cbh148

What would be a good knuckle/FLCA setup for street cars that see lots of daily action as well as drift event action too?

My buddy and I have s13's that are very similarly modified and we're having some issues when drifting that we're assuming are the result of riding too low with stock knuckles (with the resulting geometry issues that low ride heights yield).

It's like the car really really wants to spin out during tighter or slower slides, like after coming out of a long slide (turn #3 in video), but seems to feel ok and not so spin-happy during wide-open higher speed sweepers (turn #1 and #2 in video). Even at the last drift event I did, I was able to connect the whole course pretty well, and I even tackled the bigger sweeper that had lots of elevation change in it with no problem, but in the basic little figure 8 at the end of the course I spun out so many times because the tight turns made my car feel like it really didn't want to comfortably remain sideways -- almost as if my front brakes were magically grabbing anytime the car would be sideways in those tighter slower turns.

Neither one of us are looking for some particular super crazy steering angle number. More angle would be nice I'd imagine, but these are still street cars.

Basically, we've never driven/drifted a car with modified knuckles, corrected roll center or any of that jazz. I'm assuming that if we had knuckles with corrected roll center and bump steer that this would be remedied?

Our setups:
s13's, SR's, t25g & 2871r (.64, 52t), welded diffs, coilovers, Circuit Sports inner & outer tie rods (set to "max" bump steer correction, but still diagonal as hell), subframe collars, ES rack bushings, stock knuckles

We've been considering going with Cor Integration's knuckle/crossmember/extended FLCA setup, or perhaps PBM knuckles with stock FLCA, or who knows. Just figured I'd see what setup you guys recommended.

"Phantom front brakes grabbing while sideways" spin-out runs @ 0:10 and 1:02

And the exact same phenomenon @ 2:07

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InsTanCeZ

Sneak peek: KPI / SAI / Camber 3 position lockout front lower mount set



Parts Shop MAX going HAM. They're slowly becoming my go to company for all my suspension needs lol. They also recently got a new shock dyno and are releasing a new line of dampers soon.

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ACE マジック HEART

Def

Yep. It was better than back to back testing, as I had lots of time on the same track with both. The S14 subframe was faster. I could get on the power sooner and harder in every corner. In fact, it changed the car to where it was actually really close to oversteer at light power application on corner exit to where the S14 subframe made it have almost stupid grip on throttle application in the rear.

It honestly made the car "feel" slower because of the apparent rear grip increase, but whereas before most cars would kick my ass on corner exit, my car then became one of the faster cars out there on corner exit. Being able to now use the throttle more aggressively meant that the same alignment that would generate mild steady state understeer now could be rotated more.


Rear diff was the same S15 HLSD in both cases, so it's about as mild as they come.

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S13 Hatch - Goes around tracks quickly
DEFSPORT

Def

What anti-squat percentage do you aim for? IRS cars don't seem to like much of it.

And you can't run a car that's actually fast stupid low with a stock unibody. You need some level of suspension movement or you'll be slow, and when you generate well over 1+ lateral G and can take full throttle in 3rd gear at the same time, you need lots of travel for wide tires.


So yea, for the track on anything that's still an S-chassis - the S14 rear subframe is faster.

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S13 Hatch - Goes around tracks quickly
DEFSPORT

jaysgottaredtop

How much longer are these than S13 and S14 LCAs?

Their [rather uninformative] post on FB mentions that these should be used along with 50mm overs… which means approximately jack shit with the combination of camber plates, wheel offsets, tire sizes, etc.

I currently have +56mm FLCAs and I'd love to switch to this integrated style, but I'm not going to consider buying it without any basic measurements.

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PoorMans180SX

They look at least 40-50mm wider. There's no real performance advantage if your arms already have heims in them.

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jaysgottaredtop

My arms do already have inner heims, but the kinked and pinned tension rod would be nice, as would the adjustable sway bar mount.

Anyone here with PBM care to chime in with actual specs? Dan?

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PoorMans180SX

Just posted to Dave Briggs Instagram claiming seventy degrees of lock. That's a 255/35/18 btw.

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Motary

So far I have it in a way it will not pro-squat under 1,2 G. I do have brackets made for with lowering rear lower arm front pivot 25 or 50mm so I can try out different settings. It is very much down to ride heights so it should not be said that one is better than another indefinately.

Def

My car is as low as you can run a stock bodied car with wide tires in the rear. Top of rear fenderwell is even with 255/40-17's. Any lower and you'll run the tire up into the unibody all over the place. Proved it to a couple of S-chassis guys when we went out and I showed them what happens when you have a car fully loaded up in a corner then have the balls to go WOT in a fast car. Tire smoke out the azz... and not from dorifto sliding.

