This is the roll center, suspension pickup, and steering angle modification thread.

[stuckonfresh]

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On the topic of steering angle, I went to test out the steering with the new version GKTech knuckles with the extended front lower control arms. The steering rack has been moved forward 25mm as well. The caster settings are near OEM spec (around 6). Currently one has to fight the wheel to return to center. I'm assuming more caster needs to be added, but not sure how much to start.

Is anyone else using a similar setup?

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[PoorMans180SX]

Originally Posted by stuckonfresh

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On the topic of steering angle, I went to test out the steering with the new version GKTech knuckles with the extended front lower control arms. The steering rack has been moved forward 25mm as well. The caster settings are near OEM spec (around 6). Currently one has to fight the wheel to return to center. I'm assuming more caster needs to be added, but not sure how much to start.



Is anyone else using a similar setup?



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Probably less caster needs to be used actually. Sounds like overcentering.

[stuckonfresh]

Originally Posted by PoorMans180SX

Probably less caster needs to be used actually. Sounds like overcentering.

Just to clarify, by over centering, do you mean like steering bind?

If so, it DOES feel like over centering, but the other symptoms I was getting included: intermittent wheel shake when going straight and the wheel didn't want to go back to center- by "fight" I meant had to turn the wheel back manually back to center.

Everything is tight in the front too, all to spec. Oh and at full lock, the wheels can be turned back straight and do not get stuck- it just won't really do it by itself.

The power steering works well too, no leaks. When sitting still, if one turns the wheel, the steering wheel moves maybe 25 degrees and feels normal then any more steering input past that, the steering gets extremely light and almost seems to steer itself...if that makes sense. The steering starts feeling light at maybe half lock, maybe not even.

[epik1]

TO BE ADDED TO THE DIMENSIONS STICKY:
Just got GK Tech's new Inner Tie rods for s-chassis.
FYI
They measure to be about 14.5" tip to tip.
PS: GK Tech states on the page that they are meant to be cut where needed (outer tie rod side)

[PoorMans180SX]

Originally Posted by stuckonfresh

Just to clarify, by over centering, do you mean like steering bind?

If so, it DOES feel like over centering, but the other symptoms I was getting included: intermittent wheel shake when going straight and the wheel didn't want to go back to center- by "fight" I meant had to turn the wheel back manually back to center.

Everything is tight in the front too, all to spec. Oh and at full lock, the wheels can be turned back straight and do not get stuck- it just won't really do it by itself.

The power steering works well too, no leaks. When sitting still, if one turns the wheel, the steering wheel moves maybe 25 degrees and feels normal then any more steering input past that, the steering gets extremely light and almost seems to steer itself...if that makes sense. The steering starts feeling light at maybe half lock, maybe not even.

Wait, so you're saying that the steering is smooth, but it just doesn't self-center?

[stuckonfresh]

Originally Posted by PoorMans180SX

Wait, so you're saying that the steering is smooth, but it just doesn't self-center?

Yes, the steering doesn't self -center too well and there was a left and right shaking motion in the steering wheel while going straight. The steering feel was strange too, how it felt really light past a certain degree of steering.

The car was aligned, your question just reminded me though (I dunno why) that the front and rear height were raised while at the alignment shop. I assumed that they wouldn't allow a test drive unless it was aligned, but perhaps this was overlooked?

A toe change would occur if raising height and would explain the left to right wheel shake going straight (I think). The caster definitely needs to be adjusted (aiming for 7-8 degrees now for the next alignment). The camber would also obviously change with height adjustment.

Would positive camber in the front cause this light steering feel? (Less tire to road friction as the wheel is turned and rolled onto its sidewall).

there were indications that the sidewall touched a bit

*I feel dumb, for not thinking of this stuff sooner
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[stuckonfresh]

^A loose power steering belt may have been causing the intermittent "light steering feel".
*it actually WAS aligned during the test drive though, so something else is going on.

The steering rack mounts have been moved forward about 25mm. Will adding more caster (wheels further forward) increase or decrease the chances of steering bind?

[PoorMans180SX]

More caster will increase the chance of overcentering, but it shouldn't be an issue with the rack moved forward.

It honestly sounds like your rack or pump is messed up.

