How's my numbers?

[Squeegee]

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.

Thanks a ton, I’ll work on it more in the morning! Do you have a recommendation for where you like to see the antidive? I primarily use it for driving around Montana to camp, and then I drive it to Utah every year for a week long wheeling trip and then drive it home. And I’d I see whoops… I try my best to hit them😂

 

[Treefrog]

Thanks a ton, I’ll work on it more in the morning! Do you have a recommendation for where you like to see the antidive? I primarily use it for driving around Montana to camp, and then I drive it to Utah every year for a week long wheeling trip and then drive it home. And I’d I see whoops… I try my best to hit them😂

In that calculator, aiming for 50-60 will help keep the ride softer when braking. Much lower than that and it will pitch a lot when braking.

 

[Squeegee]

I read a while ago that for the front end, there’s an association with a lower anti dive and an increase likelihood that the car will unload on climbs. I also read that an anti dive over 100% will help the front end squat down when you’re bumping ip a ledge.l
Is this internet hearsay?

 

[Treefrog]

I read a while ago that for the front end, there’s an association with a lower anti dive and an increase likelihood that the car will unload on climbs. I also read that an anti dive over 100% will help the front end squat down when you’re bumping ip a ledge.l
Is this internet hearsay?

Anti over 100% will pull the front down. But it needs traction to do that, and front traction is lower the steeper it is.

So higher anti will help keep the front down. But that's only if the rig is moving.

 

[Squeegee]

Anti over 100% will pull the front down. But it needs traction to do that, and front traction is lower the steeper it is.

So higher anti will help keep the front down. But that's only if the rig is moving.

So if I’m understanding correctly, antidive over 100% is helpful if you’re bumping up an obstacle (with available traction) but it can be at a detriment for on-road drivability and hitting g outs at speed?

 

[Yodabob]

So this build has been taking up space in the garage for too long now, and I need to start putting it together.

It's an LS Jeep Scrambler with Spring Over Leafs in the front, and a 4 link in the rear. It's intended to be an all purpose vehicle with mostly Street driving, but some time on the Sand Dunes, Trails, and Rocks.

The Frame side uppers are adjustable up or down an inch, which bumps my Anti-squat up or down about 7%.

I would really appreciate some feedback on the suspension. Thanks!

 

[Treefrog]

So if I’m understanding correctly, antidive over 100% is helpful if you’re bumping up an obstacle (with available traction) but it can be at a detriment for on-road drivability and hitting g outs at speed?

Anti lift in this case, anti dive is braking related. The only difference value wise is a scale factor. My bad if I had been unclear or used them incorrectly.

Your understanding is correct. Antilift over 100 will help keep the front down. But generally, the times when you want it to help. It probably is not.

Not so much driveability and g outs as it is whoops and general rough road.

It is possible to have a antilift value that rises as the suspension extends. I think you should be able to run version 5 of the calculator. It will give values through travel without having the issues that keep it from running outside of Excel.

 

[Treefrog]

So this build has been taking up space in the garage for too long now, and I need to start putting it together.

It's an LS Jeep Scrambler with Spring Over Leafs in the front, and a 4 link in the rear. It's intended to be an all purpose vehicle with mostly Street driving, but some time on the Sand Dunes, Trails, and Rocks.

The Frame side uppers are adjustable up or down an inch, which bumps my Anti-squat up or down about 7%.

I would really appreciate some feedback on the suspension. Thanks!

What does moving the links do to the roll slope?

 

[Yodabob]

What does moving the links do to the roll slope?

It shifts it about half a degree. Not much change.

 

[Treefrog]

It shifts it about half a degree. Not much change.

Roll slope is probably a bit high. Dropping the antis 7% would probably perform a bit better.

 

[Yodabob]

Roll slope is probably a bit high. Dropping the antis 7% would probably perform a bit better.

ok, Thanks for the Feedback!

 

[Squeegee]

Anti lift in this case, anti dive is braking related. The only difference value wise is a scale factor. My bad if I had been unclear or used them incorrectly.

Your understanding is correct. Antilift over 100 will help keep the front down. But generally, the times when you want it to help. It probably is not.

Not so much driveability and g outs as it is whoops and general rough road.

It is possible to have a antilift value that rises as the suspension extends. I think you should be able to run version 5 of the calculator. It will give values through travel without having the issues that keep it from running outside of Excel.

