements. Let me know what your thoughts are.
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dustinboost said:
Hey guys, i am using the link calculator to try and improve at least pinion angle chage on my triangulated four link on my f150 prerunner and i wanted some other opinions. The truck does work well besides the vibration starting at about halfway to droop but i figured might as well try and make some other improvements while i'm here. here is my current set up, that has a lot of pinion angle change, I measured 2.9° pinion rotation up during droop physically on the truck, here are the numbers inputed into the link calculator with the trend graphs.

...

Here is a few that i've been working on, it does seem to me that the upper link pockets need to go up, and the upper links probably need to be shortened here is a few what I think are improvements. Let me know what your thoughts are.
Click to expand...
How many u-joints are you running at the frame end?

I would also recommend taking a look at the driveshaft tab, it is likely to be more insightful than just pinion angle change.
 
GregFromNz said:
Thanks for the reply much appreciated

It'll be used in winch challenge racing locally the tracks are mud/ rock and clay based

Just playing with angles etc at the mo trying to get a grasp on 4 link stuff

Loosely following the busted knuckle video on YouTube with level top links lowers at 7 deg upwards angle towards the chassis / frame

Again appreciate the help !

Greg
Click to expand...
I would guess that an anti of about 80% would probably be a good target. High enough to drive some force down and low enough to avoid hop.

You can get away with less vertical axle separation if you want / need as well.
 
Hi Folks, helping a friend building his fj40 for jungle trails and competitions like "RFC Americas".
We tried a lot of measurements and due to space this is the best we could do. I see a lot of difference compressed vs uncompressed, will this be an issue?
We noticed that changing the Rear Upper Link - Upper Frame affects this quite a lot. Any thoughts on this?


1771175259665.png
 
mautico said:
Hi Folks, helping a friend building his fj40 for jungle trails and competitions like "RFC Americas".
We tried a lot of measurements and due to space this is the best we could do. I see a lot of difference compressed vs uncompressed, will this be an issue?
We noticed that changing the Rear Upper Link - Upper Frame affects this quite a lot. Any thoughts on this?
Click to expand...
If you can get the upper links longer in side view it would probably help keep the antis more consistent. I would put more effort into the rear than the front, since the front increases when the suspension unloads. You can get away with the uppers being more parallel as well. I would watch out for tire clearance on all links. One thing that may help with lack of space in the rear is to have the upper behind the axle centerline.
 
Treefrog said:
If you can get the upper links longer in side view it would probably help keep the antis more consistent. I would put more effort into the rear than the front, since the front increases when the suspension unloads. You can get away with the uppers being more parallel as well. I would watch out for tire clearance on all links. One thing that may help with lack of space in the rear is to have the upper behind the axle centerline.
Click to expand...

1771260042361.png

I have extended the length between the upper link joints at the axle, this pushed the links forward and straightened the link a little bit.
Still is a low number when un-compressed, but this would help to send more force to the shock right? Correct me if I am wrong, but I believe from full uncompressed > to > Ride Height, this will be sending good amount of force to the shock, then from ride height > to > full compressed the 4 link will start to compensate the force. (?)
 
mautico said:
I have extended the length between the upper link joints at the axle, this pushed the links forward and straightened the link a little bit.
Still is a low number when un-compressed, but this would help to send more force to the shock right? Correct me if I am wrong, but I believe from full uncompressed > to > Ride Height, this will be sending good amount of force to the shock, then from ride height > to > full compressed the 4 link will start to compensate the force. (?)
Click to expand...
You have to keep in mind that as the suspension droops out, there is not much force going through it to cause movement. So while the force from the shock is increasing, it is still less than at ride. And the reaction is reduced as a result. The range from ride to fully compressed is more important to focus on for the inverse reason; the forces and reactions are increased.
 
This is a project Ive been working on for couple years. Its mainly a snow wheeler that sometimes turns into a rally race coming off the mountain. And I would like to bomb it around the desert in the summer. The rear uppers on the chassis can be moved up couple inches. My intended ride height was to have the lower links flat. But Its possible to raise the car some. The summer tire is a 39.5, and winter tire was slated to be a 42, but I just acquire some 44s.
Ive been looking for numbers and handling characteristics basics and I come across the talk about the old calculator and new calculator numbers, so Im always unsure if Im looking at accurate numbers to use or not.
Any in sites into how this will perform going fast and on climbs and critiques on my numbers would be appreciated.
Thanks Much.

Rav-Erado 4 Link Specs.png
 
44newman said:
This is a project Ive been working on for couple years. Its mainly a snow wheeler that sometimes turns into a rally race coming off the mountain. And I would like to bomb it around the desert in the summer. The rear uppers on the chassis can be moved up couple inches. My intended ride height was to have the lower links flat. But Its possible to raise the car some. The summer tire is a 39.5, and winter tire was slated to be a 42, but I just acquire some 44s.
Ive been looking for numbers and handling characteristics basics and I come across the talk about the old calculator and new calculator numbers, so Im always unsure if Im looking at accurate numbers to use or not.
Any in sites into how this will perform going fast and on climbs and critiques on my numbers would be appreciated.
Thanks Much.
Click to expand...
By bomb around the desert, is that more on the desert racing style, U4 style, or rock crawler? If it is one of the latter two, it may be beneficial to have the lowers angle up some. Even the first one will not suffer that much from a slight angling of the lower links. It may be beneficial to get the individual axle roll axis to be flatter even if the vehicle roll axis moves away from flat some.