An alignment issue really shouldn't cause any of those issues. But they definitely shouldn't change the ride height after alignment.

Lower caster makes for easier steering effort. Camber doesn't have much to do with effort.

[stuckonfresh]

Originally Posted by PoorMans180SX

More caster will increase the chance of overcentering, but it shouldn't be an issue with the rack moved forward.

It honestly sounds like your rack or pump is messed up.

An alignment issue really shouldn't cause any of those issues. But they definitely shouldn't change the ride height after alignment.

Lower caster makes for easier steering effort. Camber doesn't have much to do with effort.

Thanks for clearing that up. The power steering pump is kinda want I'm leaning towards too. As of right now, the plan is to put more tension on the ps belt and then put settings (caster, camber, toe, height) on that have worked well on the same chassis and see if the problems still exist; so we could at least take "having a bad alignment" out of the equation.

Thanks for your help, I should have some updates this coming week.

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[epik1]

TO BE ADDED TO THE DIMENSIONS STICKY:
Just got PBM spherical bearing cromoly Inner Tie rods for s-chassis.
FYI
They measure to be about 12.5" tip to tip.
PS: PBM states on the page that they are meant to be cut where needed (outer tie rod side)

yes...I basically copy and pasted my previous report haha.
Not sure if this has already been contributed.

And yes, I was curious about both inner tie rods so I bought both. nothing wrong with spares.

[O$mo]

I cant find any info on Ikyea Formula inner tie rod length vs PBM's inner tie rod. Im trying to decide if I should buy new outer tie rods vs, buy PBM's as well as newer tie rods. Anyone with experience with both can you please chime in?

[stuckonfresh]

I picked up the outers first, but this was mainly because I didn't have the right tools and I didn't want to touch the inners. I eventually caved though when the rack was swapped and just went with both. The GKTech outer's are nice because they have a few different length options, plus they are spherical ends with rollcenter adjustment. I mainly went with these because I ended up doing most of the front suspension at once and didn't really have time to sit there and take measurements. I figured the PBM inners are longer to begin with, so I could just play with the lengths of the outers and then trim the inners if needed. I also had a bolt on rack spacer (male and female threaded ends); just incase there wasn't quite enough length, but ended up not using it.

I'm currently using PBM inner tie rods with GKTech's outers (came with three different size lengths) and this setup is currently being used with a rack that has been moved forward 25mm and with FLCA's that are adjustable from +30mm to +65mm over OEM spec (I don't have the exact measurement, but I believe its a little over +30mm; maybe +40mm currently?). With the current settings there is still enough thread to adjust toe with the PBM inners (+20mm) and using the longest tie rod end attachment that came with the GKTech's (+35mm).

GKTech's new inners are 340mm in length and can be trimmed down to 195mm (came out well after I had picked up the current tierods I'm using).

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[epik1]

Been up a few late nights working on a cold dark single car driveway, so apologies if the answer is obvious.

I installed the GKTech rc kit, and now when I turn lock to lock, I rub both on the front of the fender and the back of the fender/front of the skirt.

Pulled/rolled front fenders S13 Silvia front end.
Tein inners, oe replacement outers.
S14 FLCA
aftermarket tc rods.

[PoorMans180SX]

Are you running really wide wheels? Now that you've moved the wheel out 25mm, things get crowded, but I've never experienced rub on both sides...

[epik1]

Alignment is yet to be done but it was done just before my last track day. and it is basically a track car. not street registered.

and I changed my outer tie rods.

I am running 17 x 9 + 15 (with 3mm or 5mm spacer for caliper clearance)

I have a set of poop aftermarket fiberglass fenders i could run but I don't know if that would help as it would be wider, but clearance front-back would be same, no?

[TheRealSy90]

That doesn't make sense. I'm running +25mm s13 flca, GKTech RC kit and 17x10+0 up front and I don't rub on anything.

[PoorMans180SX]

Monster truck tires? Lol.

[epik1]

225/45/17 ns2r

[epik1]

Originally Posted by TheRealSy90

That doesn't make sense. I'm running +25mm s13 flca, GKTech RC kit and 17x10+0 up front and I don't rub on anything.

what aero are you running?