Here’s where I’m at currently! I’ll check out the v5 tonight. Here’s what I have currently. I can’t have the roll axis any more negative whithout having almost the entire frame side lower off of the frame. And I’d widen the axle side lower but I’m a bit stuck due to tire clearance. I’m a bit undecided about what to do for the antidive! Thank you for all of the help, I really appreciate it

 

[Treefrog]

Here’s where I’m at currently! I’ll check out the v5 tonight. Here’s what I have currently. I can’t have the roll axis any more negative whithout having almost the entire frame side lower off of the frame. And I’d widen the axle side lower but I’m a bit stuck due to tire clearance. I’m a bit undecided about what to do for the antidive! Thank you for all of the help, I really appreciate it

With a 3 link and a mechanical steering linkage, I would focus more on having the panhard the same length and as parallel as possible to the drag link. Slight oversteer and slight understeer are not naturally differentiable by most people. Having one end of the suspension be slightly oversteering, may not be noticeable if all of the other suspension stuff is understeering.

For the antidive, consider raising the axle end of the lowers 0.5". It will lower it some, and will make the roll axis slightly more negative. Raising both of the upper link points .5 inch will help keep the forces on the upper link down.

 

[Squeegee]

With a 3 link and a mechanical steering linkage, I would focus more on having the panhard the same length and as parallel as possible to the drag link. Slight oversteer and slight understeer are not naturally differentiable by most people. Having one end of the suspension be slightly oversteering, may not be noticeable if all of the other suspension stuff is understeering.

For the antidive, consider raising the axle end of the lowers 0.5". It will lower it some, and will make the roll axis slightly more negative. Raising both of the upper link points .5 inch will help keep the forces on the upper link down.

Thanks for the reality check on the roll center.

It looks like moving things around like you asked that will bring the antisquat to about 65%🤔

 

[Squeegee]

I had a chance to run my numbers through the version 5 calculator and I’m curious why my anti dive went down so much. I’m not sure what to do with this new found data.

 

[Treefrog]

I had a chance to run my numbers through the version 5 calculator and I’m curious why my anti dive went down so much. I’m not sure what to do with this new found data.

That should be expected. V4 and newer account for the split of forces front and rear. The default is the front doing 60% of the braking. The older calcs have a hardcoded 100%.

As for the new information, the front antis get higher as the suspension unloads and lower as it compresses. This means that as the hill gets steeper, the front will want to suck down more, but as it pitches forward while braking the ride is less rough.

 

[Squeegee]

That should be expected. V4 and newer account for the split of forces front and rear. The default is the front doing 60% of the braking. The older calcs have a hardcoded 100%.

As for the new information, the front antis get higher as the suspension unloads and lower as it compresses. This means that as the hill gets steeper, the front will want to suck down more, but as it pitches forward while braking the ride is less rough.

Thanks for explaining that! It makes much more sense now

 

[06h3]

Treefrog do you think the rear suspension plays a bigger role on steep climbing ability or front?

 

[Treefrog]

Treefrog do you think the rear suspension plays a bigger role on steep climbing ability or front?

It goes without saying that both are important.

Rear gets you up, but the front will take you for a ride. The rear's job is to get a much traction as it can, while the front's job is to not get in the way. A bad rear is less likely to cause issues with stability than a good front is.

The rear can only cause 4 things to happen: keep climbing, hopping, spinning the tires, and trying to rotate the front up. The last one is not sudden, you should have warning that the front is getting light enough that the rear is starting to torque pitch it.

The front will act stiff when it try's to react to a change in the surface. It will seem stiff in equal and unequal travel. That is, the axle will not smoothly flex over a rock. This stiffness makes the front want to pop up. The tendency gets worse the higher the farther the IC is from the surface.

 

[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?

It goes without saying that both are important.

Rear gets you up, but the front will take you for a ride. The rear's job is to get a much traction as it can, while the front's job is to not get in the way. A bad rear is less likely to cause issues with stability than a good front is.

The rear can only cause 4 things to happen: keep climbing, hopping, spinning the tires, and trying to rotate the front up. The last one is not sudden, you should have warning that the front is getting light enough that the rear is starting to torque pitch it.