I must admit to not knowing much about snow wheeling. What sort of desired behavior is typical? Is it bursts of throttle hoping to get traction? Is the goal to have the vehicle dig down to a higher traction surface? Is it higher speed with the suspension being put to work? You'll have to help me help you here. I have a general grasp of geometry to behavior, but no idea of what the behavior should be.
 
Treefrog said:
By bomb around the desert, is that more on the desert racing style, U4 style, or rock crawler? If it is one of the latter two, it may be beneficial to have the lowers angle up some. Even the first one will not suffer that much from a slight angling of the lower links. It may be beneficial to get the individual axle roll axis to be flatter even if the vehicle roll axis moves away from flat some.

I must admit to not knowing much about snow wheeling. What sort of desired behavior is typical? Is it bursts of throttle hoping to get traction? Is the goal to have the vehicle dig down to a higher traction surface? Is it higher speed with the suspension being put to work? You'll have to help me help you here. I have a general grasp of geometry to behavior, but no idea of what the behavior should be.
Click to expand...
Bombing the desert for me is just open trail riding, up to 40mph ish on unimproved roads and trails, I usually use my RZR but would replace it if this rig is more comfy to drive.
Eastern OR spring snow wheeling is usually on a deep base, 6-12'. and slow and technical, picking lines where there is moisture in the snow to pack it and avoiding deep tree wells, Steep climbs in low/low sometimes zigzaging up a Mtn face to reach the top. And when the sun goes down the temp can pull the moisture right out of the snow leaving you spinning your tires on sugar, it can change in minuets.
This pic the ground is so steep my tires are on the line, you drive pointing up the hill but crab crawl across the face. Usuall so slow you watch the tires load then pulse forward. Its usually very slow and the lowest gearing you can get.
Last pic is my current project on roller 37s at full bump.
20230513_154901.jpg
20240330_120004.jpg
 
44newman said:
Bombing the desert for me is just open trail riding, up to 40mph ish on unimproved roads and trails, I usually use my RZR but would replace it if this rig is more comfy to drive.
Eastern OR spring snow wheeling is usually on a deep base, 6-12'. and slow and technical, picking lines where there is moisture in the snow to pack it and avoiding deep tree wells, Steep climbs in low/low sometimes zigzaging up a Mtn face to reach the top. And when the sun goes down the temp can pull the moisture right out of the snow leaving you spinning your tires on sugar, it can change in minuets.
This pic the ground is so steep my tires are on the line, you drive pointing up the hill but crab crawl across the face. Usuall so slow you watch the tires load then pulse forward. Its usually very slow and the lowest gearing you can get.
Last pic is my current project on roller 37s at full bump.
Click to expand...
Sounds like a lower antisquat to keep hopping down and consistency up is preferred over a bit high antisquat that can get some a little bit of extra traction with a throttle burst.
 
Sounds good. In the calculator in the Antis box 0 is ride height, are the "-" numbers droop?

I used the top bellhousing bolt for CG Height, I guess I didnt realize how important it is. As a non completed project I was guessing.

In your Link Bible, Under ANTIS "Below 0% means that the springs take more force than just the weight transfer". Is that meant to say Below 100%?

Thanks for the help.
 
44newman said:
Sounds good. In the calculator in the Antis box 0 is ride height, are the "-" numbers droop?
Click to expand...
Yes.
44newman said:
I used the top bellhousing bolt for CG Height, I guess I didnt realize how important it is. As a non completed project I was guessing.
Click to expand...
It's a good estimate for getting started. And probably isn't too far off for your rig.
44newman said:
In your Link Bible, Under ANTIS "Below 0% means that the springs take more force than just the weight transfer". Is that meant to say Below 100%?

Thanks for the help.
Click to expand...
No. Over 100%, the rear end wants to go up. At 100%, no movement. Between 0% and 100%, the rear end squats, but the suspension adds to the spring rate reducing how much it squats. At 0%, the links do not impact how much it squats. Below 0%, the geometry increases squatting.

At least based on common anti squat thinking.
 
Ovrez said:
I am only doing the rear at the moment
60% road driving to the trails, 40% trail no hard rock crawling

hows my numbers.png
Click to expand...
Antis are might be slightly high. But if your trails are on the wet side, you may not want to go too low. Moving the upper frame up slightly might help get it down and get the IC forward some more. Roll slope is probably okay.
 
Ovrez said:
so i would like to be as close to 100% anti squat
why do i read such a difference in anti-squat between the New Version of the 4 Link Calculator vs the older 4 link cal 2004.
Maybe i do not know how to read the New Version of the 4 Link Calculator anti-squat
Only difference is axle end lower link is at 18.25" 4 link cal 2004 vs 19" in the New Version of the 4 Link Calculator


New Version of the 4 Link Calculator anti-squat at 37.6 to 61.0%?


2004 4 link cal anti-squat at 100%
Click to expand...
There are three main reasons for the difference.
  • The newer calculator take drive and brake bias into account. If you set drive bias to be rwd, the numbers will look more familiar.
  • The way it calculators the antis involves wants it to have the other ends info for CG determination. At least tire size and mass are needed.
  • A bug found 2 days ago (thanks YeeP ) where I got mixed up with some variables when determining the height of the CG line. I plan to have a new version out in the next few days to correct this.
 
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