[stuckonfresh]

Originally Posted by epik1

225/45/17 ns2r

Adjustable flca and/or tension rods? I would think these would just move the knuckle up and out of th wheel well.

Also Im not completely familiar with the roll center kit, do these have a specific orientation to install marked on them?
Please don't be offended by this question, I cannot tell you how many times I've installed something and had to flip the orientation to get it to work
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[epik1]

I have adjustable TC rods, S14 FLCA (not modified).
As far as I could tell, there's only one way they'll fit because it's basically an offset spacer that attaches to the bottom of the knuckle and you can't really install it the wrong way because of the size of the studs from the outer tie rod and the flca bj.

[TheRealSy90]

Originally Posted by epik1

what aero are you running?

BN Type II, Origin +40 Front fenders. Doesn't rub skirt, fender or front bumper, wheel well, nothing.

[epik1]

lol I think you missed the part where I said I was running STOCK silvia fenders with roll and pull.

and I don't think the average roll and pull is +40mm haha

[PoorMans180SX]

That shouldn't make a difference in the clearance to the bumper and back of the fender.

[TheRealSy90]

Originally Posted by epik1

lol I think you missed the part where I said I was running STOCK silvia fenders with roll and pull.

You said it yourself, clearance front and back should be the same. Some aftermarket skirts/bumpers do have a ton of material that overlaps into the wheel well, idk if that's what you're rubbing on.

[epik1]

Aftermarket fenders have more clearance that starts earlier on the fender "wheel well" if that makes sense.

Whereas my roll/pull fender is like the top 1/3 of the fender.

Yeah, I have origin stylish side skirts. I just noticed in your wheel well, it seems your skirts don't go into the wheel well as much or you've trimmed it. My skirts sort of extend into the wheel well I guess for mounting purposes. Will trim.

[epik1]

Originally Posted by TheRealSy90

You said it yourself, clearance front and back should be the same. Some aftermarket skirts/bumpers do have a ton of material that overlaps into the wheel well, idk if that's what you're rubbing on.

on another note, how are you liking the rc kit ?

and how close do you get to rubbing the TC rod?

did you have to notch your FLCA too?

[TheRealSy90]

I actually don't even have my skirts mounted in that pic lol. But I didn't chop off the part that wraps around the fender either.
Unfortunately I haven't driven the car with this new steering setup yet :'(
My FLCA's aren't notched.
At full lock both directions the tie rod on the leading wheel hits the lca about 1/16" before my wheel hits my sway bar. My TC rods are further inward than my sway bar. If I wanted more lock I could go to the gktech sway bar and notch the lca, but it already is very close to overcentering, and my rack is already moved forward. In that case I'd have to shorten the TC rod and move the wheel/lca forward in the well I guess.
However I'm also currently maxed out in rack travel as well. So the rack/knuckles can't physically go any further. I believe this is the most lock you could potentially get with these RC knuckles. Pretty sure leading wheel is getting over 60 degrees.

[epik1]

ah ok. I'm considering cutting off the bumpstop on my S14 FLCA as well.
Yeah, it sounds like the the most lock you can get out of stock knuckle with various inner/outer/flca/tcrod combos. I'm ok with ~60degrees of lock to start with. I'm just looking for a bit more angle than S14 FLCA + inner/outer combos.

[TheRealSy90]

Originally Posted by epik1

ah ok. I'm considering cutting off the bumpstop on my S14 FLCA as well.
Yeah, it sounds like the the most lock you can get out of stock knuckle with various inner/outer/flca/tcrod combos. I'm ok with ~60degrees of lock to start with. I'm just looking for a bit more angle than S14 FLCA + inner/outer combos.

Forgot to mention I did remove the bump stop and flattened the small lip that protrudes horizontally at the bottom of the LCA as the tie rod end was hitting it. So I gained a little lock right there.


Yes this is the most lock possible with a stock knuckle, without the GKTech rc kit a stock knuckle would never go this far imo.
It's a TON more than S14 lca and changing tie rods.


To clarify I'm running a George's rack extension on the passenger side and PBM tie rod spacer on the driver side to be specific. This is the most potential inner rack travel you can have without cutting an additional tooth into the inner rack. A rack extension on the driver side will not net additional rack travel in that direction without cutting another tooth. Same with running tie rod spacers on the extension itself lol.