How's my numbers?

[06h3]

Thanks for the input. I didn’t know the triangulation on the lowers gives more “axle steering” aka swinging in its arc of travel? Changing the track bar to a higher location on the axle probably flattens the roll axis and helps give less swing correct?

I fixed my COG. I used the top of the bellhousing bolt. I have an aluminum block so I think the recommendation is camshaft centerline but since I’m heavy and have creature comforts I went to the top bellhousing bolt.

How is my anti lift up front? Is a lower anti lift number allowing the suspension to droop out on climbs and forward momentum or does it suck it down?

 

[Treefrog]

Thanks for the input. I didn’t know the triangulation on the lowers gives more “axle steering” aka swinging in its arc of travel? Changing the track bar to a higher location on the axle probably flattens the roll axis and helps give less swing correct?

Kinda to the first part, yes to roll axis, not really to less swing. It is due to the side to side movement caused by the panhard. At ride it looks like this: /\ . But as it moves side to side it looks more like this: /|. Since the one link is getting longer in side view and the other shorter, the axle turns.

I fixed my COG. I used the top of the bellhousing bolt. I have an aluminum block so I think the recommendation is camshaft centerline but since I’m heavy and have creature comforts I went to the top bellhousing bolt.

Seems about right for an H3 on 43s. Inline engines are generally recommended to use the bellhousing bolt as well.

How is my anti lift up front? Is a lower anti lift number allowing the suspension to droop out on climbs and forward momentum or does it suck it down?

Anti lift seems alright. If you can lower it you will have a smoother ride when braking hard. A lower anti-lift is causing it to want to droop out. Higher will suck it down. It should be noted that on a climb the percent torque to the front goes down and the anti-lift goes down as a result.

 

[PCStang]

Hello, I am currently reworking the rear suspension in my 4 seat buggy. Its Chevy based with 1 tons and 42s and used mainly for trail riding/rockcrawling in MN and WI. I used a previous version to design the front 4 link with good results on the trails. If you could take a look and provide any feedback it would be appreciated. Thanks!

 

[Treefrog]

Hello, I am currently reworking the rear suspension in my 4 seat buggy. Its Chevy based with 1 tons and 42s and used mainly for trail riding/rockcrawling in MN and WI. I used a previous version to design the front 4 link with good results on the trails. If you could take a look and provide any feedback it would be appreciated. Thanks!

Wow. Those are some flat lines. The only thing two things that stick out are the lack of pinion angle change in the rear and the rear anti is just on the edge of switching behavior from squatting the rear to lifting the rear.

The oversteer tendencies might start to show up if speed starts to increase. Somewhat related, flex steer might be a bit high, but it is hard to avoid on taller rigs.

 

[PCStang]

Thanks for your thoughts... mind elaborating on which lines are "wow flat" and if its a concern? Also I am helping a buddy with his front 4 link on his JK Unlimited on tons and 42s. Do you mind taking a look at his #s also? (see below) Thanks for your time!

 

[Treefrog]

Thanks for your thoughts... mind elaborating on which lines are "wow flat" and if its a concern? Also I am helping a buddy with his front 4 link on his JK Unlimited on tons and 42s. Do you mind taking a look at his #s also? (see below) Thanks for your time!

Anti's mostly and roll to a smaller degree. Not a concern at all. Just not often they deviate so little during travel.

As for the new plots, the front needs more triangulation. 40 degrees combined is the minimum and more is better as weight goes up. The antis could benefit from being flatter, more so the rear in up travel. Rear anti may be a tad high in down travel, but not usually an big issue. Pinion's look pretty good.

 

[06h3]

Wow. Those are some flat lines. The only thing two things that stick out are the lack of pinion angle change in the rear and the rear anti is just on the edge of switching behavior from squatting the rear to lifting the rear.

I thought it changed behavior at 100% not 50%?

 

[Treefrog]

I thought it changed behavior at 100% not 50%?

Right. But as load shift to the rear, such as climbing, the drive bias shifts more to the rear and the anti starts to go up.

