Rear LCA Lowering?

[logr]

Has anybody figured out how lowering just the LCA at the ball joint would change the rear suspension characteristics? It seems that separating the arms would have to change something.

[Equinox]

It will increase camber gain and roll steer. (ie. change in toe with suspension travel)

[djsilver]

Has anybody figured out how lowering just the LCA at the ball joint would change the rear suspension characteristics? It seems that separating the arms would have to change something.

Just lowering the RLCA will mess things up because the RLCA and toe-links are longer than the RUCA and a lot longer than the traction arm. If you lower the RLCA with something like an extended ball-joint, the RLCA will be pointing down and the upper arms will be pointing up. Under compression the RLCA will be getting longer while the toe-link will change very little but the RUCA and traction rod will be getting shorter and will cause severe camber gain and toe-in.

[Def]

Just lowering the RLCA will mess things up because the RLCA and toe-links are longer than the RUCA and a lot longer than the traction arm. If you lower the RLCA with something like an extended ball-joint, the RLCA will be pointing down and the upper arms will be pointing up. Under compression the RLCA will be getting longer while the toe-link will change very little but the RUCA and traction rod will be getting shorter and will cause severe camber gain and toe-in.

The toe link starts pointing up around the same point the traction rod and camber arm start going about horizontal(the camber arm being the least angled upward out of all of them).

Hard to say what is really going to happen without doing extensive analysis, which is why multilink suspensions did not come into being until computers were available to companies to run through the analysis.

[mmdb]

I'm currently using the moonface roll center adjusters to lower the pivot point, and what I noticed after raising my car a bit was a major gain in rear toe out. At the time I was using the smart strings toe kit. In other words the toe gain/loss was huge! Camber wasn't off that much though.

[SoSideways]

Wait, shouldn't the toe go out as the toe arms start to get an upward angle on them?

Since they'll be getting shorter, and the toe arms bolt up to the uprights in the rear, thus pulling them in, causing toe out, no?

[logr]

So, are you guys saying that lowering the ball joint pivot in the rear is not such a great thing?

Isn't that one of the things that adj. rear LCA's do?

My car is significantly lower than stock, as I would guess most of ours are.
Would it be good to lower only the outboard toe arm pivot point to reduce toe change?

[mmdb]

Good question. I'll have to put the strings on the car again and raise the rear and see what it does. I'll plot some points with the moonface stuff.

[Equinox]

My rear wheels toed out with travel but I was able to fix this through my usable range of suspension travel by adjusting the traction rod.

I don't know if that'll be possible with RCAs in the LCA though. The toe change might be too extreme. I'll measure it eventually when I get a chance to space down my rear LCA but the parts wont be here for a month or two.

Interested to see your results mmdb.

[mmdb]

Sorry been kind of busy. I fried my clutch so I have to spend this weekend replacing it. I'll try to get around to it soon enough. In the meanwhile, if someone would create a custom hub that works with the z32 rear brakes that'd be great!