Antisquat % differences???

[offroadwerks]

Any 1st hand experience with higher and lower antisquat differences? To be exact, what would say 50% antisquat perform like vs 100%? I've done several 4 link set ups and always use 4link calculator and always try to keep AS% #s around 80%. I'm working on a rear 4 link now where AS could be 65% with 0* oversteer. How low is too low and whats too high?? And should front 4 link have higher or lower AS #s than rear?

 

[the_white_shadow]

Bumping this back to the top for some comments. Im working on my front suspension design for my truck and have the front anti-dive (braking) around 30% at ride height. This isnt going to be a racecar just a trail rig. Roll axis is at -0.22 degrees. Pinion change is about +5* during bump travel and -2.2* at droop. All of my other numbers look good except the AS number. Whats the consensus on lower v.s higher AS numbers? Whats a good number to shoot for for the front? Rear?

Dual triangulated front with 40" lowers and 34" uppers. 9" Vertical separation at axle and 7" at frame. Flat to slightly negative lowers at ride height. 42" tires.

Side question: When using the calculator what does everyone put in for the CoG value? Typical buggy style chassis with 8" deep subframe. Engine is stuffed back and low. This value affects the outputs in the spreadsheet greatly.

 

[Beerj]

I think most go with the camshaft centerline for things like LS motors and the top bellhousing bolt for older style engines.

 

[Rjhoward32006]

What he said. I've been changing my antisquat in the rear just to see if it makes a difference.
70% has been the best so far. I'm now lower and will report back as to how it works. You may want a little more seperation in the front. You will find out real quick when you hit a hill and its any bit loose, the front end will start hopping looking for traction

 

[the_white_shadow]

Im running the artec truss up front with their upper brackets. Not sure how much higher i can go. Ive heard the rule of 25% tire height for the axle separation.

 

[TRD]

Lower AS tends to be better, especially in the front.

Having some brake dive improves traction and stopping distance.

In the rear lower AS lets the suspension move more naturally and find traction.
Most high performance off-road vehicles are moving to lower AS numbers.

When building a link suspension it's most important to try and keep the lowers nearly flat in the side view.

 

[Beerj]

I thought it was flat uppers and no more than 10° slope on the lowers?

 

[redneckengineered]

I thought it was flat uppers and no more than 10° slope on the lowers?

Flat lowers (parallel with ground) and uppers that run downhill to the chassis will get you close.

 

[TBItoy]

I thought it was flat uppers and no more than 10° slope on the lowers?

That's old school.

laughing1


Actually I remember 10+ years ago when most linked rigs had the lowers on a 45° from the ground, and uppers on a ~30° with coils and white shocks.... and they bunny-humped ledges till they bounced to the top...

 

[patooyee]

I read a good explanation of AS% on Pirate recently by a very reputable source. I think it was BIgger Valves or someone.

The forces that reach the tires are equal no matter what. It is merely a matter of how they get there and how you control them.

AS (and most other suspension geometry numbers) are an expression of the fast, uncontrollable way to get the force to the tires. IE, it happens instantly and basically can not be controlled. The percentages are an expression of how much of the total forces bypass the shocks and go straight to the tires via the links. You may or may not want some of that built into your suspension. But recognize that, once it's there, only modification of suspension design can change it.

What doesn't go through the links goes through the shocks and therefore happens much slower and has a means of being controlled via tuning. If you want a suspension that is more predictable and responsive to tuning, you want a neutral suspension, or as close to it as possible.

Many of the go fast rigs these days are designing as close as possible to 0% as they can. (0 in the calculator is neutral.) One I am working on now is 12% in the rear. My rigs in the past have been, in this order (going by rough memory) 200%, 110%, 80%, 65%. Each rig has had successively better ride quality and performance. Not just because of AS. But AS has been a component in the improvements IMO.

 

[the_white_shadow]

First time using the calculator for my link suspensions. Previous was a 3-link front where the options to install everything was limited due to having an LS under the hood of a 82 toyota. It did sit low and worked great. I followed the basic rules as close as I could but had to make some concessions on placement.

Anywho, onto the new build where its pretty much a blank canvas. These are the numbers I am planning on going with. as you can see, the AS numbers are pretty low 43% front and 28% rear. No racing here so im not sure how it will work out. We will see.
Any comments on the numbers would be appreciated. First timer here.

 

[TRD]

I read a good explanation of AS% on Pirate recently by a very reputable source. I think it was BIgger Valves or someone.

The forces that reach the tires are equal no matter what. It is merely a matter of how they get there and how you control them.

AS (and most other suspension geometry numbers) are an expression of the fast, uncontrollable way to get the force to the tires. IE, it happens instantly and basically can not be controlled. The percentages are an expression of how much of the total forces bypass the shocks and go straight to the tires via the links. You may or may not want some of that built into your suspension. But recognize that, once it's there, only modification of suspension design can change it.