 

[drozg]

I am wondering what happens to geometry (mainly roll axis) when adding a rear sway bar. If in case I have rear roll center slightly lower than front, which means I get roll axis at about 1 degree of understeer. What would happened if I add rear sway bar, would that change things to oversteery roll axis or not?
Thanks 👍🏻

 

[Treefrog]

It would not change the geometry understeer. The roll bar will have some impact on the overall understeer or oversteer. I am not well read on that part

 

[CrawlWyo24]

I am working on putting a 3 link on my rig, no street time, mainly low speed crawling and trail running. The 4 link has been there for years but I have never been very happy with it. I ran all my numbers and am looking for any ideas on how to improve the 4 link, as well as any changes recommended for the 3 link before I burn it all in.

 

[Treefrog]

I am working on putting a 3 link on my rig, no street time, mainly low speed crawling and trail running. The 4 link has been there for years but I have never been very happy with it. I ran all my numbers and am looking for any ideas on how to improve the 4 link, as well as any changes recommended for the 3 link before I burn it all in.

What don't you like about the 4 link? Relating behavior to geometry helps us all.

I would guess that making the 4 link more horizontal will help. And maybe shortening the upper a bit.

As for the front, are you running a drag link style steering? If not, having the panhard pointing up at ride may be a good idea with the travel split.

 

[CrawlWyo24]

What don't you like about the 4 link? Relating behavior to geometry helps us all.

I would guess that making the 4 link more horizontal will help. And maybe shortening the upper a bit.

As for the front, are you running a drag link style steering? If not, having the panhard pointing up at ride may be a good idea with the travel split.

With the 4 link I have had issues with the body raising up on acceleration and flex steer. Shortening the upper is a good idea, I’ll play with numbers on that.

For the front I am running drag link style steering for now. Full hydro will come at some point and I could get more angle then. But as it sits now was to try to keep drag link and panhard as close to the same angle as possible.

For the front and/or rear are there any numbers that are critical to keep within a certain range?

 

[Treefrog]

With the 4 link I have had issues with the body raising up on acceleration and flex steer. Shortening the upper is a good idea, I’ll play with numbers on that.

Making the upper and lower links flatter should help with both. The raising up is interesting. Is it raising or excessive squatting that feels like rising up? What conditions is it doing that under? Flat ground, climbs, launching, etc.?

For the front I am running drag link style steering for now. Full hydro will come at some point and I could get more angle then. But as it sits now was to try to keep drag link and panhard as close to the same angle as possible.

For the front and/or rear are there any numbers that are critical to keep within a certain range?

Usually good to keep the 100% bias antis below 100%. And to keep all the roll axes flat.

 

[CrawlWyo24]

Making the upper and lower links flatter should help with both. The raising up is interesting. Is it raising or excessive squatting that feels like rising up? What conditions is it doing that under? Flat ground, climbs, launching, etc.?

Usually good to keep the 100% bias antis below 100%. And to keep all the roll axes flat.

Thank you, I’ll work on flattening out the rear links.

From what I’m looking at my front roll axis is pretty flat, but my rear could use some flattening.

Sorry I’m new to the calculator, but when you say “bias antis” which results in the calculator am I looking at? The anti squat, Dive and lift? On the calculator am I trying to get the numbers closer to zero or closer to 100 or right in the middle?

I have read through the threads linked at the start of this thread and feel good understanding the general concept, but I’m struggling to understand how interpret my results.

 

[Treefrog]

Thank you, I’ll work on flattening out the rear links.

From what I’m looking at my front roll axis is pretty flat, but my rear could use some flattening.

Flatter roll axis should help with the flex steer issue.

Sorry I’m new to the calculator, but when you say “bias antis” which results in the calculator am I looking at? The anti squat, Dive and lift? On the calculator am I trying to get the numbers closer to zero or closer to 100 or right in the middle?

I have read through the threads linked at the start of this thread and feel good understanding the general concept, but I’m struggling to understand how interpret my results.

The torque split front to rear has an effect on the antis. The drive bias input accounts for that. The general trend among current crawlers is that if all of the torque is going to one end (100% bias), you want the responding anti to be less than 100%. Currently you have the drive bias set to 50%, so you want to keep the anti's (rear anti squat and front anti lift) below 50%. Closer to 50 or closer to 0 is up to you. Generally, faster prefers lower antis.

 

[CrawlWyo24]

Flatter roll axis should help with the flex steer issue.

