PSM F&R Lower Control Arms (To be released soon it seems)

[prego]

so really the only good methods for rear roll centre correction are raising the rear subframe and getting droped rear knuckles, i see in your build thread jason you have longer shanks on your rlca although not by much, how come?

[Jason M]

Usually it gives more camber gain with all things equal. You're making the upper arm go to a larger angle at the same angle for the lower arm (since it behaves as a virtual dual a-arm setup). I don't think more camber gain in the rear is what any of our cars need.

I agree, it will slightly increase camber gain & change the curve charactoristics, since leveling out the RLCA arm keeps the bottom of the spindle from tilting inward as much as an unlevel RLCA would. The more unlevel (talking about the ball joint pivot to the inside pivot point levelness) the RLCA, while in Drift mode (arms pointing upward) the more positive camber gain it would introduce to counter act the extremely short & highly angled upper control arms that are responsible for our .9-1.2 deg's of camber change per inch of travel.

[Def]

Usually it gives more camber gain with all things equal. You're making the upper arm go to a larger angle at the same angle for the lower arm (since it behaves as a virtual dual a-arm setup). I don't think more camber gain in the rear is what any of our cars need.

[prego]

How will dropping the rlca with the longer shank effect the rear camber gain?

[PoorMans180SX]

Ahhhh I think the main problem was I was thinking you were talking about the FLCA this whole time for some reason. I see what you're saying. Hmm yeah I definitely won't be doing too much adjusting back there.

[Jason M]

I'am not trying to say I know everything about the rear multilink suspension, but I've spent countless hours setting up my suspension over the last few months. There is in fact a lot happening when adjusting things that effect things in a way that I don't understand, like when you lengthen the trac rod how the spindle roll's reaward, the instant center of the uncoupled upper arms moves forwards. When the spindle roll's as it moves up & down the instant centers are all over the place... Anyways back onto the subject.

I think that it is a big deal to have the adjustability at the inner pivot's. When you try to adjust the roll center with the lower ball joint, the spindle will camber in/out, toe in/out, roll forwards/backwards, and move forwards/rearwards.

When you adjust the roll center you have to lengthen the rear inner rod end a different amount then the front inner rod end on the RLCA to keep the spindle in the same location as the OEM RLCA. I'am willing to bet that the rod end/ball joint adjustability is not adequate.

When setting up my RLCA's, I put a digital protractor on the hub, measure the camber angle, carefully measure the setback of the hub in the wheel well (wheel base), support the upright, unbolt the oem rlca, then adjust my rlca's to the spindle, so that when they are bolted up, the camber and set back is the same.

The setback of the upright is important, because it effects the bumpsteer curve, instant centers, wheel base & who knows what else. I would rather keep all those specs as close to OEM as possible until I understand how and where I want thoose specs.

[PoorMans180SX]

I didn't mean that in a condescending way honestly. I was just cracking a joke on the fact that after only a few days people have already pointed out the flaws in the product.

I do agree, I don't see what the big deal is personally. If I saw a need for them on my car I would most likely buy them and consider the improvements over stock to outweigh the flaws.
Reading the opinions on the possible flaws is a learning experience for me though.

That's cool. I just don't see the "flaws" people are pointing out. If PSM would have made them adjustable at the ball joint, people would have whined about there being a rod end in bending. There's really no other way to do it.

[Bubba]

I didn't mean that in a condescending way honestly. I was just cracking a joke on the fact that after only a few days people have already pointed out the flaws in the product.

I do agree, I don't see what the big deal is personally. If I saw a need for them on my car I would most likely buy them and consider the improvements over stock to outweigh the flaws.
Reading the opinions on the possible flaws is a learning experience for me though.

[PoorMans180SX]

Yeah, everyone knows that Mad JDM tyte construction is superior to the rest of the worlds products.

Way to be condescending. I was talking about the adjustement, considering there is no other way to adjust the length of the lca. There is some compromise in every suspension setup. Also, name an lca on the market with superior construction. This is a very nice product.

[Bubba]

Yeah, everyone knows that Mad JDM tyte construction is superior to the rest of the worlds products.

[PoorMans180SX]

I'm not sure why you guys are making such a big deal out of it...

[Tower240sx]

the angle of inclination isn't important,(assuming it still allows full articulation at installation) the fact that the balljoint adjustment direction isn't perpendicular to the C/L of the car is bothersome though

[Jason M]

I just remembered how the ball joint angle is not at a right angle, to the ground or to the centerline of the car, so when the ball joint pivot is moved up or down on the ball joint stud the spindle moves in all kinds of directions. Anyway's, I've got a head ache thinking about it. It's easier just to bolt it together and pretend that everything is ok...

[Jason M]

Ok, that makes sense. As long as the ball joint moves out perpendicular from the center line of the car, then that would actaully be easier to adjust then two rod ends at the inner pivot point's.

[Tower240sx]

ok,

Where you add length then doesn't matter, you would simply need to create a 22 degree offset of the ball joint so that it moved in the correct plane, (perpendicular to the centerline of the car)

As that arm is shown it wouldn't matter where you adjust from since the ball joint is (appears to be) setup at a right angle to the axis of rotation of the inboard mounts...