What doesn't go through the links goes through the shocks and therefore happens much slower and has a means of being controlled via tuning. If you want a suspension that is more predictable and responsive to tuning, you want a neutral suspension, or as close to it as possible.

Many of the go fast rigs these days are designing as close as possible to 0% as they can. (0 in the calculator is neutral.) One I am working on now is 12% in the rear. My rigs in the past have been, in this order (going by rough memory) 200%, 110%, 80%, 65%. Each rig has had successively better ride quality and performance. Not just because of AS. But AS has been a component in the improvements IMO.

Patooyee nailed it!

And keep those lower links parallel with the ground, it's one of the most important things.

 

[bgredjeep]

Burkey just made some changes on his rear suspension to add AS. When he initially added the trailing arms he built 0 AS thinking it would work better at speed. With the short quick runs the bouncers are doing, it ended up looking sluggish off the line and not climbing as well. He reworked the setup ~80% AS before the PowerLine park race and the results are pretty obvious.

Watch the videos from Gray Rock, then PowerLine and you'll see how much quicker he gets off the line.

Like anything, there's no magic formula that always works. Find the best for your intended use, get close, then fine tune from there.

 

[patooyee]

Burkey just made some changes on his rear suspension to add AS. When he initially added the trailing arms he built 0 AS thinking it would work better at speed. With the short quick runs the bouncers are doing, it ended up looking sluggish off the line and not climbing as well. He reworked the setup ~80% AS before the PowerLine park race and the results are pretty obvious.

Watch the videos from Gray Rock, then PowerLine and you'll see how much quicker he gets off the line.

Like anything, there's no magic formula that always works. Find the best for your intended use, get close, then fine tune from there.

Not knowing what he had before, I can't say how big a leap 80% is. And it would make sense that, if you wanted more of the forces to get to the tires quicker, one could easily accomplish that via modifying the suspension to achieve that. (IE, more through the links, less through the shocks.) But there are TONS of go-fast rigs out there that take off like drag cars and are way lower than 80% AS. I bet some of the serious suspension tuners out there could have made his shocks deliver that load faster without going crazy with AS.

Not that Jake isn't a good tuner. But there are guys out there like Triaged that are so far beyond any of us (by us I mean anyone in the SE) that they make bouncing look like soap box derby. Triaged seems to have sworn off Pirate (like so many have) but he is still active on dessert racing forums. I read one his his threads on one recently. It's like trying to understand a rocket scientist describe nuclear fusion.

 

[TBItoy]

Re:

The older videos of the Riot buggy, it sags out and torque twists like a dang trophy truck. Ride height was super low also. Looked like a lot of it was progressively tuned out over time.

Interested to see how the changes work

 

[bgredjeep]

Not knowing what he had before, I can't say how big a leap 80% is. And it would make sense that, if you wanted more of the forces to get to the tires quicker, one could easily accomplish that via modifying the suspension to achieve that. (IE, more through the links, less through the shocks.) But there are TONS of go-fast rigs out there that take off like drag cars and are way lower than 80% AS. I bet some of the serious suspension tuners out there could have made his shocks deliver that load faster without going crazy with AS.

Not that Jake isn't a good tuner. But there are guys out there like Triaged that are so far beyond any of us (by us I mean anyone in the SE) that they make bouncing look like soap box derby. Triaged seems to have sworn off Pirate (like so many have) but he is still active on dessert racing forums. I read one his his threads on one recently. It's like trying to understand a rocket scientist describe nuclear fusion.

I mentioned it in the post. 0% before, ~80% after. I'm sure he could have seen improvement with less of a jump. It comes off the line a lot faster from what I've seen and heard from him.

 

[mac5005]

Triaged seems to have sworn off Pirate (like so many have) but he is still active on dessert racing forums. I read one his his threads on one recently. It's like trying to understand a rocket scientist describe nuclear fusion.

Got a link or a hint as to where that thread is? Feel free to pm it. I like reading the threads above my grade level, and I think I've exhausted pirate for all the pertinent stuff.

 

[mcutler]

Re:

I know he still post on race desert

Matt

 

[patooyee]

Got a link or a hint as to where that thread is? Feel free to pm it. I like reading the threads above my grade level, and I think I've exhausted pirate for all the pertinent stuff.

I don't recall right now. I wasn't looking for it directly so I didn't bookmark it or anything. I came across it looking for something else entirely and I remember his screen name wasn't triaged. It took me a minute to figure out that it was him posting. He was posting CAD models of a desert truck he was helping to build for a big race team. I'm sorry. It was many, many pages long. Like 20 or 30.

 

[mcutler]

Re:

Kinetik race truck I believe

Matt