The torque split front to rear has an effect on the antis. The drive bias input accounts for that. The general trend among current crawlers is that if all of the torque is going to one end (100% bias), you want the responding anti to be less than 100%. Currently you have the drive bias set to 50%, so you want to keep the anti's (rear anti squat and front anti lift) below 50%. Closer to 50 or closer to 0 is up to you. Generally, faster prefers lower antis.

Perfect! That is exactly the information I was looking for! Thank you for all of your help

 

[Treefrog]

I very much appreciate the response and am even more appreciative of the work that's already gone into the calculator as it is. Thank you.

IIRC, the geometry in my liberty buggy moves the tire outboard as it compresses up front....but I'm not sure how to get that to happen in this new chassis. Guess it's trial and error for those of us who can't model, lol.

Thanks again!

Quoting this here to keep the other thread more about the calculator rather than suspension behavior.

I am assuming that you are talking about both tires extended and one side compressing.

First guess would be panhard bar. But if it's a 4 link, it may be doable with low up travel and links that angle down towards the axle at ride.

It's likely that high amounts of flex steer may be involved.

If you have numbers for the liberty buggy's suspension I would be interested in running them to see if it's actually doing that.

 

[Sean]

Quoting this here to keep the other thread more about the calculator rather than suspension behavior.

I am assuming that you are talking about both tires extended and one side compressing.

First guess would be panhard bar. But if it's a 4 link, it may be doable with low up travel and links that angle down towards the axle at ride.

It's likely that high amounts of flex steer may be involved.

If you have numbers for the liberty buggy's suspension I would be interested in running them to see if it's actually doing that.

Apologies for cluttering the other one. Would you like me to delete it from the other thread? If so, say the word.

It's a W shaped 4 link, only about 4" uptravel (which apparently is pretty normal for portal 4ws cars like I'll be building)....but the links will angle up to the housing from the chassis at static ride height.

I don't have numbers handy for it.....but it's far from optimal. The links themselves are IMO, too short and too steep.

 

[Treefrog]

Apologies for cluttering the other one. Would you like me to delete it from the other thread? If so, say the word.

It's a W shaped 4 link, only about 4" uptravel (which apparently is pretty normal for portal 4ws cars like I'll be building)....but the links will angle up to the housing from the chassis at static ride height.

I don't have numbers handy for it.....but it's far from optimal. The links themselves are IMO, too short and too steep.

You can leave it in the other one. It wasn't clutter. The topic changed from the calculator to suspension talk. So brought it here to a suspension talk thread.

Is the W the new one you will be building or the old one that had the outboard travel?

Regarding the tire moving outboard, I thought about it a bit more. Most suspensions will do that. The tire's contact point is below the point it rotates about. As such, the contact point moves outward when that side is compressed more than the other side.

 

[Sean]

You can leave it in the other one. It wasn't clutter. The topic changed from the calculator to suspension talk. So brought it here to a suspension talk thread.

Is the W the new one you will be building or the old one that had the outboard travel?

Regarding the tire moving outboard, I thought about it a bit more. Most suspensions will do that. The tire's contact point is below the point it rotates about. As such, the contact point moves outward when that side is compressed more than the other side.

The W is the old one.....the new one will likely be more XX.

Ah....okay...so I may be okay.

I'm so far out from starting these 2 cars that I can't exactly say where anything's going to end up....I have 3 large projects in front of them. I could easily solve this question by simply throwing out the aesthetics of the front tube work and going much more simplified....and I may end up doing just that to avoid the issue. Function over form....but I do like my designs to look cool.

 

[YeeP]

Need some input on a possible revision I am looking into. I have a "current" design and an "updated" version. Both versions are only for the front of the car. I am trying to see if I can lower the engine in the chassis, but this will require the chassis side uppers to be lower. As expected this has caused an increase in pinion change throughout the cycle, however I am still in an acceptable area. The part that concerns me is the instant center has moved more than I'd like toward the axle, which I think will cause more steering while flexing.

I believe we talked about having a slight understeer overall going downward toward the front, this hasn't changed much between the two designs. Moving the upper chassis side has also increased the understeer there as well. Any input as far as positives and negatives between the two, as well has insight into if the rear will be more difficult to setup some balance with would be much appreciated (I realize you can't look at the chassis, just trying to avoid setting myself up for difficulty in making the rear work well with the front).

Thank you!