The front will act stiff when it try's to react to a change in the surface. It will seem stiff in equal and unequal travel. That is, the axle will not smoothly flex over a rock. This stiffness makes the front want to pop up. The tendency gets worse the higher the farther the IC is from the surface.

Would you adjust anti lift or anything else to make this climb better?

 

[Treefrog]

Would you adjust anti lift or anything else to make this climb better?

Getting the antisquat and front antilift below 100 may help prevent some hopping. Trying to get the ICs further away from their respective ends may help with keeping the ends from popping up some.

 

[Squeegee]

After a day or two and a bit more remeasuring. This is what I came up with, I found that pushing the frame side lowers out and pulling the frame side upper a little bit brought the roll axis into the negatives. I don’t believe I can push the axle side lowers out anymore due to tire clearance.

Is there any issue with the having the roll axis transition from understeer to oversteer on compression. I saw earlier in this thread that having the antidive transition from under 100% to over 100% can make for some odd characteristics and I didn’t know if the rolls axis was similar

 

[Treefrog]

After a day or two and a bit more remeasuring. This is what I came up with, I found that pushing the frame side lowers out and pulling the frame side upper a little bit brought the roll axis into the negatives. I don’t believe I can push the axle side lowers out anymore due to tire clearance.

Is there any issue with the having the roll axis transition from understeer to oversteer on compression. I saw earlier in this thread that having the antidive transition from under 100% to over 100% can make for some odd characteristics and I didn’t know if the rolls axis was similar

No inherent issue. Just have to be aware that the front may want to oversteer when braking.

The anti transition can cause hopping and all the beating up of parts that comes with it. Roll axis has no such issue.

 

[Squeegee]

No inherent issue. Just have to be aware that the front may want to oversteer when braking.

The anti transition can cause hopping and all the beating up of parts that comes with it. Roll axis has no such issue.

Thanks for clarifying that for me!

 

[Peter S]

I'm batteling with my rear suspension it kicks and is realy harsh my numbers anti squad and lift looks a whole different from the others i see here

it was like this when i bought the car. we already gave it a little bit more preload on the spring to get the rear uppers pointing up. so its squads a less. first we where using 5 inch compression just by accelerating.

In the little movie you see the back kicking on the smallest obstacle.
is this a suspension problem or a numbers problem ?
Thanks

 

[Treefrog]

I'm batteling with my rear suspension it kicks and is realy harsh my numbers anti squad and lift looks a whole different from the others i see here

it was like this when i bought the car. we already gave it a little bit more preload on the spring to get the rear uppers pointing up. so its squads a less. first we where using 5 inch compression just by accelerating.

In the little movie you see the back kicking on the smallest obstacle.
is this a suspension problem or a numbers problem ?
Thanks

Two things come to mind. First one is the springs and shock tune. I am not experience or well informed on shock tuning. From the video it looked like either the shocks where too stiff or it blew through the travel and was on the bumps. Hopefully a member more experienced in it will chime in. Mind if I ask you to take a look at the spring tab of the calculator? Given that it is a competition vehicle I understand if you are not willing to share that info.

The second thing is link length in side view. They are on the shorter end for the amount of travel. But I don't think the link geometry is the biggest issue.

 

[Peter S]

Two things come to mind. First one is the springs and shock tune. I am not experience or well informed on shock tuning. From the video it looked like either the shocks where too stiff or it blew through the travel and was on the bumps. Hopefully a member more experienced in it will chime in. Mind if I ask you to take a look at the spring tab of the calculator? Given that it is a competition vehicle I understand if you are not willing to share that info.

The second thing is link length in side view. They are on the shorter end for the amount of travel. But I don't think the link geometry is the biggest issue.

i just want to improve and learn so no secrets
Wil measure everything tonight for the shocks

 

[Peter S]

 

[Treefrog]

Hmm. My guess would be to talk to a shock tuner.

Other than that, do the coilovers have slider stops installed?

 

[Peter S]

Hmm. My guess would be to talk to a shock tuner.

Other than that, do the coilovers have slider stops installed?

slider stops are 2 inch front and 2.5 inch rear above slider.
Problem is the shock tuners in belgium are rare. we try to make it better but the kicking stays thats why i wasnt sure if there is a link geometry problem or just find the right tune.
The rear squads, ... when full throttle it is kinda oke, but slow its terrible kicking the back