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S13 Hatch - Goes around tracks quickly
DEFSPORT

rbs14kouki

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AV FABRICATION

Built thread sr20vet s14
http://zilvia.net/f/showthread.php?t=535574

TheRealSy90

Stoked on my new VooDoo13 front tension rods. Other than the one piece flca/tension setups I don't think there's anything else with as much wheel clearance. Figured I would post up some more pictures of them from different angles since I only saw the original link to the website posted. There's a ridiculous amount of adjustment available in the heim lol. www.voodoo13usa.com check em out! Also, they're made in Glendale, AZ and not in china or taiwan etc...

https://scontent-b-sjc.xx.fbcdn.net/...21833623_n.jpg
https://scontent-b-sjc.xx.fbcdn.net/...20224079_n.jpg
https://scontent-b-sjc.xx.fbcdn.net/...00759059_n.jpg
https://scontent-a-sjc.xx.fbcdn.net/...89437765_n.jpg
https://scontent-a-sjc.xx.fbcdn.net/...51343513_n.jpg

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RumInDaCoconut

the new pbm flca seem to have so many adjustment slots for the swaybar because they have a swaybar shortening kit now > http://www.partsshopmax.com/e107_plu...php?19248.last

PoorMans180SX

Yuppp I just bought one. I want to test out sway bar vs no sway bar on my setup. We'll see how the welds holds up.

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InsTanCeZ

So, is 0 Ackerman the new standard in professional drifting? It seems like everyone is going for that now.

PoorMans180SX

Pretty much. The latest and greatest kits have a lot of caster trail built into them so there isn't so much of a need for ackerman and caster to increase self steer.

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TheRealSy90

I want to go 0 ackerman but I hear it's pretty bad driving on the street.

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InsTanCeZ

How many degrees of Ackerman approximately is there with OEM knuckles? Just wondering.

PoorMans180SX

I'll let you know how it goes.

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az_240

I remember reading something about 8 degrees on a stock setup but I could be wrong.


With the PBM sway bar kit, could you drill out OEM FLCAs to make it work or is it just for their new FLCAs? Or is the amount of change so little that you don't have to do anything?

PoorMans180SX

Stock ackerman is progressive so the more travel you have the greater the difference in wheel angle. I'm betting at max rack travel it's closer to 15 degrees.

You could just drill the flca but I might weld a washer on for reinforcing that hole.

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TheRealSy90

Definitely just drill a new hole in the FLCA, i'm considering doing the sway bar narrowing myself just need a tube with the right ID. Probably go as narrow as possible without relocating the sway bar mounts.

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PoorMans180SX

To me it looks like the car spins because you come off throttle too abruptly, transferring weight to the front, which is all kinds of soft and mushy according to your setup above.

You need tension rods and a Stealth Custom Fab tension rod brace. Those two combined with some modified FLCA with heims on the crossmember pickup points, would put your cars light years ahead of where they are now. Seriously it will blow you away with how improved the steering becomes. Even a solid SCF strut tower brace would help.

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TheRealSy90

What's the easiest way to do a heim on the inboard lca mount? I'm not wanting it to adjust length necessarily since I extend between the tension and ball joint, but to get rid of the rubber/poly bushing and actually be able to adjust caster with the tension rod. I tried looking at the road racing forum but I couldn't figure out part numbers. Just looking for the heim I can weld in and whatever spacers it needs.

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jaysgottaredtop

^

Two of these plus two of these plus two of these plus four bushings machined to fit the ID of the heims, the OD of the LCA bolt, and the width of the crossmember opening.

Then bring it all to a local fab shop and have them cut and weld your LCAs. Make sure you have plenty of reinforcement on that bung, or else you'll run the risk of this.

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TheRealSy90

Dude thank you! What did you do for the bushings?

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jaysgottaredtop

My roommate machined a couple sets of bushings for us at our school shop. Any local machine shop should be able to make you some fairly easily.




See attached MS Paint doodle for bung welding. Grey is the heim, black is the bung, green is the LCA.

This broken LCA was the result of the first style of attachment. Bending loads will try to rip the bung out of that steel wall (and succeeded in doing so in that particular case).

My LCAs are made using the second style of attachment. Basically same as the first, plus notched pieces of 90deg angle steel welded all around that bung and all around the LCA end for loads more material thickness and strength to combat the bending loads.

The best way to do it is the third style of attachment, as that inner plate drastically reduces stresses under bending loads. The bung no longer "see-saws" about a single steel wall, but is instead clamped in by two separate walls.

Hope this helps.

Attached Images

LCA_bungs.png (12.2 KB, 65 views)

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jaysgottaredtop

Option #2:

These and two of these.

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PoorMans180SX

One of the best pics I've found of the S13 rear wisefab kit, from Nigel Colfers page:

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TheRealSy90

Now that's even better! Seems perfect.

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