EDIT: I should mention that I am moving the axle vertically 6" upwards as a mark for "enough" up travel. This is limited by the upper control arm coming in contact with the alternator when the entire axle comes up (no problems flexing). Another option would be to limit up travel which I really would like to avoid. Thoughts?

EDIT 2: Overall the engine has only lowered about 2 inches. I can bring it up if needed, just trying to find a compromise.

Current:

Updated:

 

[Treefrog]

Need some input on a possible revision I am looking into. I have a "current" design and an "updated" version. Both versions are only for the front of the car. I am trying to see if I can lower the engine in the chassis, but this will require the chassis side uppers to be lower. As expected this has caused an increase in pinion change throughout the cycle, however I am still in an acceptable area. The part that concerns me is the instant center has moved more than I'd like toward the axle, which I think will cause more steering while flexing.

I believe we talked about having a slight understeer overall going downward toward the front, this hasn't changed much between the two designs. Moving the upper chassis side has also increased the understeer there as well. Any input as far as positives and negatives between the two, as well has insight into if the rear will be more difficult to setup some balance with would be much appreciated (I realize you can't look at the chassis, just trying to avoid setting myself up for difficulty in making the rear work well with the front).

Thank you!

EDIT: I should mention that I am moving the axle vertically 6" upwards as a mark for "enough" up travel. This is limited by the upper control arm coming in contact with the alternator when the entire axle comes up (no problems flexing). Another option would be to limit up travel which I really would like to avoid. Thoughts?

EDIT 2: Overall the engine has only lowered about 2 inches. I can bring it up if needed, just trying to find a compromise.

On the revised, the antis get a bit high with down travel, but there is less weight on the tires then. The roll center does get a bit higher, but I don't think it will be hard to balance with the rear. The understeer is getting rather high, but the flex steer is pretty low since the links are similar in length and are somewhat flat.

As far as a comparison, the revision will ride a bit stiffer when braking. It will also want to roll a little less.

 

[06h3]

Treefrog can you dive into the link sizing a little more?

Desired yield, buckling, bending, etc.

I see 15, 6,2,6 as values? That are those values? I assume red is bad, green is good

 

[Treefrog]

Treefrog can you dive into the link sizing a little more?

Desired yield, buckling, bending, etc.

I see 15, 6,2,6 as values? That are those values? I assume red is bad, green is good

The desired values are for the factors of safeties.

Green means above the desired value, red means below it. If I remember correctly, the lowest FOS is shown, but the FOSs are shown for each link.

One of the earlier contributors made that page originally. As part of one of the versions, I added the desired F.O.S. when researching if there was any values out there as recommendations, I found those numbers on another forum. I think it was PBB or NC4x4. I can track down the source later if wanted.

Thanks for bringing this up. I don't often get feedback on stuff other than the geometry portion.

 

[06h3]

No problem. So I see 15 (value) on desired yield. Is that 15,000 lbs of force?

 

[Treefrog]

It is

No problem. So I see 15 (value) on desired yield. Is that 15,000 lbs of force?

A factor of safety of 15.

 

[Squeegee]

Hi! This is my first time posting and I’ve never used a link calculator before. I’m doing a front 3 on a 80 series Land Cruiser. How’s my numbers? I didn’t use the irate calculator because I’m on ios. Anybody see anything glaring?

 

[06h3]

Hi! This is my first time posting and I’ve never used a link calculator before. I’m doing a front 3 on a 80 series Land Cruiser. How’s my numbers? I didn’t use the irate calculator because I’m on ios. Anybody see anything glaring?

wait for tree frog to get the 100% ok but I think roll axis is great. Anti dive is good. Roll center height seems low. (Tree frog can probably give more insight)

 

[Treefrog]

Hi! This is my first time posting and I’ve never used a link calculator before. I’m doing a front 3 on a 80 series Land Cruiser. How’s my numbers? I didn’t use the irate calculator because I’m on ios. Anybody see anything glaring?

In a front application, the antisquat value in that calculator is actually anti dive. Getting it down some will help keep the ride soft when braking at the expense of it pitching more.

I would recommend getting the roll axis angle negative for understeer behavior.

Did notice somethings. The rolling radius seems really small for that size of a tire. Additionally, your panhard bar's Y values have the same sign, so they are on the same side of the vehicle. You may want to check the clearances of the panhard as well, with it being on the pinion side of the axle.